阅读说明：本技术 图像编码方法以及图像解码方法 (Image encoding method and image decoding method ) 是由 远间正真 西孝启 寺田健吾 于 2014-10-16 设计创作，主要内容包括：本发明提供图像编码方法以及图像解码方法。图像编码方法中,按属于多个层级的每个层级的每个图片,不参照属于比该图片所属的层级高的层级的其他图片而将运动图像编码,其中决定运动图像中包含的多个图片各自的解码时刻,以使不属于最高层级的多个下层图片各自的解码时刻成为等间隔,并且多个下层图片各自在将被编码的运动图像中包含的多个图片解码的情况下被解码的定时与在仅将多个下层图片解码的情况下被解码的定时相同；按照与所决定的解码时刻相应的编码顺序,将上述运动图像中包含的多个图片分别编码；生成编码流,该编码流包含被编码的多个图片和对多个图片分别决定的解码时刻；多个图片的显示顺序与多个图片的解码顺序不同。(The invention provides an image encoding method and an image decoding method. In an image encoding method for encoding a moving image without referring to another picture belonging to a higher hierarchy than a hierarchy to which the picture belongs, for each picture belonging to each of a plurality of hierarchies, decoding times of a plurality of pictures included in the moving image are determined such that the decoding times of a plurality of lower pictures not belonging to the highest hierarchy are at equal intervals, and timing at which each of the plurality of lower pictures is decoded when the plurality of pictures included in the moving image to be encoded are decoded is the same as timing at which the plurality of lower pictures are decoded when only the plurality of lower pictures are decoded; encoding a plurality of pictures included in the moving picture in an encoding order corresponding to the determined decoding time; generating a coded stream including a plurality of coded pictures and decoding times determined for the plurality of coded pictures; the display order of the plurality of pictures is different from the decoding order of the plurality of pictures.)

1. An image encoding method for encoding a moving image without referring to another picture belonging to a higher hierarchy than a hierarchy to which the picture belongs, for each picture belonging to each of a plurality of hierarchies,

determining respective decoding times of a plurality of pictures included in the moving image such that respective decoding times of a plurality of lower pictures not belonging to a highest hierarchical level among the plurality of hierarchical levels among the plurality of pictures included in the moving image are at equal intervals, and a timing at which each of the plurality of lower pictures is decoded when the plurality of pictures included in the moving image to be encoded are decoded is the same as a timing at which each of the plurality of lower pictures included in the moving image to be encoded is decoded when only the plurality of lower pictures included in the plurality of pictures are decoded;

encoding a plurality of pictures included in the moving picture in an encoding order corresponding to the determined decoding time;

generating a coded stream including the plurality of coded pictures and decoding times determined for the plurality of coded pictures;

the display order of the plurality of pictures is different from the decoding order of the plurality of pictures.

2. The image encoding method according to claim 1,

the lower layer pictures include an I picture, a P picture, and a B picture.

3. An image encoding method performed by an encoding apparatus, the image encoding method comprising the steps of:

acquiring pictures arranged according to a display sequence, wherein the pictures comprise a plurality of layer 1 pictures and a plurality of layer 2 pictures;

associating said pictures with Temporal IDs, i.e. temporals IDs, defined in a video coding standard, such that each of said layer 1 pictures is associated with a minimum temporals ID and each of said layer 2 pictures is associated with a maximum temporals ID;

determining decoding times of the pictures arranged in the display order such that the 1 st decoding times of the 1 st layer pictures are spaced at equal intervals, and the 1 st decoding time does not depend on whether all coded pictures are decoded by a decoding apparatus or only the coded picture associated with the minimum Temporal ID is decoded by the decoding apparatus;

encoding the pictures arranged in an encoding order according to the decoding time to generate the encoded pictures, the encoding order corresponding to the decoding time and being different from the display order; and

and generating a coded stream including the coded picture and the decoding time.

4. The image encoding method according to claim 3,

determining a 2 nd decoding time for each of the 2 nd layer pictures;

the 1 st decoding time and the 2 nd decoding time are alternately arranged on a time axis such that each of the 2 nd decoding time is adjacent to one 1 st adjacent decoding time and the other 1 st adjacent decoding time and is between the one 1 st adjacent decoding time and the other 1 st adjacent decoding time, and the 1 st adjacent decoding time is included in the 1 st decoding time and is spaced apart at the equal intervals.

5. An image decoding method for decoding a coded stream including a moving image coded for each picture belonging to each of a plurality of layers without referring to another picture belonging to a layer higher than the layer to which the picture belongs,

obtaining, from the encoded stream, respective decoding times of a plurality of pictures included in the encoded stream, the respective decoding times of the plurality of pictures being determined such that respective decoding times of a plurality of lower-layer pictures that do not belong to a highest hierarchical level among the plurality of hierarchical levels among the plurality of pictures included in the encoded stream are at equal intervals, and such that timings at which the plurality of lower-layer pictures are decoded when the plurality of pictures included in the encoded stream are decoded are the same as timings at which the plurality of lower-layer pictures are decoded when only the plurality of lower-layer pictures among the plurality of pictures are decoded;

decoding each of a plurality of pictures included in the encoded stream or decoding only the plurality of lower layer pictures according to the acquired decoding time;

the display order of the plurality of pictures is different from the decoding order of the plurality of pictures.

6. The image decoding method according to claim 5,

the lower layer pictures include an I picture, a P picture, and a B picture.

7. An image decoding method performed by a decoding apparatus, the image decoding method comprising:

obtaining, from an encoded stream, encoded pictures including a plurality of layer 1 pictures and a plurality of layer 2 pictures, the encoded pictures being associated with a Temporal ID defined in a video encoding standard, such that each of the layer 1 pictures is associated with a minimum Temporal ID and each of the layer 2 pictures is associated with a maximum Temporal ID;

obtaining, from the encoded stream, decoding time points of the encoded pictures, the decoding time points being determined such that the 1 st decoding time points of the 1 st layer pictures are spaced at equal intervals, and the 1 st decoding time point is not dependent on whether all the encoded pictures are decoded by the decoding apparatus or only the encoded picture associated with the minimum Temporal ID is decoded by the decoding apparatus; and

decoding the coded picture included in the coded stream or decoding only the layer 1 picture arranged in a decoding order different from a display order of the coded picture according to the decoding time.

8. The image decoding method according to claim 7,

the decoding time of the coded picture includes a 2 nd decoding time of each of the 2 nd layer pictures;

the 1 st decoding time and the 2 nd decoding time are alternately arranged on a time axis such that each of the 2 nd decoding time is adjacent to one 1 st adjacent decoding time and the other 1 st adjacent decoding time and is between the one 1 st adjacent decoding time and the other 1 st adjacent decoding time, and the 1 st adjacent decoding time is included in the 1 st decoding time and is spaced apart at the equal intervals.

9. An image encoding method performed by an encoding apparatus, the image encoding method comprising the steps of:

acquiring pictures arranged according to a display sequence, wherein the pictures comprise I pictures, P pictures and B pictures which respectively correspond to intra-frame coding frames, prediction frames and bidirectional prediction frames of an efficient video coding standard (HEVC);

associating Temporal IDs, i.e., Temporal IDs, defined in the HEVC standard with the pictures arranged in display order, such that a largest Temporal ID is associated with a B picture of a highest hierarchical level among the B pictures, and any one of smaller Temporal IDs is associated with a lower-level B picture among the I picture, the P picture, and the B picture;

determining respective decoding times of the pictures such that 1 st decoding times of pictures having any of the smaller Temporal IDs are spaced at equal intervals, and the 1 st decoding time does not depend on whether all coded pictures are decoded in a decoding apparatus or only coded pictures having any of the smaller Temporal IDs are decoded in the decoding apparatus;

encoding the pictures arranged in an encoding order corresponding to the decoding time and different from the display order to generate encoded pictures; and

and generating a coded stream including the coded pictures and the decoding time arranged in the coding order.

10. The image encoding method according to claim 9,

determining a 2 nd decoding time for each B picture of the highest layer;

the 1 st decoding time and the 2 nd decoding time are alternately arranged on a time axis such that each of the 2 nd decoding time is adjacent to one 1 st adjacent decoding time and the other 1 st adjacent decoding time and is between the one 1 st adjacent decoding time and the other 1 st adjacent decoding time, and the 1 st adjacent decoding time is included in the 1 st decoding time and is spaced apart at the equal intervals.

11. A method for decoding an image, characterized in that,

receiving the multiplexing data;

acquiring identification information from the multiplexed data;

determining whether or not the video data included in the multiplexed data meets a predetermined standard based on the identification information;

outputting a1 st instruction signal to a circuit that processes the video data so that the circuit operates at a1 st driving frequency when it is determined that the video data meets the predetermined standard;

outputting a 2 nd instruction signal to the circuit to operate the circuit at a 2 nd driving frequency lower than the 1 st driving frequency when it is determined that the video data does not meet the predetermined standard;

the video data includes a plurality of pictures, a Temporal ID that is a time ID associated with each picture, and a decoding time associated with each picture;

the above specified standard includes high efficiency video coding, HEVC.

Technical Field

The present invention relates to an image encoding method for hierarchically encoding an image, an image decoding method for decoding an image that is hierarchically encoded, and the like.

Background

Conventionally, an image encoding method for hierarchically encoding an image and an image decoding method for decoding an image encoded by hierarchical encoding have been proposed (for example, see non-patent document 1).

Disclosure of Invention

An image encoding method according to an aspect of the present invention is an image encoding method for encoding a moving image without referring to another picture belonging to a higher hierarchy than a hierarchy to which the picture belongs, for each picture belonging to each of a plurality of hierarchies, wherein decoding times of a plurality of pictures included in the moving image are determined such that the decoding times of a plurality of lower pictures not belonging to a highest hierarchy among the plurality of hierarchies, among the plurality of pictures included in the moving image, are equally spaced, and a timing at which each of the plurality of lower pictures is decoded when the plurality of pictures included in the moving image to be encoded are decoded is the same as a timing at which the plurality of lower pictures included in the plurality of pictures are decoded; encoding a plurality of pictures included in the moving picture in an encoding order corresponding to the determined decoding time; generating a coded stream including the plurality of coded pictures and decoding times determined for the plurality of coded pictures; the display order of the plurality of pictures is different from the decoding order of the plurality of pictures.

The inclusion or specific aspects may be realized by a system, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

The image encoding method and the image decoding method of the present invention can suppress the processing load.

Drawings

Fig. 1A is a diagram illustrating an example of implementing HEVC-based temporal scalability.

Fig. 1B is a diagram representing another example for implementing HEVC-based temporal scalability.

Fig. 2 is a diagram for explaining a problem that a 120fps coded stream cannot be decoded.

Fig. 3 is a diagram for explaining an image coding apparatus according to embodiment 1.

Fig. 4 is a diagram showing an example of encoding a moving image using 3 layers according to embodiment 1.

Fig. 5 is a diagram showing an example of encoding a moving image using 4 levels according to embodiment 1.

Fig. 6 is a diagram showing another example of encoding a moving image using 3 hierarchies according to embodiment 1.

Fig. 7 is a diagram for explaining an image decoding device according to embodiment 1.

Fig. 8 shows the decoding order and display order of each picture, and the DTS and PTS when a coded stream is reproduced at 120fps according to variation 1 of embodiment 1.

Fig. 9 is a block diagram showing the configuration of an image decoding apparatus according to modification 1 of embodiment 1.

Fig. 10 is a flowchart showing an example of an operation performed when the image decoding device according to variation 1 of embodiment 1 decodes pictures of all the layers.

Fig. 11 is a diagram showing an example of a change in DTS according to modification 2 of embodiment 1.

Fig. 12 is a diagram for explaining a picture to be decoded in an open-ended random access unit according to modification 3 of embodiment 1.

Fig. 13 is a flowchart showing an example of an operation of the image decoding apparatus according to modification 3 of embodiment 1 for decoding a moving image based on auxiliary information for playback control.

Fig. 14 is a diagram showing an example of conversion of the DTS or PTS according to modification 4 of embodiment 1.

Fig. 15A is a block diagram of an image encoding device according to an embodiment of the present invention.

Fig. 15B is a flowchart showing an image encoding method according to an embodiment of the present invention.

Fig. 15C is a block diagram of an image decoding device according to an embodiment of the present invention.

Fig. 15D is a flowchart showing an image decoding method according to an embodiment of the present invention.

Fig. 16 is an overall configuration diagram of a content providing system that realizes a content distribution service.

Fig. 17 is an overall configuration diagram of a digital broadcast system.

Fig. 18 is a block diagram showing a configuration example of a television.

Fig. 19 is a block diagram showing a configuration example of an information reproducing/recording unit that reads and writes information from and on a recording medium, which is an optical disc.

Fig. 20 is a diagram showing a structural example of a recording medium as an optical disc.

Fig. 21A is a diagram showing an example of a mobile phone.

Fig. 21B is a block diagram showing a configuration example of the mobile phone.

Fig. 22 is a diagram showing a structure of multiplexed data.

Fig. 23 is a diagram schematically showing how each stream is multiplexed in multiplexed data.

Fig. 24 is a diagram showing in more detail how a video stream is stored in a PES packet sequence.

Fig. 25 is a diagram showing the structure of a TS packet and a source packet in multiplexed data.

Fig. 26 shows a data structure of the PMT.

Fig. 27 is a diagram showing an internal configuration of multiplexed data information.

Fig. 28 is a diagram showing an internal configuration of stream attribute information.

Fig. 29 is a diagram showing a procedure of recognizing video data.

Fig. 30 is a block diagram showing an example of the configuration of an integrated circuit of the moving picture coding method and the moving picture decoding method according to each embodiment.

Fig. 31 is a diagram showing a configuration for switching the drive frequency.

Fig. 32 is a diagram showing a procedure of recognizing video data and switching a driving frequency.

Fig. 33 is a diagram showing an example of a lookup table in which the standard of the video data is associated with the driving frequency.

Fig. 34A is a diagram showing an example of a configuration in which modules of the signal processing unit are shared.

Fig. 34B is a diagram showing another example of a configuration in which modules of the signal processing unit are shared.

Detailed Description

(knowledge as a basis of the present invention)

The present inventors have found that the following problems occur with respect to the above-mentioned non-patent document 1 described in the section "background art".

In Coding schemes such as MPEG-4 AVC (Moving Picture Experts Group-4 Advanced Video Coding) and hevc (high Efficiency Video Coding), temporal scalability (hereinafter referred to as temporal scalability) can be realized by Coding pictures hierarchically. For example, by decoding all pictures, playback at 120fps is possible, and by decoding only pictures belonging to a specific hierarchy, playback at 60fps is possible.

By utilizing such temporal scalability, 2-time speed reproduction by decoding only pictures belonging to a specific hierarchy at intervals of 120fps can be realized. Furthermore, in a playback device that does not support decoding at 120fps intervals (hereinafter referred to as a 120fps non-compliant playback device), it is possible to play back a 120fps encoded stream at 60 fps.

Fig. 1A and 1B are diagrams illustrating an example of implementing HEVC-based temporal scalability. These figures show the reference relationship between layers and the decoding order (i.e., encoding order) of each picture.

Fig. 1A shows an example of encoding each picture by a 3-layer structure. The TId in fig. 1A is a Temporal ID, which is an identification code for identifying the hierarchy. In addition, I denotes an I picture (intra prediction picture), P denotes a P picture (for example, a forward reference prediction picture), and B denotes a B picture (for example, a bidirectional reference prediction picture). The numerals attached to the right side of I, P and B indicate the display order of these pictures. Further, arrows indicate reference relationships between pictures, for example, picture B2 refers to picture I0 and picture P4. In other words, in the reference relationship between the levels, a picture is encoded by referring to a picture belonging to the same level as or a level lower than the level to which the picture belongs, without referring to a picture belonging to a level higher than the level to which the picture belongs. Here, if each picture belonging to any one of all the hierarchies with Temporal IDs of 0 to 2 is decoded, the frame rate is 120 fps. In this case, if each picture belonging to a certain level whose Temporal ID is 0 to 1 is decoded, the frame rate is 60 fps.

Fig. 1B shows an example of encoding each picture by a 4-layer structure. In this case, if each picture belonging to one of all the levels whose Temporal IDs are 0 to 3 is decoded, the frame rate is 120 fps. In this case, if each picture belonging to a certain level having a Temporal ID of 0 to 2 is decoded, the frame rate is 60 fps.

As described above, the 120fps non-compliant playback apparatus can possibly achieve playback of 60fps by using temporal scalability, that is, by decoding only pictures belonging to a part of the levels in the 120fps encoded stream.

However, in this case, the 120fps non-compliant playback apparatus may have to decode each picture at intervals shorter than 1/60 seconds. Therefore, even when the 120fps non-compliant playback device uses temporal scalability, the 120fps encoded stream cannot be decoded because the interval for decoding each picture is short.

Fig. 2 is a diagram for explaining a problem that a 120fps non-compliant playback apparatus cannot decode a 120fps encoded stream. The encoded stream shown in fig. 2 is the encoded stream of 120fps shown in fig. 1A. When the 120fps non-compliant playback device plays back the coded stream at 60fps, it decodes only the pictures belonging to the level with the Temporal ID of 0 and the pictures belonging to the level with the Temporal ID of 1.

T in fig. 2 corresponds to a time corresponding to 120fps, i.e., 1/120 seconds. In broadcast content or stored content, when the content is displayed at a fixed frame rate, decoding is typically performed at a fixed frame rate as well. Therefore, in 120fps playback, the interval at which each picture is decoded (hereinafter referred to as the decoding interval) and the interval at which each picture is displayed (hereinafter referred to as the display interval) are both T.

Therefore, in the case of 60fps playback, both the decoding interval and the display interval need to be 2T intervals, which is the time corresponding to 60 fps. However, as shown in fig. 2, in the case of reproduction at 60fps, the decoding interval of picture I0 and picture P4 or the decoding interval of picture P4 and picture B2 is T. In a 120fps non-compliant playback apparatus that requires 2T of time as a decoding interval, there is a problem that decoding of pictures cannot catch up. That is, the 120fps non-compliant playback apparatus has a problem of a high processing load.

In order to solve the above-described problems, an image encoding method according to an aspect of the present invention is an image encoding method for encoding a moving image without referring to another picture belonging to a higher hierarchy than a hierarchy to which the picture belongs, for each picture belonging to one of a plurality of hierarchies, wherein decoding times of a plurality of pictures included in the moving image are determined such that decoding times of a plurality of pictures included in the moving image are equally spaced from each other and timings at which the plurality of lower pictures are decoded are the same between a case where the plurality of pictures included in the moving image are decoded and a case where only the plurality of lower pictures included in the plurality of pictures are decoded; encoding a plurality of pictures included in the moving picture in an encoding order corresponding to the determined decoding time; and generating a coded stream including the plurality of coded pictures and decoding times determined for the plurality of coded pictures.

In this way, each of the plurality of pictures included in the encoded stream is encoded without referring to another picture belonging to a higher hierarchy than the hierarchy to which the picture belongs. Thus, the image decoding apparatus can decode only a plurality of lower layer pictures in the encoded stream. The decoding times of the lower layer pictures included in the coded stream are at equal intervals. Therefore, when decoding only a plurality of lower layer pictures in a coded stream, the image decoding apparatus can sequentially decode the lower layer pictures at every elapse of an equal interval. Therefore, by setting the interval to an appropriate time, the processing load of the image decoding apparatus can be reduced. That is, the image decoding apparatus can decode each picture at a frame rate according to its own processing capability without performing decoding at a high frame rate. Further, between a case where a plurality of pictures (for example, all pictures) included in the encoded stream are decoded and a case where only the plurality of lower layer pictures are decoded, the timings at which the plurality of lower layer pictures are decoded are the same. Therefore, the image decoding apparatus does not need to change the respective decoding timings of the plurality of lower layer pictures between the case of decoding all the pictures of the coded stream and the case of decoding only the plurality of lower layer pictures. Therefore, the processing load of the image decoding apparatus can be further reduced.

In the determination of the decoding time, the decoding time of each of a plurality of pictures that are part of a plurality of pictures included in the moving picture and a plurality of uppermost pictures that belong to the highest hierarchy may be determined to be between the decoding times of the plurality of lower pictures.

Thus, when the encoded stream is decoded, the uppermost picture and the lower picture are alternately decoded. Therefore, in the coded stream, the intervals of the times at which the plurality of lower layer pictures are decoded are all longer than the intervals of the times at which all the pictures of the decoded stream are decoded. As a result, when decoding only a plurality of lower layer pictures, the image decoding apparatus can decode each picture at a frame rate that is lower than when decoding all pictures of the decoded stream individually. Therefore, the processing load of the image decoding apparatus can be reliably reduced.

In the determination of the decoding time, the decoding time of each of the plurality of pictures included in the moving picture may be determined such that a time 2 times an interval of the decoding times of each of the uppermost picture and the lower picture, which are consecutive in decoding order, among the plurality of uppermost pictures and the plurality of lower pictures is equal to the time of the equal interval.

Thus, the interval of the decoding times of the respective lower pictures is 2 times the interval of the respective decoding times of the uppermost picture and the lower pictures that are consecutive in decoding order, that is, the interval of the times at which all pictures of the decoded stream are decoded. Therefore, when the frame rate at which all pictures of the encoded stream are decoded and displayed is 120fps, the image decoding apparatus can decode a plurality of lower layer pictures included in the encoded stream at time intervals of the inverse of the frame rate of 60fps without a burden.

In the case where the moving image has a plurality of random access units each including a plurality of pictures consecutive in decoding order, the decoding time of each picture in the random access unit may be determined for each random access unit in the determination of the decoding time so that all pictures other than the picture displayed before the picture at the head in decoding order in display order can be decoded in the random access unit without referring to pictures included in other random access units. For example, the first picture is an I picture in which a picture later in decoding order than the first picture is prohibited from referring to a picture earlier in decoding order than the first picture. Alternatively, the first picture is an I picture to which a picture later in decoding order than the first picture and earlier in display order than the first picture is permitted to refer to a picture earlier in decoding order than the first picture.

Thus, the image decoding device can appropriately decode each of the plurality of pictures included in the random access unit for each random access unit.

In the determination of the decoding time, the decoding time of each of all pictures included in the moving image to be encoded may be determined such that, when a frame rate at which all the pictures are decoded and displayed is f, the decoding time of each of the plurality of lower layer pictures included in all the pictures is shifted by a time represented by n times the reciprocal of f (n is an integer equal to or greater than 2).

Thus, the image decoding apparatus can sequentially decode each of the plurality of lower layer pictures at a time interval n times the reciprocal of the frame rate without a burden.

In the image encoding method, display delay information indicating a display delay between a decoding time of a picture at the head in decoding order included in the moving image and a display time of a picture at the head in display order included in the moving image may be included in the encoded stream.

Thus, the image decoding device can acquire the display delay information from the encoded stream. Therefore, if the image decoding device starts decoding of the coded stream from a time point before the display start time and at which the display is delayed, which is indicated by the display delay information, the image decoding device can display the moving image without delay from the display start time.

In the image encoding method, the encoded stream may further include unequal interval information indicating that decoding times determined for each of a plurality of pictures included in the moving image are not equal intervals.

Thus, the image decoding device can acquire unequal interval information from the coded stream. Therefore, the image decoding apparatus can determine that the plurality of pictures included in the coded stream cannot be sequentially decoded at the frame rate of display. As a result, the image decoding apparatus can decode a plurality of pictures included in the coded stream at appropriate timings while referring to the decoding times determined for the plurality of pictures.

In addition, an image decoding device according to an aspect of the present invention decodes a coded stream including a moving picture coded for each picture belonging to one of a plurality of layers without referring to another picture belonging to a layer higher than the layer to which the picture belongs, in the image decoding method, the decoding time of each of a plurality of pictures included in the coded stream is acquired from the coded stream, the decoding times of the plurality of pictures are determined so that the decoding times of a plurality of pictures that are part of the plurality of pictures included in the coded stream and a plurality of lower pictures that do not belong to the highest hierarchical level among the plurality of hierarchical levels are at equal intervals, and the timing at which each of the plurality of lower layer pictures is decoded is the same between the case where the plurality of pictures included in the coded stream are decoded and the case where only the plurality of lower layer pictures among the plurality of pictures are decoded; and decoding each of the plurality of pictures included in the coded stream or the plurality of lower layer pictures according to the acquired decoding time.

In this way, each of the plurality of pictures included in the encoded stream is encoded without referring to another picture belonging to a higher hierarchy than the hierarchy to which the picture belongs. Thus, the image decoding apparatus can decode only a plurality of lower layer pictures in the encoded stream. The decoding times of the lower layer pictures included in the coded stream are at equal intervals. Therefore, when decoding only a plurality of lower layer pictures in a coded stream, the image decoding apparatus can sequentially decode the lower layer pictures at every elapse of an equal interval. Therefore, if the interval is an appropriate time, the processing load of the image decoding apparatus can be reduced. That is, the image decoding apparatus can decode each picture at a frame rate according to its own processing capability without performing decoding at a high frame rate. Further, the timings at which the plurality of lower layer pictures are decoded are the same between a case where a plurality of pictures (for example, all pictures) included in the encoded stream are decoded and a case where only the plurality of lower layer pictures are decoded. Therefore, the image decoding apparatus does not need to change the respective decoding timings of the plurality of lower layer pictures when all the pictures of the coded stream are decoded and when only the plurality of lower layer pictures are decoded. Therefore, the processing load of the image decoding apparatus can be further reduced.

In addition, the image decoding method may be configured to change the decoding time of each of the plurality of pictures included in the coded stream to an equal interval when the decoding time of each of the plurality of pictures is not an equal interval; in the decoding of the coded stream, the plurality of pictures or the plurality of lower layer pictures included in the coded stream are decoded at the changed decoding time.

In this way, the decoding times of the plurality of pictures are changed to equal intervals, and therefore the image decoding apparatus can decode each of the plurality of pictures included in the encoded stream every time the equal intervals elapse. Therefore, the processing load of the image decoding apparatus can be further reduced.

In the decoding of the coded stream, it may be determined, for each picture included in the coded stream, whether or not a decoding time acquired for the picture matches a generation timing of a processing signal generated at every predetermined cycle, and the picture may be decoded when the decoding time matches the generation timing. For example, the image decoding method may further determine an inverse number of a frame rate at which all pictures included in the coded stream are decoded and displayed as the predetermined period.

Thus, even if the decoding times of the plurality of pictures are not at equal intervals, the plurality of pictures can be appropriately decoded at the decoding times of the pictures.

The inclusion or specific aspects may be realized by a system, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

The embodiments are described below in detail with reference to the drawings.

The embodiments described below are specific examples of the present invention. The numerical values, shapes, materials, constituent elements, arrangement positions and connection forms of the constituent elements, steps, order of the steps, and the like shown in the following embodiments are examples, and do not limit the present invention. Further, among the components of the following embodiments, components that are not recited in the independent claims indicating the highest concept will be described as arbitrary components.

(embodiment mode 1)

Fig. 3 is a diagram for explaining the image coding apparatus according to the present embodiment.

The image encoding device 10 of the present embodiment acquires a moving image at a frame rate of 120fps, encodes the moving image, generates a coded stream, and outputs the coded stream. When all pictures included in the coded stream are decoded, a moving image is displayed at a frame rate of 120 fps. When a plurality of pictures included in the coded stream are partially decoded, a moving image is displayed at a frame rate of 60 fps. For example, a part of the plurality of pictures included in the coded stream is a plurality of pictures belonging to a hierarchy other than the highest hierarchy.

Fig. 4 is a diagram showing an example of encoding a moving image using 3 levels according to the present embodiment. The image encoding device 10 of the present embodiment encodes a moving image based on a prediction structure similar to that of the picture shown in fig. 1A, and generates a 120fps encoded stream. At this Time, the image coding device 10 adjusts the Decoding Time (DTS) of the picture to be decoded only at the Time of playback at 120fps so that the Decoding interval becomes 2T (1/60 seconds) when the coded stream is played back at 60 fps. That is, the image encoding device 10 adjusts the DTS of the plurality of pictures belonging to the highest hierarchy level among the plurality of hierarchy levels.

Fig. 5 is a diagram showing an example of encoding a moving image using 4 levels according to the present embodiment. The image encoding device 10 of the present embodiment encodes a moving image based on a prediction structure similar to that of the picture shown in fig. 1B, and generates a 120fps encoded stream. At this time, the image encoding device 10 adjusts the decoding time of the picture to be decoded only at the time of reproduction at 120fps so that the decoding interval becomes 2T (1/60 seconds) when the coded stream is reproduced at 60 fps.

Here, in encoding a moving image, a random access unit called gop (group Of pictures) or the like is configured so that decoding can be started from a picture in the middle Of an encoded stream. A picture that is first in decoding order in a random access unit is a random access point. For example, the picture I0 through the picture B9 shown in fig. 4 are the 1 st random access unit, and the picture I16 is the leading picture of the 2 nd random access unit. Here, in the 2 nd random access unit, a picture such as picture B11 does not refer to picture I16 or pictures after picture I16 in decoding order, but is included in the 2 nd random access unit.

In recording of a broadcasted coded stream (i.e., a broadcast stream), the stream may be recorded to the end of a random access unit such as the 1 st random access unit. At this time, although the picture P12 can be decoded, the picture B11 cannot be decoded since it is included in the 2 nd random access unit. Thus, the operation at the time of decoding becomes complicated.

Here, a picture satisfying a predetermined condition is referred to as an advance picture (advance picture). The specified conditions for the pictures are: (1) the picture refers to a picture included in a random access unit immediately preceding in decoding order; (2) the display order of the picture is earlier than any one of pictures included in random access units immediately preceding the picture in decoding order. The random access unit is defined by an encoding order and a decoding order, and the encoding order and the decoding order are the same. Further, a random access unit immediately preceding a random access unit including a leading picture, such as the 1 st random access unit, is referred to as an open-ended random access unit. In addition, a picture included in the open-ended random access unit and having a display order later than that of the preceding picture is referred to as an isolated picture. For example, the picture B11 in fig. 4 is a leading picture, and the picture P12 is an isolated picture.

Fig. 6 is a diagram showing another example of encoding a moving image using 3 levels according to the present embodiment.

When the image coding apparatus 10 of the present embodiment implements temporal scalability using 3 levels, it is also possible to code an image so as not to generate an open-ended random access unit, as shown in fig. 6.

Any picture included in the 2 nd random access unit is later in display order than the last picture P12 of the 1 st random access unit. Therefore, all pictures included in the 2 nd random access unit do not become leading pictures. As a result, the 1 st random access unit does not become an open-ended random access unit. However, since the decoding order of the picture B2 is later than that of the picture B1, the picture B1 cannot refer to the picture B2. Also, since the decoding order of the picture B6 is later than that of the picture B5, the picture B5 cannot refer to the picture B6. In this way, the prediction structure of the picture with Temporal ID 2 is limited.

In the examples of fig. 4 to 6, the cases where the layer numbers are 3 and 4 are explained, taking the temporal scalability of 60p and 120p as an example. However, the combinations of frame rates and the number of layers that can be realized are not limited to these. When only pictures of a lower hierarchy level are decoded and displayed, if the display interval of each picture at the frame rate of display is T _ pts, it is sufficient to ensure that the decoding interval of any picture consecutive in decoding order is equal to or greater than T _ pts. The image encoding device 10 encodes an image so as to satisfy this condition.

Fig. 7 is a diagram for explaining the image decoding device 20 according to the present embodiment.

The image decoding device 20 of the present embodiment acquires the coded stream generated by the image coding device 10. The image decoding apparatus 20 decodes all pictures included in the coded stream, thereby displaying a moving image at a frame rate of 120 fps. Further, the image decoding apparatus 20 decodes a plurality of pictures included in a part of the coded stream, thereby displaying a moving image at a frame rate of 60 fps. For example, a part of the plurality of pictures included in the coded stream is a plurality of pictures belonging to a hierarchy other than the highest hierarchy.

As described above, in the present embodiment, the decoding times of a plurality of pictures (hereinafter, referred to as lower pictures) included in a coded stream and not belonging to the highest layer are equally spaced. Therefore, when decoding only a plurality of lower layer pictures in a coded stream, the image decoding apparatus can sequentially decode the lower layer pictures at every elapse of an equal interval. Therefore, by setting these intervals to an appropriate time (for example, 2T 1/60 seconds as described above), the processing load of the image decoding apparatus can be reduced. That is, the image decoding apparatus can decode each picture at a frame rate according to its own processing capability without performing decoding at a high frame rate. For example, when a 60fps coded stream is decoded, it is sufficient to ensure that the time required for decoding 1 picture is 1/60 seconds or less.

(modification 1)

Here, the DTS of the picture at the head of the random access unit will be described.

Fig. 8 shows the decoding order and display order of each picture and the DTS and PTS (Presentation Time Stamp) when the coded stream shown in fig. 4 is reproduced at 120 fps.

Here, the suffix (numeral) of each of the DTS and PTS indicates the display order. The DTS or PTS is represented by a header of a PES packet in, for example, a broadcast MPEG-2 TS (transport stream). In mmt (mpeg Media Transport) or RTP (Real-time Transport Protocol), the DTS or PTS is indicated by a header of a packet of a Transport layer, header information of a coded stream included in a payload, or the like. In a format of a type such as MPEG-dash (dynamic Adaptive Streaming over http) in which a file is transmitted without being packetized, a DTS or PTS is included in a header portion of the file. Alternatively, in MPEG-4 AVC or HEVC, DTS or PTS can be expressed within the code stream by using SEI (supplemental Enhancement information) such as Picture Timing SEI or Buffering Period SEI.

In a conventional coded stream, if the interval of PTSs of two pictures that are displayed at a fixed frame rate and are consecutive in display order is T, the interval of DTSs of two pictures that are consecutive in decoding order is always T. Therefore, the playback device (or the image decoding device) can start decoding of a picture at the timing of the DTS of the picture that is the head in the decoding order, and can decode each subsequent picture sequentially at intervals of T without referring to the DTS of each subsequent picture.

On the other hand, in the coded stream according to the present embodiment, as shown in fig. 8, the interval of DTS between the picture I0 and the picture P4 and the interval of DTS between the picture P4 and the picture B2 are 2T (T is 1/120 seconds, for example). Further, the interval of the DTS between the picture B2 and the picture B1 and the interval of the DTS between two consecutive pictures that are, in decoding order, the picture B1 and thereafter are T. Therefore, in the coded stream according to the present embodiment, the inter-picture DTS interval is variable. Therefore, the image decoding apparatus (or the playback apparatus) needs to refer to the DTS of each picture and decode the picture at the timing of the DTS.

The image decoding apparatus 20 according to the present modification decodes or displays a picture based on the timing of a video processing signal generated at a constant interval. For example, if the frame rate of display is 120fps, the image decoding apparatus 20 generates a video processing signal every T (e.g., 1/120 seconds), and performs decoding or display of a picture at the timing of generation of the video processing signal. In the encoded stream shown in fig. 8, the interval of DTS between the picture I0 and the picture P4 and the interval of DTS between the picture P4 and the picture B2 are 2 times the period T of the video processing signal. Further, the interval of DTS between two consecutive pictures after picture B2 in decoding order is equal to the period T of the video processing signal.

Fig. 9 is a block diagram showing the configuration of the image decoding apparatus 20 according to the present modification.

The image decoding device 20 according to the present modification has the same function as the image decoding device 20 according to the above-described embodiment, and decodes a picture to be coded at a timing indicated by the DTS of the picture. The image decoding device 20 includes a signal interval setting unit 21, a DTS acquisition unit 22, a determination unit 23, and a decoding unit 24.

Fig. 10 is a flowchart showing an example of an operation performed when the image decoding device 20 according to the present modification decodes pictures of all the layers.

First, the signal interval setting unit 21 of the image decoding apparatus 20 sets an interval or a period (hereinafter referred to as V _ period) at which the video processing signal is generated such that V _ period is an inverse number of a frame rate at the time of decoding and displaying all the layers (step S21).

Next, the DTS acquisition unit 22 acquires a DTS (hereinafter referred to as DTS _ i) of a picture to be decoded from the header of a PES packet in which encoded data of the picture is stored (step S22). Next, the determination unit 23 monitors the timing of the generation of the video processing signal, and determines whether or not the timing matches dts _ i (step S23). When the interval of DTS of a picture is N times V _ period, the timing of the video processing signal generated at the nth time counted from the decoding time of the immediately preceding decoded picture matches DTS _ i. If it is determined that the timings match (yes in step S23), the decoding unit 24 decodes the picture to be decoded (step S24). On the other hand, if it is determined that the timings do not match (no in step S23), the determination unit 23 repeatedly executes the process of step S23.

Step S21 may be performed 1 time before the start of decoding the top picture, and need not be performed every time a picture is decoded. In the determination at step S23, it may be considered that the timing of the generation of the video processing signal and the difference value between dts _ i are equal to each other when the difference value is smaller than a predetermined threshold value. Further, the actions shown in fig. 10 are applicable not only to temporal scalability between decoding of all levels and decoding of lower levels, but also to temporal scalability between different two lower levels.

As described above, in the image decoding device 20 according to the present modification, even if the DTS interval is variable, when the DTS interval can be expressed by an integral multiple of the period of the video processing signal, it is possible to decode a picture in accordance with the variable DTS. As a result, the amount of processing for determining the timing of decoding can be reduced.

Here, a case is considered in which the Frame Rate in the case of decoding All hierarchies (hereinafter referred to as Frame Rate All) is not an integral multiple of the Frame Rate in the case of decoding only low hierarchies (hereinafter referred to as Frame Rate Part), as in the temporal scalability of 50fps and 120 fps. In this case, in order to ensure decoding in an image decoding device having a decoding capability of 50fps, it is necessary to set the interval of DTS at 1/50 seconds only when decoding the lower layer. However, since the Frame Rate All is not an integral multiple of the Frame Rate Part, not only is the decoding interval of a picture at the time of reproduction at 120fps not a constant interval (i.e., a fixed interval), but also the interval of DTS (1/50 seconds) is not an integral multiple of the period of the video processing signal (1/120 seconds). As a result, decoding cannot be performed at the time indicated by the DTS, and overflow or underflow may occur in a buffer or the like of the coded picture. Therefore, when providing temporal scalability, the image coding apparatus 10 according to the present modification may determine the combination of layers that achieve temporal scalability so that the frame rate of display when decoding all layers is an integral multiple of the frame rate of display when decoding only low layers. The image encoding device 10 may store, in the encoded stream, information indicating that the frame rate when all the layers are decoded is an integral multiple of the frame rate when only a part of the layers are decoded. Alternatively, the image encoding device 10 may store the information in a descriptor of ts (transport stream) or the like configured by multiplexing encoded streams.

In addition, in the random access unit, the difference between the DTS of the picture at the beginning in decoding order and the PTS of the picture at the beginning in display order is referred to as a display delay. In the example shown in fig. 8, the difference between DTS0 and PTS0 is the display delay. In a conventional coded stream in which the display frame rate is fixed, the interval of the DTS is also fixed, and this interval is the same as the interval of the PTS. Therefore, the display delay is expressed by a value obtained by multiplying the number of pictures decoded before the PTS of the picture that is the first in display order by the interval of the PTS. In the example shown in fig. 8, since two pictures, I0 and P4, are decoded before the PTS of the picture I0, the display delay is calculated to be 2 × T in the conventional calculation method. However, in the example shown in fig. 8, since the interval of the PTS between the picture I0 and the picture P4 and the interval of the PTS between the picture P4 and the picture B2 are 2 times T, the actual display delay is 4 × T. Thus, the conventional method cannot properly express the display delay.

Therefore, the image encoding device 10 according to the present modification may include information indicating that the display delay is several times the interval of the PTS in the encoded stream so as to accurately express the display delay even in the encoded stream in which the interval of the DTS is not constant. In the example shown in fig. 8, the interval of PTS is T, and the display delay is 4 times T, so the image encoding device 10 indicates the display delay as 4. Alternatively, the image encoding device 10 may represent the display delay with an actual time length as "4 × T". In the case where the number of pictures to be decoded before the PTS of the picture that is the first in display order is required, the image coding apparatus 10 may indicate the number of pictures separately from the information indicating the display delay. Further, the image encoding device 10 may connect a plurality of streams or a plurality of specific sections of a stream without interruption. At this time, the image encoding device 10 encodes the streams or specific sections before and after the connection so that the display delays are equal, taking into account the variable DTS interval. In this case, the image encoding device 10 may store information indicating that the display delay is equal before and after the non-intermittent connection in the encoded stream. In the case of encoding streams that are not connected to each other without interruption, the image encoding device 10 may encode the streams such that the display delays defined in the present modification are equal to each other before and after the point of connection without interruption, instead of encoding the streams such that the number of pictures decoded before the PTS of the picture that is the head in display order is equal to each other before and after the point of connection without interruption.

In addition, the image coding apparatus 10 according to the present modification may notify (signaling) auxiliary information indicating that the interval of the DTS is not constant when the frame rate of display is constant, that is, when the interval of the PTS is constant. For example, the auxiliary information is a flag indicating whether the interval of the DTS is constant. In this case, the image decoding apparatus 20 performs the operation shown in fig. 10 when the flag indicating that the DTS is not necessary is set, and if not, the DTS interval is constant, so the image decoding apparatus may operate without referring to the DTS of each picture.

The image encoding device 10 according to the present modification may set the auxiliary information for each random access unit, for each encoded stream unit, or for each unit referred to by a playlist in a storage content. In the TS packet, an area (private _ data _ bytes, etc.) for storing private data, management information of content in which content is stored, or auxiliary information can be stored in any of a plurality of layers of a transmission/reception system for content such as SEI in a coded stream such as MPEG-4 AVC or HEVC. However, it is preferable that the auxiliary information be referred to before decoding of the encoded stream, and therefore the image encoding device 10 may store the auxiliary information in a multiplexing layer such as a TS or in a higher layer of a transmission/reception system in which contents such as management information of data are multiplexed. As described above, in the present modification, unequal interval information indicating that the decoding times determined for a plurality of pictures included in a moving picture are not equal intervals is included in the coded stream as the auxiliary information.

In addition, when the image coding apparatus 10 according to the present modification decodes only the lower layer of the coded stream having temporal scalability, information indicating that the interval of the DTSs of two arbitrary pictures consecutive in the decoding order is variable may be stored in the coded stream. The information indicates that: when only the low-level layer is decoded, if the frame rate (hereinafter referred to as frame _ rate) to be displayed is constant, the interval of the DTS between two arbitrary pictures consecutive in decoding order is equal to or greater than 1/frame _ rate (sec). For example, in MPEG 2-TS, pmt (programmaptables) indicates identification information of a coded stream constituting a program. The image encoding device 10 according to the present modification may specify a descriptor in the PMT to represent the information. For example, when the interval at which the descriptor in the PMT indicates DTS is less than 1/60 seconds, the image decoding device 20 having a decoding capability of 60fps or less does not decode or reproduce the coded stream. Alternatively, the image decoding device 20 may reset the DTS so that the decoding interval of each picture becomes 1/60 seconds or more, and perform operations such as decoding each picture. When the PTS needs to be changed when the DTS is reset, the image decoding device 20 changes the PTS as well.

(modification 2)

Next, a change in the decoding time of a picture will be described.

When the image decoding device 20 of the above embodiment decodes all the layers, the DTS of a picture may be changed so that the interval of the DTS becomes 1/frame _ rate (sec) before the start of decoding.

Fig. 11 is a diagram showing an example of changing the DTS.

As shown in fig. 11, the image decoding device 20 according to the present modification changes the DTS of the picture I0 and the picture P4 so that the DTS intervals are all 1/frame _ rate (sec). The picture with a variable DTS interval is a picture that is decoded before the PTS of the picture that is at the head in display order. By changing the DTS of these pictures, the interval of the DTS can be kept constant. Further, if the interval of DTS is fixed, the decoding timing of a picture can be determined and decoded by the same method as in the conventional art. Note that only the DTS of the picture to be decoded before the PTS of the first picture in the display order is changed to be later, and the interval of the DTS after the change is 1/frame _ rate (sec). Therefore, no particular problem occurs in decoder models such as HRD (predictive decoder) of MPEG-4 AVC or HEVC.

The image encoding device 10 according to the present modification may indicate the value of the DTS after the change in the tref (timestamp reference) field of the PES header when the encoded stream is multiplexed by the TS. In the case of using another multiplexing method, the image coding apparatus 10 may indicate the DTS before and after the change. Further, information indicating the correspondence between the decoding hierarchy and the used DTS or PTS, such as the use of the DTS after the change when all the hierarchies are decoded, may be indicated in, for example, a descriptor of the TS, program information in the transport layer, or management information in the storage content. The image encoding device 10 may display information indicating that the interval of the DTS after the change is fixed or equal to the interval of the PTS in the program information in the transport layer or the management information in the stored content.

In this way, the image decoding device 20 can decode only the low hierarchy level even if the processing capability is low. The image decoding device 20 having a high processing capability for decoding all layers recognizes that the DTS or PTS after the change has been transmitted, by analyzing a descriptor of the MPEG-2 TS or the like, or determining whether or not a TREF field of a PES packet header exists. Thus, the image decoding apparatus 20 can decode the coded stream using the changed DTS or PTS.

When the video decoding device 20 records a coded stream on the premise that all the layers can be decoded, the coded stream with the DTS changed may be recorded as described above. In this case, instead of using a field for storing the DTS or PTS after the change, such as TREF, the DTS or PTS field of the PES header may be changed.

(modification 3)

Next, the auxiliary information for playback control will be described.

Fig. 12 is a diagram for explaining a picture to be decoded in an open-ended random access unit.

For example, in the example shown in fig. 12, the end of the stored coded stream or the coded stream acquired via the communication network coincides with the end of the 1 st random access unit, which is an open-end random access unit. At this time, the pictures B11, B13, B14, B15 included in the 2 nd random access unit cannot be decoded. However, the picture P12 belonging to the 1 st random access unit can be decoded. Here, the picture B11 is a leading picture, and the picture P12 is an isolated picture.

In the random access unit in the coded stream, all pictures can be decoded without referring to other random access units except for a predetermined picture among the pictures constituting the random access unit. When the random access unit is configured as an open gop (group Of pictures), the predetermined picture is a picture in the random access unit that is earlier in display order than the picture at the head in decoding order. Such a predetermined picture may refer to a picture included in a random access unit immediately preceding the random access unit in decoding order. Therefore, when decoding is started from the head of the random access unit which is an open GOP, the predetermined picture cannot be decoded. Therefore, the image decoding apparatus decodes and displays all pictures that are later in display order than the first picture in decoding order as decodable pictures in a random access unit.

Here, the image decoding apparatus 20 that has acquired the encoded data up to the open-ended random access unit in the bit stream cannot decode the leading picture because it has not acquired the leading picture. Therefore, the image encoding device 10 according to the present modification includes auxiliary information for playback control in the encoded stream.

The auxiliary information used for playback control is, for example, the following information (1) to (5).

(1) Information indicating whether a random access unit is an open-ended random access unit

(2) Information indicating whether the random access unit is the last random access unit in a section in which the random access unit is continuously reproduced, such as the last random access unit indicated by a playlist or the like, or the last random access unit indicated by a coded stream

(3) Information indicating whether or not a picture is an isolated picture or information indicating whether or not a picture is an isolated picture that is the last in display order in a random access unit

(4) Information indicating whether a picture is a leading picture

(5) Information indicating whether or not there is an isolated picture in the random access unit that is displayed later than the specified picture

In addition, in the above (2), when discontinuous sections in a coded stream or mutually different coded streams are concatenated, the random access unit preceding the concatenated section cannot refer to the picture of the subsequent random access unit. Therefore, the random access unit before the connection portion is also treated in the same manner as the last random access unit in the playback section.

The image encoding device 10 according to the present modification may set the auxiliary information for playback control as described above for each random access unit, or may set the auxiliary information for each encoded stream unit or for each unit referred to by the playlist in the storage content. In addition, in the TS packet, an area (private _ data _ bytes, etc.) for storing private data, management information of content stored in the content, SEI in an encoded stream such as MPEG-4 AVC or HEVC, etc., and auxiliary information can be stored in any of a plurality of layers in a transmission/reception system of the content. However, since it is preferable that the auxiliary information be referred to before decoding of the coded stream, the image encoding device 10 may store the auxiliary information in a multiplex layer such as a TS or in a higher layer in a transmission/reception system of contents such as management information of multiplexed data.

The information (1) and (2) is attribute information indicating an attribute of a random access unit. The image encoding device 10 stores the attribute information in an SEI preceding the decoding order of the leading picture in random access units, a packet header or payload of a transport layer such as a TS packet or an MMT packet storing the leading picture in random access units, or a table managing the attribute of random access units in the management information of the content. When the transport layer notifies information indicating a random access point, such as random _ access _ indicator of a TS packet, for example, the transport layer may store the attribute information in a packet indicating a random access point.

The information (3) to (4) is attribute information on each picture constituting a random access unit. The image coding apparatus 10 may store these attribute information in random access units together, or may store the attribute information for each picture. When storing the information for each picture, the image encoding device 10 adds SEI to each random access unit in the encoded stream, or stores the attribute information in the header or payload of a TS packet storing the header data of the picture. Further, the image encoding device 10 may store the attribute information on the picture only when the random access unit is the open-ended random access unit.

Next, an image decoding method of an open end random access unit will be described.

Fig. 13 is a flowchart showing an example of an operation of the image decoding device 20 according to the present modification to decode a moving image based on auxiliary information for playback control.

First, the image decoding device 20 determines whether or not auxiliary information for playback control is present in the management information of the content, the transport layer of the TS, or the encoded stream (step S211). In the playback section that is played back continuously, auxiliary information for playback control is provided or not provided in all of the random access units that constitute the playback section. Therefore, the processing in step S211 may be performed only for the first random access unit in the playback section.

Here, if it is determined that auxiliary information for playback control is present (yes in step S211), image decoding apparatus 20 performs the process in step S212, and if it is determined that auxiliary information for playback control is not present (no in step S211), image decoding apparatus 20 performs the process in step S215.

In step S215, image decoding apparatus 20 determines a picture to be decoded based on a predetermined method (step S215). In step S212, image decoding apparatus 20 determines whether the following condition is satisfied: the random access unit to be decoded is the last random access unit in the section to be continuously reproduced and is an open-ended random access unit (step S212).

Here, if it is determined that the condition is satisfied (yes in step S212), the image decoding apparatus 20 determines a picture to be decoded with reference to the auxiliary information for reproduction control (step S213). On the other hand, if it is determined that the condition is not satisfied (no in step S212), the image decoding apparatus 20 determines to decode all pictures included in the random access unit (step S214). However, in this case, when the random access unit to be decoded is the first random access unit in the playback section, the image decoding device 20 does not decode a picture that refers to a picture included in a random access unit immediately before the random access unit to be decoded.

Then, the image decoding device 20 decodes the picture determined in any one of the processes of steps S213, S214, and S215 (step S216).

The process of step S212 may be performed for each random access unit. In addition, when the auxiliary information of each of the plurality of pictures is stored in the random access unit, the picture is determined in step S213 at the start of decoding in the random access unit. In addition, when the auxiliary information of each of the plurality of pictures is stored for each picture, the determination of the picture is performed for each picture.

In addition, when the auxiliary information for playback control does not indicate information for each picture, image decoding apparatus 20 may determine whether or not a picture to be referred to is present in step S213. Thus, the image decoding apparatus 20 determines whether or not a picture is decodable, and can determine a picture to be decoded.

Further, the image decoding device 20 may determine the picture in step S213 as follows.

For example, the image decoding apparatus 20 determines only a picture whose display order is earlier than the preceding picture as a picture to be decoded, and determines an isolated picture as a picture not to be decoded.

Alternatively, the image decoding apparatus 20 determines a picture and an isolated picture in the display order before the leading picture as pictures to be decoded. The leading picture, which is displayed in the order of presentation before the isolated picture, cannot be decoded. Therefore, the image decoding apparatus 20 freezes (freezes) the decoding result of the picture immediately preceding the leading picture in display order among decodable pictures at the timing indicated by the PTS of the leading picture, and displays the frozen picture. That is, the image decoding apparatus 20 continues to display the decoding result of the immediately preceding picture also at the timing indicated by the PTS of the leading picture. Alternatively, the image decoding apparatus 20 may display an image obtained by interpolating a decoding result of a picture immediately before a leading picture in display order and a decoding result of the leading picture among decodable pictures.

Here, the image decoding apparatus having a decoding capability of 120fps can perform special playback such as playback at 4 × speed by decoding only pictures belonging to a level whose Temporal ID is 0 at decoding intervals of 120 fps. Therefore, the method of determining a picture to be decoded may be switched between normal reproduction and special reproduction in which pictures of all layers are decoded and displayed. For example, in the example shown in fig. 1A or 1B, each picture having a Temporal ID of 0 is only an I picture and a P picture, and the leading picture is not included in each picture. Therefore, the image decoding apparatus 20 may decode the isolated picture when only the picture belonging to the hierarchy having the Temporal ID of 0 is decoded and reproduced at the time of special reproduction without decoding the isolated picture at the time of normal reproduction. More generally, the image decoding apparatus 20 may decode only pictures whose display order is earlier than the preceding picture among the pictures of the hierarchy to be decoded in the case of the special playback.

In addition, when the random access unit is an open-ended random access unit, the image coding device 10 may store information for specifying a leading picture or an isolated picture that is the last in the display order in the coded stream as attribute information of the random access unit. For example, if the decoding order of the leading picture is the nth within the random access unit, the image decoding apparatus 20 may decide to decode only a picture having a PTS earlier than the PTS of the nth picture. Alternatively, if the isolated picture that is the last in display order is the nth in decoding order, the image decoding apparatus 20 may decide not to decode a picture that is later in display order than the isolated picture.

(modification 4)

For example, when a coded stream having a frame rate exceeding 60fps is acquired, the image decoding device 20 according to the present modification, in which 60fps is the upper limit of the decoding capability, may convert the DTS or PTS of each picture so as to decode each picture included in the coded stream. For example, when the image decoding device 20 acquires and records a coded stream via a broadcast or communication network, it may convert a DTS or a PTS. Alternatively, the image decoding apparatus 20 may convert the DTS or PTS when transmitting the encoded stream recorded in the memory, the hard disk, or the like to an external device via a communication network or the like.

Fig. 14 shows an example of DTS or PTS conversion. The line 1 from the top in fig. 14 shows the original DTS of all pictures constituting all layers included in the original coded stream. If all pictures are decoded and displayed, a moving image is displayed at a frame rate of 120 fps. The 2 nd row from the top in fig. 14 shows each picture recorded when the above-described original coded stream is recorded as a coded stream of 60fps, and the original DTS of these pictures. In the coded stream of 60fps thus recorded, the DTS interval between pictures cannot be guaranteed to be 1/60 (seconds).

The 3 rd row from the top in fig. 14 shows each picture recorded when the original coded stream is recorded as a coded stream of 60fps and the DTS after the change of the picture. The image decoding apparatus 20 of the present modification changes the DTS shown in the 3 rd line. As a result of changing the DTS, the DTS interval between pictures is guaranteed to be 1/60 (seconds). The 4 th row from the top in fig. 14 shows each picture recorded when the above-described original coded stream is recorded as a coded stream of 60fps, and the original PTS of these pictures. The same value as the original PTS may be used without alteration of the PTS. Here, the DTS is changed to be delayed from the original DTS, and the PTS is not changed. Therefore, neither overflow nor underflow occurs in the Buffer (corresponding to Coded Picture Buffer in MPEG-4 AVC or HEVC) of the preceding stage of the image decoding device 20 or the Buffer for holding reference pictures (corresponding to Decoded Picture Buffer in MPEG-4 AVC or HEVC).

In addition, when a change of PTS is required, the PTS may be changed so as to satisfy a buffer model (corresponding to a Hypothetical Reference Decode in MPEG-4 AVC or HEVC). When an encoded stream is multiplexed with MPEG-2 TS, PTS or DTS is represented in the header of a PES packet. Therefore, the image decoding device 20 may change the PTS or DTS in the header of the PES packet. Alternatively, the image decoding apparatus 20 may store the value after the change in the tref (timestamp reference) field in the PES packet header without changing the value of the PTS or DTS. Alternatively, the image decoding device 20 may change the PTS or DTS and then store the original PTS or DTS value in the TREF field.

In the above-described embodiment and its modified examples, the temporal scalability based on the combination of 60fps and 120fps was described as an example, but the present invention can also be applied to temporal scalability based on a combination of other frame rates. In the above-described embodiment and the modifications thereof, the description has been given, as an example, of a combination of all the levels and the levels other than the uppermost level as the level to be decoded when temporal scalability is realized, but the present invention is also applicable to other combined levels.

While the image encoding device and the image decoding device according to one or more embodiments have been described above based on the embodiments and modifications thereof, the present invention is not limited to the embodiments and modifications thereof.

Fig. 15A is a block diagram of an image encoding device according to an embodiment of the present invention.

An image encoding device 100 according to an aspect of the present invention is a device that encodes a moving image for each picture belonging to one of a plurality of levels without referring to another picture belonging to a level higher than the level to which the picture belongs, and includes a determination unit 101, an encoding unit 102, and a generation unit 103.

The determination unit 101 determines the decoding times of a plurality of pictures included in a moving image so that the decoding times of a plurality of pictures included in the moving image are equally spaced from each other and a plurality of lower pictures not belonging to the highest hierarchy among the plurality of hierarchies. In this case, the determination unit 101 also determines the decoding time of each of the plurality of pictures included in the moving image so that the timing at which each of the plurality of lower layer pictures is decoded is the same between the case where the plurality of pictures included in the encoded moving image are decoded and the case where only the plurality of lower layer pictures among the plurality of pictures are decoded.

The encoding unit 102 encodes a plurality of pictures included in the moving image in an encoding order corresponding to the determined decoding time. The generation unit 103 generates a coded stream including a plurality of coded pictures and decoding time points determined for the plurality of pictures.

Fig. 15B is a flowchart showing an image encoding method according to an embodiment of the present invention.

An image encoding method according to an aspect of the present invention is a method in which the image encoding device 100 encodes a moving image for each picture belonging to one of a plurality of hierarchies without referring to another picture belonging to a higher hierarchy than the hierarchy to which the picture belongs. The image encoding method includes step S101, step S102, and step S103. In step S101, the respective decoding times of a plurality of pictures included in a moving picture are determined so that the respective decoding times of a plurality of pictures that are part of the plurality of pictures included in the moving picture and a plurality of lower pictures that do not belong to the highest hierarchical level among the plurality of hierarchical levels are at equal intervals. In this case, the decoding time of each of the plurality of pictures included in the moving image is determined so that the timing at which each of the plurality of lower layer pictures is decoded is the same between the case where the plurality of pictures included in the encoded moving image are decoded and the case where only the plurality of lower layer pictures among the plurality of pictures are decoded.

In step S102, the plurality of pictures included in the moving picture are encoded in the encoding order corresponding to the determined decoding time. In step S103, a coded stream including a plurality of coded pictures and decoding time determined for each of the plurality of pictures is generated.

In this way, each of the plurality of pictures included in the encoded stream is encoded without referring to another picture belonging to a higher hierarchy than the hierarchy to which the picture belongs. Thus, the image decoding apparatus can decode only a plurality of lower layer pictures in the encoded stream. The decoding times of the lower layer pictures included in the coded stream are at equal intervals. Therefore, when decoding only a plurality of lower layer pictures in a coded stream, the image decoding apparatus can sequentially decode the lower layer pictures at every elapse of an equal interval. Therefore, by setting the interval to an appropriate time such as 1/60 seconds, the processing load of the image decoding apparatus can be reduced. That is, the image decoding apparatus can decode each picture at a frame rate of 60fps or the like according to its own processing capability, instead of a high frame rate of 120fps or the like. Further, between the case where a plurality of pictures (for example, all pictures) included in the encoded stream are decoded and the case where only the plurality of lower layer pictures are decoded, the timings at which the plurality of lower layer pictures are decoded are the same. For example, as shown in fig. 4 or fig. 6, pictures I0, P4, B2, I8, B6, and the like, which are a plurality of lower layer pictures, are decoded at the same timing between the case of decoding at 120fps and the case of decoding at 60 fps. Therefore, the image decoding apparatus does not need to change the respective decoding timings of the plurality of lower layer pictures between a case of decoding all the pictures of the coded stream and a case of decoding only the plurality of lower layer pictures. Therefore, the processing load of the image decoding apparatus can be further reduced.

In the determination of the decoding time in step S101, the decoding time of each of a plurality of pictures that are part of the plurality of pictures included in the moving image and a plurality of uppermost pictures that belong to the highest hierarchy is determined between the decoding times of the plurality of lower pictures. For example, in the example shown in fig. 6, the decoding time of the picture B1, which is the uppermost picture, is determined between the picture P4 and the picture B2, which are lower pictures, and the decoding time of the picture B3, which is the uppermost picture, is determined between the picture B2 and the picture I8, which are lower pictures.

Thus, when the encoded stream is decoded, the uppermost picture and the lower picture are alternately decoded, respectively. Therefore, the interval of the time when each of the plurality of lower layer pictures is decoded in the coded stream is longer than the interval of the time when all the pictures in the decoded stream are decoded. As a result, when decoding only a plurality of lower layer pictures, the image decoding apparatus can decode each picture at a frame rate that is lower than when decoding all pictures of the decoded stream individually. Therefore, the processing load of the image decoding apparatus can be reliably reduced.

In the determination of the decoding time in step S101, the decoding time of each of the plurality of pictures included in the moving image is determined such that a time 2 times the interval between the decoding times of the uppermost picture and the lower picture among the plurality of uppermost pictures and the plurality of lower pictures which are consecutive in decoding order is equal to the time of the equal interval. For example, in the example shown in fig. 6, the interval between the decoding times of the picture B1 as the uppermost picture and the picture B2 as the lower picture that are consecutive in decoding order is T1/120 seconds. Therefore, in step S101, the decoding time of each of the plurality of pictures included in the moving image is determined so that 2 × T1/60 seconds is equal to the time of the equal interval.

Thus, the interval of the decoding times of the plurality of lower pictures is 2 times the interval of the decoding times of the uppermost picture and the lower pictures that are consecutive in decoding order, that is, the interval of the decoding times of all the pictures of the decoded stream. Therefore, when the frame rate at which all pictures of the coded stream are decoded and displayed is 120fps, the image decoding apparatus can decode each of the plurality of lower layer pictures included in the coded stream at a time interval that is the inverse of the frame rate of 60fps without a burden.

When a moving picture has a plurality of random access units each of which is composed of a plurality of pictures consecutive in decoding order, the decoding time may be determined in step S101 as follows. That is, in step S101, the decoding time of each picture in the random access unit is determined for each random access unit so that all pictures other than the picture displayed earlier in display order than the picture at the head in decoding order can be decoded in the random access unit without referring to the pictures included in the other random access units. Here, the first Picture is an I Picture (so-called IDR Picture) in which a Picture later than the first Picture in Decoding order is prohibited from referring to a Picture earlier than the first Picture in Decoding order. Alternatively, the leading Picture is an I Picture (so-called CRA Picture: clean random Access Picture, new random Access Picture) which is permitted for a Picture which is later in decoding order than the leading Picture and is earlier in display order than the leading Picture to refer to a Picture which is earlier in decoding order than the leading Picture. For example, in step S101, image coding apparatus 100 determines the decoding time of each of a plurality of pictures included in a moving image as shown in fig. 6. In the example shown in fig. 6, since picture B13 located earlier in display order than picture I16 refers to picture P12 in the 1 st random access unit, picture I16 is a CRA picture.

Thus, the image decoding device can appropriately decode each of the plurality of pictures included in the random access unit for each random access unit.

Here, the processing operation of image coding apparatus 100 to determine the decoding time of a plurality of pictures included in a moving image in step S101 as in the example shown in fig. 6 will be described in detail.

When the frame rate at which all pictures included in the coded moving image are decoded and displayed is, for example, 120fps, the image coding apparatus 100 determines the decoding time of each of the all pictures in units of time (1/120 seconds) that is the reciprocal of the frame rate (120fps) in step S101. That is, the decoding time determined for each picture is expressed as a time obtained by adding an offset value to an integral multiple of the time unit. In step S101, the image coding apparatus 100 may determine tids of a plurality of pictures included in the moving image, and then determine decoding orders of the plurality of pictures. Then, the image coding apparatus 100 determines the DTS of each of the plurality of pictures in the time unit based on the determined decoding order.

For example, the image encoding device 100 determines TId, which is a value for identifying the hierarchy of each picture, in a range of 0 to K (K is an integer of 1 or more) for each picture arranged in the display order. The tier where TId is K is the highest tier, and the tier where TId is 0 is the lowest tier. Specifically, the determination unit 101 determines Tid of the top I picture among a plurality of pictures arranged in display order in the moving image to be 0. Further, the determination unit 101 determines TId of an I picture or a P picture, which is the last picture in a picture group, to be 0 for each M (M is an integer equal to or greater than 2) pictures (hereinafter, referred to as the picture group) consecutive to each of a plurality of pictures following the first I picture arranged in the display order. The picture that is the last in the display order in the picture group is an I picture or a P picture, and the TId of the I picture or the P picture is determined to be 0. The picture whose TId is determined to be 0 is hereinafter referred to as a 0-level picture. For example, in the example shown in fig. 1A, 4 pictures including the picture B1, the picture B2, the picture B3, and the picture P4 correspond to the above-described picture set. Then, the picture P4 is determined to be a 0-level picture.

Next, the determination unit 101 determines, as candidate pictures, at least 1 picture (for example, B picture) other than the 0-level picture included in the picture set and at least 1 picture that is a candidate for determining TId. The candidate picture is a picture displayed in the middle of two predetermined pictures for which TId has been determined. For example, in the example shown in fig. 1A, in a case where the respective tids of the picture I0 and the picture P4 have been determined, the picture I0 and the picture P4 are given pictures. In this case, in the picture set including the pictures B1 to B3 and the picture P4, the picture B2, which is a picture displayed in the middle of the picture I0 and the picture P4, is determined as a candidate picture.

Furthermore, if there are a plurality of candidate pictures thus identified, the determination unit 101 determines the TId of the candidate picture that is at the head in the display order of the candidate pictures as a value N obtained by adding 1 to the TId that is not lower than the TId of the two predetermined pictures corresponding to the candidate picture at the head. For example, in the example shown in fig. 1B, if the TId of each of the picture I0, the picture P8, and the picture B4 is already determined, the picture I0, the picture P8, and the picture B4 are predetermined pictures. In this case, in the picture set including the pictures B1 to B7 and the picture P8, the picture B2 that is a picture displayed in the middle of the picture I0 and the picture B4 and the picture B6 that is a picture displayed in the middle of the picture B4 and the picture P8 are determined as candidate pictures. Therefore, the determination unit 101 determines the TId of the candidate picture B2 that is at the beginning in the display order among the candidate pictures B2 and B6 as a value obtained by adding 1 to the not-lower TId of the two predetermined pictures I0 and B4 corresponding to the candidate picture B2 at the beginning (N-2).

The determination unit 101 repeats such determination of candidate pictures and determination of Tid until ITd of all pictures other than the 0-level pictures included in the picture set are determined, where N is a range of K or less. As a result, TId is determined for each picture as shown in fig. 1A or 1B.

Next, the determination unit 101 determines the decoding order of the first I picture as No. 1. For example, as shown in fig. 6, the determination unit 101 determines the decoding order of the picture I0, which is the first I picture, to be No. 1.

The determination unit 101 determines, for each of the picture sets, the decoding order of each of the plurality of pictures in the picture set. Specifically, the determination unit 101 determines the decoding order of the 0-level picture as the head in the picture set. Then, the determination unit 101 determines the decoding order of a picture immediately after the determined decoding order from the picture immediately before in the display order among the plurality of pictures other than the 0-level picture included in the picture group. For example, the determination unit 101 determines the decoding order of the picture P8, which is a 0-level picture, as the head in the picture set including the pictures B1 to B7 and the picture P8. The decision unit 101 decides the decoding order of pictures B1 to B3 so that picture B1, picture B2, and picture B3 are sequentially succeeding picture P8,

the determination unit 101 determines to decode a plurality of picture sets arranged in the display order in the order in which the picture sets are arranged. That is, the determination unit 101 determines the decoding order of the top of the picture set as the last decoding order of the immediately preceding picture set in the display order or the number of orders obtained by adding 1 to the decoding order of the top I picture (picture I0).

Further, if the determination unit 101 determines the decoding time of the first I picture (picture I0), the determination unit determines the decoding time of the picture (picture P4) that is immediately subsequent in the decoding order of the I picture as the time obtained by adding the time unit (1/120 seconds) × 2 to the decoding time of the I picture. The determination unit 101 determines the decoding time of each picture whose decoding order is later than the immediately subsequent picture (picture P4) as the time obtained by adding the time unit to the decoding time of the immediately preceding picture in decoding order.

As described above, the determination unit 101 determines the decoding time of each picture, and the decoding times of the lower pictures are at equal intervals, that is, at intervals of the time unit (1/120 seconds) × 2.

In the determination of the decoding time in step S101, when the frame rate at which all pictures included in the encoded moving image are decoded and displayed is f, the respective decoding times of all the pictures may be determined such that the respective decoding times of a plurality of lower layer pictures included in all the pictures are shifted by a time represented by n times the reciprocal of f (n is an integer equal to or greater than 2).

Thus, the image decoding apparatus can sequentially decode each of the plurality of lower layer pictures at a time interval n times the reciprocal of the frame rate without a burden.

In the image encoding method according to the aspect of the present invention, the display delay information indicating the display delay between the decoding time of the picture at the head in the decoding order included in the moving image and the display time of the picture at the head in the display order included in the moving image may be further included in the encoded stream.

Thus, the image decoding device can acquire the display delay information from the encoded stream. Therefore, as shown in fig. 8, if the image decoding device starts decoding of the coded stream from a time point before the display start time and at which the display is delayed, which is indicated by the display delay information, the moving image can be displayed without delay from the display start time.

In the image encoding method according to the aspect of the present invention, the encoded stream may further include unequal interval information indicating that the decoding times determined for the plurality of pictures included in the moving image are not equal intervals.

Thus, the image decoding device can acquire unequal interval information from the coded stream. Therefore, the image decoding apparatus can determine that each of the plurality of pictures included in the coded stream cannot be sequentially decoded at the frame rate to be displayed. As a result, the image decoding apparatus can decode a plurality of pictures included in the coded stream at appropriate timing while referring to the decoding times determined for the plurality of pictures according to the flowchart shown in fig. 10.

Fig. 15C is a block diagram of an image decoding device according to an embodiment of the present invention.

An image decoding device 200 according to an aspect of the present invention is a device that decodes a coded stream including a moving image coded for each picture belonging to one of a plurality of layers without referring to another picture belonging to a layer higher than the layer to which the picture belongs. The image decoding device 200 includes an acquisition unit 201 and a decoding unit 202.

The acquisition unit 201 acquires, from a coded stream, the decoding time of each of a plurality of pictures included in the coded stream. Here, the decoding time of each of the plurality of pictures is determined as follows. That is, the decoding times are determined so that the respective decoding times of a plurality of pictures that are part of a plurality of pictures included in the coded stream and a plurality of lower layer pictures that do not belong to the highest hierarchical level among the plurality of hierarchical levels are at equal intervals. Further, these decoding times are determined so that the timings at which the plurality of lower layer pictures are decoded are the same between the case where the plurality of pictures included in the encoded stream are decoded and the case where only the plurality of lower layer pictures among the plurality of pictures are decoded.

The decoding unit 202 decodes each of the plurality of pictures or the plurality of lower layer pictures included in the coded stream according to the acquired decoding time.

Fig. 15D is a flowchart showing an image decoding method according to an embodiment of the present invention.

An image decoding method according to an aspect of the present invention is a method in which the image decoding apparatus 200 decodes a coded stream including a moving image coded for each picture belonging to one of a plurality of layers without referring to another picture belonging to a layer higher than the layer to which the picture belongs. The image decoding method includes step S201 and step S202.

In step S201, the decoding time of each of a plurality of pictures included in the coded stream is acquired from the coded stream. Here, the decoding time of each of the plurality of pictures is determined as follows. That is, the decoding times are determined so that the respective decoding times of a plurality of pictures that are part of a plurality of pictures included in the coded stream and a plurality of lower layer pictures that do not belong to the highest hierarchical level among the plurality of hierarchical levels are at equal intervals. Further, these decoding times are determined so that the timings at which the plurality of lower layer pictures are decoded are the same between the case where the plurality of pictures included in the encoded stream are decoded and the case where only the plurality of lower layer pictures among the plurality of pictures are decoded.

In step S202, a plurality of pictures or a plurality of lower layer pictures included in the coded stream are decoded according to the acquired decoding time.

In this way, each of the plurality of pictures included in the encoded stream is encoded without referring to another picture belonging to a higher hierarchy than the hierarchy to which the picture belongs. Thus, the image decoding apparatus 200 can decode only a plurality of lower layer pictures in the encoded stream. The decoding times of the lower layer pictures included in the coded stream are at equal intervals. Therefore, when decoding only a plurality of lower layer pictures in the coded stream, the image decoding apparatus 200 can sequentially decode these lower layer pictures every time an equal interval elapses. Therefore, if the intervals are appropriate times, the processing load of the image decoding apparatus 200 can be reduced. That is, the image decoding apparatus 200 decodes each picture at a frame rate according to its own processing capability without performing decoding at a high frame rate. Further, between the case where a plurality of pictures (for example, all pictures) included in the encoded stream are decoded and the case where only the plurality of lower layer pictures are decoded, the timings at which the plurality of lower layer pictures are decoded are the same. Therefore, the image decoding apparatus 200 does not need to change the respective decoding timings of the plurality of lower layer pictures when all the pictures of the coded stream are decoded and when only the plurality of lower layer pictures are decoded. Therefore, the processing load of the image decoding apparatus 200 can be further reduced.

In the image decoding method according to the aspect of the present invention, when the decoding times of the plurality of pictures included in the coded stream are not at equal intervals, the decoding times of the plurality of pictures may be changed to be at equal intervals, and in the decoding of the coded stream, the plurality of pictures or the plurality of lower layer pictures included in the coded stream may be decoded at the changed decoding times.

Thus, for example, as shown in fig. 11, since the decoding times of the plurality of pictures are changed to be at equal intervals, the image decoding apparatus 200 can decode the plurality of pictures included in the coded stream every time the equal intervals elapse. Therefore, the processing load of the image decoding apparatus 200 can be further reduced.

In the image decoding method according to one aspect of the present invention, it may be determined, for each picture included in the coded stream, whether or not the decoding time acquired for the picture matches the generation timing of a processing signal (corresponding to the video processing signal) generated at predetermined intervals, and when it is determined that the decoding time matches the generation timing, the picture may be decoded. For example, the image decoding method may further determine the inverse of the frame rate when all pictures included in the coded stream are decoded and displayed as the predetermined period.

As a result, as shown in the flowchart of fig. 10, even if the decoding times of the plurality of pictures are not at equal intervals, each of the plurality of pictures can be appropriately decoded at the decoding time of the picture.

In the above embodiments, each component may be implemented by dedicated hardware or by executing a software program suitable for each component. Each component may be realized by reading and executing a software program recorded in a recording medium such as a hard disk or a semiconductor memory by a program execution unit such as a CPU or a processor. Here, the software that realizes the image coding apparatuses 10 and 100 according to the above-described embodiments or modifications causes a computer to execute the steps included in the flowchart shown in fig. 15B. Further, software that implements the image decoding apparatuses 20 and 200 according to the above-described embodiments or modifications causes a computer to execute the steps included in the flowchart shown in fig. 15D.

(embodiment mode 2)

The processes described in the above embodiments can be easily implemented in a separate computer system by recording a program for realizing the configuration of the moving image encoding method (image encoding method) or the moving image decoding method (image decoding method) described in the above embodiments in a storage medium. The storage medium may be a magnetic disk, an optical magnetic disk, an IC card, a semiconductor memory, or the like, as long as the storage medium can store a program.

Further, an application example of the moving image encoding method (image encoding method) and the moving image decoding method (image decoding method) described in the above embodiments and a system using the same will be described. The system is characterized by comprising an image encoding device using an image encoding method and an image decoding device using an image decoding method. Other configurations of the system may be changed as appropriate according to the situation.

Fig. 16 is a diagram showing the overall configuration of a content providing system ex100 that realizes a content distribution service. The area where the communication service is provided is divided into desired sizes, and base stations ex106, ex107, ex108, ex109, and ex110, which are fixed wireless stations, are installed in the respective cells.

The content providing system ex100 is connected to the internet ex101 via an internet service provider ex102, a telephone network ex104, and base stations ex106 to ex110, and is connected to devices such as a computer ex111, a pda (personal Digital assistant) ex112, a camera ex113, a mobile phone ex114, and a game machine ex 115.

However, the content providing system ex100 is not limited to the configuration shown in fig. 16, and some elements may be connected in combination. Note that each device may be directly connected to the telephone network ex104 without passing through the base stations ex106 to ex110 as fixed wireless stations. Further, the respective devices may be directly connected to each other via short-range wireless or the like.

The camera ex113 is a device such as a digital video camera capable of shooting a moving image, and the camera ex116 is a device such as a digital camera capable of shooting a still image or a moving image. The cellular phone ex114 may be a gsm (global System for Mobile communications) System, a CDMA (Code Division Multiple Access) System, a W-CDMA (Wideband-Code Division Multiple Access) System, an lte (long term evolution) System, a cellular phone with hspa (high Speed Packet Access), a phs (personal handyphone System), or the like.

In the content providing system ex100, live broadcasting and the like can be performed by connecting the camera ex113 and the like to the streaming server ex103 via the base station ex109 and the telephone network ex 104. In live broadcasting, content (for example, videos of a concert live or the like) captured by the user using the camera ex113 is encoded as described in the above embodiments (that is, functions as an image encoding device according to an aspect of the present invention) and transmitted to the streaming server ex 103. On the other hand, the streaming server ex103 streams the transmitted content data to the requesting client. The clients include a computer ex111, a PDAex112, a camera ex113, a mobile phone ex114, a game machine ex115, and the like, which are capable of decoding the data subjected to the encoding processing. Each device that receives the distributed data decodes and reproduces the received data (that is, functions as an image decoding apparatus according to an embodiment of the present invention).

The encoding process of the data to be captured may be performed by the camera ex113, the streaming server ex103 that performs the data transmission process, or may be shared with each other. Similarly, the decoding process of the distributed data may be performed by the client, may be performed by the streaming server ex103, or may be shared with each other. Further, the camera ex116 may transmit still images and/or moving image data captured by the camera ex116 to the streaming server ex103 via the computer ex111, instead of being limited to the camera ex 113. In this case, the encoding process may be performed by the camera ex116, the computer ex111, or the streaming server ex103, or may be performed in a shared manner.

Further, these encoding and decoding processes are generally processed in the computer ex111 or the LSIex500 possessed by each device. LSIex500 may be a single chip or may be a structure composed of a plurality of chips. Alternatively, the software for encoding and decoding the moving picture may be loaded into some recording medium (such as a CD-ROM, a flexible disk, and a hard disk) that can be read by the computer ex111, and the encoding and decoding processes may be performed using the software. Further, when the mobile phone ex114 is equipped with a camera, the moving image data acquired by the camera may be transmitted. The moving image data at this time is data subjected to the LSIex500 encoding process of the cellular phone ex 114.

The streaming server ex103 may be a plurality of servers or a plurality of computers, and may process, record, and distribute data variances.

As described above, in the content providing system ex100, the client can receive and reproduce encoded data. As described above, in the content providing system ex100, the client can receive, decode, and reproduce information transmitted by the user in real time, and even a user who does not have any special right or device can realize personal broadcasting.

Further, the content providing system ex100 is not limited to the example, and as shown in fig. 17, at least either of the moving image coding apparatus (image coding apparatus) and the moving image decoding apparatus (image decoding apparatus) according to the above-described embodiments may be incorporated in the digital broadcasting system ex 200. Specifically, the broadcasting station ex201 transmits multiplexed data obtained by multiplexing video data with music data or the like to the communication or broadcasting satellite ex202 via radio waves. The video data is data encoded by the moving image encoding method described in each of the above embodiments (that is, data encoded by the image encoding device according to one aspect of the present invention). The broadcast satellite ex202 that has received the data transmits a broadcast radio wave, a home antenna ex204 that can receive the broadcast radio wave by satellite broadcast receives the radio wave, and the received multiplexed data is decoded and reproduced by an apparatus such as a television (receiver) ex300 or a set-top box (STB) ex217 (that is, the image decoding apparatus according to an embodiment of the present invention functions).

The moving picture decoding apparatus or the moving picture coding apparatus described in each of the above embodiments may be mounted to the reader/recorder ex218 that reads and decodes multiplexed data recorded on the recording medium ex215 such as a DVD or a BD, or codes video data and multiplexes the coded data with a music signal and writes the coded data on the recording medium ex 215. In this case, the reproduced video signal can be displayed on the monitor ex219, and the video signal can be reproduced by another device or system via the recording medium ex215 on which the multiplexed data is recorded. Further, a moving picture decoding apparatus may be installed in the set-top box ex217 connected to the cable ex203 for cable television or the antenna ex204 for satellite/terrestrial broadcasting, and the moving picture decoding apparatus may be displayed on the monitor ex219 of the television. In this case, the moving picture decoding apparatus may be incorporated in a television set, not in the set-top box.

Fig. 18 is a diagram showing a television (receiver) ex300 using the moving picture decoding method and the moving picture encoding method described in each of the above embodiments. The television ex300 includes a tuner ex301 that acquires or outputs multiplexed data in which audio data is multiplexed with video data via an antenna ex204 or a cable ex203 that receives the broadcast, a modulation/demodulation unit ex302 that demodulates or modulates the received multiplexed data into encoded data to be transmitted to the outside, and a multiplexing/demultiplexing unit ex303 that demultiplexes the demodulated multiplexed data into video data and audio data or multiplexes the video data and audio data encoded by a signal processing unit ex 306.

The television ex300 further includes: a signal processing unit ex306 having an audio signal processing unit ex304 and a video signal processing unit ex305 (that is, a video encoding device or a video decoding device according to an embodiment of the present invention) for decoding audio data and video data, respectively, or encoding information of each; and an output unit ex309 having a speaker ex307 for outputting the decoded audio signal and a display unit ex308 such as a display for displaying the decoded video signal. The television ex300 further includes an interface unit ex317 having an operation input unit ex312 and the like for receiving input of user operations. The television set ex300 further includes a control unit ex310 for controlling the respective units in a combined manner, and a power supply circuit unit ex311 for supplying power to the respective units. The interface unit ex317 may include, in addition to the operation input unit ex312, a bridge unit ex313 connected to an external device such as the reader/recorder ex218, a slot unit ex314 to which a recording medium ex216 such as an SD card can be attached, a drive ex315 connected to an external recording medium such as a hard disk, a modem ex316 connected to a telephone network, and the like. The recording medium ex216 is configured to be capable of electrically recording information by a nonvolatile/volatile semiconductor memory element stored therein. Each unit of the television ex300 is connected to each other via a synchronous bus.

First, the television ex300 will be described with respect to a configuration for decoding and reproducing multiplexed data acquired from the outside via the antenna ex204 and the like. The television ex300 receives a user operation from the remote control ex220 or the like, and under the control of the control unit ex310 having a CPU or the like, separates the multiplexed data demodulated by the modulation/demodulation unit ex302 by the multiplexing/separation unit ex 303. The television ex300 decodes the separated audio data by the audio signal processing unit ex304, and decodes the separated video data by the video signal processing unit ex305 by using the decoding method described in each of the above embodiments. The decoded audio signal and video signal are output from the output unit ex309 to the outside. At the time of output, these signals may be temporarily stored in the buffers ex318, ex319, and the like so that the audio signal and the video signal are reproduced in synchronization. The television ex300 may read out the encoded multiplexed data from the recording media ex215 and ex216 such as a magnetic/optical disk and an SD card, instead of broadcasting. Next, a configuration in which the television ex300 encodes an audio signal or a video signal and transmits or writes the encoded audio signal or video signal to a recording medium or the like will be described. The television ex300 receives a user operation from the remote controller ex220 or the like, and under the control of the control unit ex310, the audio signal processing unit ex304 encodes the audio signal, and the video signal processing unit ex305 encodes the video signal using the encoding method described in each of the above embodiments. The encoded audio signal and video signal are multiplexed by the multiplexing/demultiplexing unit ex303 and output to the outside. In multiplexing, these signals may be temporarily stored in buffers ex320, ex321, and the like so that the audio signal and the video signal are reproduced in synchronization with each other. The buffers ex318, ex319, ex320, and ex321 may be provided in plural as shown in the drawing, or may share one or more buffers. Further, in addition to the illustration, data may be stored in a buffer as a buffer unit for avoiding overflow and underflow of the system, for example, between the modulation/demodulation unit ex302 and the multiplexing/demultiplexing unit ex 303.

The television ex300 may be configured to receive an AV input from a microphone or a camera, in addition to audio data or video data acquired from a broadcast or the like or a recording medium, and encode the data acquired from them. Note that, although the television ex300 has been described as a configuration capable of performing the above-described encoding processing, multiplexing, and external output, the television ex may be configured so that only the above-described reception, decoding processing, and external output are possible without performing these processes.

When the reader/recorder ex218 reads or writes the multiplexed data from or to the recording medium, the decoding process or the encoding process may be performed by the television ex300 or the reader/recorder ex218, or the television ex300 and the reader/recorder ex218 may be shared with each other.

Fig. 19 shows, as an example, a configuration of an information reproducing/recording unit ex400 in the case of reading or writing data from or to an optical disc. The information reproducing/recording unit ex400 includes units ex401, ex402, ex403, ex404, ex405, ex406, and ex407, which are described below. The optical head ex401 writes information by irradiating a recording surface of the recording medium ex215, which is an optical disc, with a laser spot, and reads information by detecting reflected light from the recording surface of the recording medium ex 215. The modulation recording unit ex402 electrically drives the semiconductor laser incorporated in the optical head ex401, and modulates the laser beam in accordance with the recording data. The reproduction demodulation unit ex403 amplifies a reproduction signal obtained by electrically detecting the reflected light from the recording surface by a photodetector incorporated in the optical head ex401, separates and demodulates a signal component recorded in the recording medium ex215, and reproduces necessary information. The buffer ex404 temporarily holds information for recording to the recording medium ex215 and information for reproduction from the recording medium ex 215. The disc motor ex405 rotates the recording medium ex 215. The servo control unit ex406 moves the optical head ex401 to a predetermined information track while controlling the rotational driving of the disc motor ex405, and performs a tracking process of the laser spot. The system control unit ex407 controls the entire information reproducing/recording unit ex 400. The above-described reading and writing processes are realized by the system control unit ex407 by generating and adding new information as necessary by using various information held in the buffer ex404 and by performing recording and reproduction of information by the optical head ex401 while causing the modulation and recording unit ex402, the reproduction and demodulation unit ex403, and the servo control unit ex406 to operate in cooperation. The system control unit ex407 is constituted by, for example, a microprocessor, and executes processing of reading and writing programs.

The above description has been made on the assumption that the optical head ex401 irradiates a laser spot, but a configuration for performing high-density recording using near-field light is also possible.

Fig. 20 shows a schematic diagram of a recording medium ex215 as an optical disc. On the recording surface of the recording medium ex215, a guide groove (groove) is formed in a spiral shape, and in the information track ex230, address information indicating an absolute position on the disc is recorded in advance by a change in the shape of the groove. The address information includes information for specifying the position of the recording block ex231, which is a unit of recording data, and the recording block can be specified by reading the address information by reproducing the information track ex230 in the recording and reproducing apparatus. The recording medium ex215 includes a data recording area ex233, an inner peripheral area ex232, and an outer peripheral area ex 234. The area used for recording the user data is the data recording area ex233, and the inner circumference area ex232 and the outer circumference area ex234 which are disposed on the inner circumference or the outer circumference of the data recording area ex233 are used for a specific purpose other than recording of the user data. The information reproducing/recording unit ex400 reads and writes encoded audio data, video data, or encoded data in which these data are multiplexed, to the data recording area ex233 of the recording medium ex 215.

While the optical disc such as DVD and BD having 1 layer has been described above as an example, the optical disc is not limited to this, and may have a multilayer structure and be capable of recording on a surface other than the surface. Further, the optical disc may have a structure for performing multi-dimensional recording/reproduction, such as recording information using light of different wavelengths and colors in the same area of the disc, or recording different information layers from various angles.

In the digital broadcasting system ex200, the vehicle ex210 having the antenna ex205 may receive data from the satellite ex202 or the like, and the display device such as the car navigation system ex211 included in the vehicle ex210 may reproduce a moving image. The car navigation system ex211 may have a configuration in which a GPS receiver is added to the configuration shown in fig. 18, for example, and the same configuration may be considered for the computer ex111 and the mobile phone ex 114.

Fig. 21A is a diagram showing a mobile phone ex114 that uses the moving picture decoding method and the moving picture coding method described in the above embodiments. The cellular phone ex114 includes an antenna ex350 for transmitting and receiving radio waves to and from the base station ex110, a camera unit ex365 capable of capturing video and still images, and a display unit ex358 such as a liquid crystal display for displaying decoded data such as video captured by the camera unit ex365 and video received by the antenna ex 350. The cellular phone ex114 further includes a main body unit including an operation key unit ex366, a voice output unit ex357 such as a speaker for outputting voice, a voice input unit ex356 such as a microphone for inputting voice, a memory unit ex367 for storing coded data or decoded data of captured video, still image, or recorded voice, or received video, still image, or mail, or an insertion slot 364 serving as an interface unit with a recording medium for storing data in the same manner.

Further, a configuration example of the cellular phone ex114 will be described with reference to fig. 21B. The mobile phone ex114 connects a power supply circuit unit ex361, an operation input control unit ex362, a video signal processing unit ex355, a camera interface unit ex363, an LCD (liquid crystal Display) control unit ex359, a modulation/demodulation unit ex352, a multiplexing/demultiplexing unit ex353, an audio signal processing unit ex354, a slot unit 364, and a memory unit ex367 to a main control unit ex360 that integrally controls each unit of a main body including a Display unit ex358 and an operation key unit ex366, via a bus ex 370.

When the user operates the power supply circuit unit ex361 to turn on the power key and to terminate a call, the mobile phone ex114 is activated to be operable by supplying power from the battery pack to each unit.

The cellular phone ex114 converts an audio signal collected by the audio input unit ex356 into a digital audio signal by the audio signal processing unit ex354, performs spectrum spreading processing on the digital audio signal by the modulation/demodulation unit ex352, performs digital-to-analog conversion processing and frequency conversion processing by the transmission/reception unit ex351, and transmits the digital audio signal via the antenna ex350 in the voice call mode under the control of the main control unit ex360 having a CPU, a ROM, a RAM, and the like. In the voice call mode, the cellular phone ex114 amplifies the received data received by the antenna ex350, performs frequency conversion processing and analog-to-digital conversion processing, performs spectrum inverse diffusion processing by the modulation/demodulation unit ex352, converts the data into analog voice data by the voice signal processing unit ex354, and outputs the analog voice data via the voice output unit ex 357.

Further, when an electronic mail is transmitted in the data communication mode, text data of the electronic mail input by an operation of the operation key unit ex366 or the like of the main body unit is transmitted to the main control unit ex360 via the operation input control unit ex 362. The main control unit ex360 performs spectrum spreading processing on the text data by the modulation/demodulation unit ex352, performs digital-to-analog conversion processing and frequency conversion processing by the transmission/reception unit ex351, and transmits the data to the base station ex110 via the antenna ex 350. When receiving the electronic mail, the received data is subjected to the process substantially inverse to the above process, and is output to the display unit ex 358.

In the data communication mode, when transmitting a video, a still image, or a video and a sound, the video signal processing unit ex355 performs compression coding on the video signal supplied from the camera unit ex365 by the moving image coding method described in each of the above embodiments (that is, functions as an image coding device according to an aspect of the present invention), and sends the coded video data to the multiplexing/demultiplexing unit ex 353. The audio signal processing unit ex354 encodes an audio signal collected by the audio input unit ex356 during shooting of a video, a still image, or the like by the camera unit ex365, and sends the encoded audio data to the multiplexing/demultiplexing unit ex 353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded video data supplied from the video signal processing unit ex355 and the coded audio data supplied from the audio signal processing unit ex354 in a predetermined manner, performs spectrum spreading processing on the resulting multiplexed data by a modulation/demodulation unit (modulation/demodulation circuit unit) ex352, performs digital-to-analog conversion processing and frequency conversion processing by the transmission/reception unit ex351, and transmits the result via the antenna ex 350.

When receiving data of a moving image file linked to a homepage or the like in the data communication mode, or when receiving an e-mail to which a video or audio is attached, the multiplexing/demultiplexing unit ex353 demultiplexes the multiplexed data into a bit stream of video data and a bit stream of audio data by demultiplexing the multiplexed data, supplies the encoded video data to the video signal processing unit ex355 and the encoded audio data to the audio signal processing unit ex354, respectively, in order to decode the multiplexed data received via the antenna ex 350. The video signal processing unit ex355 decodes the video signal by a video decoding method corresponding to the video encoding method described in each of the above embodiments (that is, functions as a video decoding apparatus according to an aspect of the present invention), and displays, for example, a video or a still image included in a video file linked to a home page from the display unit ex358 via the LCD control unit ex 359. The audio signal processing unit ex354 decodes the audio signal, and the audio output unit ex357 outputs the audio signal.

Similarly to the television ex300, the terminal such as the mobile phone ex114 may be 3 types of mounting types, i.e., a transmission terminal having only an encoder and a reception terminal having only a decoder, in addition to a transmission/reception type terminal having both an encoder and a decoder. In addition, in the digital broadcasting system ex200, the explanation has been made on the transmission and reception of multiplexed data obtained by multiplexing music data and the like with video data, but data such as character data and the like associated with video may be multiplexed in addition to audio data, and video data itself may be used instead of multiplexed data.

As described above, the moving image encoding method or the moving image decoding method described in each of the above embodiments can be applied to any of the above-described apparatuses and systems, and thus the effects described in each of the above embodiments can be obtained.

The present invention is not limited to the above-described embodiments, and various modifications and corrections can be made without departing from the scope of the present invention.

(embodiment mode 3)

The video data may be generated by appropriately switching the video encoding method or apparatus described in each of the above embodiments and the video encoding method or apparatus conforming to a standard different from MPEG-2, MPEG 4-AVC, VC-1, or the like, as necessary.

Here, when a plurality of pieces of video data conforming to different standards are generated, it is necessary to select a decoding method corresponding to each standard at the time of decoding. However, since it is not possible to identify which standard the video data to be decoded is based on, there is a problem that an appropriate decoding method cannot be selected.

In order to solve this problem, multiplexed data in which audio data and the like are multiplexed with video data is configured to include identification information indicating which standard the video data conforms to. Hereinafter, a specific configuration of multiplexed data including video data generated by the moving image encoding method or apparatus described in each of the above embodiments will be described. The multiplexed data is a digital stream in the form of an MPEG-2 transport stream.

Fig. 22 is a diagram showing a structure of multiplexed data. As shown in fig. 22, the multiplexed data is obtained by multiplexing 1 or more of a video stream, an audio stream, a presentation graphics stream (PG), and an interactive graphics stream. The video stream represents main video and sub-video of a movie, the audio stream (IG) represents a main audio portion of the movie and sub-audio mixed with the main audio, and the presentation graphics stream represents subtitles of the movie. Here, the main video is a normal video displayed on the screen, and the sub-video is a video displayed on a smaller screen in the main video. The interactive graphics stream represents a dialog screen created by arranging GUI components on the screen. The video stream is encoded by the video encoding method or apparatus described in the above embodiments, or by a video encoding method or apparatus conforming to a standard such as conventional MPEG-2, MPEG 4-AVC, or VC-1. The audio stream is encoded by Dolby AC-3, Dolby Digital Plus, MLP, DTS-HD, or linear PCM, etc.

Each stream contained in the multiplexed data is identified by a PID. For example, 0x1011 is assigned to a video stream used in the movie picture, 0x1100 to 0x111F is assigned to an audio stream, 0x1200 to 0x121F is assigned to presentation graphics, 0x1400 to 0x141F is assigned to interactive graphics streams, 0x1B00 to 0x1B1F is assigned to a video stream used in the movie sub-picture, and 0x1a00 to 0x1A1F is assigned to an audio stream used in the sub-sound mixed with the main sound.

Fig. 23 is a diagram schematically showing how multiplexed data is multiplexed. First, a video stream ex235 composed of a plurality of video frames and an audio stream ex238 composed of a plurality of audio frames are converted into PES packet sequences ex236 and ex239, respectively, and converted into TS packets ex237 and ex 240. Similarly, the data of the presentation graphics stream ex241 and the interactive graphics stream ex244 are converted into PES packet sequences ex242 and ex245, and further into TS packets ex243 and ex 246. The multiplexed data ex247 is formed by multiplexing these TS packets into 1 stream.

Fig. 24 shows in more detail how the video stream is stored in a PES packet sequence. Section 1 of fig. 24 represents a sequence of video frames of a video stream. Segment 2 represents a PES packet sequence. As indicated by arrows yy1, yy2, yy3, and yy4 in fig. 24, a plurality of I pictures, B pictures, and P pictures, which are Video Presentation units, in a Video stream are divided for each picture and stored in the payload of a PES packet. Each PES packet has a PES header, and the PES header stores a PTS (Presentation Time-Stamp) as a picture display Time and a DTS (Decoding Time-Stamp) as a picture Decoding Time.

Fig. 25 shows the format of the TS packet finally written in the multiplexed data. The TS packet is a 188-byte fixed-length packet composed of a 4-byte TS header having information identifying the stream such as PID and a 184-byte TS payload storing data, and the PES packet is divided and stored in the TS payload. In the case of a BD-ROM, 4 bytes of TP _ Extra _ Header are added to TS packets, and 192 bytes of source packets are formed and written in multiplexed data. Information such as ATS (Arrival _ Time _ Stamp) is described in TP _ Extra _ Header. ATS indicates the start time of transfer of the TS packet to the PID filter of the decoder. In the multiplexed data, source packets are arranged as shown in the lower part of fig. 25, and the number incremented from the head of the multiplexed data is called SPN (source packet number).

In addition to the respective streams such as video, audio, and subtitle, TS packets included in multiplexed data include pat (program Association table), pmt (program Map table), pcr (program clock reference), and the like. The PAT indicates what the PID of the PMT used in the multiplexed data is, and the PID of the PAT itself is registered as 0. The PMT has PIDs of streams such as video, audio, and subtitles included in the multiplexed data, attribute information of the streams corresponding to the PIDs, and various descriptors for the multiplexed data. In the descriptor, there are copy control information indicating permission/non-permission of copying of multiplexed data and the like. The PCR has information on the STC Time corresponding to the ATS to which the PCR packet is transferred to the decoder in order to synchronize the atc (arrival Time clock) which is the Time axis of the ATS with the STC (system Time clock) which is the Time axis of the PTS and the DTS.

Fig. 26 is a diagram illustrating the data structure of the PMT in detail. At the head of the PMT, a PMT head describing the length of data included in the PMT is arranged. Thereafter, a plurality of descriptors for the multiplexed data are arranged. The copy control information and the like are described as descriptors. After the descriptor, a plurality of stream information on each stream contained in the multiplexed data is configured. The stream information is composed of a stream descriptor in which stream type, PID of the stream, and attribute information (frame rate, aspect ratio, and the like) of the stream are described for identifying a compression codec of the stream. The stream descriptor indicates the number of streams present in the multiplexed data.

In the case of recording in a recording medium or the like, the above-mentioned multiplexed data is recorded together with a multiplexed data information file.

As shown in fig. 27, the multiplexed data information file is management information of multiplexed data, corresponds one-to-one to the multiplexed data, and is composed of multiplexed data information, stream attribute information, and an entry map.

As shown in fig. 27, the multiplexed data information includes a system rate, a playback start time, and a playback end time. The system rate indicates a maximum transfer rate of the multiplexed data to a PID filter of a system target decoder described later. The interval of ATS included in the multiplexed data is set to be equal to or less than the system rate. The reproduction start time is the PTS of the first video frame of the multiplexed data, and the reproduction end time is set to a value obtained by adding a reproduction interval corresponding to 1 frame to the PTS of the last video frame of the multiplexed data.

As shown in fig. 28, the stream attribute information is registered for each PID, and attribute information on each stream included in the multiplexed data is registered. The attribute information has information that differs according to video stream, audio stream, presentation graphics stream, and interactive graphics stream. The video stream attribute information includes information on what compression codec the video stream is compressed by, what resolution, what aspect ratio, what frame rate each picture data constituting the video stream is, and the like. The audio stream attribute information has information of what compression codec the audio stream is compressed by, what the number of channels included in the audio stream is, what language corresponds to, what sampling frequency is, and the like. This information is used in initialization of the decoder and the like before reproduction by the player.

In the present embodiment, the stream type included in the PMT in the multiplexed data is used. Further, in the case where multiplexed data is recorded in the recording medium, video stream attribute information contained in the multiplexed data information is used. Specifically, the moving picture coding method or apparatus described in each of the above embodiments includes a step or means for setting specific information indicating that the specific information is the video data generated by the moving picture coding method or apparatus described in each of the above embodiments, for the stream type or video stream attribute information included in the PMT. With this configuration, it is possible to identify video data generated by the video encoding method or apparatus described in each of the above embodiments and video data conforming to another standard.

Fig. 29 shows the steps of the moving picture decoding method according to the present embodiment. In step exS100, the stream type included in the PMT or the video stream attribute information included in the multiplexed data information is acquired from the multiplexed data. Next, in step exS101, it is determined whether or not the stream type or the video stream attribute information indicates that the multiplexed data is generated by the moving picture encoding method or apparatus described in each of the above embodiments. When it is determined that the stream type or the video stream attribute information is the multiplexed data generated by the moving picture encoding method or apparatus described in each of the above embodiments, the decoding is performed by the moving picture decoding method described in each of the above embodiments in step exS 102. When the stream type or the video stream attribute information indicates that the data is multiplexed in accordance with the standard such as the conventional MPEG-2, MPEG 4-AVC, or VC-1, the data is decoded in step exS103 by a moving picture decoding method in accordance with the conventional standard.

In this way, by setting a new unique value in the stream type or the video stream attribute information, it is possible to determine whether or not decoding is possible by the moving picture decoding method or device described in each of the above embodiments at the time of decoding. Therefore, even when multiplexed data according to different standards is input, an appropriate decoding method or device can be selected, and thus decoding can be performed without errors. Further, the moving image encoding method or apparatus or the moving image decoding method or apparatus shown in this embodiment mode is used in any of the above-described devices and systems.

(embodiment mode 4)

The moving image encoding method and apparatus and the moving image decoding method and apparatus described in the above embodiments can be typically realized by an LSI which is an integrated circuit. Fig. 30 shows, as an example, a structure of 1-chip LSIex 500. The LSIex500 includes units ex501, ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509, which will be described below, and the units are connected via a bus ex 510. The power supply circuit unit ex505 is started to be operable by supplying power to each unit when the power supply is in the on state.

For example, when performing encoding processing, the LSIex500 inputs AV signals from the microphone ex117, the camera ex113, and the like via the AV I/Oex509 under the control of the control unit ex501 including the CPUex502, the memory controller ex503, the flow controller ex504, the drive frequency control unit ex512, and the like. The input AV signal is temporarily stored in an external memory ex511 such as an SDRAM. The stored data is divided into a plurality of times as appropriate according to the processing amount and the processing speed under the control of the control unit ex501, and is transmitted to the signal processing unit ex507, and the signal processing unit ex507 performs coding of an audio signal and/or coding of a video signal. Here, the encoding process of the video signal is the encoding process described in each of the above embodiments. The signal processing unit ex507 also performs processing such as multiplexing of the encoded audio data and the encoded video data, as the case may be, and outputs the multiplexed data from the stream I/Oex506 to the outside. The output bit stream is transmitted to the base station ex107 or written to the recording medium ex 215. In addition, at the time of multiplexing, data may be temporarily stored in the buffer ex508 to be synchronized.

In the above description, the memory ex511 is described as being external to the LSIex500, but may be included in the LSIex 500. The buffer ex508 is not limited to one, and a plurality of buffers may be provided. In addition, LSIex500 may form 1 chip or may form a plurality of chips.

In the above description, the control unit ex501 includes the CPUex502, the memory controller ex503, the flow controller ex504, the drive frequency control unit ex512, and the like, but the configuration of the control unit ex510 is not limited to this configuration. For example, the signal processing unit ex507 may further include a CPU. The CPU is also provided in the signal processing unit ex507, whereby the processing speed can be further increased. As another example, the CPUex502 may include the signal processing unit ex507, or may include, for example, an audio signal processing unit as a part of the signal processing unit ex 507. In this case, the control unit ex501 has a structure including the CPUex502 having the signal processing unit ex507 or a part thereof.

Here, although LSI is used, depending on the difference in the degree of integration, IC, system LSI, super LSI, and extra LSI may be used.

The method of forming an integrated circuit is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. An fpga (field Programmable Gate array) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure connection and setting of circuit cells inside LSI may be used.

Furthermore, if a technique for realizing an integrated circuit instead of the LSI appears due to the progress of the semiconductor technology or another derivative technique, it is needless to say that the functional blocks may be integrated using this technique. Possibly biotechnological applications, etc.

(embodiment 5)

In the case of decoding video data generated by the video encoding method or apparatus described in each of the above embodiments, it is considered that the amount of processing increases compared to the case of decoding video data conforming to the standard of conventional MPEG-2, MPEG 4-AVC, VC-1, or the like. Therefore, the LSIex500 needs to be set to a drive frequency higher than the drive frequency of the CPUex502 when decoding video data according to the conventional standard. However, if the driving frequency is set high, a problem occurs in that the power consumption becomes high.

In order to solve this problem, the moving picture decoding apparatuses such as the television ex300 and the LSIex500 recognize which standard the video data conforms to, and switch the driving frequency according to the standard. Fig. 31 shows a configuration ex800 of the present embodiment. The drive frequency switching unit ex803 sets the drive frequency to be high when the video data is generated by the moving image coding method or device described in each of the above embodiments. Then, the decoding processing unit ex801 that executes the moving picture decoding method described in each of the above embodiments instructs the decoding of the video data. On the other hand, when the video data is video data conforming to the conventional standard, the driving frequency is set to be lower than when the video data is data generated by the moving image encoding method or apparatus described in each of the above embodiments. Then, the decoding processing unit ex802 compliant with the conventional standard is instructed to decode the video data.

More specifically, the drive frequency switching unit ex803 is composed of the CPUex502 and the drive frequency control unit ex512 in fig. 30. The decoding processing unit ex801 that executes the moving picture decoding method described in each of the above embodiments and the decoding processing unit ex802 that conforms to the conventional standard correspond to the signal processing unit ex507 in fig. 30. The CPUex502 identifies which standard the image data is based on. Then, based on the signal from the CPUex502, the drive frequency control unit ex512 sets the drive frequency. Further, the signal processing unit ex507 decodes the video data based on the signal from the CPUex 502. Here, it is conceivable to use the identification information described in embodiment 3, for example, for identification of video data. The identification information is not limited to the information described in embodiment 3, and may be any information that can identify to which standard the video data conforms. For example, when it is possible to identify which standard the video data conforms to based on an external signal that identifies whether the video data is used for a television or a disk, the identification may be performed based on such an external signal. The selection of the driving frequency of the CPUex502 may be performed, for example, by considering a lookup table in which the standard of the video data is associated with the driving frequency as shown in fig. 33. The lookup table is stored in advance in the buffer ex508 or an internal memory of the LSI, and the CPUex502 can select the drive frequency by referring to the lookup table.

Fig. 32 shows a procedure for carrying out the method of the present embodiment. First, in step exS200, the signal processing unit ex507 acquires identification information from the multiplexed data. Next, in step exS201, the CPUex502 identifies whether or not the video data is data generated by the encoding method or apparatus described in each of the above embodiments, based on the identification information. When the video data is generated by the encoding method or the encoding device described in each of the above embodiments, in step exS202, the CPUex502 transmits a signal for setting the driving frequency to be high to the driving frequency control unit ex 512. Then, the drive frequency control unit ex512 sets a high drive frequency. On the other hand, when video data conforming to the standards of conventional MPEG-2, MPEG 4-AVC, VC-1, and the like is shown, in step exS203, the CPUex502 transmits a signal for setting the drive frequency low to the drive frequency control unit ex 512. The drive frequency control unit ex512 is set to a drive frequency lower than that in the case where the video data is generated by the encoding method or the encoding device described in each of the above embodiments.

Further, by changing the voltage applied to the LSIex500 or the device including the LSIex500 in conjunction with the switching of the driving frequency, the power saving effect can be further improved. For example, when the driving frequency is set to be low, it is conceivable that the voltage applied to the LSIex500 or the device including the LSIex500 is set to be lower than when the driving frequency is set to be high.

The method of setting the drive frequency is not limited to the above-described setting method, as long as the drive frequency is set to be high when the processing amount at the time of decoding is large, and the drive frequency is set to be low when the processing amount at the time of decoding is small. For example, when the processing amount for decoding the video data conforming to the MPEG 4-AVC standard is larger than the processing amount for decoding the video data generated by the moving picture coding method or device described in each of the above embodiments, it is conceivable to set the driving frequency in the reverse manner to the above case.

Further, the method of setting the drive frequency is not limited to the configuration of making the drive frequency low. For example, it is also conceivable that the voltage applied to LSIex500 or a device including LSIex500 is set high when the identification information is video data generated by the moving picture coding method or device described in each of the above embodiments, and the voltage applied to LSIex500 or a device including LSIex500 is set low when video data conforming to the conventional standards such as MPEG-2, MPEG 4-AVC, and VC-1 is indicated. As another example, it is also conceivable that the drive of the CPUex502 is not stopped when the identification information indicates that the video data is generated by the video encoding method or apparatus described in each of the above embodiments, but the drive of the CPUex502 is suspended when the identification information indicates that the video data is compliant with the standard such as the conventional MPEG-2, MPEG 4-AVC, or VC-1, because there is a margin in the processing. Even when the identification information indicates that the video data is generated by the moving picture coding method or device described in each of the above embodiments, it is conceivable to suspend the driving of the CPUex502 as long as there is a margin in the processing. In this case, it is conceivable to set the stop time shorter than in the case of video data according to the standard of conventional MPEG-2, MPEG 4-AVC, VC-1, or the like.

In this way, power saving can be achieved by switching the driving frequency according to the standard to which the image data is based. Further, in the case of driving the LSIex500 or a device including the LSIex500 using a battery, the life of the battery can be extended with power saving.

(embodiment mode 6)

In the above-described devices and systems such as a television and a mobile phone, a plurality of pieces of video data conforming to different standards may be input. In this way, in order to enable decoding even when a plurality of video data conforming to different standards are input, the signal processing unit ex507 of the LSIex500 needs to correspond to the plurality of standards. However, if the signal processing units ex507 corresponding to the respective standards are used individually, the LSIex500 has a problem that the circuit scale becomes large and the cost increases.

In order to solve this problem, a decoding processing unit for executing the moving picture decoding method described in each of the above embodiments and a decoding processing unit conforming to the standard of conventional MPEG-2, MPEG 4-AVC, VC-1, or the like are partially shared. Ex900 in fig. 34A shows this configuration example. For example, the moving image decoding method described in each of the above embodiments and the moving image decoding method conforming to the MPEG 4-AVC standard share some processing contents in the processes of entropy encoding, inverse quantization, deblocking filter, motion compensation, and the like. The following structure can be considered: the decoding processing unit ex902 corresponding to the MPEG 4-AVC standard is used in common for common processing contents, and the dedicated decoding processing unit ex901 is used for other processing contents unique to an embodiment of the present invention not corresponding to the MPEG 4-AVC standard. The common use of the decoding processing unit may be configured as follows: the common processing contents are those obtained by sharing a decoding processing unit for executing the moving picture decoding method described in each of the above embodiments, and the processing contents specific to the MPEG 4-AVC standard are those obtained by using a dedicated decoding processing unit.

Another example in which a part of the processing is shared is shown in ex1000 of fig. 34B. In this example, a configuration is adopted in which a dedicated decoding processing unit ex1001 corresponding to processing contents unique to one embodiment of the present invention, a dedicated decoding processing unit ex1002 corresponding to processing contents unique to another conventional standard, and a common decoding processing unit ex1003 corresponding to processing contents common to a moving image decoding method according to one embodiment of the present invention and a moving image decoding method according to another conventional standard are used. Here, the dedicated decoding processing units ex1001 and ex1002 are not necessarily specialized for the processing contents specific to one embodiment of the present invention or other conventional standards, and may be configured to be able to execute other general-purpose processing. The configuration of the present embodiment may be attached to LSIex 500.

As described above, the video decoding method according to one embodiment of the present invention and the conventional standard video decoding method share the common processing contents of the decoding processing unit, thereby reducing the circuit scale of the LSI and reducing the cost.

The image encoding method and the image decoding method according to one or more aspects have been described above based on the embodiments, but the present invention is not limited to the embodiments. The present invention may be embodied in various forms, such as a modified form, or a form constructed by combining constituent elements of different embodiments, which are conceivable by those skilled in the art, without departing from the spirit of the present invention.

Industrial applicability

The present invention can be applied to, for example, an image encoding device, an image decoding device, and the like, and more specifically, to information display devices and imaging devices such as televisions, digital video cameras, car navigation systems, mobile phones, digital still cameras, and digital video cameras.

Description of the reference symbols

10. 100 image coding device

20. 200 image decoding device

21 signal interval setting unit

22 DTS acquisition unit

23 determination unit

24 decoding unit

101 determination part

102 coding part

103 generation part

201 acquisition unit

202 decoding unit