阅读说明：本技术 用于帧内预测模式与块差分脉冲编码调制模式之间交互的方法和装置 (Method and apparatus for interaction between intra prediction mode and block differential pulse code modulation mode ) 是由 赵欣 李翔 赵亮 刘杉 于 2020-04-30 设计创作，主要内容包括：一种在视频解码器中执行的视频解码方法,包括：确定是否使用块差分脉冲编码调制(BDPCM)模式对与第二块相关联的第一块进行编码。方法进一步包括：响应于确定使用BDPCM模式对第一块进行编码,基于BDPCM方向标志将第一块与帧内预测模式值相关联。方法进一步包括：使用与第一块相关联的帧内预测模式值来确定针对第二块的帧间预测模式值。方法进一步包括：使用所确定的帧内预测模式值对第二块进行重建。(A video decoding method performed in a video decoder, comprising: a determination is made whether to encode a first block associated with a second block using a Block Differential Pulse Code Modulation (BDPCM) mode. The method further comprises the following steps: in response to determining to encode the first block using the BDPCM mode, the first block is associated with an intra-prediction mode value based on the BDPCM direction flag. The method further comprises the following steps: an intra-prediction mode value associated with the first block is used to determine an inter-prediction mode value for the second block. The method further comprises the following steps: reconstructing the second block using the determined intra prediction mode value.)

1. A video decoding method performed in a video decoder, the method comprising:

determining whether to encode a first block using a Block Differential Pulse Code Modulation (BDPCM) mode, the first block associated with a second block;

in response to determining to encode the first block with the BDPCM mode, associating the first block with an intra-prediction mode value based on a BDPCM direction flag;

determining an inter prediction mode value for the second block using the intra prediction mode value associated with the first block; and

reconstructing the second block using the determined intra prediction mode value.

2. The method of claim 1, wherein the BDPCM direction flag is one of:

(i) a first value associated with a horizontal intra prediction direction mode; and

(ii) a second value associated with a vertical intra prediction direction mode.

3. The method of claim 2, wherein the total number of intra prediction modes is 67, wherein the horizontal intra prediction direction mode is associated with angular mode 18 and the vertical intra prediction direction mode is associated with angular mode 50.

4. The method of claim 1, wherein determining whether to encode the first block using the BDPCM mode is based on a value of a BDPCM flag indicating a presence of the BDPCM direction flag.

5. The method of claim 1, wherein the first block and the second block are included in a same picture, and the first block is spatially adjacent to the second block.

6. The method of claim 5, further comprising:

for the second block, deriving a candidate list using a Most Probable Mode (MPM) derivation process, the derivation process comprising: determining whether to encode the first block using the BDPCM mode, wherein,

determining the inter-prediction mode value for the second block further comprises: the derived candidate list is used.

7. The method of claim 6, wherein the candidate list comprises:

a first candidate intra prediction Mode value Mode corresponding to the intra prediction Mode of the first block₁(ii) a And

a second candidate intra prediction Mode value Mode determined according to a predetermined offset from the first candidate intra prediction Mode value and a remainder on M₂And a third candidate intra prediction Mode value Mode₃Where M is a power of 2.

8. The method of claim 1, wherein the second block is a chroma block and the first block is a luma block co-located with the chroma block.

9. The method of claim 8, further comprising:

determining whether the second block is encoded using a direct copy mode (DM); and

in response to determining to encode the second block with the direct copy mode, determining whether to encode the first block using the BDPCM mode.

10. A video decoder for video decoding, comprising:

a processing circuit configured to:

determining whether to encode a first block using a Block Differential Pulse Code Modulation (BDPCM) mode, the first block associated with a second block;

in response to determining to encode the first block with the BDPCM mode, associating the first block with an intra-prediction mode value based on a BDPCM direction flag;

determining an inter prediction mode value for the second block using the intra prediction mode value associated with the first block; and

reconstructing the second block using the determined intra prediction mode value.

11. The video decoder of claim 10, wherein the BDPCM direction flag is one of:

(i) a first value associated with a horizontal intra prediction direction mode; and

(ii) a second value associated with a vertical intra prediction direction mode.

12. The video decoder of claim 11, wherein the total number of intra-prediction modes is 67, wherein the horizontal intra-prediction direction mode is associated with angular mode 18 and the vertical intra-prediction direction mode is associated with angular mode 50.

13. The video decoder of claim 10, wherein determining whether to encode the first block using the BDPCM mode is based on a value of a BDPCM flag indicating a presence of the BDPCM direction flag.

14. The video decoder of claim 10, wherein the first block and the second block are included in the same picture, and the first block is spatially adjacent to the second block.

15. The video decoder of claim 14, wherein the processing circuit is further configured to:

for the second block, deriving a candidate list using a Most Probable Mode (MPM) derivation process, the derivation process comprising: determining whether to encode the first block using the BDPCM mode, wherein,

determining the inter-prediction mode value for the second block further comprises: the derived candidate list is used.

16. The video decoder of claim 15, wherein the candidate list comprises:

and the above-mentionedA first candidate intra prediction Mode value Mode corresponding to the intra prediction Mode of the first block₁(ii) a And

a second candidate intra prediction Mode value Mode determined according to a predetermined offset from the first candidate intra prediction Mode value and a remainder on M₂And a third candidate intra prediction Mode value Mode₃Where M is a power of 2.

17. The video decoder of claim 10, wherein the second block is a chroma block and the first block is a luma block that is co-located with the chroma block.

18. The video decoder of claim 17, wherein the processing circuit is further configured to:

determining whether the second block is encoded using a direct copy mode (DM); and

in response to determining to encode the second block with the direct copy mode, determining whether to encode the first block using the BDPCM mode.

19. A non-transitory computer readable medium storing instructions that, when executed by a processor in a video decoder, cause the video decoder to perform a method comprising:

determining whether to encode a first block using a Block Differential Pulse Code Modulation (BDPCM) mode, the first block associated with a second block;

in response to determining to encode the first block with the BDPCM mode, associating the first block with an intra-prediction mode value based on a BDPCM direction flag;

determining an inter prediction mode value for the second block using the intra prediction mode value associated with the first block; and

reconstructing the second block using the determined intra prediction mode value.

20. The non-transitory computer-readable medium of claim 19, wherein the BDPCM direction flag is one of:

(i) a first value associated with a horizontal intra prediction direction mode; and

(ii) a second value associated with a vertical intra prediction direction mode.

Technical Field

The present disclosure describes embodiments that relate generally to video encoding.

Background

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Video encoding and decoding may be performed using inter-picture prediction with motion compensation. Uncompressed digital video may comprise a series of pictures, each picture having spatial dimensions of, for example, 1920 x 1080 luma samples and associated chroma samples. The series of pictures may have a fixed or variable picture rate (also informally referred to as frame rate), for example 60 pictures per second or 60 Hz. Uncompressed video has very high bit rate requirements. For example, at 8 bits per sample, 1080p 604: 2: a video of 0 (with 1920 x 1080 luminance sample resolution at 60Hz frame rate) requires a bandwidth close to 1.5 Gbit/s. An hour of such video requires more than 600GB of storage space.

One purpose of video encoding and decoding may be to reduce redundancy in the input video signal by compression. Compression may help reduce the bandwidth or storage requirements described above, in some cases by two orders of magnitude or more. Lossless compression and lossy compression, and combinations thereof, may be employed. Lossless compression refers to a technique by which an exact copy of an original signal can be reconstructed from a compressed original signal. When lossy compression is used, the reconstructed signal may be different from the original signal, but the distortion between the original signal and the reconstructed signal is small enough that the reconstructed signal is useful for the intended application. In the case of video, lossy compression is widely used. The amount of distortion that can be tolerated depends on the application; for example, some users consuming streaming applications may tolerate higher distortion than users consuming television distribution applications. The achievable compression ratio may reflect: higher allowable/tolerable distortion may result in higher compression rates.

Video encoders and decoders may utilize techniques from several broad categories, including, for example, motion compensation, transform, quantization, and entropy coding.

Video codec techniques may include a technique referred to as intra-coding. In intra coding, sample values are represented without reference to samples or other data from previously reconstructed reference pictures. In some video codecs, a picture is spatially subdivided into blocks of samples. When all sample blocks are encoded in intra mode, the picture may be an intra picture. Intra pictures and their derivatives (e.g., independent decoder refresh pictures) can be used to reset the decoder state and thus can be used as the first picture in an encoded video bitstream and video session, or as still images. Samples of an intra block may be exposed to a transform, and the transform coefficients may be quantized prior to entropy encoding. Intra prediction may be a technique that minimizes sample values in the pre-transform domain. In some cases, the smaller the DC value after transform and the smaller the AC coefficient, the fewer bits are needed to represent the block after entropy encoding at a given quantization step.

Conventional intra-frame coding (e.g., intra-frame coding known from, for example, MPEG-2 generation coding techniques) does not use intra-prediction. However, some newer video compression techniques include techniques that attempt from, for example, surrounding sample data and/or metadata obtained during spatially adjacent encoding/decoding and decoding order preceding the data block. This technique is hereinafter referred to as an "intra prediction" technique. It is noted that in at least some cases, intra prediction only uses reference data from the current picture being reconstructed, and not reference data from the reference picture.

There may be many different forms of intra prediction. When more than one such technique is available in a given video encoding technique, the technique used may be encoded in intra-prediction mode. In some cases, a mode may have sub-modes and/or parameters, and the mode may be encoded separately or included in a mode codeword. Which codeword is used for a given mode/sub-mode/parameter combination may have an impact on the coding efficiency gain through intra-prediction, and entropy coding techniques may also be used to convert the codeword into a bitstream.

Some intra prediction modes are introduced with h.264, improved in h.265, and further improved in newer coding techniques such as joint detection model (JEM), next generation video coding (VVC), and reference set (BMS). The predictor block may be formed using neighboring sample values belonging to existing available samples. The sample values of adjacent samples are copied into the predictor block according to the direction. The reference to the direction in use may be encoded in the bitstream or may itself be predicted.

Referring to fig. 1A, a subset of 9 prediction directions known from the 33 possible prediction directions of h.265 (33 angular modes corresponding to 35 intra modes) is depicted in the bottom right. The point (101) where the arrows converge represents the predicted sample. The arrows indicate the direction along which the samples are predicted. For example, arrow (102) indicates that the sample (101) is predicted from one or more samples at the upper right, 45 degrees to the horizontal direction. Similarly, arrow (103) indicates that the sample (101) is predicted from one or more samples at 22.5 degrees to the horizontal at the lower left of the sample (101).

Still referring to fig. 1, a square block (104) of 4 × 4 samples is depicted at the upper left (indicated by the dashed bold line). The square block (104) includes 16 samples, each labeled with "S", its position in the Y dimension (e.g., row index), and its position in the X dimension (e.g., column index). For example, sample S21 is the second sample in the Y dimension (starting from above) and the first sample in the X dimension (starting from the left). Similarly, sample S44 is the fourth sample in block (104) in the Y and X dimensions. Since the block size is 4 × 4 samples, S44 is located at the lower right corner. Reference samples following a similar numbering scheme are also shown. The reference sample is labeled with R, its Y position (e.g., row index) and X position (column index) relative to block (104). In both h.264 and h.265, the prediction samples are adjacent to the block being reconstructed; therefore, negative values need not be used.

Intra picture prediction can work by copying reference sample values from neighboring samples suitable for the signaled prediction direction. For example, assume that the encoded video bitstream comprises signaling indicating for the block a prediction direction coinciding with the arrow (102), i.e. predicting samples from one or more prediction samples at an angle of 45 degrees to the horizontal direction, at the upper right. In that case, samples S41, S32, S23 and S14 are predicted from the same reference sample R05. Samples S44 are then predicted from reference sample R08.

In some cases, the values of multiple reference samples may be combined, for example by interpolation, to compute a reference sample; especially when the directions are not evenly separated by 45 degrees.

As video coding techniques evolve, the number of possible directions increases. In h.264 (2003), nine different directions can be represented. In h.265 (2013), there are an increase to 33 directions, and, as of the present disclosure, JEM/VVC/BMS can support up to 65 directions. Experiments have been performed to identify the most likely directions, and some techniques in entropy coding are used to represent those possible directions with a small number of bits, at the expense of accepting some for the less likely directions. Furthermore, sometimes the direction itself can be predicted from the neighboring directions used in the neighboring blocks that have already been decoded.

Fig. 1B shows intra prediction modes used in HEVC (high performance video coding). In HEVC, there are a total of 35 intra prediction modes, where mode 10 is horizontal mode, mode 26 is vertical mode, and mode2, mode 18, and mode 34 are diagonal modes. The intra prediction mode is signaled by three Most Probable Modes (MPMs) and 32 remaining modes.

Fig. 1C shows an intra prediction mode used in VVC. As shown in fig. 1C, in VVC, there are 95 intra prediction modes in total, in which the mode 18 is the horizontal mode, the mode 50 is the vertical mode, and the mode2, the mode 34, and the mode 66 are the diagonal modes. Modes-1 to-14 and 67 to 80 are referred to as wide-angle intra prediction (WAIP) modes.

The mapping of intra prediction direction bits representing directions in the encoded video bitstream may differ depending on the video coding technique; for example, its range may be simply mapped directly from the prediction direction to intra prediction modes, to codewords, to complex adaptive schemes involving MPM, and similar techniques. In all cases, however, there may be certain directions that are statistically less likely to appear in the video content than certain other directions. Since the goal of video compression is to reduce redundancy, in a well-functioning video coding technique, those unlikely directions will be represented by a larger number of bits than the more likely directions.

Disclosure of Invention

According to an exemplary embodiment, a video decoding method performed in a video decoder includes: it is determined whether a first block associated with a second block is encoded using a Block Differential Pulse Code Modulation (BDPCM) mode. The method further comprises the following steps: in response to determining to encode the first block using the BDPCM mode, the first block is associated with an intra-prediction mode value based on the BDPCM direction flag. The method further comprises the following steps: an intra-prediction mode value associated with the first block is used to determine an inter-prediction mode value for the second block. The method further comprises the following steps: reconstructing the second block using the determined intra prediction mode value.

According to an exemplary embodiment, a video decoder for video decoding comprises a processing circuit configured to: a determination is made whether to encode a first block associated with a second block using a Block Differential Pulse Code Modulation (BDPCM) mode. In response to determining to encode the first block using the BDPCM mode, the processing circuit is further configured to: the first block is associated with an intra prediction mode value based on the BDPCM direction flag. The processing circuit is further configured to: an intra-prediction mode value associated with the first block is used to determine an inter-prediction mode value for the second block. The processing circuit is further configured to: reconstructing the second block using the determined intra prediction mode value.

According to an exemplary embodiment, a non-transitory computer readable medium stores instructions that, when executed by a processor in a video decoder, cause the processor to perform a method comprising: a determination is made whether to encode a first block associated with a second block using a Block Differential Pulse Code Modulation (BDPCM) mode. The method further comprises the following steps: in response to determining to encode the first block using the BDPCM mode, the first block is associated with an intra-prediction mode value based on the BDPCM direction flag. The method further comprises the following steps: an intra-prediction mode value associated with the first block is used to determine an inter-prediction mode value for the second block. The method further comprises the following steps: reconstructing the second block using the determined intra prediction mode value.

Drawings

Other features, properties, and various advantages of the disclosed subject matter will become more apparent from the following detailed description and the accompanying drawings, in which:

FIG. 1A is a diagram of an exemplary subset of intra prediction modes;

fig. 1B is a diagram of exemplary intra prediction directions.

Fig. 1C is a diagram of exemplary intra prediction directions.

Fig. 2 is a schematic diagram of a simplified block diagram of a communication system (200) according to one embodiment.

Fig. 3 is a schematic diagram of a simplified block diagram of a communication system (300) according to one embodiment.

Fig. 4 is a schematic diagram of a simplified block diagram of a decoder according to an embodiment.

FIG. 5 is a schematic diagram of a simplified block diagram of an encoder according to one embodiment.

Fig. 6 shows a block diagram of an encoder according to another embodiment.

Fig. 7 shows a block diagram of a decoder according to another embodiment.

Fig. 8 is a schematic diagram of a current block and its surrounding neighboring blocks.

Fig. 9 is an illustration of an embodiment of a process performed by a decoder.

FIG. 10 is a schematic diagram of a computer system according to an embodiment of the present disclosure.

Detailed Description

Fig. 2 shows a simplified block diagram of a communication system (200) according to one embodiment of the present disclosure. The communication system (200) includes a plurality of terminal devices that can communicate with each other through, for example, a network (250). For example, a communication system (200) includes a first pair of end devices (210) and (220) interconnected by a network (250). In the example of fig. 2, the first terminal apparatus performs unidirectional data transmission to the pair (210) and (220). For example, a terminal device (210) may encode video data, such as a video picture stream captured by the terminal device (210), for transmission over a network (250) to another terminal device (220). The encoded video data may be transmitted in the form of one or more encoded video bitstreams. The terminal device (220) may receive encoded video data from the network (250), decode the encoded video data to recover video pictures, and display the video pictures according to the recovered video data. Unidirectional data transmission is common in applications such as media services.

In another example, the communication system (200) includes a second pair of terminal devices (230) and (240) that perform a bi-directional transmission of encoded video data, which may occur, for example, during a video conference. For bi-directional data transmission, in an example, each of the terminal device (230) and the terminal device (240) may encode video data (e.g., a stream of video pictures captured by the terminal device) for transmission over the network (250) to the other of the terminal device (230) and the terminal device (240). Each of the terminal device (230) and the terminal device (240) may also receive encoded video data transmitted by the other of the terminal device (230) and the terminal device (240), and may decode the encoded video data to recover the video picture, and may display the video picture on an accessible display device according to the recovered video data.

In the example of fig. 2, the terminal device (210), the terminal device (220), the terminal device (230), and the terminal device (240) may be illustrated as a server, a personal computer, and a smart phone, but the principles of the present disclosure may not be limited thereto. Embodiments of the present disclosure are applicable to laptop computers, tablet computers, media players, and/or dedicated video conferencing equipment. Network (250) represents any number of networks that convey encoded video data between terminal device (210), terminal device (220), terminal device (230), and terminal device (240), including, for example, wired (wired) and/or wireless communication networks. The communication network (250) may exchange data in circuit-switched and/or packet-switched channels. Representative networks include telecommunications networks, local area networks, wide area networks, and/or the internet. For purposes of this discussion, the architecture and topology of the network (250) may be immaterial to the operation of the present disclosure, unless explained below.

As an example of an application of the disclosed subject matter, fig. 3 shows the placement of a video encoder and a video decoder in a streaming environment. The disclosed subject matter is equally applicable to other video-enabled applications including, for example, video conferencing, digital TV, storing compressed video on digital media including CDs, DVDs, memory sticks, and the like.

The streaming system may include an acquisition subsystem (313) that may include a video source (301), such as a digital camera, that creates an uncompressed video picture stream (302), for example. In one example, the video picture stream (302) includes samples taken by a digital camera. Compared to encoded video data (304) (or encoded video bitstream), a video picture stream (302) depicted as a thick line to emphasize high data volume may be processed by an electronic device (320) comprising a video encoder (303) coupled to a video source (301). The video encoder (303) may comprise hardware, software, or a combination of hardware and software to implement or embody aspects of the disclosed subject matter as described in more detail below. Encoded video data (304) (or encoded video bitstream (304)) depicted as thin lines to emphasize lower data volumes may be stored on a streaming server (305) for future use as compared to a video picture stream (302). One or more streaming client subsystems, such as client subsystem (306) and client subsystem (308) in fig. 3, may access streaming server (305) to retrieve copies (307) and copies (309) of encoded video data (304). The client subsystem (306) may include, for example, a video decoder (310) in an electronic device (330). A video decoder (310) decodes incoming copies (307) of the encoded video data and generates an output video picture stream (311) that may be presented on a display (312), such as a display screen, or another presentation device (not depicted). In some streaming systems, encoded video data (304), encoded video data (307), and encoded video data (309) (e.g., a video bitstream) may be encoded according to certain video encoding/compression standards. Examples of such standards include ITU-T recommendation H.265. In one example, the Video Coding standard being developed is informally referred to as next generation Video Coding (VVC). The disclosed subject matter may be used in the context of VVCs.

It should be noted that electronic device (320) and electronic device (330) may include other components (not shown). For example, the electronic device (320) may include a video decoder (not shown), and the electronic device (330) may also include a video encoder (not shown).

Fig. 4 shows a block diagram of a video decoder (410) according to one embodiment of the present disclosure. The video decoder (410) may be included in an electronic device (430). The electronic device (430) may include a receiver (431) (e.g., a receive circuit). The video decoder (410) may be used in place of the video decoder (310) in the example of fig. 3.

The receiver (431) may receive one or more encoded video sequences to be decoded by the video decoder (410); in the same or another embodiment, the encoded video sequences are received one at a time, wherein the decoding of each encoded video sequence is independent of the decoding of other encoded video sequences. The encoded video sequence may be received from a channel (401), which may be a hardware/software link to a storage device that stores encoded video data. The receivers (431) may receive encoded video data, as well as other data, such as encoded audio data and/or auxiliary data streams, which may be forwarded to their respective usage entities (not depicted). The receiver (431) may separate the encoded video sequence from other data. To prevent network jitter, a buffer memory (415) may be coupled between the receiver (431) and the entropy decoder/parser (420) (hereinafter "parser (420)"). In some applications, the buffer memory (415) is part of the video decoder (410). In other cases, buffer memory (415) may be disposed external (not depicted) to video decoder (410). While in other cases a buffer memory (not depicted) may be provided external to the video decoder (410), e.g., to prevent network jitter, and another buffer memory (415) may be configured internal to the video decoder (410), e.g., to handle playout timing. When the receiver (431) receives data from a store/forward device with sufficient bandwidth and controllability or from an isochronous network, the buffer memory (415) may not be needed or may be made smaller. In an effort to use over a traffic packet network such as the internet, a buffer memory (415) may be required, which may be relatively large and may advantageously be of an adaptive size, and may be implemented at least partially in an operating system or similar element (not depicted) external to the video decoder (410).

The video decoder (410) may include a parser (420) to reconstruct symbols (421) from the encoded video sequence. The categories of these symbols include information for managing the operation of the video decoder (410), as well as potential information for controlling a presentation device (412) (e.g., a display screen), which is not an integral part of the electronic device (430), but may be coupled to the electronic device (430), as shown in fig. 4. The control Information for the rendering device may be in the form of parameter set fragments (not depicted) of Supplemental Enhancement Information (SEI messages) or Video Usability Information (VUI). The parser (420) may parse/entropy decode the received encoded video sequence. Encoding of the encoded video sequence may be performed in accordance with video coding techniques or standards and may follow various principles, including variable length coding, Huffman coding, arithmetic coding with or without contextual sensitivity, and so forth. A parser (420) may extract a subgroup parameter set for at least one of the subgroups of pixels in the video decoder from the encoded video sequence based on at least one parameter corresponding to the group. A subgroup may include a Group of Pictures (GOP), a picture, a tile, a slice, a macroblock, a Coding Unit (CU), a block, a Transform Unit (TU), a Prediction Unit (PU), and so on. The parser (420) may also extract information from the encoded video sequence, such as transform coefficients, quantizer parameter values, motion vectors, and so on.

The parser (420) may perform entropy decoding/parsing operations on the video sequence received from the buffer memory (415), thereby creating symbols (421).

The reconstruction of the symbol (421) may involve a number of different units depending on the type of the encoded video picture or portion of the encoded video picture (e.g., inter and intra pictures, inter and intra blocks), among other factors. Which units are involved and the way in which they are involved can be controlled by subgroup control information parsed from the coded video sequence by a parser (420). For simplicity, such a subgroup control information flow between parser (420) and a plurality of units below is not depicted.

In addition to the functional blocks already mentioned, the video decoder (410) may be conceptually subdivided into several functional units as described below. In a practical implementation operating under business constraints, many of these units interact closely with each other and may be at least partially integrated with each other. However, for the purposes of describing the disclosed subject matter, a conceptual subdivision into the following functional units is appropriate.

The first unit is a sealer/inverse transform unit (451). The sealer/inverse transform unit (451) receives the quantized transform coefficients as symbols (421) from the parser (420) along with control information including which transform scheme to use, block size, quantization factor, quantization scaling matrix, etc. The sealer/inverse transform unit (451) may output a block comprising sample values, which may be input into the aggregator (455).

In some cases, the output samples of sealer/inverse transform (451) may belong to an intra-coded block; namely: predictive information from previously reconstructed pictures is not used, but blocks of predictive information from previously reconstructed portions of the current picture may be used. Such predictive information may be provided by intra picture prediction unit (452). In some cases, the intra picture prediction unit (452) generates a block of the same size and shape as the block being reconstructed using the surrounding reconstructed information extracted from the current picture buffer (458). For example, the current picture buffer (458) buffers a partially reconstructed current picture and/or a fully reconstructed current picture. In some cases, the aggregator (455) adds, on a per-sample basis, the prediction information generated by the intra prediction unit (452) to the output sample information provided by the scaler/inverse transform unit (451).

In other cases, the output samples of sealer/inverse transform unit (451) may belong to inter-coded and potential motion compensated blocks. In this case, motion compensated prediction unit (453) may access reference picture memory (457) to extract samples for prediction. After motion compensating the extracted samples according to the symbols (421) belonging to the block, the samples may be added to the output of the scaler/inverse transform unit (451), in this case referred to as residual samples or residual signals, by an aggregator (455), thereby generating output sample information. The fetching of prediction samples by motion compensated prediction unit (453) from addresses within reference picture memory (457) may be controlled by a motion vector, and the motion vector is used by motion compensated prediction unit (453) in the form of a symbol (421), which symbol (421) may have, for example, X, Y and a reference picture component. Motion compensation may also include interpolation of sample values fetched from the reference picture memory (457), motion vector prediction mechanisms, etc., when using sub-sample exact motion vectors.

The output samples of the aggregator (455) may be subjected to various loop filtering techniques in a loop filter unit (456). The video compression techniques may include in-loop filter techniques that are controlled by parameters included in the encoded video sequence (also referred to as the encoded video bitstream) and available to the loop filter unit (456) as symbols (421) from the parser (420), however, the video compression techniques may also be responsive to meta-information obtained during decoding of previous (in decoding order) portions of the encoded picture or encoded video sequence, as well as to sample values previously reconstructed and loop filtered.

The output of the loop filter unit (456) may be a sample stream that may be output to a rendering device (412) and stored in a reference picture memory (457) for subsequent inter picture prediction.

Once fully reconstructed, some of the coded pictures may be used as reference pictures for future prediction. For example, once the encoded picture corresponding to the current picture is fully reconstructed and the encoded picture is identified (by, e.g., parser (320)) as a reference picture, current picture buffer (458) may become part of reference picture memory (457) and a new current picture buffer may be reallocated before reconstruction of a subsequent encoded picture begins.

The video decoder (410) may perform decoding operations according to predetermined video compression techniques, such as in the ITU-T recommendation h.265 standard. The encoded video sequence may conform to the syntax specified by the video compression technique or standard used, in the sense that the encoded video sequence conforms to the syntax of the video compression technique or standard and the configuration files recorded in the video compression technique or standard. In particular, the configuration file may select certain tools from all tools available in the video compression technology or standard as the only tools available under the configuration file. For compliance, the complexity of the encoded video sequence may also be required to be within a range defined by the level of the video compression technique or standard. In some cases, the hierarchy limits the maximum picture size, the maximum frame rate, the maximum reconstruction sampling rate (measured in units of, e.g., mega samples per second), the maximum reference picture size, and so on. In some cases, the limits set by the hierarchy may be further defined by a Hypothetical Reference Decoder (HRD) specification and metadata signaled HRD buffer management in the encoded video sequence.

In one embodiment, receiver (431) may receive additional (redundant) data along with the reception of the encoded video. The additional data may be included as part of the encoded video sequence. The additional data may be used by the video decoder (410) to properly decode the data and/or more accurately reconstruct the original video data. The additional data may be in the form of, for example, a temporal, spatial, or signal-to-noise ratio (SNR) enhancement layer, a redundant slice, a redundant picture, a forward error correction code, and so forth.

Fig. 5 shows a block diagram of a video encoder (503) according to one embodiment of the present disclosure. The video encoder (503) is included in an electronic device (520). The electronic device (520) includes a transmitter (540) (e.g., a transmission circuit). The video encoder (503) may be used in place of the video encoder (303) in the example of fig. 3.

The video encoder (503) may receive video samples from a video source (501) (not part of the electronics (520) in the example of fig. 5) that may capture video images to be encoded by the video encoder (503). In another example, the video source (501) is part of an electronic device (520).

The video source (501) may provide a source video sequence in the form of a stream of digital video samples to be encoded by the video encoder (503), which may have any suitable bit depth (e.g., 8-bit, 10-bit, 12-bit … …), any color space (e.g., bt.601y CrCB, RGB … …), and any suitable sampling structure (e.g., Y CrCB 4: 2: 0, Y CrCB 4: 4: 4). In the media service system, the video source (501) may be a storage device that stores previously prepared video. In a video conferencing system, the video source (501) may be a camera that captures local image information as a video sequence. Video data may be provided as a plurality of individual pictures that are given motion when viewed in sequence. The picture itself may be constructed as an array of spatial pixels, where each pixel may comprise one or more samples, depending on the sampling structure, color space, etc. used. The relationship between the pixel and the sample can be easily understood by those skilled in the art. The following text focuses on describing the samples.

According to one embodiment, the video encoder (503) may encode and compress pictures of a source video sequence into an encoded video sequence (543) in real-time or under any other temporal constraints required by the application. It is a function of the controller (550) to perform the appropriate encoding speed. In some embodiments, the controller (550) controls and is functionally coupled to other functional units as described below. For simplicity, the coupling is not depicted in the figures. The parameters set by the controller (550) may include rate control related parameters (picture skip, quantizer, lambda value … … for rate distortion optimization techniques), picture size, group of pictures (GOP) layout, maximum motion vector search range, etc. The controller (550) may be configured with other suitable functions relating to the video encoder (503) optimized for a system design.

In some embodiments, the video encoder (503) is configured to operate in an encoding loop. As a brief description, in one example, an encoding loop may include a source encoder (530) (e.g., responsible for creating symbols, e.g., a stream of symbols, based on input pictures and reference pictures to be encoded) and a (local) decoder (533) embedded in a video encoder (503). The decoder (533) reconstructs the symbols to create sample data in a manner similar to how a (remote) decoder can also create sample data (since any compression between the symbols and the encoded video bitstream is lossless in the video compression techniques contemplated by the disclosed subject matter). The reconstructed sample stream (sample data) is input to a reference picture memory (534). Since the decoding of the symbol stream produces bit accurate results independent of decoder location (local or remote), the content in the reference picture store (534) also corresponds bit-accurately between the local encoder and the remote encoder. In other words, the reference picture samples that the prediction portion of the encoder "sees" are identical to the sample values that the decoder would "see" when using prediction during decoding. This reference picture synchronization philosophy (and the drift that occurs if synchronization cannot be maintained due to, for example, channel errors) is also used in some related techniques.

The operation of "local" decoder (533) may be the same as the operation of a "remote" decoder, such as video decoder (410) that has been described in detail above in connection with fig. 4. However, referring briefly to fig. 4 additionally, when symbols are available and the entropy encoder (545) and parser (420) can losslessly encode/decode the symbols into an encoded video sequence, the entropy decoding portion of the video decoder (410), including the buffer memory (415) and parser (420), may not be fully implemented in the local decoder (533).

At this point it is observed that any decoder technique other than the parsing/entropy decoding present in the decoder must also be present in the corresponding encoder in substantially the same functional form. For this reason, the disclosed subject matter focuses on decoder operation. The description of the encoder techniques may be simplified because the encoder techniques are reciprocal to the fully described decoder techniques. A more detailed description is needed only in certain areas and is provided below.

During operation, in some examples, the source encoder (530) may perform motion compensated predictive encoding that predictively encodes an input picture, referencing one or more previously encoded pictures from the video sequence that are designated as "reference pictures". In this way, the encoding engine (532) encodes differences between pixel blocks of an input picture and pixel blocks of a reference picture that may be selected as a prediction reference for the input picture.

The local video decoder (533) may decode encoded video data for a picture that may be designated as a reference picture based on the symbols created by the source encoder (530). The operation of the encoding engine (532) may advantageously be a lossy process. When the encoded video data can be decoded at a video decoder (not shown in fig. 5), the reconstructed video sequence may typically be a copy of the source video sequence, but with some errors. The local video decoder (533) replicates a decoding process that may be performed on reference pictures by the video decoder, and may cause reconstructed reference pictures to be stored in the reference picture cache (534). In this way, the video encoder (503) may locally store a copy of the reconstructed reference picture that has common content (no transmission errors) with the reconstructed reference picture to be obtained by the far-end video decoder.

The predictor (535) may perform a prediction search against the coding engine (532). That is, for a new picture to be encoded, the predictor (535) may search the reference picture memory (534) for sample data (as candidate reference pixel blocks) or some metadata, such as reference picture motion vectors, block shapes, etc., that may be referenced as appropriate predictions for the new picture. The predictor (535) may operate on a block-by-block basis of samples to find a suitable prediction reference. In some cases, the input picture may have prediction references derived from multiple reference pictures stored in a reference picture memory (534), as determined by search results obtained by the predictor (535).

The controller (550) may manage encoding operations of the source encoder (530), including, for example, setting parameters and subgroup parameters for encoding video data.

The outputs of all of the above functional units may be entropy encoded in an entropy encoder (545). The entropy encoder (545) losslessly compresses the symbols generated by the various functional units according to techniques such as huffman coding, variable length coding, arithmetic coding, etc., to transform the symbols into an encoded video sequence.

The transmitter (540) may buffer the encoded video sequence created by the entropy encoder (545) in preparation for transmission over a communication channel (560), which may be a hardware/software link to a storage device that will store the encoded video data. The transmitter (540) may combine the encoded video data from the video encoder (503) with other data to be transmitted, such as encoded audio data and/or an auxiliary data stream (sources not shown).

The controller (550) may manage the operation of the video encoder (503). During encoding, the controller (550) may assign a certain encoded picture type to each encoded picture, but this may affect the encoding techniques that may be applied to the respective picture. For example, pictures may be generally assigned to any of the following picture types:

intra pictures (I pictures), which may be pictures that can be encoded and decoded without using any other picture in the sequence as a prediction source. Some video codecs tolerate different types of intra pictures, including, for example, Independent Decoder Refresh ("IDR") pictures. Those skilled in the art are aware of variations of picture I and their corresponding applications and features.

A predictive picture (P picture), which may be a picture that can be encoded and decoded using intra prediction or inter prediction that uses at most one motion vector and a reference index to predict sample values of each block.

Bi-predictive pictures (B-pictures), which may be pictures that can be encoded and decoded using intra prediction or inter prediction that uses at most two motion vectors and a reference index to predict sample values of each block. Similarly, multiple predictive pictures may use more than two reference pictures and associated metadata for reconstructing a single block.

A source picture may typically be spatially subdivided into blocks of samples (e.g., blocks of 4 x 4, 8 x 8, 4 x 8, or 16 x 16 samples) and encoded block-wise. These blocks may be predictively encoded with reference to other (encoded) blocks determined by the encoding allocation applied to the respective pictures of the block. For example, a block of an I picture may be non-predictively encoded, or the block may be predictively encoded (spatial prediction or intra prediction) with reference to an encoded block of the same picture. The pixel block of the P picture may be predictively encoded by spatial prediction or by temporal prediction with reference to one previously encoded reference picture. A block of a B picture may be predictively encoded by spatial prediction or by temporal prediction with reference to one or two previously encoded reference pictures.

Video encoder (503) may perform encoding operations according to a predetermined video encoding technique or standard, such as ITU-T recommendation h.265. In operation, the video encoder (503) may perform various compression operations, including predictive encoding operations that exploit temporal and spatial redundancies in the input video sequence. Thus, the encoded video data may conform to syntax specified by the video coding technique or standard used.

In one embodiment, the transmitter (540) may transmit the additional data while transmitting the encoded video. The source encoder (530) may include such data as part of an encoded video sequence. The additional data may include temporal/spatial/SNR enhancement layers, redundant pictures and slices, among other forms of redundant data, SEI messages, VUI parameter set segments, and the like.

The captured video may be provided as a plurality of source pictures (video pictures) in a time sequence. Intra-picture prediction, often abbreviated as intra-prediction, exploits spatial correlation in a given picture, while inter-picture prediction exploits (temporal or other) correlation between pictures. In one example, a particular picture being encoded/decoded, referred to as a current picture, is partitioned into blocks. When a block in a current picture is similar to a reference block in a reference picture that has been previously encoded in video and is still buffered, the block in the current picture may be encoded by a vector called a motion vector. The motion vector points to a reference block in a reference picture, and in case multiple reference pictures are used, the motion vector may have a third dimension that identifies the reference pictures.

In some embodiments, bi-directional prediction techniques may be used in inter-picture prediction. According to bi-prediction techniques, two reference pictures are used, e.g., a first reference picture and a second reference picture that are both prior to the current picture in video in decoding order (but may be past and future, respectively, in display order). A block in a current picture may be encoded by a first motion vector pointing to a first reference block in a first reference picture and a second motion vector pointing to a second reference block in a second reference picture. The block may be predicted by a combination of the first reference block and the second reference block.

Furthermore, merge mode techniques may be used in inter picture prediction to improve coding efficiency.

According to some embodiments of the present disclosure, prediction such as inter-picture prediction and intra-picture prediction is performed in units of blocks. For example, according to the HEVC standard, pictures in a sequence of video pictures are partitioned into Coding Tree Units (CTUs) for compression, the CTUs in the pictures having the same size, e.g., 64 × 64 pixels, 32 × 32 pixels, or 16 × 16 pixels. In general, a CTU includes three Coding Tree Blocks (CTBs), which are one luminance CTB and two chrominance CTBs. Each CTU may be recursively split into one or more Coding Units (CUs) in a quadtree. For example, a 64 × 64-pixel CTU may be split into one 64 × 64-pixel CU, or 4 32 × 32-pixel CUs, or 16 × 16-pixel CUs. In one example, each CU is analyzed to determine a prediction type for the CU, such as an inter prediction type or an intra prediction type. Depending on temporal and/or spatial predictability, a CU is split into one or more Prediction Units (PUs). In general, each PU includes a luma Prediction Block (PB) and two chroma blocks PB. In one embodiment, the prediction operation in encoding (encoding/decoding) is performed in units of prediction blocks. Taking a luma prediction block as an example of a prediction block, the prediction block includes a matrix of values (e.g., luma values) for pixels, such as 8 × 8 pixels, 16 × 16 pixels, 8 × 16 pixels, 16 × 8 pixels, and so on.

Fig. 6 shows a diagram of a video encoder (603) according to another embodiment of the present disclosure. A video encoder (603) is configured to receive a processing block (e.g., a prediction block) of sample values within a current video picture in a sequence of video pictures and encode the processing block into an encoded picture that is part of an encoded video sequence. In one example, the video encoder (603) is used in place of the video encoder (303) in the example of fig. 3.

In the HEVC example, a video encoder (603) receives a matrix of sample values for a processing block, e.g., a prediction block of 8 × 8 samples, etc. The video encoder (603) uses, for example, rate-distortion (RD) optimization to determine whether to use intra mode, inter mode, or bi-prediction mode to optimally encode the processing block. When encoding a processing block in intra mode, the video encoder (603) may use intra prediction techniques to encode the processing block into an encoded picture; and when the processing block is encoded in inter mode or bi-prediction mode, the video encoder (603) may use inter prediction or bi-prediction techniques, respectively, to encode the processing block into the encoded picture. In some video coding techniques, the merge mode may be an inter-picture prediction sub-mode, in which motion vectors are derived from one or more motion vector predictors without resorting to coded motion vector components outside the predictor. In some other video coding techniques, there may be motion vector components that are applicable to the subject block. In one example, the video encoder (603) includes other components, such as a mode decision module (not shown) for determining a mode of processing the block.

In the example of fig. 6, the video encoder (603) includes an inter encoder (630), an intra encoder (622), a residual calculator (623), a switch (626), a residual encoder (624), a general controller (621), and an entropy encoder (625) coupled together as shown in fig. 6.

The inter encoder (630) is configured to receive samples of a current block (e.g., a processed block), compare the block to one or more reference blocks in a reference picture (e.g., blocks in previous and subsequent pictures), generate inter prediction information (e.g., redundant information descriptions, motion vectors, merge mode information according to inter coding techniques), and calculate an inter prediction result (e.g., a predicted block) using any suitable technique based on the inter prediction information. In some examples, the reference picture is a decoded reference picture that is decoded based on encoded video information.

The intra encoder (622) is configured to receive samples of a current block (e.g., a processing block), in some cases compare the block to an already encoded block in the same picture, generate quantized coefficients after transformation, and in some cases also generate intra prediction information (e.g., intra prediction direction information according to one or more intra coding techniques). In one example, the intra encoder (622) also computes an intra prediction result (e.g., a predicted block) based on the intra prediction information and a reference block in the same picture.

The general purpose controller (521) is configured to determine general purpose control data and to control other components of the video encoder (603) based on the general purpose control data. In one example, a general purpose controller (621) determines a mode of a block and provides a control signal to a switch (626) based on the mode. For example, when the mode is intra, the general controller (621) controls the switch (626) to select an intra mode result for use by the residual calculator (623), and controls the entropy encoder (625) to select and include intra prediction information in the bitstream; and when the mode is an inter mode, the general purpose controller (621) controls the switch (626) to select an inter prediction result for use by the residual calculator (623), and controls the entropy encoder (625) to select and include inter prediction information in the bitstream.

The residual calculator (623) is configured to calculate a difference (residual data) between the received block and a prediction result selected from the intra encoder (622) or the inter encoder (630). A residual encoder (624) is configured to operate on the residual data to encode the residual data to generate transform coefficients. In one example, a residual encoder (624) is configured to convert residual data from a spatial domain to a frequency domain and generate transform coefficients. The transform coefficients are then subjected to a quantization process to obtain quantized transform coefficients. In embodiments, the video encoder (603) further comprises a residual decoder (628). A residual decoder (628) is configured to perform an inverse transform and generate decoded residual data. The decoded residual data may be suitably used by an intra encoder (622) and an inter encoder (630). For example, inter encoder (630) may generate a decoded block based on decoded residual data and inter prediction information, and intra encoder (622) may generate a decoded block based on decoded residual data and intra prediction information. The decoded block is processed appropriately to generate a decoded picture, and in some examples, the decoded picture may be buffered in a memory circuit (not shown) and used as a reference picture.

The entropy encoder (625) is configured to format the bitstream to include encoded blocks. The entropy encoder (625) is configured to include various information according to a suitable standard, such as the HEVC standard. In one example, the entropy encoder (625) is configured to include general control data, selected prediction information (e.g., intra prediction information or inter prediction information), residual information, and other suitable information in the bitstream. It should be noted that, according to the disclosed subject matter, there is no residual information when a block is encoded in the merge sub-mode of the inter mode or bi-prediction mode.

Fig. 7 shows a diagram of a video decoder (710) according to another embodiment of the present disclosure. A video decoder (710) is configured to receive an encoded picture that is part of an encoded video sequence and decode the encoded picture to generate a reconstructed picture. In one example, the video decoder (710) is used in place of the video decoder (310) in the example of fig. 3.

In the example of fig. 7, the video decoder (710) includes an entropy decoder (771), an inter-frame decoder (780), a residual decoder (773), a reconstruction module (774), and an intra-frame decoder (772) coupled together as shown in fig. 7.

The entropy decoder (771) may be configured to reconstruct from the encoded picture certain symbols representing syntax elements constituting the encoded picture. Such symbols may include, for example, a mode used to encode the block (e.g., intra mode, inter mode, bi-prediction mode, a merge sub-mode of the latter two, or another sub-mode), prediction information (e.g., intra prediction information or inter prediction information) that may identify certain samples or metadata used by the intra decoder 772 or inter decoder 780, respectively, for prediction, residual information in the form of, for example, quantized transform coefficients, and so forth. In one example, when the prediction mode is inter or bi-directional prediction mode, inter prediction information is provided to an inter decoder (780); and providing the intra prediction information to an intra decoder (772) when the prediction type is an intra prediction type. The residual information may be subjected to inverse quantization and provided to a residual decoder (773).

An inter-frame decoder (780) is configured to receive the inter-frame prediction information and generate an inter-frame prediction result based on the inter-frame prediction information.

An intra-frame decoder (772) is configured to receive intra-frame prediction information and generate a prediction result based on the intra-frame prediction information.

A residual decoder (773) is configured to perform inverse quantization to extract dequantized transform coefficients and to process the dequantized transform coefficients to transform the residual from the frequency domain to the spatial domain. The residual decoder (773) may also need certain control information (to include Quantizer Parameters (QP)) and this information may be provided by the entropy decoder (771) (data path not depicted, as this is only low-level control information).

The reconstruction module (774) is configured to combine in the spatial domain the residuals output by the residual decoder (773) with the prediction results (which may be output by the inter prediction module or the intra prediction module as the case may be) to form a reconstructed block, which may be part of a reconstructed picture, which in turn may be part of a reconstructed video. It should be noted that other suitable operations, such as deblocking operations, may be performed to improve visual quality.

It should be noted that video encoder (303), video encoder (503), and video encoder (603) as well as video decoder (310), video decoder (410), and video decoder (710) may be implemented using any suitable techniques. In one embodiment, video encoder (303), video encoder (503), and video encoder (603) and video decoder (310), video decoder (410), and video decoder (710) may be implemented using one or more integrated circuits. In another embodiment, the video encoder (303), the video encoder (503), and the video decoder (310), the video decoder (410), and the video decoder (710) may be implemented using one or more processors executing software instructions.

According to some embodiments, the Most Probable Mode (MPM) list is set equal to 6 for both neighboring reference lines (e.g., zero reference lines) and non-neighboring reference lines (e.g., non-zero reference lines). As shown in fig. 8, the positions of the neighboring modes used to derive the 6 MPM candidates may also be the same for the neighboring reference lines and the non-neighboring reference lines. In fig. 8, a block a and a block B represent upper and left neighboring coding units of a current block 800, respectively, and variables candirapredmodea and candirapredmodeb represent associated intra prediction modes of the block a and the block B, respectively. The variables candirapredmodea and candirapredmodeb may initially be set equal to INTRA _ plan. If block a (or block B) is marked as available, candirapredmodea (or candirapredmodeb) can be set equal to the actual intra prediction mode of block a (or block B).

The MPM candidate derivation process may be different for neighboring and non-neighboring reference lines. For example, for a zero reference line, if the modes for two neighboring blocks are planar mode or DC mode, the MPM list is constructed using default modes, where the first two candidates are planar mode and DC mode, and the remaining four modes are angular modes (e.g., angular default modes). For non-zero reference lines, if the mode of two neighboring blocks is planar or DC mode, the MPM list may be constructed using 6 angular default modes. An embodiment of the MPM list derivation process is shown in appendix 1, where candModeList [ x ] (x ═ 0..5) represents 6 MPM candidates, intralumarehlineidx [ xCb ] [ yCb ] represents the reference line index of the block to be predicted, and intralumarehlineidx [ xCb ] [ YCb ] may be 0, 1, or 3. In some examples, a unified intra mode encoding method is implemented, in which a planar mode is set as a first MPM.

Block differential pulse code modulation (BPDCM) is an intra-coding tool that uses a Differential Pulse Code Modulation (DPCM) method at the block level. In some embodiments, the bdpcm _ flag is transmitted at the CU level whenever there are luma intra CUs with each dimension less than or equal to 32. The flag indicates whether conventional intra-coding or DPCM is used. The flag may be encoded using a single Context-based Adaptive Binary Arithmetic Coding (CABAC) Context.

In some implementations, BDPCM uses the Median Edge Detector (media Edge Detector) of LOCO-I (for JPEG-LS). For a current pixel X having pixel a as the left-neighboring pixel, pixel B as the top-neighboring pixel, and pixel C as the top-left neighboring pixel, prediction p (X) may be determined by:

equation (1): p (X) ═ min (A, B) if C ≧ max (A, B)

max (A, B) if C is less than or equal to min (A, B)

A + B-C in other cases.

The predictor may use unfiltered reference pixels when predicting from the top row and left column of the CU. The predictor may then use the reconstructed pixels for the rest of the CU. Pixels may be processed in raster scan order within a CU. After rescaling, the prediction error can be quantized in the spatial domain in the same way as a Transform Skip quantizer. Each pixel may be reconstructed by adding the dequantized prediction error to the prediction. Thus, the reconstructed pixel can be used to predict the next pixel in raster scan order. The magnitude and sign of the quantized prediction error can be encoded separately.

In some embodiments, the cbf _ bdcpcm _ flag is encoded. If the flag is equal to 0, all amplitudes of the block may be decoded to 0. If the flag is equal to 1, all amplitudes of the block can be encoded individually in raster scan order. To keep the complexity low, in some examples, the amplitude may be limited to at most 31 (including 31). The amplitude may be encoded using unary binarization, where the first bin has three contexts, then every additional bin up to the 12 th bin has one context, and all remaining bins have one context. The symbols may be encoded in a bypass mode for each zero residual.

In some embodiments, to maintain consistency of conventional intra mode prediction, the first mode in the MPM list is associated with the BDPCM CU (not sent) and is available for MPM generation for subsequent blocks. The deblocking filter may not be activated at the boundary between two BDPCM blocks because neither block uses the transform stage that is typically responsible for blocking artifacts. In some embodiments, the BDPCM does not use any other steps than those disclosed herein. For example, BPDCM does not use any transform.

According to some embodiments, the BDPCM method uses reconstructed samples to predict rows or columns of a CU row by row. The signaled BDPCM direction may indicate whether vertical prediction or horizontal prediction is used. The reference pixels used may be unfiltered samples. The prediction error may be quantized in the spatial domain. The pixels may be reconstructed by adding the dequantized prediction error to the prediction.

In some embodiments, quantized residual domain BDPCM may be performed as an alternative to BDPCM. The signaling and prediction direction used in the quantized residual BDPCM may be the same as the BPCM scheme. Intra prediction can be performed on the entire block by sample copying in a prediction direction (horizontal prediction or vertical prediction) similar to intra prediction. The residual may be quantized and a delta between the quantized residual and a predictor (horizontal or vertical) quantization value of the quantized residual may be encoded, as may be described in the embodiments disclosed below.

For a block of size M (rows) N (columns), let r be assumed_i,jI ≦ 0 ≦ M-1, and j ≦ 0 ≦ N-1 is the prediction residual after performing intra prediction either horizontally (copying left neighboring pixel values in the prediction block row by row) or vertically (copying the upper neighboring row to each row in the prediction block) using unfiltered samples from the upper or left block boundary samples. Suppose Q (r)_i,j) I is more than or equal to 0 and less than or equal to M-1, and j is more than or equal to 0 and less than or equal to N-1 represents residual error r_i,jWherein the residual is a difference between the original block value and the prediction block value. BDPCM is then applied to the quantized residual samples, resulting in improved samples with elementsM x N array ofIn some examples, when signaling a vertical BDPCM:

equation (2):

in some examples, for horizontal prediction, applying a similar rule, residual quantized samples may be obtained by the following equation:

equation (3):

samples for which residual may be quantizedTo the decoder. At the decoder side, in some examples, the above calculations are processed in reverse to generate Q (r)_i，j) I is more than or equal to 0 and less than or equal to M-1, and j is more than or equal to 0 and less than or equal to N-1. In some embodiments, for the vertical prediction case:

equation (4):

in some embodiments, for the horizontal prediction case:

equation (5):

the inverse quantized residual Q may be^-1(Q(r_i，j) Is added to the intra block prediction value to produce reconstructed sample values. One advantage of this scheme is: by adding the predictor when the coefficients are parsed, the inverse DPCM may be performed quickly during coefficient parsing, or may be performed after parsing. Thus, the division of 4 × N and N × 4 blocks into 2 blocks processed in parallel can be eliminated.

In some embodiments, a BDPCM encoded block is associated with an intra-prediction mode that is the first MPM (i.e., MPM 0). As such, when deriving the MPM list, if the neighboring block is encoded in the BDPCM mode, the intra prediction mode (i.e., MPM0) associated with the neighboring block is used. Also, when the chroma block is encoded using the DM mode and the co-located luma block is encoded using the BDPCM mode, an intra prediction mode associated with the co-located luma block (i.e., MPM0) is used as an intra prediction mode of the current chroma block.

Table 1 (below) shows an example of the syntax and semantics of the BDPCM method:

TABLE 1

In some embodiments, the variable bdpcm _ flag x0 y0 equal to 1 specifies the presence of a bdpcm _ dir _ flag in the coding unit that includes the luma coding block at position (x0, y 0). In some embodiments, bdpcm _ dir _ flag x0 y0 equal to 0 specifies that the prediction direction to be used in the bdpcm block is the horizontal direction, otherwise the prediction direction is the vertical direction.

As understood by those of ordinary skill in the art, BDPCM contributes significant coding gain on screen video content that is typically characterized by strong edges. However, when BDPCM is used with MPM mode or DM mode, BDPCM encoded blocks are always associated with planar mode, which may cause a penalty to the coding gain of screen video content. Embodiments of the present disclosure address these shortcomings.

The embodiments of the present disclosure may be used alone or in any order in combination. Furthermore, each of the method, encoder and decoder according to embodiments of the present disclosure may be implemented by processing circuitry (e.g., one or more processors or one or more integrated circuits). In one example, one or more processors execute a program stored in a non-transitory computer readable medium. According to an embodiment of the present disclosure, the term "block" may be interpreted as a prediction block, a coding block, or a coding unit (i.e., CU).

According to some embodiments, when BDPCM _ dir _ flag is equal to 0, horizontal prediction is used for BDPCM residual prediction, and when BDPCM _ dir _ flag is equal to 1, vertical prediction is used for BDPCM residual prediction. However, in other embodiments, the opposite method applies when the prediction directions of bdpcm _ dir _ flag equal to 0 and 1 are swapped.

In some embodiments, horizontal INTRA prediction modes are represented using HOR _ IDX, where HOR _ IDX corresponds to INTRA prediction mode INTRA _ angul 18 in VVC and INTRA prediction mode INTRA _ angul 10 in HEVC. In some embodiments, the vertical INTRA prediction mode is represented using VER _ IDX, where in VVC VER _ IDX corresponds to the INTRA prediction mode INTRA _ ANGULAR50, and in HEVC VER _ IDX corresponds to the INTRA prediction mode INTRA _ ANGULAR 26.

According to some embodiments, when deriving the most probable intra prediction mode, if a neighboring block is encoded by a BDPCM mode, the neighboring block is associated with an intra prediction mode ipm, which is derived using a value of BDPCM _ dir _ flag applied to the BDPCM encoded neighboring block, as follows:

equation (6): ipm ═ bdpcmm _ dir _ flag? VER _ IDX, where HOR _ IDX and VER _ IDX represent horizontal and vertical intra prediction modes, respectively, and bdplcm _ dir _ flag equal to 0 represents horizontal prediction for BDPCM residual prediction, and bdplcm _ dir _ flag equal to 1 represents vertical prediction for BDPCM residual prediction. After assigning the intra prediction mode value ipm, the intra prediction mode value is treated as a neighboring block intra prediction mode and used to derive the most probable intra prediction mode for the current block.

Appendix 2 shows an embodiment of the MPM list derivation process, in which the bold section illustrates how the intra prediction mode of a BDPCM encoded block is determined based on bdpcmk _ dir _ flag. Example inputs to the process may include: (i) a luma position (xCb, yCb) specifying a top-left luma sample of the current luma coding block relative to a top-left luma sample of the current picture; (ii) a variable cbWidth specifying the width of the current coding block in the luma sample; (iii) a variable cbHeight specifying the height of the current coding block in the luma sample. In this process of appendix 2, the luma intra prediction mode IntraPredModey [ xCb ] [ yCb ] is derived.

Table 2 specifies the values and associated names of the intra prediction mode IntraPredModey [ xCb ] [ yCb ]. In table 2, in some examples, the INTRA prediction modes INTRA _ LT _ CCLM, INTRA _ L _ CCLM, and INTRA _ T _ CCLM are applicable only to the chroma components.

TABLE 2

According to some embodiments, when deriving an intra prediction mode for a chroma block while encoding a co-located luma block of the chroma block using a BDPCM mode, if the chroma block is predicted using a DM mode, an intra prediction mode for performing the intra prediction mode for the chroma block is derived as follows:

equation (7): dm-bdpcmm _ dir _ flag-0 HOR _ IDX-VER _ IDX,

wherein HOR _ IDX and VER _ IDX denote a horizontal intra prediction mode and a vertical intra prediction mode, respectively, and bdpcmp _ dir _ flag equal to 0 denotes horizontal prediction for BDPCM residual prediction, and bdpcmp _ dir _ flag equal to 1 denotes vertical prediction for BDPCM residual prediction. Therefore, after assignment of dm, this value is used as an intra prediction mode for the chroma block.

According to some embodiments, a context for entropy encoding the bdpcm _ dir _ flag depends on a value of the bdpcm _ dir _ flag of the neighboring block and/or whether the neighboring block is encoded by a horizontal intra prediction mode or a vertical intra prediction mode.

In one embodiment, only the bdpcm _ dir _ flag value and the bdpcm _ flag value of neighboring blocks are used to derive a context applied to entropy encoding the bdpcm _ dir _ flag of the current block. In one example, two neighboring blocks are used (i.e., block a on the left in fig. 8 and block B on the top in fig. 8), and the context value (ctx) is derived as follows:

equation (8): dpcm _ left ═ dpcm _ flag_left？(bdpcm_dir_flag_left？1:2):0

Equation (9): dpcm _ top ═ dpcm _ flag_top？(bdpcm_dir_flag_top？1:2):0

Equation (10): ctx is dpcm _ left 3+ dpcm _ top,

wherein, dpcm _ flag_leftAnd dpcm _ flag_topDpcm _ flag, which refers to a left neighboring block and an upper neighboring block, respectively, and bdpcm _ dir _ flag_leftAnd bdplcm dir flag_topBdpcm _ dir _ flag referring to a left adjacent block and an upper adjacent block, respectively. After the ctx is assigned, the value may be used as an index for selecting one of the context models.

In addition to the previous example, the 9 contexts may be grouped in a predefined manner, such that fewer contexts are applied. For example, in the previous example, ctx-8 and ctx-7 may be merged and only one context may be used for both ctx values.

In some embodiments, two neighboring blocks (i.e., a left neighboring block and an upper neighboring block) are used, and a context value (ctx) is derived as follows, where dpcm _ flag_leftAnd dpcm _ flag_topDpcm _ flag respectively referring to a left adjacent block and an upper adjacent block, and bdpcm _ dir _ flag_leftAnd bdplcm dir flag_topBdpcm _ dir _ flag referring to a left adjacent block and an upper adjacent block, respectively.

Equation (11): dpcm _ left ═ dpcm _ flag_left？(bdpcm_dir_flag_left？1:2):0

Equation (12): dpcm _ top ═ dpcm _ flag_top？(bdpcm_dir_flag_top？1:2):0

Equation (13): ctx? dpcm _ left: 0.

Fig. 9 illustrates an embodiment of a process performed by a decoder, such as a video decoder (710). The process may begin with step (S900) to determine whether to encode a first block associated with a second block using a BDPCM mode. In some examples, the first block may be a spatially neighboring block of a second block located in the same picture as the first block. In other examples, the first block may be a luma block and the second block is a chroma block, where the luma block is co-located with the chroma block.

If the first block is encoded in the BDPCM mode, the process proceeds from step (S900) to step (S902), where the first block is associated with an intra prediction mode value based on the BDPCM direction flag. For example, a BDPCM _ flag may indicate that a block is encoded in a BDPCM mode, and the BDPCM _ dir _ flag may be used to determine whether to use a horizontal direction or a vertical direction. The process proceeds to step (S904) to determine an inter prediction mode value for the second block using the intra prediction mode value associated with the first block. For example, the intra prediction mode value may be one of a horizontal intra prediction mode value and a vertical intra prediction mode value based on the BDPCM direction flag. Furthermore, if the first block is a spatial neighboring block of the second block, the intra prediction mode value of the first block may be used to create an MPM list, wherein the MPM list is used to derive the intra prediction mode value of the second block. Also, if the second block is a chroma block predicted using the DM mode and the first block is a co-located luma block, an intra prediction mode value of the second block may be determined based on an intra prediction mode value of the first block.

The process proceeds to step (S906), where the second block is reconstructed using the determined intra prediction mode value of the second block. The process shown in fig. 9 may end after completion of step (S906). Further, returning to step (S900), if the first block is not encoded in the BDPCM mode, the process shown in fig. 9 may end.

The techniques described above may be implemented as computer software using computer readable instructions and physically stored in one or more computer readable media. For example, fig. 10 illustrates a computer system (1000) suitable for implementing certain embodiments of the disclosed subject matter.

The computer software may be encoded using any suitable machine code or computer language that may be subject to assembly, compilation, linking, or similar mechanism to create code that includes instructions that may be executed directly by one or more computer Central Processing Units (CPUs), Graphics Processing Units (GPUs), etc., or by interpretation, microcode execution, etc.

The instructions may be executed on various types of computers or components thereof, including, for example, personal computers, tablet computers, servers, smart phones, gaming devices, internet of things devices, and so forth.

The components of computer system (1000) shown in FIG. 10 are exemplary in nature and are not intended to suggest any limitation as to the scope of use or functionality of the computer software implementing embodiments of the present disclosure. Neither should the configuration of the components be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the exemplary embodiments of the computer system (1000).

The computer system (1000) may include some human interface input devices. Such human interface input devices may be responsive to input by one or more human users through, for example: tactile input (e.g., keystrokes, strokes, data glove movements), audio input (e.g., speech, clapping hands), visual input (e.g., gestures), olfactory input (not depicted). The human interface device may also be used to capture certain media that are not necessarily directly related to human conscious input, such as audio (e.g., voice, music, ambient sounds), images (e.g., scanned images, captured images from still image cameras), video (e.g., two-dimensional video, three-dimensional video including stereoscopic video).

The input human interface device may include one or more of the following (only one shown in each): keyboard (1001), mouse (1002), touch pad (1003), touch screen (1010), data glove (not shown), joystick (1005), microphone (1006), scanner (1007), camera (1008).

The computer system (1000) may also include certain human interface output devices. Such human interface output devices may stimulate the senses of one or more human users, for example, through tactile outputs, sounds, light, and smells/tastes. Such human interface output devices may include tactile output devices (e.g., tactile feedback for a touch screen (1010), a data glove (not shown), or a joystick (1005), but may also be tactile feedback devices that do not act as input devices), audio output devices (e.g., speakers (1009), headphones (not depicted)), visual output devices (e.g., screens (1010) including CRT screens, LCD screens, plasma screens, OLED screens, each with or without touch screen input functionality — some of which are capable of outputting two-dimensional or more-than-three-dimensional visual output through devices such as stereoscopic image output, virtual reality glasses (not depicted), holographic displays and smoke boxes (not depicted), and printers (not depicted).

The computer system (1000) may also include human-accessible storage devices and their associated media, e.g., optical media including CD/DVD ROM/RW (1020) with CD/DVD or the like media (1021), finger drives (1022), removable hard or solid state drives (1023), conventional magnetic media (not depicted) such as magnetic tape and floppy disk, dedicated ROM/ASIC/PLD based devices (not depicted) such as a security dongle, and so forth.

Those skilled in the art will also appreciate that the term "computer-readable medium" used in connection with the presently disclosed subject matter does not encompass transmission media, carrier waves, or other transitory signals.

The computer system (1000) may also include an interface to one or more communication networks. The one or more networks may be, for example, wireless networks, wired networks, optical networks. The one or more networks may further be local networks, wide area networks, metropolitan area networks, vehicle and industrial networks, real time networks, delay tolerant networks, and the like. Examples of one or more networks include a local area network such as ethernet, a wireless LAN, a cellular network including GSM, 3G, 4G, 5G, LTE, etc., a television wired or wireless wide area digital network including cable television, satellite television, and terrestrial broadcast television, automotive and industrial televisions including CANBus, and so forth. Some networks typically require external network interface adapters (e.g., USB ports of computer system (1000)) that connect to some general purpose data port or peripheral bus (1049); as described below, other network interfaces are typically integrated into the kernel of the computer system (1000) by connecting to a system bus (e.g., to an Ethernet interface in a PC computer system or to a cellular network interface in a smartphone computer system). The computer system (1000) may communicate with other entities using any of these networks. Such communications may be received only one way (e.g., broadcast television), transmitted only one way (e.g., CANbus connected to certain CANbus devices), or bi-directional, e.g., connected to other computer systems using a local or wide area network digital network. As noted above, certain protocols and protocol stacks may be used on each of those networks and network interfaces.

The human interface device, human-accessible storage device, and network interface described above may be attached to the kernel (1040) of the computer system (1000).

The core (1040) may include one or more Central Processing Units (CPUs) (1041), Graphics Processing Units (GPUs) (1042), special purpose programmable processing units in the form of Field Programmable Gate Arrays (FPGAs) (1043), hardware accelerators (1044) for certain tasks, and the like. These devices, as well as Read Only Memory (ROM) (1045), random access memory (1046), internal mass storage (1047), such as internal non-user accessible hard drives, SSDs, etc., may be connected by a system bus (1048). In some computer systems, the system bus (1048) may be accessed in the form of one or more physical plugs to enable expansion by additional CPUs, GPUs, and the like. The peripheral devices may be connected directly to the system bus (1048) of the core or connected to the system bus (1048) of the core through a peripheral bus (1049). The architecture of the peripheral bus includes PCI, USB, etc.

The CPU (1041), GPU (1042), FPGA (1043) and accelerator (1044) may execute certain instructions, which may be combined to form the computer code described above. The computer code may be stored in ROM (1045) or RAM (1046). Transitional data may also be stored in RAM (1046), while persistent data may be stored in an internal mass storage (1047), for example. Fast storage and retrieval to any storage device may be made by using a cache, which may be closely associated with: one or more CPUs (1041), GPUs (1042), mass storage (1047), ROM (1045), RAM (1046), and the like.

The computer-readable medium may have thereon computer code for performing various computer-implemented operations. The media and computer code may be those specially designed and constructed for the purposes of the present disclosure, or they may be of the kind well known and available to those having skill in the computer software arts.

By way of non-limiting example, a computer system having an architecture (1000), and in particular a core (1040), may provide functionality as a result of one or more processors (including CPUs, GPUs, FPGAs, accelerators, etc.) executing software embodied in one or more tangible computer-readable media. Such computer-readable media may be media associated with user-accessible mass storage as described above, as well as some non-transitory memory of the core (1040), such as the core internal mass storage (1047) or ROM (1045). Software implementing embodiments of the present disclosure may be stored in such devices and executed by the kernel (1040). The computer readable medium may include one or more memory devices or chips, according to particular needs. The software may cause the core (1040), and in particular the processors therein (including CPUs, GPUs, FPGAs, etc.), to perform certain processes or certain portions of certain processes described herein, including defining data structures stored in RAM (1046) and modifying such data structures according to processes defined by the software. Additionally or alternatively, the functionality provided by the computer system may be provided as logic that is hardwired or otherwise embodied in circuitry (e.g., accelerator (1044)) that may operate in place of or in conjunction with software to perform certain processes or certain portions of certain processes described herein. Where appropriate, reference to portions of software may include logic and vice versa. Where appropriate, reference to portions of a computer-readable medium may include circuitry (e.g., an Integrated Circuit (IC)) that stores software for execution, circuitry embodying logic for execution, or both. The present disclosure includes any suitable combination of hardware and software.

While this disclosure has described several exemplary embodiments, there are alterations, permutations, and various substitute equivalents, which fall within the scope of this disclosure. It will thus be appreciated that those skilled in the art will be able to devise numerous systems and methods which, although not explicitly shown or described herein, embody the principles of the disclosure and are thus within the spirit and scope of the disclosure.

(1) A video decoding method performed in a video decoder, the method comprising: determining whether to encode a first block associated with a second block using a Block Differential Pulse Code Modulation (BDPCM) mode; in response to determining to encode the first block using the BDPCM mode, associating the first block with an intra-prediction mode value based on the BDPCM direction flag; determining an inter prediction mode value for the second block using the intra prediction mode value associated with the first block; and reconstructing the second block using the determined intra prediction mode value.

(2) The method of feature (1), wherein the BDPCM direction flag is one of: (i) a first value associated with a horizontal intra prediction direction mode, and (ii) a second value associated with a vertical intra prediction direction mode.

(3) The method according to feature (2), wherein the total number of intra prediction modes is 67, wherein the horizontal intra prediction direction mode is associated with angular mode 18 and the vertical intra prediction direction mode is associated with angular mode 50.

(4) The method of any of features (1) - (3), wherein determining whether to encode the first block using the BDPCM mode is based on a value of a BDPCM flag indicating a presence of a BDPCM direction flag.

(5) The method according to any of features (1) - (4), wherein the first block and the second block are included in the same picture, and the first block is spatially adjacent to the second block.

(6) The method according to feature (5), further comprising: for the second block, deriving a candidate list using a Most Probable Mode (MPM) derivation process, the derivation process comprising: determining whether to encode the first block using the BDPCM mode, wherein determining inter prediction mode values for the second block further comprises: the derived candidate list is used.

(7) The method according to feature (6), wherein the candidate list comprises: a first candidate intra prediction Mode value (Mode) corresponding to an intra prediction Mode of the first block₁) (ii) a And a second candidate intra prediction Mode value (Mode) determined according to a predetermined offset from the first candidate intra prediction Mode value and a remainder operation on M₂) And a third candidate intra prediction Mode value (Mode)₃) Where M is a power of 2.

(8) The method according to any one of features (1) - (7), wherein the second block is a chrominance block, and the first block is a luminance block that is co-located with the chrominance block.

(9) The method according to feature (8), further comprising: determining whether the second block is encoded using a direct copy mode (DM); and in response to determining to encode the second block in the direct copy mode, determining whether to encode the first block using the BDPCM mode.

(10) A video decoder for video decoding, comprising processing circuitry configured to: determining whether to encode a first block associated with a second block using a Block Differential Pulse Code Modulation (BDPCM) mode; in response to determining to encode the first block using the BDPCM mode, associating the first block with an intra-prediction mode value based on the BDPCM direction flag; determining an inter prediction mode value for the second block using the intra prediction mode value associated with the first block; and reconstructing the second block using the determined intra prediction mode value.

(11) The video decoder according to feature (10), wherein the BDPCM direction flag is one of: (i) a first value associated with a horizontal intra prediction direction mode, and (ii) a second value associated with a vertical intra prediction direction mode.

(12) The video decoder according to feature (11), wherein the total number of intra prediction modes is 67, wherein the horizontal intra prediction direction mode is associated with angular mode 18 and the vertical intra prediction direction mode is associated with angular mode 50.

(13) The video decoder of any of features (10) - (12), wherein determining whether to encode the first block using the BDPCM mode is based on a value of a BDPCM flag indicating a presence of a BDPCM direction flag.

(14) The video decoder according to any of the features (10) - (13), wherein the first block and the second block are included in the same picture, and the first block is spatially adjacent to the second block.

(15) The video decoder according to feature (14), wherein the processing circuit is further configured to: for the second block, deriving a candidate list using a Most Probable Mode (MPM) derivation process, the derivation process comprising: determining whether to encode the first block using the BDPCM mode, wherein determining inter prediction mode values for the second block further comprises: the derived candidate list is used.

(16) The video decoder according to feature (15), wherein the candidate list comprises: a first candidate intra prediction Mode value (Mode) corresponding to an intra prediction Mode of the first block₁) And a second candidate intra prediction Mode value (Mode) determined according to a predetermined offset from the first candidate intra prediction Mode value and a remainder operation on M₂) And a third candidate intra prediction Mode value (Mode)₃) Where M is a power of 2.

(17) The video decoder according to any of the features (10), wherein the second block is a chrominance block, and the first block is a luminance block that is co-located with the chrominance block.

(18) The video decoder according to feature (17), wherein the processing circuit is further configured to: determining whether the second block is encoded using a direct copy mode (DM); and in response to determining to encode the second block in the direct copy mode, determining whether to encode the first block using the BDPCM mode.

(19) A non-transitory computer readable medium storing instructions that, when executed by a processor in a video decoder, cause the video decoder to perform a method comprising: determining whether to encode a first block associated with a second block using a Block Differential Pulse Code Modulation (BDPCM) mode; in response to determining to encode the first block using the BDPCM mode, associating the first block with an intra-prediction mode value based on the BDPCM direction flag; determining an inter prediction mode value for the second block using the intra prediction mode value associated with the first block; and reconstructing the second block using the determined intra prediction mode value.

(20) The non-transitory computer readable medium of feature (19), wherein the BDPCM direction flag is one of: (i) a first value associated with a horizontal intra prediction direction mode, and (ii) a second value associated with a vertical intra prediction direction mode.

Appendix 1

-if cand rdmodeb is equal to cand rdmodea and cand rdmodea is greater than INTRA _ DC, deriving cand modelist [ x ], where x ═ 0.. 5:

-if intralumarehlineidx [ xCb ] [ yCb ] is equal to 0, the following applies:

candModeList[0]＝candIntraPredModeA (A1_4)

candModeList[1]＝INTRA_PLANAR (A1_5)

candModeList[2]＝INTRA_DC (A1_6)

candModeList[3]＝2+((candIntraPredModeA+61)％64) (A1_7)

candModeList[4]＝2+((candIntraPredModeA-1)％64) (A1_8)

candModeList[5]＝2+((candIntraPredModeA+60)％64) (A1_9)

else (intralumeforelineidx [ xCb ] [ yCb ] not equal to 0), the following applies:

candModeList[0]＝candIntraPredModeA (A1_10)

candModeList[1]＝2+((candIntraPredModeA+61)％64) (A1_11)

candModeList[2]＝2+((candIntraPredModeA-1)％64) (A1_12)

candModeList[3]＝2+((candIntraPredModeA+60)％64) (A1_13)

candModeList[4]＝2+(candIntraPredModeA％64) (A1_14)

candModeList[5]＝2+((candIntraPredModeA+59)％64) (A1_15)

otherwise, if candirapredmodeb does not equal candirapredmodea and candirapredmodea or candirapredmodeb is greater than INTRA _ DC, the following applies:

the variables minAB and maxAB are derived as follows:

minAB＝

candModeList[(candModeList[0]>candModeList[1])？1:0](A1_16)

maxAB＝

candModeList[(candModeList[0]>candModeList[1])？0:1](A1_17)

-if candxtrapredmodea and candxtrapredmodeb are both greater than INTRA _ DC, candModeList [ x ] is derived as follows, where x ═ 0.. 5:

candModeList[0]＝candIntraPredModeA (A1_18)

candModeList[1]＝candIntraPredModeB (A1_19)

-if intralumarehlineidx [ xCb ] [ yCb ] is equal to 0, the following applies:

candModeList[2]＝INTRA_PLANAR (A1_20)

candModeList[3]＝INTRA_DC (A1_21)

if maxAB-minAB is in the range of 2 to 62 (inclusive of 2 and 62), the following applies:

candModeList[4]＝2+((maxAB+61)％64) (A1_22)

candModeList[5]＝2+((maxAB-1)％64) (A1_23)

-otherwise, applying the following:

candModeList[4]＝2+((maxAB+60)％64) (A1_24)

candModeList[5]＝2+((maxAB)％64) (A1_25)

else (intralumeforelineidx [ xCb ] [ yCb ] not equal to 0), the following applies:

if maxAB-minAB equals 1, the following applies:

candModeList[2]＝2+((minAB+61)％64) (A1_26)

candModeList[3]＝2+((maxAB-1)％64) (A1_27)

candModeList[4]＝2+((minAB+60)％64) (A1_28)

candModeList[5]＝2+(maxAB％64) (A1_29)

else, if maxAB-minAB is equal to 2, the following applies:

candModeList[2]＝2+((minAB-1)％64) (A1_30)

candModeList[3]＝2+((minAB+61)％64) (A1_31)

candModeList[4]＝2+((maxAB-1)％64) (A1_32)

candModeList[5]＝2+((minAB+60)％64) (A1_33)

else, if maxAB-minAB is greater than 61, the following applies:

candModeList[2]＝2+((minAB-1)％64) (A1_34)

candModeList[3]＝2+((maxAB+61)％64) (A1_35)

candModeList[4]＝2+(minAB％64) (A1_36)

candModeList[5]＝2+((maxAB+60)％64) (A1_37)

-otherwise, applying the following:

candModeList[2]＝2+((minAB+61)％64) (A1_38)

candModeList[3]＝2+((minAB-1)％64) (A1_39)

candModeList[4]＝2+((maxAB+61)％64) (A1_40)

candModeList[5]＝2+((maxAB-1)％64) (A1_41)

else (candirapredmodea or candirapredmodeb is greater than INTRA _ DC),

candModeList [ x ], where x ═ 0..5, is derived as follows:

-if intralumarehlineidx [ xCb ] [ yCb ] is equal to 0, the following applies:

candModeList[0]＝candIntraPredModeA (A1_42)

candModeList[1]＝candIntraPredModeB (A1_43)

candModeList[2]＝1-minAB (A1_44)

candModeList[3]＝2+((maxAB+61)％64) (A1_45)

candModeList[4]＝2+((maxAB-1)％64) (A1_46)

candModeList[5]＝2+((maxAB+60)％64) (A1_47)

else (intralumeforelineidx [ xCb ] [ yCb ] not equal to 0), the following applies:

candModeList[0]＝maxAB (A1_48)

candModeList[1]＝2+((maxAB+61)％64) (A1_49)

candModeList[2]＝2+((maxAB-1)％64) (A1_50)

candModeList[3]＝2+((maxAB+60)％64) (A1_51)

candModeList[4]＝2+(maxAB％64) (A1_52)

candmodellist [5] ═ 2+ ((maxAB + 59)% 64) (a1 — 53) — otherwise, the following applies:

-if intralumarehlineidx [ xCb ] [ yCb ] is equal to 0, the following applies:

candModeList[0]＝candIntraPredModeA (A1_54)

candModeList[1]＝

(candModeList[0]＝＝INTRA_PLANAR)？INTRA_DC:(A1_55)INTRA_PLANAR

candModeList[2]＝INTRA_ANGULAR50 (A1_56)

candModeList[3]＝INTRA_ANGULAR18 (A1_57)

candModeList[4]＝INTRA_ANGULAR46 (A1_58)

candModeList[5]＝INTRA_ANGULAR54 (A1_59)

else (intralumeforelineidx [ xCb ] [ yCb ] not equal to 0), the following applies:

candModeList[0]＝INTRA_ANGULAR50 (A1_60)

candModeList[1]＝INTRA_ANGULAR18 (A1_61)

candModeList[2]＝INTRA_ANGULAR2 (A1_62)

candModeList[3]＝INTRA_ANGULAR34 (A1_63)

candModeList[4]＝INTRA_ANGULAR66 (A1_64)

candModeList[5]＝INTRA_ANGULAR26 (A1_65)

appendix 2

IntraPredModey [ xCb ] [ yCb ] was obtained by the following sequential steps:

1. the adjacent positions (xNbA, yNbA) and (xNbB, yNbB) are set equal to (xCb-1, yCb + cbHeight-1) and (xCb + cbWidth-1, yCb-1), respectively.

2. For the replacement of X by A or B, the variable candIntrarPredModex is derived as follows:

-invoking an availability derivation procedure for the block with a position (xCurr, yCurr) set equal to (xCb, yCb) and an adjacent position (xNbY, yNbY) set equal to (xNbX, yNbX) as inputs, and assigning the output to availableX.

-deriving the candidate intra prediction mode candlntrapredmodex as follows:

-candlntrapredmodex is set equal to INTRA _ plan if one or more of the following conditions is true.

The variable availableX is equal to FALSE.

CuPredMode [ xNbX ] [ yNbX ] is not equal to MODE _ INTRA, and ciip _ flag [ xNbX ] [ yNbX ] is not equal to 1.

-pcm _ flag [ xNbX ] [ yNbX ] equals 1.

X is equal to B and yCb-1 is less than

((yCb>>CtbLog2SizeY)<<CtbLog2SizeY)。

-otherwise candIntraPredModeX is set equal to

IntraPredModeY[xNbX][yNbX]。

3. The variables ispdefultmode 1 and ispdefultmode 2 are defined as follows:

-ispDefaultMode1 is set equal to INTRA _ angul 18 and ispDefaultMode2 is set equal to INTRA _ angul 5 if intrasubpartitionsplittype is equal to ISP _ HOR _ SPLIT.

Else ispdefultmode 1 is set equal to INTRA _ angul 50 and ispdefultmode 2 is set equal to INTRA _ angul 63.

4. candModeList [ x ], where x ═ 0..5, is derived as follows:

if candirapredModeB is equal to candirapredModeA, and

canddatapredmodea is greater than INTRA _ DC, candModeList [ x ] is derived as follows, where x ═ 0.. 5:

if IntraLumaRefLineIdx [ xCb ] [ yCb ] is equal to 0 and

IntraSubPartitionsSplitType equals ISP _ NO _ SPLIT, the following applies:

candModeList[0]＝candIntraPredModeA (A2_9)

candModeList[1]＝INTRA_PLANAR (A2_10)

candModeList[2]＝INTRA_DC (A2_11)

candModeList[3]＝2+((candIntraPredModeA+61)％64) (A2_12)

candModeList[4]＝2+((candIntraPredModeA-1)％64) (A2_13)

candModeList[5]＝2+((candIntraPredModeA+60)％64) (A2_14)

else (IntralmaRefLineIdx [ xCb ] [ yCb ] is not equal to 0 or

Intrasubpartitionsplit type not equal to ISP _ NO _ SPLIT), the following applies:

candModeList[0]＝candIntraPredModeA (A2_15)

candModeList[1]＝2+((candIntraPredModeA+61)％64) (A2_16)

candModeList[2]＝2+((candIntraPredModeA-1)％64) (A2_17)

-if one of the following conditions is true,

IntraSubPartitionsSplitType equal to ISP _ HOR _ SPLIT and

candlntrapredmodea is smaller than INTRA _ ANGULAR 34;

IntraSubPartitionsSplitType equals ISP _ VER _ SPLIT and

candlntrapredmodea is greater than or equal to INTRA _ ANGULAR 34;

-IntraLumaRefLineIdx [ xCb ] [ yCb ] is not equal to 0,

the following applies:

candModeList[3]＝2+((candIntraPredModeA+60)％64) (A2_18)

candModeList[4]＝2+(candIntraPredModeA％64) (A2_19)

candModeList[5]＝2+((candIntraPredModeA+59)％64) (A2_20)

-otherwise, applying the following:

candModeList[3]＝ispDefaultMode1 (A2_21)

candModeList[4]＝ispDefaultMode2 (A2_22)

candModeList[5]＝INTRA_PLANAR (A2_23)

else, if candirapredModB does not equal candirapredModA, and

candirapredmodea or candirapredmodeb is greater than INTRA _ DC, the following applies:

the variables minAB and maxAB are derived as follows:

minAB＝Min(candIntraPredModeA，candIntraPredModeB) (A2_24)

maxAB＝Max(candIntraPredModeA，candIntraPredModeB) (A2_25)

-if candxtrapredmodea and candxtrapredmodeb are both greater than INTRA _ DC, candModeList [ x ] is derived as follows, where x ═ 0.. 5:

candModeList[0]＝candIntraPredModeA (A2_26)

candModeList[1]＝candIntraPredModeB (A2_27)

if IntraLumaRefLineIdx [ xCb ] [ yCb ] is equal to 0 and

IntraSubPartitionsSplitType equals ISP _ NO _ SPLIT, the following applies:

candModeList[2]＝INTRA_PLANAR (A2_28)

candModeList[3]＝INTRA_DC (A2_29)

if maxAB-minAB is in the range of 2 to 62 (inclusive of 2 and 62), the following applies:

candModeList[4]＝2+((maxAB+61)％64) (A2_30)

candModeList[5]＝2+((maxAB-1)％64) (A2_31)

-otherwise, applying the following:

candModeList[4]＝2+((maxAB+60)％64) (A2_32)

candModeList[5]＝2+((maxAB)％64) (A2_33)

else (IntralmaRefLineIdx [ xCb ] [ yCb ] is not equal to 0 or

Intrasubpartitionsplit type not equal to ISP _ NO _ SPLIT), the following applies:

-when intrasubportionssplittype is not equal to ISP _ NO _ SPLIT and abs (candirapredmodeb-ispdefultmode 1) is smaller than abs (candirapredmodea-ispdefultmode 1), the following applies:

candModeList[0]＝candIntraPredModeB (A2_34)

candModeList[1]＝candIntraPredModeA (A2_35)

if maxAB-minAB equals 1, the following applies:

candModeList[2]＝2+((minAB+61)％64) (A2_36)

candModeList[3]＝2+((maxAB-1)％64) (A2_37)

candModeList[4]＝2+((minAB+60)％64) (A2_38)

candModeList[5]＝2+(maxAB％64) (A2_39)

else, if maxAB-minAB is equal to 2, the following applies:

candModeList[2]＝2+((minAB-1)％64) (A2_40)

candModeList[3]＝2+((minAB+61)％64) (A2_41)

candModeList[4]＝2+((maxAB-1)％64) (A2_42)

candModeList[5]＝2+((minAB+60)％64) (A2_43)

else, if maxAB-minAB is greater than 61, the following applies:

candModeList[2]＝2+((minAB-1)％64) (A2_44)

candModeList[3]＝2+((maxAB+61)％64) (A2_45)

candModeList[4]＝2+(minAB％64) (A2_46)

candModeList[5]＝2+((maxAB+60)％64) (A2_47)

-otherwise, applying the following:

candModeList[2]＝2+((minAB+61)％64) (A2_48)

candModeList[3]＝2+((minAB-1)％64) (A2_49)

candModeList[4]＝2+((maxAB+61)％64) (A2_50)

candModeList[5]＝2+((maxAB-1)％64) (A2_51)

else (candirapredModeA or candirapredModeB is greater than

INTRA _ DC), candmodellist [ x ] is derived as follows, where x ═ 0.. 5:

if IntraLumaRefLineIdx [ xCb ] [ yCb ] is equal to 0 and

IntraSubPartitionsSplitType equals ISP _ NO _ SPLIT, the following applies:

candModeList[0]＝candIntraPredModeA (A2_52)

candModeList[1]＝candIntraPredModeB (A2_53)

candModeList[2]＝1-minAB (A2_54)

candModeList[3]＝2+((maxAB+61)％64) (A2_55)

candModeList[4]＝2+((maxAB-1)％64) (A2_56)

candModeList[5]＝2+((maxAB+60)％64) (A2_57)

else, if IntraLumaRefLineIdx [ xCb ] [ yCb ] is not equal to 0, the following applies:

candModeList[0]＝maxAB (A2_58)

candModeList[1]＝2+((maxAB+61)％64) (A2_59)

candModeList[2]＝2+((maxAB-1)％64) (A2_60)

candModeList[3]＝2+((maxAB+60)％64) (A2_61)

candModeList[4]＝2+(maxAB％64) (A2_62)

candModeList[5]＝2+((maxAB+59)％64) (A2_63)

else (intrasubpartitionsplittype not equal to ISP _ NO _ SPLIT), the following applies:

candModeList[0]＝INTRA_PLANAR (A2_64)

candModeList[1]＝maxAB (A2_65)

candModeList[2]＝2+((maxAB+61)％64) (A2_66)

candModeList[3]＝2+((maxAB-1)％64) (A2_67)

candModeList[4]＝2+((maxAB+60)％64) (A2_68)

candModeList[5]＝2+(maxAB％64) (A2_69)

-otherwise, applying the following:

if IntraLumaRefLineIdx [ xCb ] [ yCb ] is equal to 0 and

IntraSubPartitionsSplitType equals ISP _ NO _ SPLIT, the following applies:

candModeList[0]＝candIntraPredModeA (A2_70)

candModeList[1]＝

(candModeList[0]＝＝INTRA_PLANAR)？INTRA_DC:(A2_71)INTRA_PLANAR

candModeList[2]＝INTRA_ANGULAR50 (A2_72)

candModeList[3]＝INTRA_ANGULAR18 (A2_73)

candModeList[4]＝INTRA_ANGULAR46 (A2_74)

candModeList[5]＝INTRA_ANGULAR54 (A2_75)

else, if IntraLumaRefLineIdx [ xCb ] [ yCb ] is not equal to 0, the following applies:

candModeList[0]＝INTRA_ANGULAR50 (A2_76)

candModeList[1]＝INTRA_ANGULAR18 (A2_77)

candModeList[2]＝INTRA_ANGULAR2 (A2_78)

candModeList[3]＝INTRA_ANGULAR34 (A2_79)

candModeList[4]＝INTRA_ANGULAR66 (A2_80)

candModeList[5]＝INTRA_ANGULAR26 (A2_81)

otherwise, if intrasubportionssplittype is equal to ISP _ HOR _ SPLIT, the following applies:

candModeList[0]＝INTRA_PLANAR (A2_82)

candModeList[1]＝INTRA_ANGULAR18 (A2_83)

candModeList[2]＝INTRA_ANGULAR25 (A2_84)

candModeList[3]＝INTRA_ANGULAR10 (A2_85)

candModeList[4]＝INTRA_ANGULAR65 (A2_86)

candModeList[5]＝INTRA_ANGULAR50 (A2_87)

otherwise, if intrasubportionssplittype is equal to ISP _ VER _ SPLIT, the following applies:

candModeList[0]＝INTRA_PLANAR (A2_88)

candModeList[1]＝INTRA_ANGULAR50 (A2_89)

candModeList[2]＝INTRA_ANGULAR43 (A2_90)

candModeList[3]＝INTRA_ANGULAR60 (A2_91)

candModeList[4]＝INTRA_ANGULAR3 (A2_92)

candModeList[5]＝INTRA_ANGULAR18 (A2_93)

IntraPredModeY [ xCb ] [ yCb ] was obtained by applying the following procedure:

-if bdpcm _ flag [ xCb ] [ yCb ] is equal to 1, IntraPredModeY [ xCb ] [ yCb ] is set equal to bdpcm _ dir _ flag [ xCb ] [ yCb ] ═ 0INTRA _ ANGULAR18:

INTRA_ANGULAR50。

else, if intra _ luma _ mpm _ flag [ xCb ] [ yCb ] is equal to 1

IntraPredModey [ xCb ] [ yCb ] is set equal to

candModeList[intra_luma_mpm_idx[xCb][yCb]]。

Else, IntraPredModeY [ xCb ] [ yCb ] is obtained by applying the following sequential steps:

1. when candModeList [ i ] is greater than candModeList [ j ] (i 0..4, and for each i,

j ═ i + 1.. 5), the two values are exchanged as follows:

(candModeList[i],candModeList[j])＝Swap(candModeList[i],

candModeList[j]) (A2_94)

IntraPredModeY [ xCb ] [ yCb ] was obtained by the following sequential steps:

IntraPredModey [ xCb ] [ yCb ] set equal to

intra_luma_mpm_remainder[xCb][yCb]。

For i equal to 0 to 5 (including 0 and 5), when

When IntraPredModey [ xCb ] [ yCb ] is greater than or equal to candModelist [ i ],

the value of IntraPredModey [ xCb ] [ yCb ] increased by 1.

The variable IntraPredModeY [ x ] [ y ] is set equal to IntraPredModeY [ xCb ] [ yCb ], where x ═ xcb.. xCb + cbWidth-1 and y ═ ycb.. yCb + cbHeight-1.