Enhanced high-order signaling for fisheye metaverse video
阅读说明：本技术 用于鱼眼虚拟实境视频的增强型高阶信号发送 (Enhanced high-order signaling for fisheye metaverse video ) 是由 王业奎 于 2018-07-09 设计创作，主要内容包括：本发明提供一种处理包含视频数据的文件的方法,其包含：处理包含鱼眼视频数据的文件,所述文件包含语法结构,所述语法结构包含指定所述鱼眼视频数据的属性的多个语法元素,其中所述多个语法元素包含指示鱼眼视频类型信息的一或多个位；基于所述语法结构的所述一或多个位确定用于所述鱼眼视频数据的所述鱼眼视频类型信息；基于所述确定输出所述鱼眼视频数据以供显现。(The invention provides a method of processing a file comprising video data, comprising: processing a file including fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information; determining the fisheye video type information for the fisheye video data based on the one or more bits of the syntax structure; outputting the fisheye video data for rendering based on the determination.)
1. A method of processing a file containing fisheye video data, the method comprising:
processing a file including fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information;
determining the fisheye video type information for the fisheye video data based on the one or more bits of the syntax structure; and
outputting the fisheye video data for rendering based on the determination.
2. The method of claim 1, wherein the fisheye video type information includes at least one of an indication of monoscopic fisheye video data or an indication of stereoscopic fisheye video data.
3. The method as claimed in claim 1, wherein the syntax structure is a fisheryeomnidirectionalvideoinfo () syntax structure of omnidirectional media format, and
wherein the one or more bits are two bits of the initial 24 reserved bits in the FisheyeOmnidirectional VideoInfo () syntax structure.
4. The method of claim 3, wherein the one or more bits is a view _ dimension _ idc syntax element, wherein a value of 0 for the view _ dimension _ idc syntax element indicates that the fisheye video data is stereoscopic fisheye video data, and wherein a value of 1 for the view _ dimension _ idc syntax element indicates that the fisheye video data is monoscopic fisheye video data.
5. The method of claim 4, wherein a value of 2 for the view _ dimension _ idc syntax element indicates that the fisheye video data is neither monoscopic fisheye video data nor stereoscopic fisheye video data.
6. The method of claim 1, wherein the fisheye video data is stereoscopic fisheye video data, and wherein the syntax structure further includes one or more flags indicating whether an image of the stereoscopic fisheye video data is in a left view or a right view.
7. The method of claim 6, wherein the one or more flags include a left view flag, wherein a value of 1 for the left view flag indicates a particular one of the pictures is in the left view, and wherein a value of 0 for the left view flag indicates a particular one of the pictures is in the right view.
8. The method of claim 6, further comprising:
determining whether an image of the stereoscopic fisheye video data is in the left view or the right view based on the one or more flags of the syntax structure; and
outputting the stereoscopic fish-eye video data for rendering based on the determination.
9. An apparatus configured to process a file including video data, the apparatus comprising:
a memory configured to store the file; and
one or more processors in communication with the memory, the one or more processors configured to:
processing the file including fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information;
determining the fisheye video type information for the fisheye video data based on the one or more bits of the syntax structure; and
outputting the fisheye video data for rendering based on the determination.
10. The apparatus of claim 9, wherein the fisheye video type information comprises at least one of an indication of monoscopic fisheye video data or an indication of stereoscopic fisheye video data.
11. The apparatus as claimed in claim 9, wherein the syntax structure is a fisheryeomnidirective videoinfo () syntax structure of omnidirectional media format, and
wherein the one or more bits are two bits of the initial 24 reserved bits in the FisheyeOmnidirectional VideoInfo () syntax structure.
12. The apparatus of claim 11, wherein the one or more bits are a view _ dimension _ idc syntax element, wherein a value of 0 for the view _ dimension _ idc syntax element indicates that the fisheye video data is stereoscopic fisheye video data, and wherein a value of 1 for the view _ dimension _ idc syntax element indicates that the fisheye video data is monoscopic fisheye video data.
13. The apparatus of claim 12, wherein a value of 2 for the view _ dimension _ idc syntax element indicates that the fisheye video data is neither monoscopic fisheye video data nor stereoscopic fisheye video data.
14. The apparatus of claim 9, wherein the fisheye video data is stereoscopic fisheye video data, and wherein the syntax structure further includes one or more flags indicating whether an image of the stereoscopic fisheye video data is in a left view or a right view.
15. The apparatus of claim 14, wherein the one or more flags comprise a left view flag, wherein a value of 1 for the left view flag indicates a particular one of the pictures is in the left view, and wherein a value of 0 for the left view flag indicates a particular one of the pictures is in the right view.
16. The apparatus of claim 14, wherein the one or more processors are further configured to:
determining whether an image of the stereoscopic fisheye video data is in the left view or the right view based on the one or more flags of the syntax structure; and
outputting the stereoscopic fish-eye video data for rendering based on the determination.
17. An apparatus configured to process a file including video data, the apparatus comprising:
means for processing a file that includes fisheye video data, the file including a syntax structure that includes a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits that indicate fisheye video type information;
means for determining the fisheye video type information for the fisheye video data based on the one or more bits of the syntax structure; and
means for outputting the fisheye video data for rendering based on the determination.
18. A non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors to:
processing a file including fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information;
determining the fisheye video type information for the fisheye video data based on the one or more bits of the syntax structure; and
outputting the fisheye video data for rendering based on the determination.
19. A method of generating a file containing video data, the method comprising:
receiving fisheye video data;
generating a file including the fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information; and
and outputting the file.
20. The method of claim 19, wherein the fisheye video type information includes at least one of an indication of monoscopic fisheye video data or an indication of stereoscopic fisheye video data.
21. The method as claimed in claim 19, wherein the syntax structure is a fisheryeomnidirectorvideoinfo () syntax structure of an omnidirectional media format, and
wherein the one or more bits are two bits of the initial 24 reserved bits in the FisheyeOmnidirectional VideoInfo () syntax structure.
22. The method of claim 21, wherein the one or more bits is a view _ dimension _ idc syntax element, wherein a value of 0 for the view _ dimension _ idc syntax element indicates that the fisheye video data is stereoscopic fisheye video data, and wherein a value of 1 for the view _ dimension _ idc syntax element indicates that the fisheye video data is monoscopic fisheye video data.
23. The method of claim 22, wherein a value of 2 for the view _ dimension _ idc syntax element indicates that the fisheye video data is neither monoscopic fisheye video data nor stereoscopic fisheye video data.
24. The method of claim 19, wherein the fisheye video data is stereoscopic fisheye video data, and wherein the syntax structure further includes one or more flags indicating whether an image of the stereoscopic fisheye video data is in a left view or a right view.
25. The method of claim 24, wherein the one or more flags include a left view flag, wherein a value of 1 for the left view flag indicates a particular one of the pictures is in the left view, and wherein a value of 0 for the left view flag indicates a particular one of the pictures is in the right view.
26. An apparatus configured to generate a file including video data, the apparatus comprising:
a memory configured to store the file; and
one or more processors in communication with the memory, the one or more processors configured to:
receiving fisheye video data;
generating the file including the fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information; and
and outputting the file.
27. The apparatus of claim 26, wherein the fisheye video type information comprises at least one of an indication of monoscopic fisheye video data or an indication of stereoscopic fisheye video data.
28. The apparatus as claimed in claim 26, wherein the syntax structure is a fisheryeomnidirectionalvideoinfo () syntax structure of omnidirectional media format, and
wherein the one or more bits are two bits of the initial 24 reserved bits in the FisheyeOmnidirectional VideoInfo () syntax structure.
29. The apparatus of claim 28, wherein the one or more bits are a view _ dimension _ idc syntax element, wherein a value of 0 for the view _ dimension _ idc syntax element indicates that the fisheye video data is stereoscopic fisheye video data, and wherein a value of 1 for the view _ dimension _ idc syntax element indicates that the fisheye video data is monoscopic fisheye video data.
30. The apparatus of claim 29, wherein a value of 2 for the view _ dimension _ idc syntax element indicates that the fisheye video data is neither monoscopic fisheye video data nor stereoscopic fisheye video data.
31. The apparatus of claim 26, wherein the fisheye video data is stereoscopic fisheye video data, and wherein the syntax structure further includes one or more flags indicating whether an image of the stereoscopic fisheye video data is in a left view or a right view.
32. The apparatus of claim 31, wherein the one or more flags comprise a left view flag, wherein a value of 1 for the left view flag indicates a particular one of the pictures is in the left view, and wherein a value of 0 for the left view flag indicates a particular one of the pictures is in the right view.
33. An apparatus configured to generate a file including video data, the apparatus comprising:
means for receiving fisheye video data;
means for generating a file that includes the fisheye video data, the file including a syntax structure that includes a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits that indicate fisheye video type information; and
means for outputting the file.
34. A non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors to:
receiving fisheye video data;
generating a file including the fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information; and
and outputting the file.
Technical Field
The present invention relates to the delivery of encoded media 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
Video compression techniques perform spatial prediction and/or temporal prediction to reduce or remove redundancy inherent in video sequences. For block-based video coding, a video frame or slice may be partitioned into macroblocks. Each macroblock may be further partitioned. Macroblocks in an intra-coded (I) frame or slice are encoded using spatial prediction with respect to neighboring macroblocks. Macroblocks in an inter-coded (P or B) frame or slice may use spatial prediction with respect to neighboring macroblocks in the same frame or slice or temporal prediction with respect to other reference frames.
After the video (and other media data) data has been encoded, the video data may be packetized for transmission or storage. The video data may be assembled 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 functionality relating to Virtual Reality (VR)/360 degree video applications. More specifically, the present invention describes enhanced high-order signaling for fisheye VR/360 video in a container file and in a media presentation description in an adaptive streaming format, such as dynamic adaptive streaming over HTTP (DASH). Although the techniques may be described herein in the context of omnidirectional media format (OMAF) and/or DASH, or in other media formats, it should be understood that these techniques may be generally applied to any Virtual Reality (VR) or 360 degree media format. Furthermore, although the present invention may refer to file formats in the form of the ISO base media file format (ISOBMFF), it should be understood that these file formats may generally be applied throughout multiple types of file formats.
In one example, this disclosure describes a method of processing a file containing video data, the method comprising: processing a file including fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information; determining the fisheye video type information for the fisheye video data based on the one or more bits of the syntax structure; and outputting the fisheye video data for rendering based on the determination.
In another example, this disclosure describes an apparatus configured to process a file including video data, the apparatus comprising: a memory configured to store the file; and one or more processors in communication with the memory, the one or more processors configured to: processing the file including fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information; determining the fisheye video type information for the fisheye video data based on the one or more bits of the syntax structure; and outputting the fisheye video data for rendering based on the determination.
In another example, this disclosure describes an apparatus configured to process a file including video data, the apparatus comprising: means for processing a file that includes fisheye video data, the file including a syntax structure that includes a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits that indicate fisheye video type information; means for determining the fisheye video type information for the fisheye video data based on the one or more bits of the syntax structure; and means for outputting the fisheye video data for rendering based on the determination.
In another example, this disclosure describes a non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors to: processing a file including fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information; determining the fisheye video type information for the fisheye video data based on the one or more bits of the syntax structure; and outputting the fisheye video data for rendering based on the determination.
In another example, this disclosure describes a method of generating a file including video data, the method comprising: receiving fisheye video data; generating a file including the fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information; and outputting the file.
In another example, this disclosure describes an apparatus configured to generate a file including video data, the apparatus comprising: a memory configured to store the file; and one or more processors in communication with the memory, the one or more processors configured to: receiving fisheye video data; generating the file including the fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information; and outputting the file.
In another example, this disclosure describes an apparatus configured to generate a file including video data, the apparatus comprising: means for receiving fisheye video data; means for generating a file that includes the fisheye video data, the file including a syntax structure that includes a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits that indicate fisheye video type information; and means for outputting the file.
In another example, this disclosure describes a non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors to: receiving fisheye video data; generating a file including the fisheye video data, the file including a syntax structure including a plurality of syntax elements that specify attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information; and outputting the file.
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 depicting an example system implementing techniques for streaming media data over a network.
FIG. 2 is a block diagram depicting an example set of components of the retrieval unit of FIG. 1 in greater detail.
FIG. 3 is a conceptual diagram showing elements of example multimedia content.
FIG. 4 is a block diagram showing elements of an example video file, which may correspond to a segment of a representation.
Fig. 5A and 5B are block diagrams showing an example device for capturing omnidirectional image content, according to one or more example techniques described in this disclosure.
Fig. 6 is an image showing an example of multiple fisheye images per video picture.
FIG. 7 is a flow diagram showing an example method for generating a file, in accordance with the techniques of this disclosure.
FIG. 8 is a flow diagram showing an example method for processing a file in accordance with the techniques of this disclosure.
Detailed Description
Certain aspects and examples of the disclosure are provided below. Some of these aspects and examples may be applied independently, and some of them may be applied in combinations as will be apparent to those of skill in the art. In the following description, for purposes of explanation, specific details are set forth in order to provide a thorough understanding of the examples of the invention. It will be apparent, however, that various examples may be practiced without these specific details. The drawings and detailed description are not intended to be limiting.
The following description provides examples only, and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the ensuing description of the examples will provide those skilled in the art with an enabling description for implementing an example of the invention. It being understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the application as set forth in the appended claims.
Specific details are given in the following description to provide a thorough understanding of the examples. However, it will be understood by one of ordinary skill in the art that the examples may be practiced without these specific details. For example, circuits, systems, networks, processes, and other components may be shown in block diagram form as components in order not to obscure the examples in unnecessary detail. In other instances, well-known circuits, processes, algorithms, structures, and techniques may be shown without unnecessary detail in order to avoid obscuring the examples.
Moreover, it is noted that individual examples may be described as a process which is depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. Further, the order of the operations may be rearranged. A process terminates when its operations are completed, but may have additional steps not included in the figure. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, and so on. When a procedure corresponds to a function, its termination may correspond to a return of the function to the calling function or the main function.
The term "computer-readable medium" includes, but is not limited to portable or non-portable storage devices, optical storage devices, and various other media capable of storing, containing, or carrying instruction(s) and/or data. Computer-readable media may include non-transitory media in which data may be stored and which do not include carrier waves and/or transitory electronic signals that propagate wirelessly or via a wired connection. Examples of non-transitory media may include, but are not limited to, magnetic disks or tapes, optical storage media such as Compact Discs (CDs) or Digital Versatile Discs (DVDs), flash memory, or memory devices. A computer-readable medium may have stored thereon code and/or machine-executable instructions, which may represent procedures, functions, subroutines, programs, routines, subroutines, modules, software packages, classes, or any combination of instructions, data structures, or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc.
Furthermore, examples of the present invention may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments (e.g., computer program products) to perform the necessary tasks may be stored in a computer-readable or machine-readable medium. The processor may perform the necessary tasks.
In general, this disclosure describes some enhanced designs, devices, and techniques for high-order signaling of fish-eye Virtual Reality (VR) video, such as also called 360 degree video or omnidirectional video data. Although the techniques may be described herein in the context of an omnidirectional media format (OMAF), it should be understood that this functionality may apply generally to any VR, omnidirectional, or 360 degree media format. Furthermore, although the present invention may refer to file formats in the form of the ISO base media file format (ISOBMFF), it should be understood that these file formats may generally be applied throughout multiple types of file formats. For example, various example methods of alternative signaling of fisheye video information are disclosed. One or more of these methods may be performed independently or in any combination.
Associated video coding standards include ITU-T H.261, ISO/IEC MPEG-1Visual, ITU-T H.262, or ISO/IEC MPEG-2Visual, ITU-T H.263, ISO/IEC MPEG-4Visual, ITU-T H.264, or ISO/IECMPEG-4AVC, 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 (i.e., scalable high efficiency video coding, SHVC) and multiview extensions (i.e., multiview high efficiency video coding, MV-HEVC) thereof. New video coding standards called multifunctional video coding (VVC) or ITU-T h.266 are being developed by the joint video experts group (jfet).
The file format standards include the ISO base media file format (ISOBMFF, ISO/IEC 14496-12), and other standards derived from ISOBMFF, including the MPEG-4 file format (ISO/IEC 14496-15), the 3GPP file format (3GPPTS 26.244), and the AVC and HEVC family of file formats (ISO/IEC 14496-15) for video codecs. Recent new versions of draft text for ISO/IEC 14496-12 and 14496-15 are available at http:// phenix. int-evry. fr/mpeg/doc _ end _ user/documents/111_ Geneva/wg11/w15177-v6-w15177.zip and http:// wg11.sc29.org/doc _ end _ user/documents/115_ Geneva/wg11/w16169-v2-w16169.zip, respectively.
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 DVB file format.
In addition to continuous media such as audio and video, static media such as images and metadata may also be stored in ISOBMFF compliant files. Files structured according to ISOBMFF may be used for many purposes, including local media file playback, progressive downloading of remote files, segments of adaptive streaming technology (e.g., dynamic adaptive streaming over HTTP (DASH), live HTTP streaming (HLS), etc.) for using containers for content to be streamed and their packetization instructions, and recording received real-time media streams.
For example, a box is a basic syntax structure in ISOBMFF, including a four-character coding box type, a byte count for the box, and a payload. An ISOBMFF file consists of a series of blocks, and a block may contain other blocks. Movie boxes ("moov") contain metadata for the successive media streams present in the file, each media stream being represented in the file as a track. 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 directly in a separate file. The media content for the track consists of a series of samples, such as audio or video access units.
ISOBMFF specifies the following types of tracks: a media track containing a primary media stream; a hint track containing media transmission instructions or representing a received data packet stream; and a timed metadata track comprising time synchronized metadata.
Although originally designed for storage, ISOBMFF has proven to be valuable for streaming processing (e.g., for progressive download or DASH). For streaming purposes, movie fragments defined in ISOBMFF may be used.
The metadata for each track includes a list of sample description entries, each entry providing the coding or encapsulation format used in the track and initialization data needed to process that format. Each sample is associated with one of the sample description entries of the track.
The ISOBMFF implementation specifies sample-specific metadata through various mechanisms. The specific boxes within the sample table box ("stbl") have been standardized to respond to common needs. For example, the sync sample box ("stss") is used to enumerate random access samples for the track. The sample grouping mechanism enables mapping of samples according to a four character grouping type into groups of samples sharing the same property specified as a sample group description entry in a file. Several packet types have been specified in ISOBMFF.
Dynamic adaptive streaming over HTTP (DASH) specified in ISO/IEC 23009-1 is a standard for HTTP (adaptive) streaming applications. DASH specifies the format of the Media Presentation Description (MPD), which is also called manifest, and media segment format. The MPD describes the media available on the server and lets DASH clients autonomously download the media version at the media time of their interest.
One example of a typical procedure for DASH-based HTTP streaming includes the following steps:
1) a DASH client obtains an MPD, such as a movie, of streaming content. 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 local information of MPD and DASH clients (e.g., network bandwidth, decoding/display capabilities, and user preferences), the client request is to be represented one segment (or portion thereof, e.g., partial segment) at a time.
3) When the DASH client detects a network bandwidth change, the DASH client 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", to respond to a user request to reverse-seek past locations or forward-seek future locations, the DASH client request begins in past or future segments that are close to the location of the user request and ideally begin in segments of the random access point. Users may also request fast forwarding content, which may be achieved by requesting data sufficient for decoding only intra-coded video pictures or only a temporary subset of the video stream.
In HTTP streaming processing such as DASH, frequently used operations include HEAD, GET, and partial GET. The HEAD operation retrieves the header of the file associated with a given Uniform Resource Locator (URL) or Uniform Resource Name (URN), but does not retrieve the payload associated with the URL or URN. The GET operation retrieves the entire file associated with a given URL or URN. The partial GET operation receives a byte range as an input parameter and retrieves 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 processing, since a partial GET operation may result in one or more individual movie fragments. In a movie fragment, there may be several track slices 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 a streaming service to the user.
In an example of streaming 3GPP data using HTTP streaming, there may be multiple representations of video and/or audio data of 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 manifest of these 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 for the same media content. The representation may be one of many alternative encoded versions of audio, video, timed text, or other such data. The representation may vary from encoding type to encoding type, e.g., for video data, from bit rate, resolution, and/or codec to encoding type, and for audio data, from codec to codec, language, and/or codec of the bit rate. 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.
Representations for a particular period may be assigned to a group indicated by an 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 can dynamically and smoothly switch between these representations, e.g., to perform broadband adaptation. For example, each representation of video data of 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) of multimedia content of the corresponding period. 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 substantially simultaneously retrieving different types of media data. For example, the client device may select an audio representation, a video representation, and a timed text representation from which to retrieve 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 the adaptation set for certain types of media (e.g., video) and directly select the representation for other types of media (e.g., audio and/or timed text).
Fig. 1 is a block diagram depicting an
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 produces 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 generates 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 need not be communicatively coupled to
Raw audio and video data may include analog or digital data. 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 a 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, when a speaking participant typically produces audio data by speaking, the audio source 22 captures audio data, and the video source 24 simultaneously (i.e., while the 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 of simultaneously captured audio data and video data, and an audio frame and a video frame respectively include simultaneously captured audio data and video data.
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 these examples, audio frames corresponding to video frames may include: audio frames including a time stamp, and video frames 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 instances, 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 a video file. Within the same representation, a stream ID may be used to distinguish PES packets belonging to one elementary stream from others. The basic unit of data of an elementary stream is a Packetized Elementary Stream (PES) packet. Thus, the coded video data generally corresponds to a base video stream. Similarly, the audio data corresponds to one or more respective elementary streams.
Many video coding standards, such as the ITU-T H.264/AVC and ITU-T H.265/High Efficiency Video Coding (HEVC) standards, define the syntax, semantics, and decoding processes of error-free bitstreams, any of which conforms to a certain profile or level. Video coding standards typically do not 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 an algorithm, feature, or tool and a constraint applied to the algorithm, feature, or tool. As defined by the h.264 standard, for example, a "profile" is a subset of the overall 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 the resolution, bit rate, and block processing rate of the picture. A profile _ idc (profile indicator) value is signaled for profile availability and a level _ idc (level indicator) value is signaled for level availability.
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 values taken by the syntax elements in the bitstream (e.g., the specified size of the decoded pictures). 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 "levels" as a specified set of constraints imposed on the values of syntax elements in the bitstream. These constraints may be simple limits on the values. Alternatively, these 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 a video transmission, a pair of profile definitions and tier definitions may be negotiated and agreed for the entire transmission session. More particularly, 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 less than 8 x 8 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 that includes coded video data from video encoder 28 and an elementary stream that includes 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 the 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 comprise 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. The 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 for 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 that addresses applications such as video telephony, storage, broadcast, or streaming. NAL units can be classified as 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 in one instance of time (typically presented as a primary coded picture) 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)). With parameter sets, such as PPS and SPS, infrequently changing information need not be repeated for each sequence or picture, so coding efficiency may be improved. Furthermore, the use of parameter sets may enable out-of-band transmission of important header information, avoiding the need for redundant transmissions for error recovery. 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 recovery, and other uses. The SEI message may be contained in a non-vcl nal unit. SEI messages are a normative 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 scalability information SEI messages in the example of SVC, and view scalability information SEI messages in MVC. These example SEI messages may convey information about, for example, the extraction of operation points and the characteristics of the operation points. Further, the packaging unit 30 may form a manifest file, such as a Media Presentation Descriptor (MPD) describing the 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 to
In some examples, representation 68 may be divided into several adaptation sets. That is, the various subsets of representations 68 may include respective common sets of characteristics, such as codecs, profiles 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 to be decoded and presented (e.g., by speakers), camera angle information that may describe camera angles or real world camera perspectives of the scenes of the representations in the adaptation set, rating information describing content suitability for a particular audience, or the like.
Manifest file 66 may include data indicating a subset of representations 68 corresponding to a particular adaptation set and common characteristics of the adaptation sets. Manifest file 66 may also include data representing individual characteristics (e.g., bit rate) of the individual representations of the adaptation sets. In this way, the adaptation set may provide simplified network bandwidth adaptation. Representations in the adaptation set may be indicated using child elements of the adaptation set elements of the manifest file 66.
The
Additionally or alternatively,
As depicted in the example of fig. 1, the
Specifically,
In general, a higher bitrate representation can result in higher quality video playback, while a lower bitrate representation can provide adequate quality video playback when the available network bandwidth is reduced. Thus, when the available network bandwidth is relatively high,
Additionally or alternatively,
The
Video encoder 28, video decoder 48, audio encoder 26, audio decoder 46, encapsulation unit 30,
As will be described in more detail below, content preparation device 20 may be configured to: receiving fisheye video data; generating a file including the fisheye video data, the file including a syntax structure including a plurality of syntax elements specifying attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information; and outputting the file. Similarly,
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 a payload of varying size. NAL units that contain video data in their payloads may include video data of various levels of granularity. For example, a NAL unit may comprise a block of video data, a plurality of blocks, a slice of video data, or all pictures of video data. Encapsulation unit 30 may receive encoded video data from video encoder 28 in the form of PES packets of an elementary stream. 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 instance, e.g., all audio and video data for one time instance. For example, if each view has a frame rate of 20 frames per second (fps), each time instance 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 (same time instance) may be rendered at the same time. In one example, an access unit may comprise a coded picture in one instance of time, which may be presented as a primary coded picture.
Thus, an access unit may include all audio and video frames of a common time instance, 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 of a common time instance. The decoding order of the access units is not necessarily the same as the output or display order.
A media presentation may include a Media Presentation Description (MPD) that may contain descriptions of different alternative representations, such as video services having different qualities, and that may include, for example, codec information, profile values, and tier values. An MPD is an example of a manifest file (e.g., manifest file 66).
Manifest file 66 (which may include, for example, an MPD) may advertise the availability of segments of representation 68. That is, the MPD may include information indicative of a wall clock time at which the first segment of one of representations 68 becomes available, and information indicative of durations of segments within representations 68. In this way,
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
FIG. 2 is a block diagram depicting an example set of components of the
In this example, the
When the
Proxy server 102 may act as a server for
In accordance with the techniques of this disclosure, encapsulation unit 30 may signal and retrieve
Fig. 3 is a conceptual diagram showing elements of example multimedia content 120. The multimedia content 120 may correspond to the multimedia content 64 (fig. 1), or another multimedia content stored in the
MPD 122 may include a separate data structure from representation 124. MPD 122 may correspond to manifest file 66 of fig. 1. Likewise, representation 124 may correspond to representation 68 of FIG. 1. In general, MPD 122 may include data that generally describes characteristics of representation 124, such as coding and presentation characteristics, adaptation sets, profiles to which MPD 122 corresponds, text type information, camera angle information, rating information, trick mode information (e.g., information indicating representations that include temporal subsequences), and/or information for retrieving remote periods (e.g., for targeted announcement insertion 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, also referred to as a Stream Access Point (SAP)), which of the segments 128 includes a random access point, a byte offset to 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 for section 132. Additionally or alternatively, these characteristics may be sufficiently 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. These characteristics may be described by data of the MPD 122, but this data is not shown in the example of fig. 3. MPD 122 may include characteristics as described by the 3GPP specifications, and add any or all of the signaled 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 retrieved using a streaming processing network protocol (e.g., DASH). In this way, a destination device, such as
FIG. 4 is a block diagram depicting elements of an
File Type (FTYP) block 152 generally describes the file type for
In some examples, a segment such as
In the example of fig. 4,
In some examples,
As noted above, encapsulation unit 30 may store sequence datasets in the video samples that do not include the actual coded video data. A video sample may generally correspond to an access unit, which is a representation of a coded picture at a particular instance in time. In the case of AVC, a coded picture includes one or more VCL NAL units (which contain information that constructs all pixels of the access unit), and other associated non-VCL NAL units (e.g., SEI messages). Accordingly, encapsulation unit 30 may include a sequence data set, which may include sequence level SEI messages, in one of movie fragments 164. Encapsulation unit 30 may further signal the presence of sequence data sets and/or sequence level SEI messages as being present in one of movie fragments 164 in MVEX block 160 that corresponds within one of movie fragments 164.
A SIDX block 162 is an optional element of the
SIDX block 162 generally represents information that provides one or more sub-segments of a segment included in
In some examples, movie fragments 164 may include one or more Stream Access Points (SAPs), such as IDR pictures. Likewise,
In accordance with the techniques of this disclosure,
Virtual Reality (VR) is the ability to virtually exist in a non-physical world created by the appearance of natural and/or synthetic images and sounds related to the movements of an immersive user, allowing interaction with the world. With recent advances made in rendering devices, such as Head Mounted Displays (HMDs), and VR video (also commonly referred to as 360 degree video or omni-directional video) creation, significant quality of experience can be provided. VR applications include gaming, training, education, sports video, online shopping, adult entertainment, and the like.
One example of a VR system includes the following components and steps:
1) a camera rig, which typically consists of a plurality of individual cameras pointing in different directions and ideally collectively covering all viewpoints around the camera rig.
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 cubic mapping.
3) The video in the mapped rectangular format is encoded/compressed using a video codec, such as h.265/HEVC or h.264/AVC or other video coding standard.
4) The compressed video bitstream may be stored and/or packaged in a media format and transmitted (possibly only over a subset covering the region being viewed by the user) over a network to a receiver.
5) The receiver receives a video bitstream, or portion thereof, which may be packaged in a format, and sends the decoded video signal, or portion thereof, to a rendering device.
6) The rendering device may be, for example, an HMD that may track head movements and even eye movement moments, and render corresponding portions of the video such that an immersive experience is delivered to the user.
At the time of authoring of this document, the omnidirectional media format (OMAF) is being developed by MPEG to define a media format that enables omnidirectional media applications, which focus on VR applications with 360 ° video and associated audio. It first specifies the following list: a projection method that can be used to convert spherical or 360 ° video to two-dimensional rectangular video, then how to store the omnidirectional media and associated metadata using ISO base media file format (ISOBMFF), and how to use dynamic adaptive streaming over HTTP (DASH) encapsulation, signaling and streaming the omnidirectional media, and ultimately which video and audio codecs and media coding configurations can be used to compress and playback the omnidirectional media signal.
OMAF will become ISO/IEC 23090-2, and when written here, the latest draft specifications can be found in: http:// wg11.sc29.org/doc _ end _ user/documents/119_ Torino/wg11/m40849-v1-m40849_ OMAF _ text _ Berlin _ output. zip.
The example techniques described in this disclosure relate to high-order signaling for omnidirectional video or image data. When omnidirectional media content is consumed with certain devices, such as head-mounted displays and headphones, only the portion of the media that corresponds to the user's viewing orientation is presented, as if the user was present at the time the media was captured and at the time the media was captured (e.g., where the camera was). One of the most popular forms of omnidirectional media applications is omnidirectional video, also known as 360 degree video. Omnidirectional video is typically captured by multiple cameras covering up to 360 degrees of a scene, for example as described above.
Generally, an omnidirectional video is formed from a series of omnidirectional images. Thus, the example techniques described in this disclosure are described with respect to generating omnidirectional image content. These omnidirectional images may then be sequentially displayed for omnidirectional video content. In some examples, the user may need to take only an omnidirectional image (e.g., as a snapshot of the user's entire 360 degree environment), and the techniques described in this disclosure are also applicable to these example situations.
Omnidirectional video may be stereoscopic or monoscopic. When the video is stereoscopic, a different image is shown to each eye so that the viewer can perceive depth. Thus, stereoscopic video is typically captured using two cameras facing in respective directions. When the video is monoscopic, the same image is shown to both eyes.
The video data may be considered to be fisheye video data, where the video data is captured using one or more fisheye lenses (or generated as if captured using one or more fisheye lenses). A fisheye lens may be an ultra-wide angle lens that produces strong visual distortions intended to create a wide panoramic or hemispherical image.
The techniques of this disclosure may be applicable to captured video content, VR, and in general to video and image display. The techniques may be used in mobile devices, but the techniques should not be considered limited to mobile applications. In general, the techniques may be used in metaverse applications, video game applications, or other applications that require a 360 degree sphere video/image environment.
In some examples, omnidirectional image content may be captured with a camera device that includes two fisheye lenses. In the case where two fisheye lenses are positioned on opposite sides of the camera device to capture opposite portions of a sphere of image content, the image content may be a single image and cover a full sphere of 360 degree video. Similarly, where two fisheye lenses are positioned on the same side of the camera device to capture the same portion of a sphere of image content, the image content may be stereoscopic and cover half of the sphere of 360 degree video. The image produced by the camera is a circular image (e.g., one image frame contains two circular images).
Fig. 5A and 5B are block diagrams showing an example device for capturing omnidirectional image content, according to one or more example techniques described in this disclosure. As shown in fig. 5A,
As described above, the camera device includes a plurality of fisheye lenses. Some example camera devices include two fisheye lenses, but the example techniques are not limited to two fisheye lenses. One example camera device may include 16 lenses (e.g., a 16-camera array for capturing 3D VR content). Another example camera device may include eight lenses, each lens having a 195 degree view angle (e.g., each lens captures image content of 195 degrees out of 360 degrees). Other example camera devices include three or four lenses. Some examples may include a 360 degree shot that captures 360 degrees of image content.
The example techniques described in this disclosure are generally described with respect to two fisheye lenses capturing omnidirectional images/video. However, the example techniques are not so limited. Example techniques may be applicable to example camera devices that include multiple (e.g., two or more) lenses (even if the lenses are not fisheye lenses) and multiple fisheye lenses. For example, the example techniques describe a manner of stitching captured images, and the techniques may be applicable to instances where there are multiple captured images from multiple lenses (which may be fisheye lenses, as an example). Although the example techniques are described with respect to two fisheye lenses, the example techniques are not so limited and are applicable to various camera types for capturing omnidirectional images/video.
The OMAF supports a fish eye VR/360 video. At the time of this writing, the latest draft OMAF specification specifies a fisheye VR/360 video format, where instead of applying projection and optionally region-by-region packing to generate 2D video prior to encoding, for each access unit, the circular image from the capturing camera is directly embedded in a 2D picture, e.g., as shown in fig. 6. Fig. 6 shows an example of multiple fisheye images per video picture. As shown in fig. 6, a first
This fisheye video may then be encoded and the bitstream may be encapsulated in an ISOBMFF file and may be further encapsulated as a DASH representation. Furthermore, the nature of the fisheye video (including parameters indicative of characteristics of the fisheye video) may be signaled and used to correctly render 360 the video at the client side. One of the main advantages of the fisheye VR/360 video approach is that it supports low-cost user-generated VR content by mobile terminals.
The use of the fisheye omni-directional video scheme for the restricted video sample entry type 'resv' indicates that the decoded picture is a fisheye video picture. The use of the fisheye omni-directional video scheme is indicated by the value of the scheme _ type syntax element within the SchemeTypeBox equal to 'fodv' (fisheye omni-directional video). The format of the fisheye video is indicated by a fisherey omnidirectionalvideobox contained in a schemelnformationbox contained in a restictedschemelnbox contained in the sample entry. In some examples, when the type of the protocol is 'fodv', one and only one fisherey omnidirective videobox should exist in the schemelnformationbox. When the fishereoomnidirectionvideobox exists in the schemelnformationbox, the StereoVideoBox and the regionwispackangbox should not exist in the same schemelnformationbox. The fishereon omni directional videobox, as specified in clause 6 of the OMAF DIS, contains a fisher omni directional videoinfo () syntax structure that contains fish-eye video property parameters.
The syntax and semantics of the fishereonnirectionalvideoinfo () syntax structure are specified in clause 6 of the latest draft OMAF specification. The syntax is as follows:
the semantics of the fishereonitiationvideoinfo () syntax structure in the current draft of OMAF DIS are as follows.
num _ circular _ images specifies the number of circular images in the coded picture for each sample to which this block applies. Typically, the value is equal to 2, but other non-zero values are possible.
image center x is a fixed point 16.16 value that specifies the horizontal coordinate of the center of the circular image in the coded picture of each sample in the luma sample to which this box applies.
image center y is a fixed point 16.16 value that specifies the vertical coordinate of the center of the circular image in the coded picture of each sample in the luma sample to which this box applies.
full _ radius is a fixed point 16.16 value that specifies the radius in the luminance sample from the center of the circular image to the edge of the full circular image.
picture _ radius is a fixed point 16.16 value that specifies the radius in the luminance sample from the center of the circular image to the nearest edge of the image boundary. The circular fisheye image may be cropped from the camera picture. Thus, this value indicates the radius of the circle in which the pixel can be used.
scene radius is a fixed point 16.16 value that specifies the radius in the luma sample from the center of the circular image to the closest edge of the region in the image, where it is guaranteed that there are no obstacles from the camera body itself and that there is no lens distortion within the enclosed region that is too large to be used for stitching.
image _ rotation is a fixed point 16.16 value that specifies the rotation amount in degrees of the circular image. The image may be rotated +/-90 degrees, or +/-180 degrees, or any other value.
image _ flip specifies whether and how the image has been flipped, and therefore the reverse flip operation needs to be applied. A value of 0 indicates that the image has not yet flipped. A value of 1 indicates that the image has flipped vertically. A value of 2 indicates that the image has flipped horizontally. A value of 3 indicates that the image has flipped vertically and horizontally.
image _ scale _ axis _ angle, image _ scale _ x, and image _ scale _ y are three fixed point 16.16 values that specify whether and how the image has been scaled along the axis. The axis is defined by a single angle as indicated by the value of image scale axis angle in degrees. An angle of 0 degrees means that the horizontal vector is perfectly horizontal and the vertical vector is perfectly vertical. The values of image scale x and image scale y indicate the scaling ratios in the directions parallel and orthogonal to the axis, respectively.
field _ of _ view is a fixed point 16.16 value that specifies the field of view in degrees of the fisheye lens. A typical value for a hemispherical fisheye lens is 180.0 degrees.
num _ angle _ for _ displaying _ fov specifies the number of corners. According to the value of num _ angle _ for _ displaying _ fov, the values of displayed _ fov and overlaid _ fov are defined at equal intervals, starting at 12 o' clock and going clockwise.
display _ fov specifies the field of view displayed and the corresponding image area for each fisheye camera image. overlapped _ fov specifies a region containing an overlapping region in terms of the field of view between a plurality of circular images, the overlapping region being commonly used for blending. The values of displayed _ fov and overlaid _ fov are less than or equal to the value of field _ of _ view.
Note that: the value of field _ of _ view is determined by the physical properties of each fisheye lens, while the values of displayed _ fov and overlaid _ fov are determined by the configuration of the fisheye lenses. For example, when the value of num _ circular _ images is equal to 2 and the two lenses are symmetrically positioned, the values of displayed _ fov and overlapped _ fov may be set to 180 and 190 by default, respectively. However, the value may vary depending on the configuration of the shot and the characteristics of the content. For example, if the stitching quality with the displayed _ fov value (170 left camera and 190 right camera) and overlapped _ fov value (185 left camera and 190 right camera) is better than the quality with the default values (180 and 190), or if the physical configuration of the cameras is not symmetric, unequal displayed _ fov and overlapped _ fov values may be taken. In addition, with respect to a plurality of (N >2) fisheye images, a single displayed _ fov value cannot specify an exact region of each fisheye image. As shown in fig. 6, displayed _ fov (602) varies according to direction. To handle multiple (N >2) fisheye images, num _ angle _ for _ displaying _ fov is introduced. For example, if this value is equal to 12, the fisheye image is divided into 12 sectors with each sector angle being 30 degrees.
Camera _ center _ yaw specifies the point at 2-16Degree is the yaw angle in units, the center pixel of the circular image in the coded picture of each sample is projected to the sphere surface. This is the first of 3 angles specifying camera extrinsic parameters with respect to the global coordinate axis. The camera _ center _ yaw should be at-180 x 216To 180 x 2161 (inclusive).
Camera _ center _ pitch specifies point at 2-16The degree is the pitch angle in units, the center pixel of the circular image in the coded picture of each sample is projected to the sphere surface. The camera _ center _ pitch should be at-90 x 216To 90 x 216In a range (including endpoints).
Camera _ center _ roll specifies point at 2-16Rolling with degree as unitCorner, the center pixel of the circular image in the coded picture of each sample is projected to the sphere surface. The camera _ center _ roll should be at-180 x 216To 180 x 2161 (inclusive).
camera _ center _ offset _ x, camera _ center _ offset _ y, and camera _ center _ offset _ z are fixed point 8.24 values that indicate XYZ offset values from the origin of the unit sphere onto which pixels in a circular image in a coded picture are projected. camera _ center _ offset _ x, camera _ center _ offset _ y, and camera _ center _ offset _ z should be in the range of-1.0 to 1.0 (inclusive).
num _ polymodal _ coefficients are integers that specify the number of polynomial coefficients present. The list of polynomial coefficients, polymodal _ coeffient _ K, is the fixed point 8.24 value, which represents the coefficients in the polynomial that specify the transformation from fisheye space to an undistorted planar image.
num _ local _ fov _ region specifies the number of locally adapted regions with different fields of view.
start _ radius, end _ radius, start _ angle, and end _ angle specify the locally adapted/warped region to change the actual field of view for local display. Start _ radius and end _ radius are set point 16.16 values that specify minimum and maximum radius values. Start _ angle and end _ angle specify minimum and maximum angular values, starting at 12 o' clock and starting at 2-16The degree increases clockwise in units. The start _ angle and end _ angle should be-180 x 216To 180 x 2161 (inclusive).
radius delta is a fixed point 16.16 value that specifies an incremental radius value for representing a different field of view for each radius.
angle _ delta is specified by 2-16The incremental angular values in degrees are used to represent different fields of view for each angle.
local _ fov _ weight is an 8.24 fixed point format that specifies the weighting values for the field of view for the location specified by start _ radius, end _ radius, start _ angle, end _ angle, angle index i, and radius index j. Positive values of local _ fov _ weight specify an expansion of the field of view, while negative values specify a contraction of the field of view.
num _ polymeric _ coeffients _ lsc shall be the order of the polynomial approximation of the lens shading curve.
The public _ coefficient _ K _ LSC _ R, polynomial _ coefficient _ K _ LSC _ G and the public _ coefficient _ K _ LSC _ B are in an 8.24 fixed point format that specifies LSC parameters to compensate for color-reducing shading artifacts along the radial direction. The compensation weight (w) multiplied to the original color is a curve function approximated as a radius from the center of the image using a polynomial expression. It is formulated as
num _ slices is an integer that specifies the number of dead zones in the coded picture for each sample to which this block applies.
The deadzone _ left _ horizontal _ offset, deadzone _ top _ vertical _ offset, deadzone _ width, and deadzone _ height are integer values that specify the location and size of the dead zone rectangular area for which pixels are unavailable. The deadzone _ left _ horizontal _ offset and deadzone _ top _ vertical _ offset specify the horizontal and vertical coordinates, respectively, of the top-left corner of the dead zone in the coded picture in luma samples. The deadzone _ width and deadzone _ height specify the width and height, respectively, of the dead zone in the luma samples. To save bits for representing video, all pixels within the dead zone should be set to the same pixel value, e.g., all black.
The high-order fisheye video signaling is addressed in item 4 of MPEG document m 40783. MPEG document m40783 describes the following high-order fisheye video signaling. The change is indicated as follows: (wherein the text surrounded by the start and end plus symbols "[ + > ]" and "[ + < ]", respectively, is added, and the text surrounded by the start and end delete symbols "[ - > ]" and "[ - < ]", respectively, is removed, and the other parts remain unchanged):
whether the fisheye video is monoscopic or stereoscopic is indicated using one of the initial 24 bits of fishereon directionalvideoinfo (), and a view ID is added for each circular image.
[ + > ] monoscopic _ flag equal to 1 indicates that the fisheye omnidirectional video is monoscopic. A value of 0 indicates that the fisheye omnidirectional video is not monoscopic.
view _ id indicates a view identifier of a view to which the circular image belongs. When there are only two values 0 and 1 of view _ id for all circular images, the fisheye video is stereoscopic, the circular image with view _ id equal to 0 belongs to the left view, and the circular image with view _ id equal to 1 belongs to the right view. [ + < ]
The present invention identifies problems and disadvantages in methods proposed for examples of higher order signaling schemes for fish-eye VR video. The following are three examples of these problems:
(1) signaling a fisheye video using a view identification syntax element (e.g., view _ id) may not be optimal for fisheye cameras (or other arrangements) spatially arranged on a sphere surface, since one circular image captured by one fisheye camera may belong to multiple views.
(2) Current techniques lack any mechanism for indicating whether the video data is a stereoscopic fisheye VR video.
(3) Current technology lacks any mechanism for signaling higher-order fisheye VR video information for DASH.
This disclosure describes techniques and functional improvements to reduce the number of problems in higher order signaling schemes for fisheye VR video. The proposed techniques described below may be applied independently and/or may be applied in combination.
In one example of the present invention, to address issues related to the use of view identification syntax elements, the content preparation device 20 may be configured to indicate fisheye video type information using one or more of the initial 24 reserved bits in a fisherey omnidirective video info () syntax structure (e.g., as defined in OMAF). For example, the content preparation device 20 may use one or more of the initial 24 reserved bits in the fisherey omnidirective videoinfo () syntax structure to indicate whether the fisheye video is monoscopic, stereoscopic (e.g., consisting of left and right views), or otherwise (e.g., neither monoscopic nor stereoscopic). Any hardware or software unit of content preparation device 20 may be configured to generate bits of the fishereon directionalvideoinfo () syntax structure to indicate fisheye video type information, including video encoder 28 and/or encapsulation unit 30. The content preparation device 20 may be configured to signal a fishereon directionalvideoinfo () syntax structure in the encoded video bitstream. In some examples, content preparation device 20 may be configured to indicate the fisheye video type information using two of the initial 24 reserved bits in the fishereonnirectionalvideoinfo () syntax structure. In other examples, content preparation device 20 may be configured to indicate the fisheye video type information using three of the initial 24 reserved bits in the fishereonnirectionalvideoinfo () syntax structure.
In another example of the disclosure, to address issues related to indicating stereoscopic fisheye VR video, content preparation device 20 may be configured to generate and add a flag to the fishereon @ directional videoinfo () syntax structure to indicate fisheye video stereoscopic information for each circular image of the video data. For example, the flag may indicate whether a circular image of the fisheye video data belongs to a left view or a right view. Any hardware or software unit of content preparation device 20 may be configured to generate a flag in the fishereon directionalvideoinfo () syntax structure to indicate fisheye video stereo information, including video encoder 28 and/or packing unit 30. The content preparation device 20 may be configured to signal a fishereon directionalvideoinfo () syntax structure in the encoded video bitstream.
The following is an example implementation of the techniques described above for signaling bits and flags in the fishereon informational videoinfo () syntax structure to indicate fisheye video type information and fisheye video stereo information. The following syntax and semantic changes to the syntax structure fishereomentitionvelofo () are as follows (where the text enclosed by the start and end plus symbols "[ + > ]" and "[ + < ]" respectively is an addition, and the text enclosed by the start and end delete symbols "[ - > ]" and "[ - < ]" respectively is a removal; other parts remain unchanged):
[ + > ] ] view _ dimension _ idc equal to 0 indicates that the fisheye omnidirectional video is monoscopic. A value of 1 indicates that the fisheye omnidirectional video is stereoscopic (i.e., consists of a left view and a right view). A value of 2 indicates that the fisheye omnidirectional video is neither monoscopic nor stereoscopic. The value 3 is reserved.
A value of left _ view _ flag equal to 1 indicates that the circular picture belongs to the left view. A value of 0 indicates that the circular image belongs to the right view. [ + < ]
In another example of this disclosure, to address the issue of higher-order fisheye VR video information for DASH, content preparation device 20 may be configured to generate DASH Fisheye Video Information (FVI) descriptors for signaling whether the fisheye video data is monoscopic, stereoscopic (e.g., consisting of left and right views), or otherwise (e.g., neither monoscopic nor stereoscopic). When stereoscopic, content preparation device 20 may be configured to generate an indication in the FVI descriptor whether the circular image in the picture belongs to a left view or a right view. Any hardware or software unit of content preparation device 20 may be configured to generate the FVI descriptor, including video encoder 28 and/or encapsulation unit 30. Content preparation device 20 may be configured to signal the FVI descriptor in an encoded video bitstream.
The following is an example of a proposed implementation of the FVI descriptor for DASH. An example implementation of this proposal includes the following syntax and semantics.
A Fisheye Video Information (FVI) supplementalProperty element with the @ schemeIdUri attribute equal to "urn: mpeg: omaf: FVI: 2017" may exist at the adaptation set level (i.e., directly in the AdaptionSet element) and should not exist at other levels (i.e., should not exist at the MPD level or directly in any replication element).
The FVI descriptor indicates whether the fisheye video carried in each repetition is monoscopic, stereoscopic (i.e., consists of left and right views), or otherwise, and when stereoscopic, whether the circular image in the picture belongs to the left or right view.
The @ value of the FVI descriptor with @ schemeIdUri equal to "urn: mpeg: omaf: FVI: 2017" is a comma-separated list of values as specified in the following table:
FIG. 7 is a flow diagram showing an example method for generating a file, in accordance with the techniques of this disclosure. The techniques of fig. 7 may be performed by one or more structural units of content preparation device 20, including video encoder 28 and/or encapsulation unit 30.
In one example of the present disclosure, content preparation device 20 may be configured to: receiving fisheye video data (700); generating a file including fisheye video data, the file including a syntax structure including a plurality of syntax elements specifying attributes of the fisheye video data, wherein the plurality of syntax elements includes one or more bits indicating fisheye video type information (702); and outputting the file (704).
In one example, the fisheye video type information includes at least one of an indication of monoscopic fisheye video data or an indication of stereoscopic fisheye video data. In one example, the syntax structure is a fisher omnidirectionvideoinfo () syntax structure of the omnidirectional media format, and the one or more bits are two bits of the initial 24 reserved bits in the fisher omnidirectionvideoinfo () syntax structure.
In one example, the one or more bits are a view _ dimension _ idc syntax element, wherein a value of 0 for the view _ dimension _ idc syntax element indicates that the fisheye video data is stereoscopic fisheye video data, and wherein a value of 1 for the view _ dimension _ idc syntax element indicates that the fisheye video data is monoscopic fisheye video data. In one example, a value of 2 for the view _ dimension _ idc syntax element indicates that the fisheye video data is neither monoscopic fisheye video data nor stereoscopic fisheye video data.
In one example, the fisheye video data is stereoscopic fisheye video data, and the syntax structure further includes one or more flags indicating whether an image of the stereoscopic fisheye video data is in a left view or a right view. In one example, the one or more flags include a left view flag, wherein a value of 1 for the left view flag indicates that a particular one of the pictures is in the left view, and wherein a value of 0 for the left view flag indicates that a particular one of the pictures is in the right view.
FIG. 8 is a flow diagram showing an example method for processing a file in accordance with the techniques of this disclosure. The techniques of fig. 8 may be performed by one or more structural units of
In one example of the present disclosure,
In one example, the fisheye video type information includes at least one of an indication of monoscopic fisheye video data or an indication of stereoscopic fisheye video data. In one example, the syntax structure is a fisher omnidirectionvideoinfo () syntax structure of the omnidirectional media format, and the one or more bits are two bits of the initial 24 reserved bits in the fisher omnidirectionvideoinfo () syntax structure.
In one example, the one or more bits are a view _ dimension _ idc syntax element, wherein a value of 0 for the view _ dimension _ idc syntax element indicates that the fisheye video data is stereoscopic fisheye video data, and wherein a value of 1 for the view _ dimension _ idc syntax element indicates that the fisheye video data is monoscopic fisheye video data. In one example, a value of 2 for the view _ dimension _ idc syntax element indicates that the fisheye video data is neither monoscopic fisheye video data nor stereoscopic fisheye video data.
In one example, the fisheye video data is stereoscopic fisheye video data, and the syntax structure further includes one or more flags indicating whether an image of the stereoscopic fisheye video data is in a left view or a right view. In one example, the one or more flags include a left view flag, wherein a value of 1 for the left view flag indicates that a particular one of the pictures is in the left view, and wherein a value of 0 for the left view flag indicates that a particular one of the pictures is in the right view.
In one example,
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. The computer-readable medium may include: a computer-readable storage medium corresponding to a tangible medium such as a data storage medium; 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 tangible computer-readable storage medium that is non-transitory, or (2) a communication medium such as 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 retrieve instructions, code and/or data structures for implementation of the techniques described herein. 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 rather refer 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. Further, 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. Furthermore, 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. Rather, as described above, the various units may be combined in a codec hardware unit, or provided through a set of interoperability hardware units (including one or more processors as described above) along with suitable software and/or firmware.
Various examples have been described. These and other examples are within the scope of the following claims.
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