阅读说明：本技术 增强区域取向包封及视区独立高效视频译码媒体配置文件 (Enhanced region-oriented encapsulation and view-independent high-efficiency video coding media profile ) 是由 王业奎 托马斯·斯托克哈默 于 2018-07-10 设计创作，主要内容包括：本发明提供一种用于处理媒体内容的装置，其可经配置以：从视频文件内的区域取向包封框获得指示媒体内容的第一经包封区域的第一大小及第一位置的第一值集合，及指示所述媒体内容的第二经包封区域的第二大小及第二位置的第二值集合，其中所述第一值集合及所述第二值集合呈解包封的左上角明度样本的相对单位；解包封所述第一经包封区域以产生第一解包封区域；从所述第一解包封区域形成第一经投影区域；解包封所述第二经包封区域以产生第二解包封区域；及从所述第二解包封区域形成第二经投影区域，所述第二经投影区域不同于所述第一经投影区域。(The present invention provides a device for processing media content, which may be configured to: obtaining, from a region-oriented encapsulation box within a video file, a first set of values indicative of a first size and a first position of a first encapsulated region of media content, and a second set of values indicative of a second size and a second position of a second encapsulated region of the media content, wherein the first set of values and the second set of values are in relative units of unpacked upper left-hand luma samples; decapsulating the first encapsulated region to produce a first decapsulated region; forming a first projected region from the first decapsulated region; decapsulating the second encapsulated region to produce a second decapsulated region; and forming a second projected region from the second decapsulated region, the second projected region different from the first projected region.)

1. A method of processing media content, the method comprising:

obtaining, from a region-oriented encapsulation box within a video file, a first set of values indicative of a first size and a first position of a first encapsulated region of media content, and a second set of values indicative of a second size and a second position of a second encapsulated region of the media content, wherein the first set of values and the second set of values are in relative units of upper left corner luma samples of an unpackaged picture that includes the first encapsulated region and the second encapsulated region;

decapsulating the first encapsulated region to produce a first decapsulated region;

forming a first projected region from the first decapsulated region;

decapsulating the second encapsulated region to produce a second decapsulated region; and

forming a second projected region from the second decapsulated region, the second projected region being different from the first projected region.

2. The method of claim 1, wherein the first set of values includes a first width value, a first height value, a first top value, and a first left value, and wherein the second set of values includes a second width value, a second height value, a second top value, and a second left value, the method further comprising:

determining a first width of the first encapsulated region from the first width value;

determining a first height of the first encapsulated region from the first height value;

determining a first top offset for the first encapsulated region from the first top value;

determining a first left-side offset of the first encapsulated region from the first left-side value;

determining a second width of the second encapsulated region from the second width value;

determining a second height of the second encapsulated region from the second height value;

determining a second top offset for the second encapsulated region from the second top value; and

determining a second left-side offset of the second encapsulated region from the second left-side value.

3. The method of claim 2, wherein the first width value comprises a packed _ reg _ width [ i ] value, the first height value comprises a packed _ reg _ height [ i ] value, the first top value comprises a packed _ reg _ top [ i ] value, the first left value comprises a packed _ reg _ left [ i ], the second width value comprises a packed _ reg _ width [ j ] value, the second height value comprises a packed _ reg _ height [ j ] value, the second top value comprises a packed _ reg _ top [ j ] value, and the second left value comprises a packed _ reg _ left [ j ] value.

4. The method of claim 1, further comprising:

obtaining a projected picture width and a projected picture height from the region-oriented encapsulation frame within the video file, wherein the projected picture width and the projected picture height are in the relative units.

5. The method of claim 1, wherein the container of the region-oriented encapsulation box comprises a projected omnidirectional video box.

6. The method of claim 1, wherein the media content is monoscopic.

7. The method of claim 1, wherein the media content is stereoscopic.

8. The method of claim 7, wherein the first wrapped area corresponds to a first picture of the media content, and wherein the second wrapped area corresponds to a second picture of the media content.

9. An apparatus for processing media content, the apparatus comprising:

a memory configured to store media content; and

one or more processors implemented in circuitry and configured to:

obtaining, from a region-oriented encapsulation box within a video file, a first set of values indicative of a first size and a first position of a first encapsulated region of media content, and a second set of values indicative of a second size and a second position of a second encapsulated region of the media content, wherein the first set of values and the second set of values are in relative units of upper left corner luma samples of an unpackaged picture that includes the first encapsulated region and the second encapsulated region;

decapsulating the first encapsulated region to produce a first decapsulated region;

forming a first projected region from the first decapsulated region;

decapsulating the second encapsulated region to produce a second decapsulated region; and

forming a second projected region from the second decapsulated region, the second projected region being different from the first projected region.

10. The device of claim 9, wherein the first set of values comprises a first width value, a first height value, a first top value, and a first left value, and wherein the second set of values comprises a second width value, a second height value, a second top value, and a second left value, wherein the one or more processors are further configured to:

determining a first width of the first encapsulated region from the first width value;

determining a first height of the first encapsulated region from the first height value;

determining a first top offset for the first encapsulated region from the first top value;

determining a first left-side offset of the first encapsulated region from the first left-side value;

determining a second width of the second encapsulated region from the second width value;

determining a second height of the second encapsulated region from the second height value;

determining a second top offset for the second encapsulated region from the second top value; and

determining a second left-side offset of the second encapsulated region from the second left-side value.

11. The device of claim 10, wherein the first width value comprises a packed reg width [ i ] value, the first height value comprises a packed reg height [ i ] value, the first top value comprises a packed reg top [ i ] value, the first left value comprises a packed reg left [ i ], the second width value comprises a packed reg width [ j ] value, the second height value comprises a packed reg height [ j ] value, the second top value comprises a packed reg top [ j ] value, and the second left value comprises a packed reg left [ j ] value.

12. The device of claim 9, wherein the one or more processors are further configured to:

obtaining a projected picture width and a projected picture height from the region-oriented encapsulation frame within the video file, wherein the projected picture width and the projected picture height are in the relative units.

13. The device of claim 9, wherein a container of the region-oriented encapsulation frame comprises a projected omnidirectional video frame.

14. The device of claim 9, wherein the media content is monoscopic.

15. The device of claim 9, wherein the media content is stereoscopic.

16. The device of claim 15, wherein the first wrapped area corresponds to a first picture of the media content, and wherein the second wrapped area corresponds to a second picture of the media content.

17. The apparatus of claim 9, wherein the apparatus comprises at least one of:

an integrated circuit;

a microprocessor; and

a wireless communication device.

18. The device of claim 9, wherein the device comprises a client device.

19. A computer-readable storage medium having stored thereon instructions that, when executed, cause a processor to:

obtaining, from a region-oriented encapsulation box within a video file, a first set of values indicative of a first size and a first position of a first encapsulated region of media content, and a second set of values indicative of a second size and a second position of a second encapsulated region of the media content, wherein the first set of values and the second set of values are in relative units of upper left corner luma samples of an unpackaged picture that includes the first encapsulated region and the second encapsulated region;

decapsulating the first encapsulated region to produce a first decapsulated region;

forming a first projected region from the first decapsulated region;

decapsulating the second encapsulated region to produce a second decapsulated region; and

forming a second projected region from the second decapsulated region, the second projected region being different from the first projected region.

20. The computer-readable storage medium of claim 19, wherein the first set of values comprises a first width value, a first height value, a first top value, and a first left value, and wherein the second set of values comprises a second width value, a second height value, a second top value, and a second left value, wherein the one or more processors are further configured to:

determining a first width of the first encapsulated region from the first width value;

determining a first height of the first encapsulated region from the first height value;

determining a first top offset for the first encapsulated region from the first top value;

determining a first left-side offset of the first encapsulated region from the first left-side value;

determining a second width of the second encapsulated region from the second width value;

determining a second height of the second encapsulated region from the second height value;

determining a second top offset for the second encapsulated region from the second top value; and

determining a second left-side offset of the second encapsulated region from the second left-side value.

21. The computer-readable storage medium of claim 20, wherein the first width value comprises a packed reg _ width [ i ] value, the first height value comprises a packed reg _ height [ i ] value, the first top value comprises a packed reg _ top [ i ] value, the first left value comprises a packed reg _ left [ i ], the second width value comprises a packed reg _ width [ j ] value, the second height value comprises a packed reg _ height [ j ] value, the second top value comprises a packed reg _ top [ j ] value, and the second left value comprises a packed reg _ left [ j ] value.

22. The computer-readable storage medium of claim 19, wherein the one or more processors are further configured to:

obtaining a projected picture width and a projected picture height from the region-oriented encapsulation frame within the video file, wherein the projected picture width and the projected picture height are in the relative units.

23. The computer-readable storage medium of claim 19, wherein a container of the region-oriented encapsulation frame comprises a projected omnidirectional video frame.

24. The computer-readable storage medium of claim 19, wherein the media content is monoscopic.

25. The computer-readable storage medium of claim 19, wherein the media content is stereoscopic.

26. The computer-readable storage medium of claim 25, wherein the first wrapped area corresponds to a first picture of the media content, and wherein the second wrapped area corresponds to a second picture of the media content.

27. An apparatus for processing media content, the apparatus comprising:

means for obtaining, from a region-oriented encapsulation frame within a video file, a first set of values indicative of a first size and a first position of a first encapsulated region of media content, and a second set of values indicative of a second size and a second position of a second encapsulated region of the media content, wherein the first set of values and the second set of values are in relative units of upper left corner luma samples of an unpackaged picture that includes the first encapsulated region and the second encapsulated region;

means for decapsulating the first encapsulated region to generate a first decapsulated region;

means for forming a first projected region from the first decapsulated region;

means for decapsulating the second encapsulated region to generate a second decapsulated region; and

means for forming a second projected region from the second decapsulated region, the second projected region different from the first projected region.

28. The device of claim 27, wherein the first set of values includes a first width value, a first height value, a first top value, and a first left value, and wherein the second set of values includes a second width value, a second height value, a second top value, and a second left value, the device further comprising:

means for determining a first width of the first encapsulated region from the first width value;

means for determining a first height of the first encapsulated region from the first height value;

means for determining a first top offset of the first encapsulated region from the first top value;

means for determining a first left-side offset of the first encapsulated region from the first left-side value;

means for determining a second width of the second encapsulated region from the second width value;

means for determining a second height of the second encapsulated region from the second height value;

means for determining a second top offset for the second encapsulated region from the second top value; and

means for determining a second left-side offset of the second encapsulated region from the second left-side value.

29. The device of claim 28, wherein the first width value comprises a packed reg width [ i ] value, the first height value comprises a packed reg height [ i ] value, the first top value comprises a packed reg top [ i ] value, the first left value comprises a packed reg left [ i ], the second width value comprises a packed reg width [ j ] value, the second height value comprises a packed reg height [ j ] value, the second top value comprises a packed reg top [ j ] value, and the second left value comprises a packed reg left [ j ] value.

30. The device of claim 27, further comprising:

obtaining a projected picture width and a projected picture height from the region-oriented encapsulation frame within the video file, wherein the projected picture width and the projected picture height are in the relative units.

31. The device of claim 27, wherein a container of the region-oriented encapsulation frame comprises a projected omnidirectional video frame.

Technical Field

The present invention relates to the storage and transfer of encoded video data.

Background

Digital video capabilities can be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, Personal Digital Assistants (PDAs), laptop or desktop computers, digital cameras, digital recording devices, digital media players, video gaming devices, video gaming consoles, cellular or satellite radio telephones, video teleconferencing devices, and the like. Digital video devices implement video compression techniques, such as those described in standards defined by MPEG-2, MPEG-4, ITU-T h.263, or ITU-T h.264/MPEG-4, part 10, Advanced Video Coding (AVC), ITU-T h.265, also known as High Efficiency Video Coding (HEVC), and extensions of such standards to more efficiently transmit and receive digital video information.

After the video data has been encoded, the video data may be packetized for transmission or storage. The video data may be compiled into a video file that conforms to any of a variety of standards, such as the international organization for standardization (ISO) base media file format and extensions thereof, such as AVC.

Disclosure of Invention

In general, this disclosure describes techniques related to processing media data, and more specifically to region-oriented encapsulation.

According to one example, a method of processing media content includes: obtaining, from a region-oriented encapsulation frame within a video file, a first set of values indicative of a first size and a first position of a first encapsulated region of media content, and a second set of values indicative of a second size and a second position of a second encapsulated region of media content, wherein the first set of values and the second set of values are in relative units of upper left corner luma samples of an unpackaged picture that includes the first encapsulated region and the second encapsulated region; decapsulating the first encapsulated region to produce a first decapsulated region; forming a first projected region from the first unpackaged region; decapsulating the second encapsulated region to produce a second decapsulated region; and forming a second projected area from the second decapsulated area, the second projected area being different from the first projected area.

According to another example, a device for processing media content includes: a memory configured to store media content; and one or more processors implemented in the circuitry and configured to: obtaining, from a region-oriented encapsulation frame within a video file, a first set of values indicative of a first size and a first position of a first encapsulated region of media content, and a second set of values indicative of a second size and a second position of a second encapsulated region of media content, wherein the first set of values and the second set of values are in relative units of upper left corner luma samples of an unpackaged picture that includes the first encapsulated region and the second encapsulated region; decapsulating the first encapsulated region to produce a first decapsulated region; forming a first projected region from the first unpackaged region; decapsulating the second encapsulated region to produce a second decapsulated region; and forming a second projected area from the second decapsulated area, the second projected area being different from the first projected area.

According to another example, a computer-readable storage medium having stored thereon instructions that, when executed, cause a processor to: obtaining, from a region-oriented encapsulation frame within a video file, a first set of values indicative of a first size and a first position of a first encapsulated region of media content, and a second set of values indicative of a second size and a second position of a second encapsulated region of media content, wherein the first set of values and the second set of values are in relative units of upper left corner luma samples of an unpackaged picture that includes the first encapsulated region and the second encapsulated region; decapsulating the first encapsulated region to produce a first decapsulated region; forming a first projected region from the first unpackaged region; decapsulating the second encapsulated region to produce a second decapsulated region; and forming a second projected area from the second decapsulated area, the second projected area being different from the first projected area.

According to another example, a device for processing media includes: means for obtaining, from a region-oriented encapsulation frame within a video file, a first set of values indicative of a first size and a first position of a first encapsulated region of media content, and a second set of values indicative of a second size and a second position of a second encapsulated region of media content, wherein the first set of values and the second set of values are in relative units of upper left corner luma samples of an unpackaged picture that includes the first encapsulated region and the second encapsulated region; means for decapsulating the first encapsulated region to produce a first decapsulated region; means for forming a first projected region from the first decapsulated region; means for decapsulating the second encapsulated region to generate a second decapsulated region; and means for forming a second projected area from the second decapsulated area, the second projected area different from the first projected area.

The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

Drawings

Fig. 1 is a block diagram illustrating an example system implementing techniques for streaming media data over a network.

FIG. 2 is a block diagram illustrating an example set of components of a capture unit.

Fig. 3 is a conceptual diagram illustrating two examples of region orientation envelopes (RWPs) for an omni-directional media format (OMAF).

FIG. 4 is a conceptual diagram illustrating elements of example multimedia content.

FIG. 5 is a block diagram illustrating elements of an example video file.

Fig. 6 is a flow diagram illustrating an example method of receiving and processing video data in accordance with the techniques of this disclosure.

Detailed Description

The techniques of this disclosure may be applied to video files that conform to video data encapsulated according to any of the ISO base media file format (ISOBMFF), an extension to ISOBMFF, a Scalable Video Coding (SVC) file format, an Advanced Video Coding (AVC) file format, a High Efficiency Video Coding (HEVC) file format, a third generation partnership project (3GPP) file format, and/or a Multiview Video Coding (MVC) file format or other video file formats. A draft of ISO BMFF is specified in ISO/IEC 14496-12 (available from phenix. int-evry. fr/mpeg/doc _ end _ user/documents/111_ Geneva/wg11/w15177-v6-w15177. zip). Another example file format, a draft of the MPEG-4 file format, is specified in ISO/IEC 14496-15 (available from wg11.sc29.org/doc _ end _ user/documents/115_ Geneva/wg11/w16169-v2-w16169. zip).

ISOBMFF is used as a basis for many codec encapsulation formats, such as the AVC file format, and for many multimedia container formats, such as the MPEG-4 file format, the 3GPP file format (3GP), and the Digital Video Broadcast (DVB) file format.

In addition to continuous media such as audio and video, static media such as images, as well as metadata, may be stored in a file that conforms to ISOBMFF. Files structured according to ISOBMFF are available for many purposes, including local media file playback, progressive downloading of remote files, segments for dynamic adaptive streaming over HTTP (DASH), containers for content to be streamed and its packetization instructions, and recording of received real-time media streams.

A box is the basic syntax structure in ISOBMFF, including the four-character coding box type, the byte count of the box, and the payload. The ISOBMFF file includes a sequence of boxes, and the boxes may contain other boxes. According to ISOBMFF, movie boxes ("moov") contain metadata for the continuous media streams present in the file, each continuous media stream being represented in the file as a track. According to ISOBMFF, metadata for a track is enclosed in a track box ("trak"), while the media content of the track is enclosed in a media data box ("mdat") or provided directly in a separate file. The media content for a track includes a sequence of samples, such as audio or video access units.

ISOBMFF specifies the following types of tracks: a media track containing a base media stream; a hint track containing media transmission instructions or representing a received packet stream; and a timed metadata track comprising time synchronized metadata.

Although originally designed for storage, ISOBMFF has proven extremely valuable for streaming (e.g., for progressive download or DASH). For streaming purposes, movie fragments as defined in ISOBMFF may be used.

The metadata for each track includes a list of sample description entries, each entry providing a coding or encapsulation format used in the track and initialization data needed to process the format. Each sample is associated with one of the sample description entries of the track.

ISOBMFF implements sample-specific metadata specified through various mechanisms. Specific boxes within a sample table box ("stbl") have been standardized to respond to common needs. For example, a sync sample box ("stss") is used to enumerate random access samples of a track. The sample grouping mechanism enables mapping of samples according to a four character grouping type into sample groups sharing the same property specified as a sample group description entry in a file. Several packet types have been specified in ISOBMFF.

Virtual Reality (VR) is the ability to virtually exist in a virtual non-physical world created by rendering natural and/or synthetic images and sounds related to movements of an immersive user, allowing interaction with the virtual world. With recent advances in rendering devices, such as Head Mounted Displays (HMDs), and VR video (also often referred to as 360 degree video) creation, significant quality of experience may be provided. VR applications include gaming, training, education, sports video, online shopping, entertainment, and the like.

A typical VR system contains the following components and performs the following steps:

1) a camera suite, which typically contains a plurality of individual cameras directed in different directions, ideally collectively covering all viewpoints around the camera suite.

2) Image stitching, where video pictures taken by multiple individual cameras are synchronized in the time domain and stitched in the spatial domain to form a spherical video, but mapped to a rectangular format, such as an iso-rectangular (like a world map) or cube mapping.

3) Video in a mapped rectangular format is encoded/compressed using a video codec (e.g., h.265/HEVC or h.264/AVC).

4) The compressed video bitstream may be stored and/or encapsulated in a media format and transmitted (possibly covering only the area seen by the user, sometimes referred to as a subset of the view region) over a network to a receiving device (e.g., a client device).

5) The receiving device receives a video bitstream, or portion thereof, that may be encapsulated in a file format, and sends the decoded video signal, or portion thereof, to a rendering device (which may be included in the same client device as the receiving device).

6) The rendering device may be, for example, a Head Mounted Display (HMD) that may track head movement, and may even track eye movement, and may render corresponding portions of the video such that an immersive experience is delivered to the user.

The omnidirectional media format (OMAF) was developed by the Moving Picture Experts Group (MPEG) to define a media format that enables omnidirectional media applications, which focus on VR applications with 360 degrees of video and associated audio. OMAF specifies a projection method that can be used to convert spherical or 360-degree video into two-dimensional rectangular video, then how to store omnidirectional media and associated metadata using the ISO base media file format (ISOBMFF), and how to encapsulate, signal, and stream omnidirectional media using HTTP Dynamic Adaptive Streaming (DASH), and finally which video and audio codecs and media coding configurations can be used to compress and play a list of omnidirectional media signals. OMAF will become ISO/IEC 23090-2 and draft specifications are available from wg11.sc29.org/doc _ end _ user/documents/119_ Torino/wg11/m40849-v1-m40849_ OMAF _ text _ Berlin _ output. zip.

In HTTP streaming protocols such as DASH, frequently used operations include HEAD, GET, and partial GET. The HEAD operation captures the header of a file associated with a given Uniform Resource Locator (URL) or Uniform Resource Name (URN), but does not capture the payload associated with the URL or URN. The GET operation captures the entire file associated with a given URL or URN. The partial GET operation receives a byte range as an input parameter and captures a consecutive number of bytes of the file, where the number of bytes corresponds to the received byte range. Thus, movie fragments may be provided for HTTP streaming, since a partial GET operation enables one or more individual movie fragments. In a movie fragment, there may be several track fragments of different tracks. In HTTP streaming, a media presentation may be a structured collection of data accessible to a client. The client may request and download media data information to present the streaming service to the user.

DASH is specified in ISO/IEC 23009-1 and is a standard for HTTP (adaptive) streaming applications. ISO/IEC 23009-1 primarily specifies the format of a Media Presentation Description (MPD), also known as an information list or information list file, and the media segment format. The MPD describes media available on the server and allows DASH clients to autonomously download the appropriate media version at the appropriate media time.

In an example where 3GPP data is streamed using HTTP streaming, there may be multiple representations of video and/or audio data of the multimedia content. As explained below, the different representations may correspond to different coding characteristics (e.g., different profiles or levels of a video coding standard), different coding standards or extensions of a coding standard (e.g., multiview and/or scalable extensions), or different bitrates. The list of information for such representations may be defined in a Media Presentation Description (MPD) data structure. The media presentation may correspond to a structured collection of data accessible to the HTTP streaming client device. An HTTP streaming client device may request and download media data information to present a streaming service to a user of the client device. The media presentation may be described in an MPD data structure, which may include updates to the MPD.

A media presentation may contain a sequence of one or more periods. Each period may be extended until the next period begins, or in the case of the last period, until the end of the media presentation. Each period may contain one or more representations of the same media content. The representation may be one of several alternative encoded versions of audio, video, timed text, or other such data. The representation may vary by encoding type (e.g., by bitrate, resolution, and/or codec for video data, and by bitrate, language, and/or codec for audio data). The term representation may be used to refer to portions of encoded audio or video data that correspond to particular periods of multimedia content and are encoded in a particular manner.

The representations for a particular period may be assigned to the group indicated by the attribute in the MPD that indicates the adaptation set to which the representation belongs. Representations in the same adaptation set are often considered alternatives to each other, as the client device may dynamically and smoothly switch between such representations, for example, to perform bandwidth adaptation. For example, each representation of video data for a particular period may be assigned to the same adaptation set, such that any of the representations may be selected for decoding to present media data (e.g., video data or audio data) for a corresponding period of multimedia content. In some examples, media content within a period may be represented by one representation from group 0 (if present), or by a combination of at most one representation from each non-zero group. The timing data for each representation of a cycle may be expressed relative to the start time of the cycle.

The representation may include one or more segments. Each representation may include an initialization segment, or each segment of a representation may be self-initializing. When present, the initialization segment may contain initialization information for accessing the representation. In general, the initialization segment contains no media data. The segments may be uniquely referenced by an identifier, such as a Uniform Resource Locator (URL), a Uniform Resource Name (URN), or a Uniform Resource Identifier (URI). The MPD may provide an identifier for each segment. In some examples, the MPD may also provide byte ranges in the form of range attributes, which may correspond to data for segments within a file that may be accessed by a URL, URN, or URI.

Different representations may be selected for capturing different types of media data substantially simultaneously. For example, the client device may select an audio representation, a video representation, and a timed text representation from which to capture the segments. In some examples, a client device may select a particular adaptation set for performing bandwidth adaptation. That is, the client device may select an adaptation set that includes a video representation, an adaptation set that includes an audio representation, and/or an adaptation set that includes timed text. Alternatively, the client device may select adaptation sets for certain types of media (e.g., video) and directly select representations for other types of media (e.g., audio and/or timed text).

A typical procedure for DASH-based HTTP streaming contains the following steps:

1) a DASH client obtains an MPD of streaming content (e.g., a movie). The MPD contains information about different alternative representations of the streaming content (e.g., bit rate, video resolution, frame rate, audio language), and URLs of HTTP resources (initialization segment and media segment).

2) Based on information in the MPD and local information available to the DASH client, such as network bandwidth, decoding/display capabilities, and user preferences, the DASH client requests the desired representation, one segment (or portion thereof) at a time.

3) When a DASH client detects a network bandwidth change, it requests a segment with a different representation of a better matching bit rate, ideally starting with a segment that starts with a random access point.

During an HTTP streaming "session," a DASH client requests past or future segments starting from a segment that is close to the desired location and ideally begins at a random access point in response to a user request to search past locations in the reverse direction or to search future locations in the forward direction. The user may also request fast forwarding content, which may be accomplished by requesting data that is only sufficient for decoding intra-coded video pictures or only sufficient for decoding a transient subset of the video stream.

Section 5.3.3.1 of the DASH specification is preselected as follows:

the concept of preselection is primarily motivated for the purpose of Next Generation Audio (NGA) codecs to signal a suitable combination of audio elements provided in different adaptation sets. However, the pre-selection concept is introduced in a general way, so that it is scalable and also used for other media types and codecs.

Each pre-selection is associated with a bundle. Bundling is a set of elements that can be consumed by a single decoder performing individual unions. The elements are addressable and separable components of the bundle and can be dynamically selected or deselected by the application, either directly or indirectly through the use of preselection. The elements are mapped to the adaptation set by a one-to-one mapping or by including multiple elements in a single adaptation set. Furthermore, one adaptation focused representation may contain multiple elements multiplexed at the elementary stream level or file container level. In the multiplexing case, each element is mapped to a media content component as defined in DASH section 5.3.4. Each element in the bundle is thus identified and referenced by the @ id of the media content component, or if the adaptation set contains only a single element, by the @ id of the adaptation set.

Each bundle includes primary elements that contain decoder specific information and direct the decoder. The adaptation set containing the main element is referred to as a main adaptation set. The primary element should always be included in any presets associated with the bundle. In addition, each bundle may include one or more partial adaptation sets. The partial adaptation set may be processed only in conjunction with the main adaptation set.

A subset of elements in the defined set that are expected to be consumed jointly is preselected. The preselection is identified by a unique tag towards the decoder. The plurality of preselected execution individuals may reference the same stream set in the bundle. Only elements of the same bundle may facilitate decoding and rendering preselections.

In the case of next generation audio, preselection is a personalized selection that is associated with one or more audio elements from more than one additional parameter (e.g., gain, spatial position) to produce a complete audio experience. The preselection can be viewed as the NGA equivalent of an alternative audio track containing a complete mix using a conventional audio codec.

The bundle, the pre-select, the primary element, the primary adaptation set, and the partial adaptation set may be defined in one of two ways:

● preselected descriptors are defined in DASH section 5.3.11.2. This descriptor enables simple setup and traceback compatibility, but may not be suitable for advanced use cases.

● preselected elements as defined in DASH sections 5.3.11.3 and 5.3.11.4. The semantics of the preselected elements are provided in table 17c in DASH section 5.3.11.3 and the XML syntax is provided in DASH section 5.3.11.4.

An instantiation of the introduced concept using two methods is provided below.

In both cases, if the adaptation set does not include the primary adaptation set, the base descriptor should be used along with the @ schemehduri as defined in DASH section 5.3.11.2.

The DASH specification also describes the preselected descriptors as follows:

the scheme is defined to be used as "urn: mpeg: dash: preselection: 2016" together with the basic descriptor. The value of the descriptor provides two fields separated by commas:

● preselected tag

● as the id of the element/content component contained in this preselected list of white space separation lists in processing order. The first id defines the primary element.

If the adaptation set includes a primary element, a secondary descriptor may be used to describe the preselection included in the adaptation set.

If the adaptation set does not contain a primary element, a base descriptor should be used.

A bundle is essentially defined by all elements contained in all presets containing the same primary element. The preselection is defined by metadata assigned to each of the elements contained in the preselection. It should be noted that this signaling may be simple for basic use cases, but is not expected to provide full coverage for all use cases. Thus, a preselected element is introduced in DASH section 5.3.11.3 to cover more advanced usage situations.

The DASH specification also describes the semantics of the preselected elements as follows:

as an extension of the preselection descriptor, preselection may also be defined by preselection elements as provided in table 17 d. The selection of preselection is based on the attributes and elements contained in the preselected elements.

Table 17d of DASH-semantics of Pre-selected elements

Regarding frame wrapping, section 5.8.4.6 of DASH specifies preselection as follows:

for the element FramePacking, the @ schemeIdUri attribute is used to identify the adopted frame packet configuration scheme.

There may be multiple FramePacking elements. If so, each element should contain enough information to select or reject the described representation.

Note that DASH clients expect to ignore the described representation if the scheme or the values of all FramePacking elements are not recognized. The client may reject the adaptation set based on observing the FramePacking element.

The descriptor may carry the frame encapsulation scheme using a URN flag and a value defined for VideoFramePackingType in ISO/IEC 23001-8.

Note that: this section of ISO/IEC 23009 also defines the frame encapsulation scheme in DASH section 5.8.5.6. Such schemes are maintained for retrospective compatibility, but it is recommended to use signaling as defined in ISO/IEC 23001-8.

Video data may be encoded according to a variety of video coding standards. Such video coding standards include ITU-T H.261, ISO/IEC MPEG-1 Visual, ITU-T H.262, or ISO/IEC MPEG-2 Visual, ITU-T H.263, ISO/IECMPEG-4 Visual, ITU-T H.264, or ISO/IEC MPEG-4 AVC, including Scalable Video Coding (SVC) and Multiview Video Coding (MVC) extensions thereof, and High Efficiency Video Coding (HEVC), also referred to as ITU-T H.265 and ISO/IEC 23008-2, including scalable coding extensions thereof (i.e., scalable high efficiency video coding, SHVC) and multiview extensions thereof (i.e., multiview high efficiency video coding, MV-HEVC).

Fig. 1 is a block diagram illustrating an example system 10 implementing techniques for streaming media data over a network. In this example, system 10 includes content preparation device 20, server device 60, and client device 40. Client device 40 and server device 60 are communicatively coupled by a network 74, which may include the internet. In some examples, content preparation device 20 and server device 60 may also be coupled by network 74 or another network, or may be directly communicatively coupled. In some examples, content preparation device 20 and server device 60 may comprise the same device.

In the example of fig. 1, content preparation device 20 includes an audio source 22 and a video source 24. Audio source 22 may comprise, for example, a microphone that generates an electrical signal representative of captured audio data to be encoded by audio encoder 26. Alternatively, audio source 22 may comprise a storage medium storing previously recorded audio data, an audio data generator such as a computerized synthesizer, or any other source of audio data. Video source 24 may include a video camera that produces video data to be encoded by video encoder 28, a storage medium encoded with previously recorded video data, a video data generation unit such as a computer graphics source, or any other source of video data. Content preparation device 20 is not necessarily communicatively coupled to server device 60 in all examples, but may store multimedia content to a separate medium that is read by server device 60.

Raw audio and video data may include analog or digital data. The analog data may be digitized before being encoded by audio encoder 26 and/or video encoder 28. Audio source 22 may obtain audio data from the speaking participant while the speaking participant is speaking, and video source 24 may simultaneously obtain video data of the speaking participant. In other examples, audio source 22 may comprise a computer-readable storage medium comprising stored audio data, and video source 24 may comprise a computer-readable storage medium comprising stored video data. In this manner, the techniques described in this disclosure may be applied to live, streaming, real-time audio and video data or archived, pre-recorded audio and video data.

An audio frame corresponding to a video frame is typically an audio frame containing audio data captured (or generated) by audio source 22 that is accompanied by video data captured (or generated) by video source 24 that is contained within the video frame. For example, audio source 22 captures audio data while a speaking participant typically produces audio data by speaking, and video source 24 simultaneously (i.e., while audio source 22 is capturing audio data) captures video data of the speaking participant. Thus, an audio frame may correspond temporally to one or more particular video frames. Thus, an audio frame corresponding to a video frame generally corresponds to the case where audio data and video data are captured simultaneously, and an audio frame and a video frame respectively include the case where audio data and video data are captured simultaneously.

In some examples, audio encoder 26 may encode a timestamp in each encoded audio frame that represents a time at which audio data of the encoded audio frame was recorded, and similarly, video encoder 28 may encode a timestamp in each encoded video frame that represents a time at which video data of the encoded video frame was recorded. In such examples, audio frames corresponding to video frames may include: an audio frame including a time stamp and a video frame including the same time stamp. Content preparation device 20 may include an internal clock from which audio encoder 26 and/or video encoder 28 may generate timestamps, or which audio source 22 and video source 24 may use to associate audio data and video data, respectively, with timestamps.

In some examples, audio source 22 may send data to audio encoder 26 corresponding to the time at which audio data was recorded, and video source 24 may send data to video encoder 28 corresponding to the time at which video data was recorded. In some examples, audio encoder 26 may encode a sequence identifier in the encoded audio data to indicate a relative temporal ordering of the encoded audio data, but not necessarily an absolute time at which the audio data was recorded, and similarly, video encoder 28 may also use the sequence identifier to indicate a relative temporal ordering of the encoded video data. Similarly, in some examples, the sequence identifier may be mapped or otherwise correlated with a timestamp.

Audio encoder 26 typically generates an encoded audio data stream, while video encoder 28 generates an encoded video data stream. Each individual data stream (whether audio or video) may be referred to as an elementary stream. An elementary stream is a single digitally coded (possibly compressed) component of a representation. For example, the coded video or audio portion of the representation may be an elementary stream. The elementary stream may be converted to a Packetized Elementary Stream (PES) before being encapsulated within the video file. Within the same representation, a PES packet belonging to one elementary stream can be distinguished from PES packets belonging to other elementary streams using a stream ID. The basic unit of data of an elementary stream is a Packetized Elementary Stream (PES) packet. Thus, coded video data typically corresponds to a base video stream. Similarly, the audio data corresponds to one or more respective elementary streams.

Content preparation device 20 may obtain sphere video data using video source 24, for example, by capturing and/or generating (e.g., rendering) sphere video data. The sphere video data may also be referred to as projected video data. For ease of encoding, processing, and transfer, content preparation device 20 may form encapsulated video data from the projected video data (or sphere video data). An example is shown in fig. 3 below. Content preparation device 20 may generate region-oriented envelope boxes (RWPBs) that define the location and size of various envelope regions in the manner described above.

Many video coding standards, such as the ITU-T h.264/AVC and the upcoming High Efficiency Video Coding (HEVC) standard, define the syntax, semantics, and decoding procedures for error-free bitstreams, any of which conforms to a particular profile or level. Video coding standards do not typically specify an encoder, but the encoder has the task of ensuring that the generated bitstream is standard compliant for the decoder. In the context of video coding standards, a "profile" corresponds to a subset of algorithms, features, or tools and constraints applied to the algorithms, features, or tools. As defined by, for example, the h.264 standard, a "profile" is a subset of the full bitstream syntax specified by the h.264 standard. The "level" corresponds to the limit of decoder resource consumption (e.g., decoder memory and computations) related to picture resolution, bit rate, and block processing rate. The profile may be signaled with a profile _ idc (profile indicator) value and the level may be signaled with a level _ idc (level indicator) value.

For example, the h.264 standard recognizes that within the bounds imposed by the syntax of a given profile, a large variation in the performance of the encoder and decoder may still be required, depending on the value taken by the syntax element in the bitstream (e.g., the specified size of the decoded picture). The h.264 standard further recognizes that in many applications it is neither practical nor economical to implement a decoder that can handle all assumptions of syntax within a particular profile. Thus, the h.264 standard defines a "level" as a specified set of constraints imposed on the values of syntax elements in the bitstream. Such constraints may be simple limits on the values. Alternatively, such constraints may be in the form of constraints on arithmetic combinations of values (e.g., picture width multiplied by picture height multiplied by number of pictures decoded per second). The h.264 standard further specifies that individual implementations may support different levels for each supported profile.

A decoder conforming to a profile generally supports all of the features defined in the profile. For example, as a coding feature, B-picture coding is not supported in the baseline profile of h.264/AVC, but is supported in the other profiles of h.264/AVC. A decoder conforming to a level should be able to decode any bitstream that does not require resources beyond the limits defined in the level. The definition of the configuration file and hierarchy may help in interpretability. For example, during video transmission, a pair of profile definitions and tier definitions may be negotiated and agreed for the entire transmission working phase. More specifically, in h.264/AVC, a level may define limits on the number of macroblocks that need to be processed, Decoded Picture Buffer (DPB) size, Coded Picture Buffer (CPB) size, vertical motion vector range, maximum number of motion vectors per two consecutive MBs, and whether a B-block may have a sub-macroblock partition of less than 8x8 pixels. In this way, the decoder may determine whether the decoder is able to properly decode the bitstream.

In the example of fig. 1, encapsulation unit 30 of content preparation device 20 receives an elementary stream comprising coded video data from video encoder 28 and an elementary stream comprising coded audio data from audio encoder 26. In some examples, video encoder 28 and audio encoder 26 may each include packetizers for forming PES packets from encoded data. In other examples, video encoder 28 and audio encoder 26 may each interface with a respective packetizer for forming PES packets from encoded data. In still other examples, encapsulation unit 30 may include a packetizer for forming PES packets from encoded audio and video data.

Video encoder 28 may encode video data of multimedia content in a variety of ways to generate different representations of multimedia content at various bitrates and with various characteristics, such as pixel resolution, frame rate, conformance to various coding standards, conformance to various profiles and/or profile levels of various coding standards, representations having one or more views (e.g., for two-dimensional or three-dimensional playback), or other such characteristics. As used in this disclosure, a representation may include one of audio data, video data, text data (e.g., for closed captioning), or other such data. A representation may include an elementary stream such as an audio elementary stream or a video elementary stream. Each PES packet may contain a stream _ id that identifies the elementary stream to which the PES packet belongs. Encapsulation unit 30 is responsible for assembling the elementary streams into various representations of video files (e.g., segments).

Encapsulation unit 30 receives PES packets of the elementary streams represented from audio encoder 26 and video encoder 28, and forms corresponding Network Abstraction Layer (NAL) units from the PES packets. Coded video segments may be organized into NAL units that provide a "network friendly" video representation addressing applications such as video telephony, memory, broadcast, or streaming. NAL units can be classified into Video Coding Layer (VCL) NAL units and non-VCL NAL units. VCL units may contain core compression engines and may include block, macroblock, and/or slice level data. Other NAL units may be non-VCL NAL units. In some examples, a coded picture (typically presented as a primary coded picture) in a temporal execution unit may be contained in an access unit, which may include one or more NAL units.

non-VCL NAL units may include parameter set NAL units and SEI NAL units, among others. Parameter sets may contain sequence-level header information (in a Sequence Parameter Set (SPS)) and infrequently changing picture-level header information (in a Picture Parameter Set (PPS)). For parameter sets (e.g., PPS and SPS), infrequently changing information need not be repeated with respect to each sequence or picture, thus coding efficiency may be improved. Furthermore, the use of parameter sets may enable out-of-band transmission of important header information, thereby avoiding the need for redundant transmission against bit errors. In an out-of-band transmission example, a parameter set NAL unit may be transmitted on a different channel than other NAL units (e.g., SEI NAL units).

Supplemental Enhancement Information (SEI) may contain information that is not necessary for decoding coded picture samples from VCL NAL units, but may assist processes related to decoding, display, error resilience, and other purposes. The SEI message may be contained in a non-vcl nal unit. SEI messages are a standardized part of some standard specifications and are therefore not always mandatory for standard compliant decoder implementations. The SEI message may be a sequence level SEI message or a picture level SEI message. Some sequence level information may be contained in SEI messages, such as the scalability information SEI message in the example of SVC, and the view scalability information SEI message in MVC. Such example SEI messages may convey information regarding, for example, extraction of operation points and characteristics of operation points. In addition, encapsulation unit 30 may form an information list file, such as a Media Presentation Descriptor (MPD) that describes characteristics of the representation. Encapsulation unit 30 may format the MPD according to extensible markup language (XML).

Encapsulation unit 30 may provide data for one or more representations of multimedia content along with an information list file (e.g., MPD) to output interface 32. Output interface 32 may include a network interface or an interface for writing to a storage medium, such as a Universal Serial Bus (USB) interface, a CD or DVD writer or burner, an interface to a magnetic or flash storage medium, or other interface for storing or transmitting media data. Encapsulation unit 30 may provide data for each of the representations of the multimedia content to output interface 32, which may send the data to server device 60 via a network transmission or storage medium. In the example of fig. 1, server device 60 includes a storage medium 62 that stores various multimedia content 64, each including a respective information list file 66 and one or more representations 68A-68N (representations 68). In some examples, output interface 32 may also send data directly to network 74.

In some examples, representation 68 may be divided into adaptation sets. That is, the various subsets of representations 68 may include respective common sets of characteristics, such as codecs, configuration files and levels, resolution, number of views, file formats of segments, text type information that may identify language or other characteristics of text to be displayed with representations and/or audio data (e.g., emitted by speakers) to be decoded and presented, camera angle information that may describe a camera angle or real world camera perspective of a scene of a representation in adaptation set, rating information describing content suitability for a particular viewer, and so forth.

The information list file 66 may include data indicating a subset of the representation 68 corresponding to a particular adaptation set, as well as common characteristics of the adaptation sets. The information list file 66 may also include data representing individual characteristics (e.g., bit rate) of individual representations of the adaptation set. In this way, the adaptation set may provide simplified network bandwidth adaptation. Representations in adaptation sets may be indicated using child elements of adaptation set elements of information list file 66.

The server device 60 includes a request processing unit 70 and a network interface 72. In some examples, server device 60 may include multiple network interfaces. Further, any or all of the features of server device 60 may be implemented on other devices of the content delivery network (e.g., routers, bridges, proxy devices, switches, or other devices). In some examples, an intermediary device of the content delivery network may cache data of multimedia content 64 and include components that substantially conform to those of server device 60. In general, the network interface 72 is configured to send and receive data over a network 74.

Request processing unit 70 is configured to receive a network request for data of storage medium 62 from a client device, such as client device 40. For example, the request processing unit 70 may implement the Hypertext Transfer Protocol (HTTP) version 1.1, as described in RFC 2616, r.feldin et al, network working group, 1999, 6, IETF, "Hypertext Transfer Protocol-HTTP/1.1 (Hypertext Transfer Protocol-HTTP/1.1)". That is, the request processing unit 70 may be configured to receive an HTTP GET or partial GET request and provide data of the multimedia content 64 in response to the request. The request may specify a segment of one of the representations 68, e.g., using a URL of the segment. In some examples, the request may also specify one or more byte ranges of the segment, thus comprising a partial GET request. Request processing unit 70 may be further configured to service http head requests to provide header data for the segments of one of representations 68. In any case, request processing unit 70 may be configured to process the request to provide the requested data to the requesting device (e.g., client device 40).

Additionally or alternatively, request processing unit 70 may be configured to deliver media data via a broadcast or multicast protocol, such as eMBMS. Content preparation device 20 may create DASH segments and/or subsections in substantially the same manner as described, but server device 60 may deliver such segments or subsections using eMBMS or another broadcast or multicast network transport protocol. For example, request processing unit 70 may be configured to receive a multicast group join request from client device 40. That is, server device 60 may advertise an Internet Protocol (IP) address associated with a multicast group to client devices, including client device 40, associated with particular media content, such as a broadcast of a live event. Client device 40 may then submit a request to join the multicast group. This request may be propagated throughout network 74 (e.g., the routers comprising network 74) such that the routers are caused to direct traffic destined for IP addresses associated with the multicast group to subscribing client devices, such as client device 40.

As illustrated in the example of fig. 1, the multimedia content 64 includes an information list file 66, which may correspond to a Media Presentation Description (MPD). The information list file 66 may contain descriptions of different alternative representations 68, such as video services of different quality, and the descriptions may include, for example, codec information, profile values, tier values, bit rates, and other descriptive characteristics of the representations 68. Client device 40 may capture an MPD of a media presentation to determine how to access segments of representation 68.

In particular, capture unit 52 may capture configuration data (not shown) of client device 40 to determine the decoding capabilities of video decoder 48 and the rendering capabilities of video output 44. The configuration data may also include any or all of language preferences selected by the user of client device 40, one or more camera perspectives corresponding to depth preferences set by the user of client device 40, and/or rating preferences selected by the user of client device 40. For example, the capture unit 52 may comprise a web browser or media client configured to submit HTTP GET and partial GET requests. Capture unit 52 may correspond to software instructions executed by one or more processors or processing units (not shown) of client device 40. In some examples, all or part of the functionality described with respect to the capture unit 52 may be implemented in hardware or a combination of hardware, software, and/or firmware, where the necessary hardware may be provided to execute the instructions of the software or firmware.

Capture unit 52 may compare the decoding and rendering capabilities of client device 40 to the characteristics of representation 68 indicated by the information of information list file 66. The capture unit 52 may initially capture at least a portion of the information list file 66 to determine characteristics of the representation 68. For example, capture unit 52 may request a portion of information list file 66 describing characteristics of one or more adaptation sets. Capture unit 52 may select a subset of representations 68 (e.g., adaptation sets) having characteristics that may be satisfied by the coding and rendering capabilities of client device 40. Capture unit 52 may then determine a bit rate for adapting the centralized representation, determine a current amount of available network bandwidth, and capture a segment from one of the representations having a bit rate that the network bandwidth can satisfy.

In general, a higher bit rate representation may result in higher quality video playback, while a lower bit rate representation may provide sufficient quality video playback as the available network bandwidth decreases. Thus, when the available network bandwidth is relatively high, capture unit 52 may capture data from a representation of a relatively high bit rate, and when the available network bandwidth is low, capture unit 52 may capture data from a representation of a relatively low bit rate. In this manner, client device 40 may stream multimedia data over network 74 while also accommodating the changing network bandwidth availability of network 74.

Additionally or alternatively, the capture unit 52 may be configured to receive data according to a broadcast or multicast network protocol, such as eMBMS or IP multicast. In such examples, capture unit 52 may submit a request to join a multicast network group associated with particular media content. After joining the multicast group, capture unit 52 may receive the data of the multicast group without otherwise requesting to be published to server device 60 or content preparation device 20. When the data for the multicast group is no longer needed, capture unit 52 may submit a request to leave the multicast group, e.g., to stop playing or to change the channel to a different multicast group.

The network interface 54 may receive data for the segment of the selected representation and provide the data to the capture unit 52, which in turn may provide the segment to the decapsulation unit 50. De-encapsulation unit 50 may de-encapsulate elements of the video file into constituent PES streams, depacketize the PES streams to capture encoded data, and send the encoded data to audio decoder 46 or video decoder 48 depending on whether the encoded data is part of an audio stream or a video stream (e.g., as indicated by PES packet headers of the streams). Audio decoder 46 decodes encoded audio data and sends the decoded audio data to audio output 42, while video decoder 48 decodes encoded video data and sends the decoded video data to video output 44, the decoded video data may include multiple views of a stream.

Video encoder 28, video decoder 48, audio encoder 26, audio decoder 46, encapsulation unit 30, capture unit 52, and decapsulation unit 50 may each be implemented as any of a variety of suitable processing circuitry, as applicable, such as one or more microprocessors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), discrete logic circuitry, software, hardware, firmware, or any combinations thereof. Each of video encoder 28 and video decoder 48 may be included in one or more encoders or decoders, either of which may be integrated as part of a combined video encoder/decoder (CODEC). Likewise, each of audio encoder 26 and audio decoder 46 may be included in one or more encoders or decoders, either of which may be integrated as part of a combined CODEC. An apparatus including video encoder 28, video decoder 48, audio encoder 26, audio decoder 46, encapsulation unit 30, capture unit 52, and/or decapsulation unit 50 may comprise an integrated circuit, a microprocessor, and/or a wireless communication device, such as a cellular telephone.

Client device 40, server device 60, and/or content preparation device 20 may be configured to operate in accordance with the techniques of this disclosure. For purposes of example, this disclosure describes such techniques with respect to client device 40 and server device 60. It should be understood, however, that instead of (or in addition to) server device 60, content preparation device 20 may be configured to perform such techniques.

Encapsulation unit 30 may form a NAL unit that includes a header that identifies the program to which the NAL belongs, as well as a payload, such as audio data, video data, or data describing the transport or program stream to which the NAL unit corresponds. For example, in h.264/AVC, a NAL unit includes a 1 byte header and payloads of different sizes. NAL units that include video data in their payloads may include various levels of granularity of video data. For example, a NAL unit may comprise a block of video data, a plurality of blocks, a slice of video data, or an entire picture of video data. Encapsulation unit 30 may receive encoded video data in the form of PES packets of an elementary stream from video encoder 28. Encapsulation unit 30 may associate each elementary stream with a corresponding program.

Encapsulation unit 30 may also assemble access units from multiple NAL units. In general, an access unit may comprise one or more NAL units for a frame representing video data and audio data corresponding to the frame (when such audio data is available). An access unit typically includes all NAL units for one output time execution unit, e.g., all audio and video data for one time execution unit. For example, if each view has a frame rate of 20 frames per second (fps), each temporal execution individual may correspond to a time interval of 0.05 seconds. During this time interval, a particular frame of all views of the same access unit (executing an individual at the same time) may be rendered at the same time. In one example, an access unit may comprise a coded picture in a temporal execution unit, which may be presented as a primary coded picture.

Thus, an access unit may include all audio and video frames that execute an individual at a common time, e.g., all views corresponding to time X. This disclosure also refers to the encoded pictures of a particular view as "view components". That is, a view component may comprise an encoded picture (or frame) for a particular view at a particular time. Thus, an access unit may be defined to include all view components that execute an individual at a common time. The decoding order of the access units is not necessarily the same as the output or display order.

The media presentation may include a Media Presentation Description (MPD) that may contain descriptions of different alternative representations (e.g., video services having different qualities), and the descriptions may include, for example, codec information, profile values, and tier values. An MPD is an example of an information list file (e.g., information list file 66). Client device 40 may capture an MPD of a media presentation to determine how to access movie segments for various presentations. The movie fragment may be located in a movie fragment box (moof box) of the video file.

An information list file 66 (which may include, for example, an MPD) may advertise the availability of segments of the representation 68. That is, the MPD may include information indicative of the wall clock time at which the first segment of one of representations 68 becomes available, and information indicative of the duration of the segments within representations 68. In this way, capture unit 52 of client device 40 may determine when each segment is available based on the start time and the duration of the segment that precedes the particular segment.

After encapsulation unit 30 has assembled the NAL units and/or access units into a video file based on the received data, encapsulation unit 30 passes the video file to output interface 32 for output. In some examples, encapsulation unit 30 may store the video file locally or send the video file to a remote server via output interface 32, rather than sending the video file directly to client device 40. Output interface 32 may comprise, for example, a transmitter, transceiver, means for writing data to a computer-readable medium (e.g., an optical disk drive), a magnetic media drive (e.g., a floppy disk drive), a Universal Serial Bus (USB) port, a network interface, or other output interface. Output interface 32 outputs the video file to a computer-readable medium, such as a transmission signal, magnetic media, optical media, memory, flash drive, or other computer-readable medium.

Network interface 54 may receive NAL units or access units via network 74 and provide the NAL units or access units to decapsulation unit 50 via capture unit 52. De-encapsulation unit 50 may de-encapsulate elements of the video file into constituent PES streams, depacketize the PES streams to capture encoded data, and send the encoded data to audio decoder 46 or video decoder 48 depending on whether the encoded data is part of an audio stream or a video stream (e.g., as indicated by PES packet headers of the streams). Audio decoder 46 decodes encoded audio data and sends the decoded audio data to audio output 42, while video decoder 48 decodes encoded video data and sends the decoded video data to video output 44, the decoded video data may include multiple views of a stream.

Content preparation device 20 and/or server device 60 may be configured to determine the boundaries of the envelope region and set the values of packet _ reg _ width [ i ], packet _ reg _ height [ i ], packet _ reg _ top [ i ], and packet _ reg _ left [ i ] accordingly. Likewise, client device 40 may determine the boundaries (and thus the size and location) of the wrapping region from the values of packet _ reg _ width [ i ], packet _ reg _ height [ i ], packet _ reg _ top [ i ], and packet _ reg _ left [ i ] described in more detail below.

FIG. 2 is a block diagram illustrating an example set of components of the capture unit 52 of FIG. 1 in more detail. In this example, capture unit 52 includes eMBMS middleware unit 100, DASH client 110, and media application 112.

In this example, the eMBMS middleware unit 100 further includes an eMBMS reception unit 106, a cache memory 104, and a proxy server unit 102. In this example, eMBMS reception unit 106 is configured to receive data via eMBMS, such as unidirectional Delivery of Files (FLUTE) as described in "FLUTE-File Delivery over unidirectional Delivery" (network working group, RFC6726, month 11 2012) (available at tools. That is, the eMBMS reception unit 106 may receive the file via broadcast from, for example, the server device 60 (which may act as a BM-SC).

When the eMBMS middleware unit 100 receives data for a file, the eMBMS middleware unit may store the received data in the cache memory 104. Cache memory 104 may include a computer-readable storage medium, such as flash memory, a hard disk, RAM, or any other suitable storage medium.

Proxy server element 102 may act as a server for DASH client 110. For example, proxy server unit 102 may provide an MPD file or other information list file to DASH client 110. The proxy unit 102 may advertise the time of availability of a segment in the MPD file and may capture hyperlinks for the segment. Such hyperlinks may include a local host address header corresponding to client device 40 (e.g., 127.0.0.1 for IPv 4). In this manner, DASH client 110 may request segments from proxy server unit 102 using HTTP GET or partial GET requests. For example, for segments available from link 127.0.0.1/rep1/seg3, DASH client 110 may construct an HTTP GET request that includes a request for 127.0.0.1/rep1/seg3, and submit the request to proxy unit 102. Proxy server element 102 may capture requested data from cache memory 104 and provide the data to DASH client 110 in response to such requests.

Fig. 3 is a conceptual diagram illustrating two examples of region orientation envelopes (RWPs) for OMAF. OMAF specifies a mechanism called region-oriented encapsulation (RWP). RWP enables manipulation (resizing, repositioning, rotation, and mirroring) of any rectangular region of the projected picture. RWP can be used to emphasize weaknesses of certain view-area orientations or circumventing projections, such as oversampling towards poles in ERP. The latter is depicted in the example at the top of fig. 3, where the resolution of the region near the pole of the spherical video is reduced. The example at the bottom of fig. 3 depicts an emphasized view region orientation.

Existing designs of region-oriented envelopes in the latest OMAF draft specification and view-region independent HEVC media profiles in N16826 may have several potential problems. A first potential problem is that the RWP box must be present when the content (i.e., the wrapped picture) does not cover the entire sphere. However, the techniques of this disclosure involve implementing subsphere content without the use of RWPs. In the view-region independent HEVC media profile in N16826, no RWP box is allowed to exist. Thus, this media profile so specified will not support subsphere content.

A second potential problem related to the first potential problem is that the width and height of the projected picture is signaled in the RWP box. Thus, when this block is not present, the size is not signaled, and the only choice is to assume the size as the width and height syntax element of the VisualSampleEntry, which is the size of the wrapped picture. As a third potential problem, based on the two potential problems introduced above, it can be concluded that when actual RWP operations such as resizing, repositioning, rotation, and mirroring are not required, and when guard bands are not required, the role of the RWP box is only to tell the size of the projected picture, and which region of the projected picture corresponds to the wrapped picture, for the subsphere content. However, for this purpose only, it would be sufficient to signal only the size of the projected picture, and the horizontal and vertical offsets of the top left luma samples of the wrapped picture relative to the top left luma samples of the wrapped picture. All other syntax elements in the RWP box will no longer be needed and the data for those syntax elements can be saved.

A fourth potential problem is that for adaptive streaming, one video content is typically encoded into multiple bitstreams having different bandwidths, and typically also different spatial resolutions. Because the units of the signaled projected and wrapped regions are both luma samples, in the case that the spatial resolutions of the same video content are different, the encoder would need to devise different RWP schemes for the different spatial resolutions, and each spatial resolution would need separate RWP signaling.

As a fifth potential problem, in the entire conversion procedure from the luma sample position of the decoded picture to the corresponding position on the sphere of global coordinate axes (angular coordinate) via the corresponding luma sample position in the projected picture, the 2D cartesian coordinates (i, j) or (xProjPicture and ypejpicture) on the projected picture need to be fixed-point values, rather than integers.

A sixth potential problem is that from the decoder/rendering side perspective, the projected picture is only a concept, since the procedure to generate the sample values of the projected picture is not specified, and need not be done either. Based on the fourth, fifth, and sixth issues, this disclosure describes techniques for specifying a unit of size of a projected picture, and specifying the size and location of projected and enveloped regions in relative units. In this way, in the case where the spatial resolutions of the same video content are different, the encoder will not need to devise different RWP schemes for the different spatial resolutions, and one RWP signaling will apply to all the alternative bitstreams of the same video content.

As a seventh potential problem, the container of the RWP box is a scheme information box, while the containers of other projected omnidirectional video specific boxes, such as overlay and orientation, are projected omnidirectional video boxes. This will further complicate the checking and verifying of the correctness of the relationship between the RWP box and other omnidirectional video specific information.

The present invention introduces a potential solution to the problems described above. The various techniques described herein may be applied independently or in various combinations.

A first technique described in this disclosure is to add version 1 of the RWP box that provides only the size of the projected picture and the positional offset of the wrapped picture relative to the projected picture. According to a first example, it is proposed to add version 1 of the RWP box. When the projected picture is monoscopic, the RWP box only provides the size of the projected picture, and the positional offset of the wrapped picture relative to the projected picture. When the projected picture is a stereoscopic image that uses side-by-side or top-bottom frame wrapping, the RWP box only provides the size of the projected picture, and the positional offset of each wrapped picture portion belonging to one view relative to the projected picture portion belonging to the same view. According to another example, it is proposed to signal the same information as version 1 of the RWP box using another means. For example, a new box may be defined that may be included in the projected omnidirectional video box or the scheme information box, and the restriction may only exist for either the new box or the RWP box, but not both.

A second technique of this disclosure includes the view-independent HEVC media profile needed to support version 1 of the RWP box for sub-sphere content without the need for region-orientation resizing, repositioning, rotation, and mirroring. In other examples, version 0 of a RWP box may be allowed to exist, but when present, the value of the syntax element in the RWP box is limited so that only the same information as version 1 of the RWP box is conveyed by the box.

According to a third technique of this disclosure, the size and position offsets of the projected picture, the wrapped picture, the projected region, and the wrapped region are specified in relative units of luma samples rather than absolute units for all versions of the RWP box. In accordance with a fourth technique of the invention, the container of the RWP box can be changed from the solution information box to the projected omnidirectional video box.

A more detailed implementation of the first technique will now be described. Changes to the syntax and semantics of the RWP box are shown below. The syntax and semantics of the region-oriented encapsulation box may be changed as follows (with bold highlighting as added and [ [ brackets ] ] denoting removed.

The syntax may be changed as follows:

the semantics can be changed as follows:

proj _ picture _ width and proj _ picture _ height specify the width and height, respectively, of a projected picture in units of luma samples. Both proj _ picture _ width and proj _ picture _ height should be greater than 0.

The proj _ picture _ voffset and proj _ picture _ hoffset specify the vertical offset and the horizontal offset, respectively, of the wrapped picture in units of luma samples in the projected picture. The values should range from 0 (including 0, which indicates the upper left corner of the projected picture) to proj _ picture _ height-PackedPicHeight-1 (including proj _ picture _ height-PackedPicHeight-1) and proj _ picture _ width-PackedPicWidth-1 (including proj _ picture _ width-PackedPicWidth-1), respectively.

num _ regions specifies the number of wrapped regions. The value 0 is retained.

[ [ proj _ picture _ width and proj _ picture _ height specify the width and height, respectively, of the projected picture. Both proj _ picture _ width and proj _ picture _ height should be greater than 0. ]]

…

packet _ reg _ width [ i ], packet _ reg _ height [ i ], packet _ reg _ top [ i ], and packet _ reg _ left [ i ] are indicated in units of luma samples in the wrapped pictures having widths and heights equal to PackedPicWidth and PackedPicHeight, respectively.

packet _ reg _ width [ i ], packet _ reg _ height [ i ], packet _ reg _ top [ i ], and packet _ reg _ left [ i ] specify the width, height, top luma sample row, and leftmost luma sample column, respectively, of the wrapped region in the wrapped picture.

…

The following describes changes to the mapping of sample positions within a decoded picture relative to global coordinate axes to angular coordinates. The clause 7.2.2.2 of the latest OMAF draft specification changes as follows (with bold highlighting indicating addition, and [ [ square brackets ] ] indicating removal.

The width and height of the monoscopic projected luma picture (pictureWidth and pictureHeight, respectively) are derived as follows:

the variables HorDiv and VerDiv are derived as follows:

○ if a StereoVideoBox does not exist, then HorDeiv and VerDiv are set equal to 1.

○ otherwise, if a StereoVideoBox is present and indicates a side-by-side frame envelope, then HorDeiv is set equal to 2 and VerDiv is set equal to 1.

○ else (StereoVideoBox present and indicating top and bottom frame envelopes), then HorDeiv is set equal to 1 and VerDiv is set equal to 2.

-if the regionwasepackangbox does not exist, setting pictureWidth and pictureHeight equal to width/hordeiv and height/VerDiv, respectively, where width and height are syntax elements of VisualSampleEntry.

-otherwise, setting pictureWidth and pictureHeight equal to proj _ picture _ width/hordi and proj _ picture _ height/VerDiv, respectively.

If there is a RegionWisePackingBox with a version equal to 0, the following applies to each wrapped region n ranging from 0 to num _ regions-1 (including 0 and num _ regions-1):

for each sample position (xPackedPicture, yPackedPicture) belonging to the nth encapsulated region with packing _ type [ n ] equal to 0 (i.e. with rectangular region oriented encapsulation), the following applies:

○ derives the corresponding sample position (xProjPicture, yProjPicture) of the projected picture as follows:

■ sets x equal to xPacked _ packed _ reg _ left [ n ].

■ sets y equal to yPackedPicture-packed _ reg _ top [ n ].

■ sets offset x equal to 0.5.

■ sets offset equal to 0.5.

■ calls clause 5.4, where x, y, packet _ reg _ width [ n ], packet _ reg _ height [ n ], proj _ reg _ width [ n ], proj _ reg _ height [ n ], transform _ type [ n ], offset x, and offset y are used as inputs, and the output is assigned to sample position (i, j).

■ sets xProjPicture equal to proj _ reg _ left [ n ] + i.

■ sets yProjPicture equal to proj _ reg _ top [ n ] + j.

○ calls clause 7.2.2.3, where xProjPicture, ypejpicture, picture width, and picture height are taken as inputs, and outputs angular coordinates and a constitutive frame index (for frame-encapsulated stereoscopic video) indicating the luma sample position (xPackedPicture, yPackedPicture) belonging to the nth encapsulated region in the decoded picture.

Otherwise, the following applies to each sample position (x, y) within the decoded picture:

-if there is a RegionWisePackingBox with a version equal to 1, then hOffset is set equal to proj _ picture _ hOffset, and vOffset is set equal to proj _ picture _ vOffset.

Otherwise, both hfoffset and vioffset are set equal to 0.

-set xProjPicture equal to x + haffset + 0.5.

-setting ypejpicture equal to y + vOffset + 0.5.

Call clause 7.2.2.3, with xProjPicture, ypejpicture, pictewidth, and pictehight as inputs, and output angular coordinates indicating the luma sample position (x, y) within the decoded picture and the constituent frame index (for frame-wrapped stereo video).

A more detailed implementation of the first example of the first technique will now be described. The syntax of the region orientation encapsulation box is the same as example 1 above. The semantics of the region orientation envelope are changed relative to the latest OMAF draft specification text as follows (with bold highlighting indicating addition and [ [ square brackets ] ] indicating removal.

proj _ picture _ width and proj _ picture _ height specify the width and height, respectively, of a projected picture in units of luma samples. Both proj _ picture _ width and proj _ picture _ height should be greater than 0.

The proj _ picture _ voffset and the proj _ picture _ hoffset are used to infer the values of proj _ reg _ top [ i ] and proj _ reg _ left [ i ] when the version is equal to 1.

When the version is equal to 1, the values of the variables HorDiv1 and VerDiv1 are set as follows:

-if a StereoVideoBox is not present, then HorDiv1 is set equal to 1 and VerDiv1 is set equal to 1.

Else (StereoVideoBox present), the following applies:

○ if a side-by-side frame envelope is indicated, then HorDev 1 is set equal to 2 and VerDiv1 is set equal to 1.

○ otherwise (indicating upper and lower frame envelopes), hordi 1 is set equal to 1 and VerDiv1 is set equal to 2.

num _ regions specifies the number of wrapped regions. The value 0 is retained. When the version equals 1, the value of num _ regions is inferred to be equal to HorDiv1 × VerDiv 1.

[ [ proj _ picture _ width and proj _ picture _ height specify the width and height, respectively, of the projected picture. Both proj _ picture _ width and proj _ picture _ height should be greater than 0. ]]

guard _ band _ flag [ i ] equal to 0 specifies that the ith encapsulated area does not have a guard band. guard _ band _ flag [ i ] equal to 1 specifies that the ith encapsulated area has a guard band. When the version is equal to 1, the value of guard _ band _ flag [ i ] is inferred to be equal to 0.

packing _ type [ i ] specifies the type of region-oriented envelope. packing _ type [ i ] equal to 0 indicates rectangular area orientation packing. Other values are retained. When the version is equal to 1, the value of packing _ type [ i ] is inferred to be equal to 0.

…

proj reg width [ i ] specifies the width of the ith projected region. The proj reg width [ i ] should be greater than 0. When the version is equal to 1, the value of proj _ reg _ width [ i ] is inferred to be equal to PackedPiccWidth/HorDev 1.

proj reg height [ i ] specifies the height of the ith projected area. proj _ reg _ height [ i ] should be greater than 0. When the version is equal to 1, the value of proj _ reg _ height [ i ] is inferred to be equal to PackedPiccHeight/VerDiv 1.

proj reg top [ i ] and proj reg left [ i ] specify the top luma sample row and the leftmost luma sample column, respectively, of the ith projected area in the projected picture. The values should range from 0 (including 0, which indicates the upper left corner of the projected picture) to proj _ picture _ height-1 (including proj _ picture _ height-1) and proj _ picture _ width-1 (including proj _ picture _ width-1), respectively. When the version is equal to 1, the value of proj _ reg _ top [ i ] is inferred to be equal to proj _ picture _ voffset + i + proj _ picture _ height (1-1/VerDiv1), and the value of proj _ reg _ left [ i ] is inferred to be equal to proj _ picture _ hoffset + i + proj _ picture _ width (1-1/hordi 1).

…

transform _ type [ i ] specifies the rotation and mirroring process that has been applied to the ith projected area to map it to the wrapped picture prior to encoding. When the version is equal to 0, it is inferred that the value of transform _ type [ i ] is equal to 0. When transform _ type [ i ] specifies both rotation and mirroring, the rotation has been applied after mirroring in the region-oriented envelope from the projected picture to the enveloped picture prior to encoding. …

…

packet _ reg _ width [ i ], packet _ reg _ height [ i ], packet _ reg _ top [ i ], and packet _ reg _ left [ i ] are indicated in units of luma samples in the wrapped pictures having widths and heights equal to PackedPicWidth and PackedPicHeight, respectively.

packet _ reg _ width [ i ], packet _ reg _ height [ i ], packet _ reg _ top [ i ], and packet _ reg _ left [ i ] specify the width, height, top luma sample row, and leftmost luma sample column, respectively, of the wrapped region in the wrapped picture.

When the version is equal to 1, it is inferred that the values of packet _ reg _ width [ i ], packet _ reg _ height [ i ], packet _ reg _ top [ i ], and packet _ reg _ left [ i ] are equal to packet PiccWidth/HorDev 1, packet PiccHeight/VerDiv 1, i packet PiccHeight (1-1/VerDiv1), and i packet PiccWidth (1-1/HorDev 1), respectively.

…

A more detailed implementation of the second technique will now be described. According to one implementation, the following sentence in the definition of view-independent HEVC media profile

"RegionWisePackingBox should not exist in the SchemeInformationBox. "

The method can be replaced by the following steps:

"when a region-oriented encapsulation box exists, the version of the box should be equal to 1. "

In a version of the second technique that allows for version 0 of the RWP box to exist, where it exists, the value of the syntax element in the RWP box is limited so that only the same information as version 1 of the RWP box is conveyed by the box, the following sentence in the definition of the view-independent HEVC media profile

The RegionWisePackingBox should not exist in the SchemeInformationBox.

The method can be replaced by the following steps:

the values of the variables hordei 1 and VerDiv1 were set as follows:

-if a StereoVideoBox is not present, then HorDiv1 is set equal to 1 and VerDiv1 is set equal to 1.

Else (StereoVideoBox present), the following applies:

○ if a side-by-side frame envelope is indicated, then HorDev 1 is set equal to 2 and VerDiv1 is set equal to 1.

○ otherwise (indicating upper and lower frame envelopes), hordi 1 is set equal to 1 and VerDiv1 is set equal to 2.

When the region-oriented encapsulation frame is present, the following constraints apply:

the value of-num _ regions should be equal to hordeiv 1 VerDiv 1.

For each value of i in the range of 0 to num _ regions-1 (including 0 and num _ regions-1), the following applies

The value of ○ guard _ band _ flag [ i ] should be equal to 0.

○ packing _ type [ i ] should have a value equal to 0.

○ proj _ reg _ width [ i ] should have a value equal to PackedPiccWidth/HorDev 1.

○ proj _ reg _ height [ i ] should have a value equal to PackedPicHeight/VerDiv 1.

The value of ○ transform _ type [ i ] should be equal to 0.

○ the value of packed _ reg _ width [ i ] should be equal to PackedPiccWidth/HorDev 1.

○ the value of packed _ reg _ height [ i ] should equal PackedPicHeight/VerDiv 1.

○ the value of packed _ reg _ top [ i ] should be equal to i packet picheight (1-1/VerDiv 1).

○ the value of packed _ reg _ left [ i ] should be equal to i packet picwidth (1-1/hordeiv 1).

A more detailed implementation of the third technique will now be described. The definition, syntax, and semantics of the RWP box are changed relative to the design in the first technique above as follows (with bold highlighting indicating addition and [ [ brackets ] ] indicating removal.

The definition may be changed as follows:

…

the RegionWisePackingBox indicates that the projected picture is region-oriented encapsulated and needs to be un-encapsulated before rendering. The size of the projected picture is explicitly signaled in this frame. The size of the encapsulated pictures are denoted as PackedPicWidth and PackedPicHeight, respectively. If the version of the RegionWisePackingBox is 0, PackedPiccWidth and PackedPiccHeight are set equal to the Width and height syntax elements of VisualSampleEntry, respectively. Otherwise, the PackedPiccWidth and PackedPicHeight are set equal to the packet _ picture _ width and packet _ picture _ height syntax elements of the RegionWisePackingBox, respectively. [ [ the size of the wrapped pictures, denoted as PackedPiccWidth and PackedPicHeight, respectively, is indicated by the Width and height syntax elements of VisualSampleEntry. ]]

The syntax may be changed as follows:

the semantics can be changed as follows:

proj _ picture _ width and proj _ picture _ height specify the width and height, respectively, of a projected picture in relative units [ [ units of luma samples ]. Both proj _ picture _ width and proj _ picture _ height should be greater than 0. In the remainder of this clause, "relative units" means the same relative units as proj _ picture _ width and proj _ picture _ height.

The packet _ picture _ width and packet _ picture _ height specify the width and height of the packed picture in relative units, respectively. Both the pracked _ picture _ width and the packed _ picture _ height should be greater than 0.

The proj _ picture _ voffset and proj _ picture _ hoffset specify the vertical offset and the horizontal offset, respectively, of the wrapped picture in the projected picture in relative units [ [ units of luma samples ]. The values should range from 0 (including 0, which indicates the upper left corner of the projected picture) to proj _ picture _ height-PackedPicHeight-1 (including proj _ picture _ height-PackedPicHeight-1) and proj _ picture _ width-PackedPicWidth-1 (including proj _ picture _ width-PackedPicWidth-1), respectively.

…

proj _ reg _ width [ i ], proj _ reg _ height [ i ], proj _ reg _ top [ i ], and proj _ reg _ left [ i ] are indicated in relative units [ [ units of luma samples ] ] in the projected pictures having widths and heights equal to proj _ picture _ width and proj _ picture _ height, respectively.

…

packet _ reg _ width [ i ], packet _ reg _ height [ i ], packet _ reg _ top [ i ], and packet _ reg _ left [ i ] are indicated in relative units [ [ units of luma samples ] ] in the wrapped pictures having widths and heights equal to PackedPicWidth and PackedPicHeight, respectively.

…

A more detailed implementation of the third technique will now be described. The definition, syntax, and semantics of the RWP box are changed relative to the design in the first technique above as follows (with bold highlighting indicating addition and [ [ brackets ] ] indicating removal.

The definition may be changed as follows:

…

the RegionWisePackingBox indicates that the projected picture is region-oriented encapsulated and needs to be un-encapsulated before rendering. The size of the projected picture is explicitly signaled in this frame. The size of the encapsulated pictures are denoted as PackedPicWidth and PackedPicHeight, respectively. If the version of the RegionWisePackingBox is 0, PackedPiccWidth and PackedPiccHeight are set equal to the Width and height syntax elements of VisualSampleEntry, respectively. Otherwise, the PackedPiccWidth and PackedPicHeight are set equal to the packet _ picture _ width and packet _ picture _ height syntax elements of the RegionWisePackingBox, respectively. [ [ the size of the wrapped pictures, denoted as PackedPiccWidth and PackedPicHeight, respectively, is indicated by the Width and height syntax elements of VisualSampleEntry. ]]

The syntax may be changed as follows:

the semantics can be changed as follows:

proj _ picture _ width and proj _ picture _ height specify the width and height, respectively, of a projected picture in relative units [ [ units of luma samples ]. Both proj _ picture _ width and proj _ picture _ height should be greater than 0. In the remainder of this clause, "relative units" means the same relative units as proj _ picture _ width and proj _ picture _ height.

The packet _ picture _ width and packet _ picture _ height specify the width and height of the packed picture in relative units, respectively. Both the pracked _ picture _ width and the packed _ picture _ height should be greater than 0.

…

proj _ reg _ width [ i ], proj _ reg _ height [ i ], proj _ reg _ top [ i ], and proj _ reg _ left [ i ] are indicated in relative units [ [ units of luma samples ] ] in the projected pictures having widths and heights equal to proj _ picture _ width and proj _ picture _ height, respectively.

…

packet _ reg _ width [ i ], packet _ reg _ height [ i ], packet _ reg _ top [ i ], and packet _ reg _ left [ i ] are indicated in relative units [ [ units of luma samples ] ] in the wrapped pictures having widths and heights equal to PackedPicWidth and PackedPicHeight, respectively.

…

Fig. 4 is a conceptual diagram illustrating elements of example multimedia content 120. The multimedia content 120 may correspond to the multimedia content 64 (fig. 1), or to another multimedia content stored in the storage medium 62. In the example of fig. 4, multimedia content 120 includes a Media Presentation Description (MPD)122 and a plurality of representations 124A-124N (representation 124). Representation 124A includes optional header data 126 and segments 128A-128N (segment 128), while representation 124N includes optional header data 130 and segments 132A-132N (segment 132). For convenience, the letter N is used to designate the last movie fragment in each of the representations 124. In some examples, there may be different numbers of movie fragments between representations 124.

MPD 122 may include a data structure separate from representation 124. MPD 122 may correspond to information list file 66 of fig. 1. Likewise, representation 124 may correspond to representation 68 of FIG. 2. In general, MPD 122 may include data that generally describes characteristics of representation 124, such as coding and rendering characteristics, adaptation sets, a profile to which MPD 122 corresponds, text type information, camera angle information, rating information, trick mode information (e.g., information indicating a representation that includes a temporal subsequence), and/or information for capturing remote periods (e.g., for inserting targeted advertisements into media content during playback).

The header data 126, when present, may describe characteristics of the segment 128, such as a temporal location of a Random Access Point (RAP), which is also referred to as a Stream Access Point (SAP), which of the segments 128 includes a random access point, a byte offset from a random access point within the segment 128, a Uniform Resource Locator (URL) of the segment 128, or other aspects of the segment 128. Header data 130, when present, may describe similar characteristics of segment 132. Additionally or alternatively, such characteristics may be entirely included within MPD 122.

The segments 128, 132 include one or more coded video samples, each of which may include a frame or slice of video data. Each of the coded video samples of section 128 may have similar characteristics, such as height, width, and bandwidth requirements. Such characteristics may be described by data of MPD 122, although such data is not illustrated in the example of fig. 4. MPD 122 may include characteristics as described by the 3GPP specifications, and add any or all of the signaling information described in this disclosure.

Each of the segments 128, 132 may be associated with a unique Uniform Resource Locator (URL). Thus, each of the segments 128, 132 may be independently captured using a streaming network protocol (e.g., DASH). In this way, a destination device, such as client device 40, may use an HTTP GET request to capture segments 128 or 132. In some examples, client device 40 may use HTTP partial GET requests to capture a particular byte range of segments 128 or 132.

FIG. 5 is a block diagram illustrating elements of an example video file 150, which may correspond to a segment of a representation, such as one of the segments 128, 132 of FIG. 4. Each of the sections 128, 132 may include data that generally conforms to the arrangement of data illustrated in the example of fig. 5. Video file 150 may be referred to as encapsulating a segment. As described above, video files according to the ISO base media file format and its extensions store data in a series of objects (referred to as "boxes"). In the example of fig. 5, video file 150 includes a File Type (FTYP) box 152, a Movie (MOOV) box 154, a section index (sidx) box 162, a movie fragment (MOOF) box 164, and a Movie Fragment Random Access (MFRA) box 166. Although fig. 5 represents an example of a video file, it should be understood that other media files may include other types of media data (e.g., audio data, timed text data, etc.) that are similar in structure to the data of video file 150, in accordance with the ISO base media file format and extensions thereof.

A File Type (FTYP) box 152 generally describes the file type of the video file 150. File type box 152 may contain data identifying a specification describing the best use of video file 150. The file type box 152 may alternatively be placed before the MOOV box 154, movie fragment box 164, and/or MFRA box 166.

In some examples, a segment such as video file 150 may include an MPD update box (not shown) prior to FTYP box 152. The MPD update box may include information indicating that an MPD corresponding to a representation including video file 150 is to be updated, along with information for updating the MPD. For example, the MPD update box may provide a URI or URL to be used to update a resource of the MPD. As another example, the MPD update box may include data for updating the MPD. In some examples, the MPD update box may immediately follow a Segment Type (STYP) box (not shown) of video file 150, where the STYP box may define the segment type of video file 150. Fig. 7, discussed in more detail below, provides additional information regarding the MPD update block.

In the example of fig. 5, MOOV box 154 includes a movie header (MVHD) box 156, a Track (TRAK) box 158, and one or more movie extension (MVEX) boxes 160. In general, MVHD box 156 may describe general characteristics of video file 150. For example, MVHD box 156 may include data describing when video file 150 was originally created, when video file 150 was last modified, a time scale of video file 150, a duration of play of video file 150, or other data generally describing video file 150.

TRAK box 158 may contain data for a track of video file 150. TRAK box 158 may include a track header (TKHD) box that describes characteristics of the track corresponding to TRAK box 158. In some examples, TRAK box 158 may include coded video pictures, while in other examples, coded video pictures of a track may be included in movie fragment 164, which may be referenced by data of TRAK box 158 and/or sidx box 162.

In some examples, video file 150 may include more than one track. Accordingly, MOOV box 154 may include a number of TRAK boxes equal to the number of tracks in video file 150. TRAK box 158 may describe characteristics of a corresponding track of video file 150. For example, TRAK box 158 may describe temporal and/or spatial information for the corresponding track. When encapsulation unit 30 (fig. 4) includes a parameter set track in a video file, such as video file 150, a TRAK box similar to TRAK box 158 of MOOV box 154 may describe characteristics of the parameter set track. Encapsulation unit 30 may signal that sequence level SEI messages are present in the parameter set track within the TRAK box describing the parameter set track.

MVEX box 160 may describe characteristics of a corresponding movie fragment 164, for example, to signal that video file 150 includes movie fragment 164 in addition to video data contained within MOOV box 154 (if present). In the context of streaming video data, coded video pictures may be included in movie fragment 164, rather than in MOOV box 154. Accordingly, all coded video samples may be included in movie fragment 164, rather than in MOOV box 154.

MOOV box 154 may include a number of MVEX boxes 160 equal to the number of movie fragments 164 in video file 150. Each of MVEX boxes 160 may describe characteristics of a corresponding one of movie fragments 164. For example, each MVEX box may include a movie extension header box (MEHD) box that describes a temporal duration of a corresponding one of movie fragments 164.

As mentioned above, encapsulation unit 30 may store sequence datasets in video samples that do not include actual coded video data. A video sample may generally correspond to an access unit that performs a representation of a coded picture at an individual for a particular time. In the context of AVC, a coded picture includes one or more VCL NAL units that contain information to construct all pixels of an access unit, and other associated non-VCL NAL units (e.g., SEI messages). Thus, encapsulation unit 30 may include a sequence data set in one of movie fragments 164, which may include sequence level SEI messages. Encapsulation unit 30 may further signal that a sequence data set and/or a sequence level SEI message present in one of movie fragments 164 is present within one of MVEX boxes 160 corresponding to one of movie fragments 164.

A SIDX box 162 is an optional element of the video file 150. That is, a video file that conforms to the 3GPP file format or other such file format does not necessarily contain a SIDX box 162. According to an example of a 3GPP file format, the SIDX box may be used to identify subsections of a section (e.g., a section contained within video file 150). The 3GPP file format defines a subsection as a "self-contained set of one or more consecutive movie fragment boxes with one or more corresponding media data boxes and media data boxes containing data referenced by the movie fragment box, which must follow the movie fragment box and precede the next movie fragment box containing information about the same track". The 3GPP file format also indicates that the SIDX box "contains a sequence of sub-segment references to the (sub) segments recorded by the box. The referenced subsections are contiguous in presentation time. Similarly, the bytes referenced by the segment index frame are always contiguous within the segment. The referenced size gives a count of the number of bytes in the referenced material ".

The SIDX box 162 generally provides information representative of one or more sub-segments of a segment included in the video file 150. For example, such information may include a playout time at which the sub-segment begins and/or ends, a byte offset for the sub-segment, whether the sub-segment includes (e.g., begins with) a Stream Access Point (SAP), a type of the SAP (e.g., whether the SAP is an Instantaneous Decoder Refresh (IDR) picture, a Clean Random Access (CRA) picture, a Broken Link Access (BLA) picture, etc.), a location of the SAP in the sub-segment (in terms of playout time and/or byte offset), and so forth.

Movie fragment 164 may include one or more coded video pictures. In some examples, movie fragments 164 may include one or more groups of pictures (GOPs), each of which may include a number of coded video pictures, such as frames or pictures. Additionally, as described above, in some examples, movie fragments 164 may include sequence datasets. Each of movie fragments 164 may include a movie fragment header box (MFHD, not shown in fig. 5). The MFHD box may describe characteristics of the corresponding movie fragment, such as a sequence number of the movie fragment. Movie fragments 164 may be included in video file 150 in order of number.

MFRA box 166 may describe a random access point within movie fragment 164 of video file 150. This can assist in performing trick modes, such as performing a seek to a particular temporal location (i.e., play time) within a segment encapsulated by video file 150. In some examples, MFRA box 166 is generally optional and need not be included in a video file. Likewise, a client device (e.g., client device 40) does not necessarily need to refer to MFRA box 166 to correctly decode and display video data of video file 150. MFRA box 166 may include a number of Track Fragment Random Access (TFRA) boxes (not shown) that is equal to the number of tracks of video file 150, or in some examples, equal to the number of media tracks (e.g., non-implied tracks) of video file 150.

In some examples, movie fragments 164 may include one or more Stream Access Points (SAPs), such as IDR pictures. Likewise, MFRA box 166 may provide an indication of the location of the SAP within video file 150. Thus, a temporal subsequence of video file 150 may be formed from the SAP of video file 150. The temporal sub-sequence may also include other pictures, such as P-frames and/or B-frames depending on the SAP. The frames and/or slices of a temporal sub-sequence may be arranged within a section such that frames/slices of the temporal sub-sequence that depend on other frames/slices of the sub-sequence may be properly decoded. For example, in a hierarchical arrangement of data, data used for prediction of other data may also be included in the temporal sub-sequence.

In accordance with the techniques of this disclosure, video file 150 may further include a region orientation encapsulation box (RWPB), e.g., within MOOV box 154, that includes information as discussed above. The RWPB can include RWPB structures that define the encapsulated regions and the locations of the corresponding projected regions in the spherical video projection.

Fig. 6 is a flow diagram illustrating an example method of receiving and processing media content including video data in accordance with the techniques of this disclosure. In general, the method of FIG. 6 is discussed with respect to client device 40 (FIG. 1). However, it should be understood that other devices may be configured to perform this or similar methods.

Client device 40 may obtain, from a region-oriented encapsulation box within the video file, a first set of values indicating a first size and a first position of a first encapsulated region of the media content, and a second set of values indicating a second size and a second position of a second encapsulated region of the media content (200). In some examples, the projected omnidirectional video frame may be a container of a region-oriented envelope frame. The first and second sets of values may be in relative units of upper left corner luma samples of the unpackaged pictures that include the first and second packed regions. Client device 40 may additionally obtain the projected picture width and projected picture height from the region-oriented envelope within the video file. The projected picture width and the projected picture height may also be in relative units.

Client device 40 decapsulates the first encapsulated region to generate a first decapsulated region (202). The client device forms a first projected region from the first decapsulated region (204). Client device 40 decapsulates the second encapsulated region to generate a second decapsulated region (206). Client device 40 forms a second projected region from the second decapsulated region, the second projected region being different from the first projected region (208).

The first set of values may include a first width value, a first height value, a first top value, and a first left value, and wherein the second set of values includes a second width value, a second height value, a second top value, and a second left value. Client device 40 may additionally determine a first width of the first encapsulated area from the first width value; determining a first height of the first encapsulated area from the first height value; determining a first top offset for the first encapsulated region from the first top value; determining a first left offset of the first encapsulated region from the first left value; determining a second width of the second encapsulated region from the second width value; determining a second height of the second encapsulated region from the second height value; determining a second top offset for the second encapsulated region from the second top value; and determining a second left offset for the second encapsulated region from the second left value. For example, the first width value may be a packed reg width [ i ] value and the first height value may be a packed reg height [ i ] value. The first top value may be a packed _ reg _ top [ i ] value and the first left value may be a packed _ reg _ left [ i ] value. The second width value may be a packed _ reg _ width [ j ] value and the second height value may be a packed _ reg _ height [ j ] value. The second top value may be a packed _ reg _ top [ j ] value and the second left value may be a packed _ reg _ left [ j ] value.

The media content may be monoscopic or stereoscopic. If the media content includes stereoscopic content, the first enveloped region may correspond to a first picture of the media content and the second enveloped region may correspond to a second picture of the media content.

In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media (which corresponds to tangible media, such as data storage media) or communication media, including any medium that facilitates transfer of a computer program from one place to another, such as according to a communication protocol. In this manner, a computer-readable medium may generally correspond to (1) a non-transitory tangible computer-readable storage medium, or (2) a communication medium (e.g., a signal or carrier wave). A data storage medium may be any available medium that can be accessed by one or more computers or one or more processors to capture instructions, code, and/or data structures for implementing the techniques described in this disclosure. The computer program product may include a computer-readable medium.

By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if the instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but instead pertain to non-transitory tangible storage media. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

The instructions may be executed by one or more processors, such as one or more Digital Signal Processors (DSPs), general purpose microprocessors, Application Specific Integrated Circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Thus, the term "processor," as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and/or software modules configured for encoding and decoding, or incorporated in a combined codec. Also, the techniques may be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses, including wireless handsets, Integrated Circuits (ICs), or collections of ICs (e.g., chipsets). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily require realization by different hardware units. In particular, as described above, the various units may be combined in a codec hardware unit, or provided by a set of interoperability hardware units (including one or more processors as described above) in conjunction with suitable software and/or firmware.

Various examples have been described. Such and other examples are within the scope of the following claims.