Multiple decoder interface for streaming media data

Abstract

The present disclosure relates to an example device for decoding media data, including a memory configured to store the media data and one or more processors implemented in a circuit and communicatively coupled to the memory. The one or more processors are configured to determine whether two or more decoder instances are intended to be synchronized. The one or more processors are configured to control the two or more decoder instances based on the two or more decoder instances being intended to be synchronized so as to be able to present decoded data from each of the two or more decoder instances at the same presentation time.

Description

[0001] This application claims priority to U.S. Application No. 17 / 143,633, filed on January 7, 2021, which claims the benefit of U.S. Provisional Application No. 62 / 959,064, filed on January 9, 2020, the entire contents of each application are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to decoding of media data. Background Art

[0003] Digital video capabilities may be incorporated into a variety 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 game devices, video game consoles, cellular or satellite radio telephones, video teleconferencing equipment, etc. Digital video devices implement video compression techniques, such as those described in the standards defined by MPEG-2, MPEG-4, ITU-T H.263 or ITU-T H.264 / MPEG-4, Part 10, Advanced Video Coding (AVC), ITU-T H.265 (also known as High Efficiency Video Coding (HEVC)), and extensions of these standards, to more efficiently transmit and receive digital video information.

[0004] After media data such as audio and video data is encoded, the media data can be packetized for transmission or storage. The media data can be assembled into a media file that conforms to any of a variety of standards, such as the International Organization for Standardization (ISO) base media file format and its extensions, such as AVC. Summary of the invention

[0005] In general, the present disclosure describes techniques for decoding different types of media data by different corresponding decoders at a client device. Recently, various application programming interfaces (APIs) have identified a series of problems when processing immersive data. The techniques of the present disclosure can solve the identified problems.

[0006] In one example, a method for decoding media data includes determining, by a client device, whether two or more decoder instances are intended to be synchronized, and based on the two or more decoder instances being intended to be synchronized, controlling the two or more decoder instances so as to be able to present decoded data from each of the two or more decoder instances at the same presentation time.

[0007] In another example, a device for decoding media data includes a memory configured to store the media data, and one or more processors implemented in a circuit and communicatively coupled to the memory, the one or more processors configured to: determine whether two or more decoder instances are intended to be synchronized; and based on the two or more decoder instances being intended to be synchronized, control the two or more decoder instances so that decoded data from each of the two or more decoder instances can be presented at the same presentation time.

[0008] In another example, a non-transitory computer-readable storage medium stores instructions that, when executed by one or more processors, cause the one or more processors to: determine whether two or more decoder instances are intended to be synchronized; and based on the two or more decoder instances being intended to be synchronized, control the two or more decoder instances so that decoded data from each of the two or more decoder instances can be presented at the same presentation time.

[0009] In another example, an apparatus for decoding media data includes a device for determining whether two or more decoder instances are to be synchronized, and a device for controlling the two or more decoder instances so as to be able to present decoded data from each of the two or more decoder instances at the same presentation time based on the two or more decoder instances intending to be synchronized.

[0010] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a block diagram illustrating an example system that implements techniques for streaming media data over a network.

[0012] Figure 2 is a block diagram illustrating a collection of example components of a retrieval unit.

[0013] Figure 3 is a conceptual diagram illustrating elements of example multimedia content.

[0014] Figure 4is a block diagram illustrating elements of an example video file, which may correspond to segments of a representation.

[0015] Figure 5 is a conceptual diagram illustrating an example system for decoding streaming media data.

[0016] Figure 6 is a block diagram illustrating an example decoding engine and related interfaces.

[0017] Figure 7 is a block diagram illustrating an example video decoder hardware engine and an example video decoder instance.

[0018] Figure 8 is a conceptual diagram illustrating a multiple video decoder (MVD) with aggregated output buffers according to techniques of this disclosure.

[0019] Fig. 9 is a conceptual diagram illustrating an example video-based point cloud (V-PCC) decoder according to the techniques of this disclosure.

[0020] Fig.10 is a flow chart illustrating an example technique for grouping decoder instances according to the present disclosure.

[0021] Specific implementation

[0022] In some media applications, a media scene is composed of multiple videos. Such videos can be post-processed and then jointly visualized. For example, they can be stitched, overlaid, or scene-combined to produce an immersive experience. The present disclosure describes techniques that can be applied to a bitstream that includes immersive media data (e.g., audio and video data).

[0023] In some examples, multiple video decoders (MVDs) provide access to decoding hardware through APIs such as OpenMAX IL or Android's MediaCodec API. These APIs enable MVDs to create and run multiple decoder instances, even if there is only one hardware decoder.

[0024] However, these APIs may lack some capabilities for handling immersive media. For example, the API may lack the ability to discover the aggregate handling capabilities of the MVD. For example, logical grouping of multiple samples from different streams for simultaneous decoding may not be possible. In some examples, aggregation can be inferred from the nTimestamp parameter in the buffer header, but when decoding these related samples, the MVD component has no information to keep delay deviation to a minimum. In addition, fine-grained control over the scheduling of different decoder instances may not be possible.

[0025] According to the technology of the present disclosure, the abstract extension of the decoder API can provide better support for immersive media and solve the above problems. For example, these abstract extensions can be mapped to OpenMAX IL and MediaCodec.

[0026] The technology disclosed herein can be applied to video files that conform to video data encapsulated according to any of the ISO base media file format, the Scalable Video Coding (SVC) file format, the Advanced Video Coding (AVC) file format, the Third Generation Partnership Project (3GPP) file format and / or the Multiview Video Coding (MVC) file format or other similar video file formats.

[0027] In HTTP streaming, frequently used operations include HEAD, GET, and partial GET. The HEAD operation retrieves the header of a file associated with a given uniform resource locator (URL) or uniform resource name (URN) without retrieving 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. Therefore, movie fragments can be provided for HTTP streaming because the partial GET operation can obtain one or more separate movie fragments. In a movie fragment, there can be track fragments of several different tracks. In HTTP streaming, a media presentation can be a structured collection of data accessible to a client. The client can request and download media data information to present streaming services to the user.

[0028] In the example of using HTTP streaming to stream 3GPP data, there may be multiple representations of video and / or audio data of multimedia content. As described below, different representations may correspond to different coding characteristics (e.g., different profiles or levels of video coding standards), different coding standards or extensions of coding standards (such as multi-view and / or scalable extensions), or different bit rates. A list of such representations can be defined in a Media Presentation Description (MPD) data structure. A media presentation can correspond to a structured data set accessible to an HTTP streaming client device. An HTTP streaming client device can request and download media data information to present a streaming service to a user of a client device. A media presentation can be described in an MPD data structure, which can include updates to the MPD.

[0029] A media presentation may include a sequence of one or more time periods. Each time period may extend to the beginning of the next time period, or in the case of the last time period, to the end of the media presentation. Each time period may include one or more representations of the same media content. A representation may be one of a plurality of optional coded versions of audio, video, timed text or other such data. These representations may differ due to the type of coding, for example, the bit rate, resolution and / or codec of the video data and the bit rate, language and / or codec of the audio data. The term "representation" may be used to refer to a portion of coded audio or video data corresponding to a particular time period of the multimedia content and coded in a particular manner.

[0030] Representations for a particular time 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 generally considered to be interchangeable with each other because client devices can dynamically and seamlessly switch between these representations, for example, to perform bandwidth adaptation. For example, each representation of video data for a particular time period may be assigned to the same adaptation set so that any representation may be selected for decoding to present media data, such as video data or audio data, of the multimedia content for the corresponding time period. In some examples, the media content within a time period may be represented by a combination of one representation from group 0 (if any) or at most one representation from each non-zero group. The timing data for each representation of a time period may be represented relative to the start time of the time period.

[0031] A 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. Typically, the initialization segment does not contain media data. A segment 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 a byte range in the form of a range attribute, which may correspond to segmented data within a file accessible by a URL, URN, or URI.

[0032] Different representations may be selected for substantially simultaneous retrieval of different types of media data. For example, a client device may select an audio representation, a video representation, and a timed text representation from which to retrieve segments.

[0033] In some examples, the client device can select a specific adaptation set to perform bandwidth adaptation. That is, the client device can select an adaptation set that includes video representations, an adaptation set that includes audio representations, and / or an adaptation set that includes timed text. Alternatively, the client device can select an adaptation set for certain types of media (e.g., video) and directly select representations for other types of media (e.g., audio and / or timed text).

[0034] Figure 1 is a block diagram illustrating an example system 10 that implements techniques for streaming media data over a network. In this example, system 10 includes content preparation device 20, server device 60, and client device 40. Client device 40 and server device 60 are communicatively coupled via network 74, which may include the Internet. In some examples, content preparation device 20 and server device 60 may also be coupled via network 74 or another network, or may be directly communicatively coupled. In some examples, content preparation device 20 and server device 60 may include the same device.

[0035] exist Figure 1In the example of , content preparation device 20 includes an audio source 22 and a video source 24. Audio source 22 may include, for example, a microphone that produces an electrical signal representing captured audio data to be encoded by audio encoder 26. Alternatively, audio source 22 may include a storage medium storing previously recorded audio data, an audio data generator such as a computerized synthesizer, or any other source of audio data. Video source 24 may include a video camera that produces video data to be encoded by video encoder 28, a storage medium encoded with previously recorded video data, a video data generation unit such as a computer graphics source, or any other source of video data. In all examples, content preparation device 20 need not be communicatively coupled to server device 60, but may store multimedia content to a separate medium that is read by server device 60.

[0036] The original audio and video data may include analog or digital data. The analog data may be digitized before being encoded by the audio encoder 26 and / or the video encoder 28. The audio source 22 may obtain audio data from the speaking participant as the speaking participant speaks, and the video source 24 may simultaneously obtain the video data of the speaking participant. In other examples, the audio source 22 may include a computer-readable storage medium containing stored audio data, and the video source 24 may include a computer-readable storage medium containing stored video data. In this manner, the technology described in the present disclosure may be applied to live, streaming, real-time audio and video data, or to archived, pre-recorded audio and video data.

[0037] An audio frame corresponding to a video frame is typically an audio frame containing audio data that is captured (or generated) by audio source 22 simultaneously with video data contained within the video frame and captured (or generated) by video source 24. For example, when a speaking participant typically generates audio data by speaking, audio source 22 captures the audio data, and video source 24 simultaneously (that is, when audio source 22 captures the audio data) captures video data of the speaking participant. Thus, an audio frame may correspond in time to one or more specific video frames. Thus, an audio frame corresponding to a video frame typically corresponds to a situation where audio data and video data are captured simultaneously, and for this situation, the audio frame and video frame include the audio data and video data captured simultaneously, respectively.

[0038] In some examples, audio encoder 26 may encode a timestamp in each encoded audio frame that indicates the time at which the audio data of the encoded audio frame was recorded, and similarly, video encoder 28 may encode a timestamp in each encoded video frame that indicates the time at which the video data of the encoded video frame was recorded. In such an example, an audio frame corresponding to a video frame may include an audio frame including a timestamp and a video frame including the same timestamp. Content preparation device 20 may include an internal clock, and audio encoder 26 and / or video encoder 28 may generate timestamps based on the internal clock, or audio source 22 and video source 24 may use the internal clock to associate audio and video data with timestamps, respectively.

[0039] In some examples, audio source 22 may send data corresponding to the time at which the audio data was recorded to audio encoder 26, and video source 24 may send data corresponding to the time at which the video data was recorded to video encoder 28. In some examples, audio encoder 26 may encode a sequence identifier in the encoded audio data to indicate a relative temporal ordering of the encoded audio data, but not necessarily an absolute time at which the audio data was recorded, and similarly, video encoder 28 may also use the sequence identifier to indicate a relative temporal ordering of the encoded video data. Similarly, in some examples, the sequence identifier may be mapped or otherwise associated with a timestamp.

[0040] The audio encoder 26 typically produces an encoded audio data stream, while the video encoder 28 produces an encoded video data stream. Each individual data stream (whether audio or video) can be referred to as an elementary stream. An elementary stream is a single digitally encoded (possibly compressed) component of a representation. For example, the encoded video or audio portion of a representation can be an elementary stream. Before being encapsulated into a video file, the elementary stream can be converted into a packetized elementary stream (PES). In the same representation, a stream ID can be used to distinguish a PES packet belonging to one elementary stream from another. The basic data unit of an elementary stream is a packetized elementary stream (PES) packet. Therefore, encoded video data typically corresponds to an elementary video stream. Similarly, audio data corresponds to one or more corresponding elementary streams.

[0041] Many video coding standards, such as ITU-T H.264 / AVC and the upcoming High Efficiency Video Coding (HEVC) standard, define the syntax, semantics, and decoding process for error-free bitstreams, any of which conforms to a specific profile or level. Video coding standards do not usually specify encoders, but it is the encoder's task to ensure that the generated bitstream conforms to the decoder's standards. In the context of video coding standards, a "profile" corresponds to a subset of algorithms, features, or tools and constraints that apply to them. For example, as defined by the H.264 standard, a "profile" is a subset of the entire bitstream syntax specified by the H.264 standard. A "level" corresponds to a limit on decoder resource consumption, such as decoder memory and computation, which is related to image resolution, bit rate, and block processing rate. A profile can be signaled with a profile_idc (profile indicator) value, while a level can be signaled with a level_idc (level indicator) value.

[0042] For example, the H.264 standard recognizes that, within the boundaries imposed by the syntax of a given profile, it may still be necessary for the performance of encoders and decoders to vary widely, depending on the values ​​taken by syntax elements in the bitstream, such as the specified size of the decoded images. The H.264 standard further recognizes that in many applications, it is neither practical nor economical to implement a decoder that can handle all hypothetical uses of the syntax within a particular profile. Therefore, the H.264 standard defines a "level" as a set of specific constraints imposed on the values ​​of syntax elements in the bitstream. These constraints may be simple restrictions on values. Alternatively, these constraints may take the form of constraints on arithmetic combinations of values ​​(e.g., image width multiplied by image height multiplied by the number of images decoded per second). The H.264 standard further specifies that individual implementations may support different levels for each supported profile.

[0043] A decoder that complies with a profile generally supports all 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 other profiles of H.264 / AVC. A decoder that complies with the level should be able to decode any bitstream that does not require resources beyond the limits defined in the level. The definition of profiles and levels may help improve interpretability. For example, during video transmission, a pair of profile and level definitions may be negotiated and agreed upon for the entire transmission session. More specifically, in H.264 / AVC, the level may define restrictions on the number of macroblocks that need to be processed, the size of the decoded picture buffer (DPB), the size of the coded picture buffer (CPB), the range of vertical motion vectors, the maximum number of motion vectors per two consecutive MBs, and whether the B block can have a sub-macroblock partition of less than 8×8 pixels. In this way, the decoder can determine whether the decoder can correctly decode the bitstream.

[0044] exist Figure 1 In the example of , encapsulation unit 30 of content preparation device 20 receives an elementary stream including encoded video data from video encoder 28 and receives an elementary stream including encoded audio data from audio encoder 26. In some examples, video encoder 28 and audio encoder 26 may each include a packetizer for forming packetized elementary system (PES) packets from the encoded data. In other examples, video encoder 28 and audio encoder 26 may each interface with a respective packetizer to form PES packets from the encoded data. In yet another example, encapsulation unit 30 may include a packetizer for forming PES packets from the encoded audio and video data.

[0045] The video encoder 28 can encode the video data of the multimedia content in various ways to produce different representations of the multimedia content with various bit rates and various characteristics, such as pixel resolution, frame rate, compliance with various coding standards, compliance with various profiles and / or profile levels of various coding standards, representations with one or more views (e.g., for two-dimensional or three-dimensional playback), or other such characteristics. As used in the present disclosure, a representation can include one of audio data, video data, text data (e.g., for closed captions), or other such data. The representation can include elementary streams, such as audio elementary streams or video elementary streams. Each PES packet may include a stream_id that identifies the elementary stream to which the PES packet belongs. Encapsulation unit 30 is responsible for assembling elementary streams into video files (e.g., segments) of various representations.

[0046] The encapsulation unit 30 receives PES packets representing elementary streams from the audio encoder 26 and the video encoder 28, and forms corresponding network abstraction layer (NAL) units from the PES packets. The encoded video segments can be organized into NAL units, which provide a "network-friendly" video representation, addressing applications such as video telephony, storage, broadcasting, or streaming. NAL units can be classified into video coding layer (VCL) NAL units and non-VCL NAL units. The VCL unit may contain a core compression engine and may include block, macroblock, and / or slice level data. Other NAL units may be non-VCL NAL units. In some examples, a coded image in a time instance (usually presented as a primary coded image) may be contained in an access unit comprising one or more NAL units.

[0047] Non-VCL NAL units may include parameter set NAL units and Supplemental Enhancement Information (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 (e.g., PPS and SPS), infrequently changing information does not need to be repeated for each sequence or picture; therefore, coding efficiency may be improved. In addition, the use of parameter sets enables out-of-band transmission of important header information, avoiding the need for redundant transmission for error recovery. In an example of out-of-band transmission, a parameter set NAL unit may be transmitted on a different channel than other NAL units, such as a SEI NAL unit.

[0048] SEI may contain information that is not required for decoding the encoded image samples from the VCL NAL unit, but may help with processing related to decoding, display, error recovery, and other purposes. SEI messages may be included in non-VCL NAL units. SEI messages are a standard part of some standard specifications and are therefore not always mandatory for standard-compliant decoder implementations. SEI messages may be sequence-level SEI messages or image-level SEI messages. Some sequence-level information may be included in SEI messages, such as scalability information SEI messages in the SVC example 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. In addition, the encapsulation unit 30 may form a manifest file, such as a media presentation descriptor (MPD) that describes representation characteristics. The encapsulation unit 30 may format the MPD according to an extensible markup language (XML).

[0049] Encapsulation unit 30 may provide data of one or more representations of multimedia content and a manifest file (e.g., MPD) to output interface 32. Output interface 32 may include a network interface or an interface for writing to a storage medium, such as a universal serial bus (USB) interface, a compact disc (CD) or digital video disc (DVD) writer or burner, an interface to magnetic or flash media, or other interface for storing or transmitting media data. Encapsulation unit 30 may provide data of each representation of multimedia content to output interface 32, which may send the data to server device 60 via a network transmission or storage medium. Figure 1 In the example of , the server device 60 includes a storage medium 62 storing various multimedia contents 64, each of which includes a respective manifest file 66 and one or more representations 68A-68N (representations 68). In some examples, the output interface 32 may also send data directly to the network 74.

[0050] In some examples, representations 68 may be divided into adaptation sets. That is, various subsets of representations 68 may include a corresponding set of common characteristics, such as codecs, profiles and levels, resolutions, number of views, file formats for segmentation, text type information that may identify the language or other characteristics of text to be displayed with the representations and / or audio data decoded and rendered, for example, by speakers, camera angle information that may describe the camera angle or real-world camera perspective of the scene represented in the adaptation set, rating information that describes the suitability of the content for a particular audience, and the like.

[0051] The manifest file 66 may include data indicating a subset of the representations 68 corresponding to a particular adaptation set, and the common characteristics of the adaptation set. The manifest file 66 may also include data indicating individual characteristics, such as the bit rates of the individual representations of the adaptation set. In this way, the adaptation set may provide simplified network bandwidth adaptation. The representations in the adaptation set may be indicated using sub-elements of the adaptation set element of the manifest file 66.

[0052] The server device 60 includes a request processing unit 70 and a network interface 72. In some examples, the server device 60 may include multiple network interfaces. In addition, any or all features of the server device 60 may be implemented on other devices of the content delivery network, such as routers, bridges, proxy devices, switches, or other devices. In some examples, an intermediate device of the content delivery network may cache data of the multimedia content 64 and include components that are substantially consistent with the components of the server device 60. Typically, the network interface 72 is configured to send and receive data over the network 74.

[0053] The request processing unit 70 is configured to receive a network request for data of the storage medium 62 from a client device such as the client device 40. For example, the request processing unit 70 may implement the hypertext transfer protocol (HTTP) version 1.1, as described in RFC 2616, "Hypertext Transfer Protocol-HTTP / 1.1", IETF, Network Working Group, R. Fielding et al., June 1999. That is, the request processing unit 70 may be configured to receive HTTP GET or partial GET requests and provide data of the multimedia content 64 in response to the requests. These requests may, for example, specify a segment of one of the representations 68 using a segmented URL. In some examples, the request may also specify one or more byte ranges of the segment, thus including a partial GET request. The request processing unit 70 may also be configured to service HTTP HEAD (HTTP header) requests to provide header data of a segment of one of the representations 68. In any case, the request processing unit 70 may be configured to process the request to provide the requested data to a requesting device such as the client device 40.

[0054] Additionally or alternatively, the request processing unit 70 can be configured to deliver media data via a broadcast or multicast protocol, such as an evolved Multimedia Broadcast and Multicast Service (eMBMS). The content preparation device 20 can create dynamic adaptive HTTP streaming (Dynamic Adaptive Streaming over HTTP, DASH) segments and / or sub-segments in substantially the same manner as described, but the server device 60 can deliver these segments or sub-segments using eMBMS or another broadcast or multicast network transmission protocol. For example, the request processing unit 70 can be configured to receive a multicast group join request from the client device 40. That is, the server device 60 can announce the Internet Protocol (IP) address associated with the multicast group to client devices (including the client device 40) associated with specific media content (e.g., a broadcast of a live event). The client device 40 can then submit a request to join the multicast group. The request may be propagated throughout network 74 , eg, the routers comprising network 74 , such that the routers direct traffic destined for the IP address associated with the multicast group to subscribing client devices, such as client device 40 .

[0055] like Figure 1 As shown in the example of , multimedia content 64 includes a manifest file 66, which may correspond to a media presentation description (MPD). Manifest file 66 may contain descriptions of different alternative representations 68 (e.g., video services with different qualities), and the descriptions may include, for example, codec information, profile values, level values, bit rates, and other descriptive characteristics of representation 68. Client device 40 may retrieve the MPD for the media presentation to determine how to access segments of representation 68.

[0056] Specifically, the retrieval unit 52 may retrieve configuration data (not shown) of the client device 40 to determine the decoding capabilities of the video decoder 48 and the rendering capabilities of the video output 44. The configuration data may also include any or all of a language preference selected by a user of the client device 40, one or more camera viewing angles corresponding to a depth preference set by a user of the client device 40, and / or a rating preference selected by a user of the client device 40. The retrieval unit 52 may include, for example, a web browser or media client configured to submit HTTP GET and partial GET requests. The retrieval unit 52 may correspond to software instructions executed by one or more processors or processing units (not shown) of the client device 40. In some instances, all or part of the functionality described with respect to the retrieval unit 52 may be implemented in hardware or a combination of hardware, software, and / or firmware, where the necessary hardware may be provided to execute the instructions of the software or firmware.

[0057] Despite Figure 1 Only a single video decoder 48 is shown in the example of FIG. 1 , but as discussed in more detail below (e.g., see FIG. 1 ), Figure 8 ), the client device 40 may be configured to include multiple video decoders. In addition, the decapsulation unit 50 may be configured to include a demultiplexer that demultiplexes multiple encoded video bitstreams (e.g., for different tiles of cube-mapped video data) and directs the encoded video bitstreams to different video decoders. The decapsulation unit 50 may include an interface, such as an application programming interface (API) that directs the video data of the various video bitstreams to the corresponding video decoders. In addition, the client device 40 may include a synchronization unit that synchronizes the decoded video data (e.g., images) from the multiple video decoders in time, as well as the audio data decoded by the audio decoder 46.

[0058] The retrieval unit 52 may compare the decoding and rendering capabilities of the client device 40 with the characteristics of the representation 68 indicated by the information of the manifest file 66. The retrieval unit 52 may initially retrieve at least a portion of the manifest file 66 to determine the characteristics of the representation 68. For example, the retrieval unit 52 may request a portion of the manifest file 66 that describes the characteristics of one or more adaptation sets. The retrieval unit 52 may select a subset of the representation 68 (e.g., an adaptation set) that has characteristics that can be satisfied by the encoding and rendering capabilities of the client device 40. The retrieval unit 52 may then determine the bit rate of the representations in the adaptation set, determine the amount of network bandwidth that is currently available, and retrieve a segment from one of the representations that has a bit rate that can be satisfied by the network bandwidth.

[0059] In general, a higher bit rate representation can produce a higher quality video playback, while a lower bit rate representation can provide adequate quality video playback when the available network bandwidth decreases. Thus, when the available network bandwidth is relatively high, the retrieval unit 52 can retrieve data from a relatively high bit rate representation, and when the available network bandwidth is low, the retrieval unit 52 can retrieve data from a relatively low bit rate representation. In this manner, the client device 40 can stream multimedia data over the network 74 and also adapt to the changing network bandwidth availability of the network 74.

[0060] Additionally or alternatively, the retrieval unit 52 may be configured to receive data according to a broadcast or multicast network protocol, such as eMBMS or IP multicast. In such an example, the retrieval unit 52 may submit a request to join a multicast network group associated with a particular media content. After joining the multicast group, the retrieval unit 52 may receive data for the multicast group without issuing further requests to the server device 60 or the content preparation device 20. When the data of the multicast group is no longer needed, the retrieval unit 52 may submit a request to leave the multicast group, such as to stop playback or change the channel to a different multicast group.

[0061] The network interface 54 may receive and provide data of the segments of the selected representation to the retrieval unit 52, which in turn may provide the segments to the decapsulation unit 50. The decapsulation unit 50 may decapsulate the elements of the video file into constituent PES streams, depacketize the PES streams to retrieve the encoded data, and send the encoded data to the audio decoder 46 or the video decoder 48, depending on whether the encoded data is part of an audio or video stream (e.g., as indicated by a PES packet header of the stream). The audio decoder 46 decodes the encoded audio data and sends the decoded audio data to the audio output 42, while the video decoder 48 decodes the encoded video data and sends the decoded video data to the video output 44, which may include multiple views of the stream.

[0062] Each of the video encoder 28, the video decoder 48, the audio encoder 26, the audio decoder 46, the encapsulation unit 30, the retrieval unit 52, and the decapsulation unit 50 may be implemented as any of a variety of suitable processing circuits, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic circuits, software, hardware, firmware, or any combination thereof, as applicable. Each of the video encoder 28 and the video decoder 48 may be included in one or more encoders or decoders, one of which may be integrated as part of a combined video encoder / decoder (CODEC). Similarly, each of the audio encoder 26 and the audio decoder 46 may be included in one or more encoders or decoders, one of which may be integrated as part of a combined codec. Equipment including the video encoder 28, the video decoder 48, the audio encoder 26, the audio decoder 46, the encapsulation unit 30, the retrieval unit 52, and / or the decapsulation unit 50 may include an integrated circuit, a microprocessor, and / or a wireless communication device, such as a cellular phone.

[0063] Client device 40, server device 60, and / or content preparation device 20 may be configured to operate according to the techniques of this disclosure. For purposes of example, this disclosure describes these techniques with respect to client device 40 and server device 60. However, it should be understood that content preparation device 20 may be configured to perform these techniques instead of (or in addition to) server device 60.

[0064] Encapsulation unit 30 may form a NAL unit including a header identifying the program to which the NAL unit belongs, and a payload, such as audio data, video data, or data describing a transport or program stream corresponding to a NAL unit. For example, in H.264 / AVC, a NAL unit includes a 1-byte header and a payload of variable size. A NAL unit including video data in its payload may include video data at various levels of granularity. For example, a NAL unit may contain a video data block, a plurality of blocks, a video data slice, or an entire video data image. Encapsulation unit 30 may receive encoded video data in the form of PES packets of elementary streams from video encoder 28. Encapsulation unit 30 may associate each elementary stream with a corresponding program.

[0065] The encapsulation unit 30 may also assemble an access unit from multiple NAL units. In general, an access unit may include one or more NAL units representing a frame of video data and audio data corresponding to the frame (when such audio data is available). An access unit typically includes all NAL units for an output time instance, such as all audio and video data for a 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, specific frames of all views of the same access unit (same time instance) may be simultaneously displayed. In one example, in a time instance, an access unit may include a coded image, which may be presented as a primary coded image.

[0066] Thus, an access unit may contain all audio and video frames of a common time instance, for example, all views corresponding to time X. The present disclosure also refers to the coded images of a particular view as "view components". That is, a view component may include coded images (or frames) of a particular view at a particular time. Thus, an access unit may be defined as including all view components of a common time instance. The decoding order of access units is not necessarily the same as the output or display order.

[0067] The media presentation may include a media presentation description (MPD), which may contain descriptions of different alternative representations (e.g., video services with different qualities), and the description may include, for example, codec information, profile values, and level values. The MPD is an example of a manifest file, such as manifest file 66. Client device 40 may retrieve the MPD of the media presentation to determine how to access the movie fragments of the various presentations. The movie fragments may be located in a movie fragment box (MOOF box) of a video file.

[0068] Manifest file 66 (which may include, for example, an MPD) may announce the availability of segments of representations 68. That is, the MPD may include information indicating a wall clock time at which a first segment of one of representations 68 becomes available, and information indicating the duration of the segments within representations 68. In this manner, retrieval unit 52 of client device 40 may determine when each segment is available based on the start time and the duration of the segments preceding the particular segment.

[0069] After the encapsulation unit 30 assembles the NAL units and / or access units into a video file based on the received data, the encapsulation unit 30 passes the video file to the output interface 32 for output. In some examples, the encapsulation unit 30 may store the video file locally or send the video file to a remote server via the output interface 32, rather than directly sending the video file to the client device 40. The output interface 32 may include, for example, a transmitter, a transceiver, a device for writing data to a computer-readable medium, such as an optical drive, a magnetic medium drive (e.g., a floppy disk drive), a universal serial bus (USB) port, a network interface, or other output interface. The output interface 32 outputs the video file to a computer-readable medium, such as a transmission signal, a magnetic medium, an optical medium, a memory, a flash drive, or other computer-readable medium.

[0070] The network interface 54 may receive the NAL units or access units over the network 74 and provide the NAL units or access units to the decapsulation unit 50 via the retrieval unit 52. The decapsulation unit 50 may decapsulate the elements of the video file into constituent PES streams, depacketize the PES streams to retrieve the encoded data, and send the encoded data to the audio decoder 46 or the video decoder 48, depending on whether the encoded data is part of an audio or video stream (e.g., as indicated by a PES packet header of the stream). The audio decoder 46 decodes the encoded audio data and sends the decoded audio data to the audio output 42, while the video decoder 48 decodes the encoded video data and sends the decoded video data to the video output 44, which may include multiple views of the stream.

[0071] Figure 2 is a more detailed description Figure 1 FIG. 5 is a block diagram of a set of example components of a retrieval unit 52 of FIG. 5 . In this example, the retrieval unit 52 includes an eMBMS middleware unit 100 , a DASH client 110 , and a media application 112 .

[0072] In this example, the eMBMS middleware unit 100 also includes an eMBMS receiving unit 106, a cache 104, and a proxy server unit 102. In this instance, the eMBMS receiving unit 106 is configured to receive data via eMBMS, for example, according to File Delivery over Unidirectional Transport (FLUTE) as described in Network Working Group RFC 6726, "FLUTE - File Delivery over Unidirectional Transport," by T. Paila et al., November 2012, available at tools.ietf.org / html / rfc6726. That is, the eMBMS receiving unit 106 may receive files via broadcast from, for example, a server device 60, which may act as a broadcast / multicast service center (BM-SC).

[0073] When the eMBMS middleware unit 100 receives file data, the eMBMS middleware unit may store the received data in the cache 104. The cache 104 may include a computer-readable storage medium, such as a flash memory, a hard disk, a RAM, or any other suitable storage medium.

[0074] The proxy server unit 102 may act as a server for the DASH client 110. For example, the proxy server unit 102 may provide an MPD file or other manifest file to the DASH client 110. The proxy server unit 102 may announce the available times of the segments in the MPD file, as well as hyperlinks from which the segments may be retrieved. These hyperlinks may include a local host address prefix corresponding to the client device 40 (e.g., 127.0.0.1 for IPv4). In this manner, the DASH client 110 may request the segments from the proxy server unit 102 using an HTTP GET or partial GET request. For example, for a segment available from the link http: / / 127.0.0.1 / rep1 / seg3, the DASH client 110 may construct an HTTP GET request including a request for http: / / 127.0.0.1 / rep1 / seg3, and submit the request to the proxy server unit 102. The proxy server unit 102 may retrieve the requested data from the cache 104 and provide the data to the DASH client 110 in response to such a request.

[0075] Figure 3 1 is a conceptual diagram illustrating elements of example multimedia content 120. Multimedia content 120 may correspond to multimedia content 64 ( Figure 1 ), or another multimedia content stored in the storage medium 62. Figure 3 In the example of , multimedia content 120 includes a media presentation description (MPD) 122 and multiple representations 124A-124N (representations 124). Representation 124A includes optional header data 126 and segments 128A-128N (segments 128), while representation 124N includes optional header data 130 and segments 132A-132N (segments 132). For convenience, the letter N is used to designate the last movie fragment in each representation 124. In some examples, there may be different numbers of movie fragments between representations 124.

[0076] MPD 122 may include a data structure separate from representation 124. MPD 122 may correspond to Figure 1 Similarly, representation 124 may correspond to Figure 1 In general, MPD 122 may include data generally describing characteristics of representation 124, such as encoding and presentation characteristics, adaptation sets, a profile to which MPD 122 corresponds, text type information, camera angle information, rating information, trick mode information (e.g., information indicating that a representation includes a temporal subsequence), and / or information for retrieving remote time segments (e.g., for inserting targeted announcements into media content during playback).

[0077] When header data 126 is present, header data 126 may describe characteristics of segments 128, such as the temporal location of random access points (RAPs, also known as stream access points (SAPs)), which of segments 128 include random access points, byte offsets within segments 128 to random access points, uniform resource locators (URLs) for segments 128, or other aspects of segments 128. When header data 130 is present, header data 130 may describe similar characteristics of segments 132. Additionally or alternatively, these characteristics may be included entirely in MPD 122.

[0078] Segments 128, 132 include one or more coded video samples, each of which may include a frame or slice of video data. Each coded video sample of segment 128 may have similar characteristics, such as height, width, and bandwidth requirements. Such characteristics may be described by data from MPD 122, although such data is not described in the MPD 122. Figure 3 The MPD 122 may include the features described by the 3GPP specification and add any or all of the signaling information described in this disclosure.

[0079] Each segment 128, 132 can be associated with a unique uniform resource locator (URL). Therefore, each segment 128, 132 can be independently retrieved using a streaming network protocol such as DASH. In this way, a destination device such as client device 40 can use an HTTP GET request to retrieve a segment 128 or 132. In some examples, client device 40 can use an HTTP partial GET request to retrieve a specific byte range of a segment 128 or 132.

[0080] MPD 122 may include data indicating the complexity of the media file, such as a maximum number of video blocks to be processed per second, a maximum number of pixels to be processed per second, a maximum number of decoder instances, and / or a maximum number of concurrent decoder instances. In some examples, the complexity may be represented by a video profile, a tier, and / or a level value. In some examples, the profile, tier, and / or level value may be signaled (in addition or alternatively) in a parameter set, such as a video parameter set (VPS), a sequence parameter set (SPS), or a picture parameter set (PPS). That is, Figure 1 The content preparation device 20 may construct the MPD 122 (or Figure 1 A manifest file 66) is used to indicate the value of the profile, level and / or grade information of the corresponding bitstream.

[0081] Figure 4 is a block diagram illustrating elements of an example video file 150, which may correspond to segments of a representation, such as Figure 3 Each segment 128, 132 may include a substantially Figure 4 The data is arranged as shown in the example of the video file 150. It can be said that the video file 150 encapsulates the segments. As described above, the video file according to the ISO base media file format and its extensions stores data in a series of objects called "boxes". Figure 4 In the example of FIG. 1 , a video file 150 includes a file type (FTYP) box 152, a movie (MOOV) box 154, a segment index (sidx) box 162, a movie fragment (MOOF) box 164, and a movie fragment random access (MFRA) box 166. Figure 4 An example of a video file is shown, but it should be understood that other media files may include other types of media data (e.g., audio data, timed text data, etc.) structured similarly to the data of video file 150 in accordance with the ISO base media file format and its extensions.

[0082] The file type box 152 generally describes the file type of the video file 150. The file type box 152 may include data identifying specifications describing the best use of the video file 150. Optionally, the file type box 152 may be placed before the MOOV box 154, the movie fragment box 164, and / or the MFRA box 166.

[0083] In some examples, a segment such as video file 150 may include an MPD update box (not shown) before file type box 152. The MPD update box may include information indicating that the MPD corresponding to the representation including video file 150 is to be updated, as well as information for updating the MPD. For example, the MPD update box may provide a URI or URL of a resource for updating the MPD. As another example, the MPD update box may include data for updating the MPD. In some examples, the MPD update box may be immediately followed by a segment type (TYP) box (not shown) for video file 150, where the STYP box may define the segment type of video file 150.

[0084] exist Figure 4 In the example of , the MOOV box 154 includes a movie header (MVHD) box 156, a track (TRAK) box 158, and one or more movie extend (MVEX) boxes 160. In general, the MVHD box 156 can describe general characteristics of the video file 150. For example, the MVHD box 156 can include data describing the time when the video file 150 was originally created, the time when the video file 150 was last modified, the time scale of the video file 150, the playback duration of the video file 150, or other data generally describing the video file 150.

[0085] The TRAK box 158 may include data for a track of the video file 150. The TRAK box 158 may include a track header (TKHD) box that describes characteristics of the track corresponding to the TRAK box 158. In some examples, the TRAK box 158 may include encoded video images, while in other examples, the encoded video images of the track may be included in a movie fragment 164, which may be referenced by the data of the TRAK box 158 and / or the sidx box 162.

[0086] In some examples, the video file 150 may include more than one track. Thus, the MOOV box 154 may include a number of TRAK boxes equal to the number of tracks in the video file 150. The TRAK box 158 may describe the characteristics of the corresponding track of the video file 150. For example, the TRAK box 158 may describe the time and / or space information of the corresponding track. Figure 3 ) When a parameter set track is included in a video file such as video file 150, a TRAK box similar to TRAK box 158 of MOOV box 154 may describe characteristics of the parameter set track. Encapsulation unit 30 may signal the presence of a sequence level SEI message in the parameter set track within a TRAK box describing the parameter set track.

[0087] The MVEX box 160 may describe characteristics of the corresponding movie fragment 164, for example, signaling that the video file 150 includes the movie fragment 164 in addition to the video data (if any) included in the MOOV box 154. In the case of streaming video data, the encoded video images may be included in the movie fragment 164 instead of the MOOV box 154. Therefore, all encoded video samples may be included in the movie fragment 164 instead of the MOOV box 154.

[0088] The MOOV box 154 may include a number of MVEX boxes 160 equal to the number of movie fragments 164 in the video file 150. Each MVEX box 160 may describe characteristics of a corresponding one of the movie fragments 164. For example, each MVEX box may include a movie extends header (MEHD) box that describes the temporal duration of the corresponding one of the movie fragments 164.

[0089] As described above, encapsulation unit 30 may store sequence data sets in video samples that do not include actual encoded video data. Video samples may generally correspond to access units, which are representations of encoded images at a particular time instance. In the context of AVC, an encoded image includes one or more VCL NAL units that contain information for all pixels used to construct access units and other associated non-VCL NAL units, such as SEI messages. Thus, encapsulation unit 30 may include a sequence data set that may include a sequence level SEI message in one movie fragment 164. Encapsulation unit 30 may further signal the presence of a sequence data set and / or a sequence level SEI message that is present in one of the movie fragments 164 within one of the MVEX boxes 160 corresponding to one of the movie fragments 164.

[0090] The SIDX box 162 is an optional element of the video file 150. That is, a video file conforming to the 3GPP file format or other such file formats does not necessarily include the SIDX box 162. According to an example of the 3GPP file format, the SIDX box may be used to identify a sub-segment of a segment (e.g., a segment contained within the video file 150). The 3GPP file format defines a sub-segment as "a self-contained collection of one or more consecutive movie fragment boxes, which have corresponding media data boxes, and the media data boxes containing data referenced by the movie fragment box must follow the movie fragment box and precede the next movie fragment box containing information about the same track." The 3GPP file format also indicates that the SIDX box "contains a series of references to sub-segments of the (sub)segments recorded by the box. The referenced sub-segments are consecutive in presentation time. Similarly, the bytes referenced by the segment index box are always consecutive within the segment. The size of the reference gives a count of the number of bytes in the referenced material."

[0091] The SIDX box 162 generally provides information representing one or more sub-segments of a segment included in the video file 150. For example, such information may include the playback time at which the sub-segment begins and / or ends, the byte offset of the sub-segment, whether the sub-segment includes (e.g., starts at) a stream access point (SAP), the type of SAP (e.g., whether the SAP is an instantaneous decoder refresh (IDR) picture, a clean random access (CRA) picture, a broken link access (BLA) picture, etc.), the location of the SAP in the sub-segment (in terms of playback time and / or byte offset), etc.

[0092] The movie fragment 164 may include one or more encoded video images. In some examples, the movie fragment 164 may include one or more broken link access (GOP), each of which may include multiple encoded video images, such as frames or images. In addition, as described above, in some examples, the movie fragment 164 may include a sequence data set. Each movie fragment 164 may include a movie fragment header box (MFHD, Figure 4 MFHD box may describe characteristics of the corresponding movie fragment, such as a sequence number of the movie fragment. The movie fragments 164 may be included in the order of the sequence numbers in the video file 150.

[0093] MFRA box 166 may describe random access points within movie fragments 164 of video file 150. This may facilitate performing trick modes, such as performing seeks to specific time locations (i.e., playback times) within segments encapsulated by video file 150. In some examples, MFRA box 166 is generally optional and need not be included in the video file. Likewise, client devices such as client device 40 do not necessarily need to reference MFRA box 166 to properly decode and display video data of video file 150. MFRA box 166 may include a plurality of track fragment random access (TFRA) boxes (not shown), the number of which is equal to the number of tracks of video file 150, or in some examples, the number of media tracks (e.g., non-hint tracks) of video file 150.

[0094] In some examples, the movie fragment 164 may include one or more stream access points (SAPs), such as IDR pictures. Likewise, the MFRA box 166 may provide an indication of the location of the SAP within the video file 150. Thus, a temporal subsequence of the video file 150 may be formed by the SAPs of the video file 150. The temporal subsequence may also include other pictures, such as P frames and / or B frames that are subordinate to the SAPs. The frames and / or slices of the temporal subsequence may be arranged within the segment so that the frames / slices of the temporal subsequence that depend on other frames / slices of the subsequence may be correctly decoded. For example, in a hierarchical arrangement of data, data for predicting other data may also be included in the temporal subsequence.

[0095] Figure 5 300 is a conceptual diagram illustrating an example system 300 for decoding streaming media data. System 300 includes application 302, multi-decoder 310 (which may be an example of an MVD), graphics processing unit (GPU) 304, video output buffers 306A-306N (video output buffers 306), and viewport 308. In some examples, video output buffer 306 may be, for example, Figure 6 A single buffer is shown.

[0096] In general, the system 300 dynamically uses the user's gesture information and possible other interaction data to combine scenes for appropriate visualization. Specifically, the system 300 can use the gesture information to select the corresponding video stream to be retrieved from various video objects 320A-320N (video objects 320). Specifically, the system 300 retrieves synchronization units 322A-322N (synchronization units 322) from the corresponding video objects 320 based on, for example, the gesture information. For example, the system 300 can retrieve a relatively high-quality video stream of a portion of the viewport 308 that the user is directly watching, and a relatively low-quality video stream of a portion of the viewport 308 that the user cannot see or is outside the user's perspective. Each video object 320 can have different qualities (e.g., different resolutions) that can be used for retrieval. For example, a higher-resolution decoding can be applied in the field of view, while background information can be decoded with lower quality.

[0097] Generally speaking, each synchronization unit 322 includes a corresponding set of images to be presented or assembled at the same (or substantially the same) time. Therefore, by retrieving corresponding synchronization units 322, the system 300 can ensure that the retrieved synchronization units are decoded, presented and / or assembled in a synchronized manner.

[0098] The system 300 can be configured to dynamically use the available streaming / network access bitrate and the available decoding resources of the multi-decoder 310 to maximize the user experience. Thus, the system 300 can dynamically use the available network and hardware decoding resources to adapt to network conditions and user feedback. One issue is that the application 302 can provide a well-defined interface to use hardware decoding resources.

[0099] Available video objects 320 of different qualities or bit rates can be decoded by a single decoder instance. Depending on the situation, the video objects 320 can dynamically share resources. The multi-decoder 310 can output each of the video objects 320 to a separate corresponding one of the video output buffers 306 that can be referenced by the application 302, for example, to support GPU-based modifications for display. The system 300 can synchronize the output data accordingly, for example, by providing a synchronization unit 322 to the multi-decoder 310. The technology of the present disclosure can provide a well-defined multi-decoder interface / API (application programming interface) and the appropriate ability to reference the output of each decoder by a subsequent display unit (e.g., part of the GPU 304 or separate from the GPU 304). By doing so, available hardware resources can be used efficiently. The decoder interface can be codec-agnostic and even different codecs, such as AVC, HEVC and / or AV1, can be used within a decoding session.

[0100] In this way, Figure 5System 300 represents an example of a device for decoding media data, the device including a memory configured to store the media data, and one or more processors implemented in circuitry and communicatively coupled to the memory, the one or more processors configured to determine whether two or more decoder instances are intended to be synchronized, and based on the two or more decoder instances being intended to be synchronized, control the two or more decoder instances so that decoded data from each of the two or more decoder instances can be presented at the same presentation time.

[0101] Immersive media presentations typically require the display of a large number of 2D and 3D assets that are combined together to provide an immersive experience to the user. Many of these media assets may require hardware-accelerated decoding of at least some of their components to display.

[0102] As discussed in N18868, "Considerations for a working draft of a video decoding interface for immersive media", Geneva, CH, October 2019, MVD provides access to the decoding hardware through application programming interfaces (APIs) such as OpenMAX IL or Android's MediaCodec API. These APIs allow applications to create and run multiple decoder instances, even if there is only one hardware decoder.

[0103] However, these APIs may lack some capabilities for handling immersive media. For example, the API may lack the ability to discover the aggregation handling capabilities of the MVD. For example, logical grouping of multiple samples from different streams for simultaneous decoding is currently not possible. In some examples, aggregation can be inferred based on the nTimestamp parameter in the buffer header, but when decoding these related samples, the MVD component has no information to keep delay deviation to a minimum. In addition, fine-grained control over the scheduling of different decoder instances may not be possible.

[0104] According to the technology of the present disclosure, the abstract extension of the decoder API provides better support for immersive media and solves the above problems. For example, these abstract extensions can be mapped to OpenMAX IL and MediaCodec.

[0105] Now discuss the discovery of MVD capabilities. The load on media decoding hardware varies over time, depending on how many decoder instances are instantiated at the time and the characteristics of the content being decoded. Therefore, for applications such as immersive media presentation engines, it may be important to be able to discover the immediate capabilities and resource availability of MVDs such as multi-decoder 310.

[0106] An application (e.g., application 302) may use the following function to query (and determine) the instantaneous aggregate capabilities of the MVD of a particular codec component. For example, in the OpenMAX integration layer, a component represents a single functional block. A component may be a source, a sink, a codec, a filter, a separator, a mixer, or any other data operator. Depending on the implementation, a component may represent a hardware, software codec, other processor, or a combination thereof. This capability information may be used for access control to the MVD and / or for adjusting the decoding process based on resource availability.

[0107] A function could be:

[0108] object queryCurrentAggregateCapabilities(string componentName,intflags)

[0109] componentName provides the name of the media component of the MVD to which the query applies. The name "all" may be used to indicate that the query is not for a specific component, but for all components of the MVD.

[0110] The following capability flags can be queried individually or in a single function call:

[0111] CAP_INSTANCES: This flag indicates the maximum number of decoder instances that can be instantiated for the provided decoder component at this time.

[0112] CAP_BUFFER_MEMORY: This flag indicates the maximum available buffer size that can be allocated on the MVD at this time for buffer exchange with the MVD component. Note that this value is independent of any media component and applies globally to the MVD. This value can be expressed in bytes.

[0113] CAP_BITRATE: This flag queries the maximum encoding bit rate that the queried component can handle at the moment, in bits per second.

[0114] CAP_MAX_SAMPLES_SECOND: This flag queries the maximum number of samples per second that the queried component can process at this time.

[0115] CAP_MAX_PERFORMANCE_POINT: This flag is used to query the maximum performance point of a bitstream that can be decoded by the indicated component in a new instance of this decoder component. The performance point has the following parameters:

[0116] оPICTURE_RATE: The image rate at the maximum performance point, in images per second.

[0117] оHeight: Brightness sample height at the highest performance point

[0118] Width: Luminance sample width at maximum performance point

[0119] о Bit depth: The bit depth of the luminance samples at the maximum performance point

[0120] It should be noted that each parameter of the maximum performance point does not necessarily represent the maximum value in that dimension. The combination of all dimensions can constitute the maximum performance point.

[0121] Now let's discuss grouping on a decoder instance. The content of an immersive media asset may require decoding of multiple components, which may be used by a rendering engine (e.g., Figure 5 The GPU 304 of the decoder is used for reconstruction and rendering at the same time. The decoder instances can be grouped together to inform the MVD that the decoded samples will be provided at the MVD output at the same time, for example for later synchronization and joint rendering.

[0122] Figure 6 2 is a block diagram illustrating an example decoding engine and associated interfaces. A video decoding engine 200 (which may be an example of an MVD) may receive metadata streams (MD) 202A-202N and elementary streams (ES) 204A-204M at an input video decoding interface 206. An input formatting unit 208 may format the elementary streams 204A-204M and output the formatted elementary streams to video decoder instances 210A-210M. Video decoder instances 210A-210M may decode the formatted elementary streams. A time locking unit 212 may lock the elementary streams together based on, for example, a group_id, which may be included in the metadata streams 202A-202N. An output formatting unit 214 may format the decoded streams, and an output video decoding interface may output metadata streams (MD) 218A-218N and decoded sequences (DS) 220A-220M, for example, for visualization.

[0123] Figure 72 is a block diagram illustrating an example video decoder hardware engine and an example video decoder instance. The MVD 238 may include a video decoder hardware engine 240. The video decoder hardware engine 240 may create and control video decoder instances 244A-244N. The video decoder hardware engine 240 may include an engine control interface 242. The engine control interface 242 may be an interface used by the application 302 to control the video decoder hardware engine 240. Each video decoder instance 244A-244N may include an input video interface 246A-246N, respectively. The video decoder instances 244A-244N may receive independent video streams to be decoded through the input video interfaces 246A-246N, respectively. The video decoder instances 244A-244N may output decoded video through output video interfaces 248A-248N, respectively.

[0124] Figure 8 350 includes a decoder platform control 352, a clock component 354, a decoder instance 356, a decoder instance 358, a decoder instance 360, and an aggregate buffer 362. All decoder instances of the same group (e.g., all decoder instances 356, 358, and 360 of group #4) can be connected to the same clock component (e.g., clock component 354) for synchronization. All decoder instances of the same group can use the same timestamp offset and measurement unit, so that the same timestamp value (e.g., the same timestamp offset and measurement unit) indicates that the samples on the decoder instances of the same group have the same presentation time. The presentation time is the time at which the decoded stream can be visualized. For example, each decoder instance of the same group MVD 350 (e.g., decoder instances 356, 358, and 360) can be connected to the same clock (e.g., clock component 354) and use the same timestamp offset and unit. The output of each decoder instance of the same group can be aggregated in the aggregate buffer 362 and can be presented at the same presentation time.

[0125] When creating a new decoder instance, ( Figure 5The application 302 may assign a new decoder instance to a group of already existing instances by providing the group_id of the group. For example, the application 302 may create a new decoder instance of group 4 to join the decoder instances 356, 358, and 360, and may provide the new decoder instance with a group_id of 4. A group_id value of 0 indicates that the MVD assigns and returns a new group_id to the decoder instance. In other words, if the application 302 assigns a new decoder instance with a group_id of 0, the decoder instance does not need to have the same presentation time as the decoder instances 356, 358, and 360, and the decoder platform control 352 may assign a new group_id (such as 5) to the new decoder instance.

[0126] Decoder instances of the same group (e.g., group 4) may use a single output buffer, such as aggregate buffer 362. In this case, aggregate buffer 362 may be provided by MVD and used by each component to fill the buffer with decoded samples of the same timestamp. Application 302 may indicate the type of interleaving requested in aggregate buffer 362. For example, a decoded mesh or point cloud stream may have interleaved geometry, normals, and color attributes in aggregate buffer 362. The indication may include the format, offset, and stride of each sample from each decoder component, which will be discussed later in this disclosure. Figure 6 Interleaving is depicted in aggregate buffer 362 of , where the output from decoder instance 356 is shown as diagonal lines in one direction, the output from decoder instance 358 is shown as diagonal lines in the other direction, and the output from decoder instance 360 ​​is shown as cross-hatching.

[0127] Now let's discuss the functions. The functions that create a new decoder instance can be modified to support signaling (e.g., group_id) of the group (e.g., group #4) to which the new decoder instance may belong. The configuration functions can be modified to signal aggregate output buffer parameters, which will be discussed in more detail below. For example, application 302 can signal aggregate output buffer parameters.

[0128] OpenMAX IL functions include OMX_GetHandle and OMX_SetConfig. In the following, the functions are defined as abstract functions that can be mapped to OpenMAX, MediaCodec or any other similar API.

[0129] object GetInstance(string component_name,int group_id=-1)

[0130] object SetConfig(int instance_id,int parameter,object config_data)

[0131] The result of a successful call to the GetInstance function call may contain the identifier of the decoder instance and the group_id assigned or created for the decoder instance (if requested). The default (eg, when group_id equals 0) is that the decoder instance does not belong to any established group, but the MVD 350 creates a new group.

[0132] The SetConfig function may be called with a new parameter “CONFIG_OUTPUT_BUFFER”, in which case the SetConfig function provides the format of the aggregate buffer 362 .

[0133] The format of the aggregation buffer 362 may include the following parameters:

[0134] sample_format indicates the format of each sample, which can be a scalar, 2D vector, 3D vector, or 4D vector.

[0135] sample_type indicates the type of each component of the sample (eg, geometry, color attribute, normal, etc.).

[0136] sample_stride indicates the number of bytes between two consecutive samples output by the decoder instance.

[0137] line_stride indicates the number of bytes between the first byte of one line and the first byte of the next line output by the decoder instance.

[0138] buffer_offset, indicating the offset in the aggregate buffer 362 from which the output frames of the decoder instance should be written.

[0139] Scheduling and output control are now discussed. Immersive applications may require finer granularity control of the decoding process than non-immersive applications. For example, application 302 may want immediate access to all subframes, notifications about the availability of specific metadata, filtering of the output of decoder components, and / or limiting the temporal jitter of consecutive executions of decoder instances.

[0140] These functions may be implemented through the definition of decoder instance configuration parameters, which may be set as part of the decoder instance configuration. For example, when defining a new decoder instance, application 302 may determine the decoder instance configuration parameters for the new decoder instance.

[0141] For example, the GetParameter and SetParameter functions can be extended with the following configuration parameters:

[0142] PARAM_SUBFRAME_OUTPUT. This parameter may be used to indicate whether output of subframes is required, desired, or not allowed. If output of subframes is not allowed, only fully decoded frames will be passed to the aggregation buffer 362.

[0143] PARAM_METADATA_CALLBACK. This parameter can be used to set a callback function for a specific metadata type. The length of the list of supported metadata types depends on the codec and can be defined independently for each codec.

[0144] PARAM_OUTPUT_CROP. This parameter can be used to indicate that only a portion of a frame is desired to be decoded at the output (e.g., a renderer or display device). A decoder instance can use this information to intelligently reduce its decoding processing by discarding cells that do not fall within the cropped output region whenever possible.

[0145] PARAM_MAX_OFFTIME_JITTER. This parameter can be used to signal the maximum amount of time (in microseconds) between consecutive executions of a decoder instance. This parameter may be relevant whenever the underlying hardware components are shared between multiple decoder instances, which requires context switching between different decoder instances.

[0146] Example usages for immersive applications are now discussed. For example, this section of the disclosure describes how these decoder interfaces can be extended for immersive media applications in the example of video-based point cloud compressed media (V-PCC). Additional use cases may include presenting a stream of a sign language interpreter and a stream of a speaker whose voice is being interpreted by the sign language interpreter in a synchronized manner, or presenting multiple camera angles at a sporting event in a synchronized manner.

[0147] Fig. 9is a block diagram showing an example V-PCC decoder. The V-PCC stream consists of several substreams, which include metadata streams of encoded geometry, each attribute of the point cloud, occupancy maps, and patch information. For example, the demultiplexer 370 can demultiplex the V-PCC stream. The SPS pairing unit 372 can pair various attributes with sequence parameters. The patch sequence decompression unit 374 can decompress the patch sequence. The video decompression unit 376, the video decompression unit 378, and the video decompression unit 380 can decompress different video data. The geometry / attribute reconstruction unit 382 can reconstruct geometry and attributes. For example, the geometry / attribute reconstruction unit 312 determines the coordinates of points in the point cloud and reconstructs the attributes associated with these points. The geometry post-processing unit 384 can smooth the positions of these points. The attribute transfer and smoothing unit 386 can transfer the attributes to the appropriate points in the point cloud, smooth the attributes, and output the reconstructed point cloud for visualization. Depending on the number of attributes in the point cloud, decoding a V-PCC asset may require running between 3 and 16 decoders simultaneously, 1 for the geometry, 1 for the occupancy map, and one for each attribute (such as color, normal, etc.).

[0148] The V-PCC decoder can tightly synchronize the outputs of different video decoders with frame accuracy in an attempt to ensure correct point cloud reconstruction. Applications (e.g. Figure 5 The application 302 may first query the instantaneous capabilities of the MVD to determine whether all components of the V-PCC stream can be decoded. For example, if the available decoding capabilities are insufficient to decode all attributes, the application may decide to discard some attributes. The application 302 may use the GetHandle function to start creating decoder instances and assign all decoder instances to the same group_id. This may inform the MVD that tight synchronization of the outputs of these decoder instances may be required.

[0149] To run on GPU (e.g. Figure 5 3D point cloud reconstruction is effectively facilitated on the GPU 304, applications (e.g., Figure 5 The application 302 may request different decoder instances in the group to share a common buffer (e.g., Figure 8 The common buffer 362 may reside in the GPU memory and be written once per frame. In some examples, instead of interleaving samples in the common buffer, the samples may not be interleaved, because in some examples, sample interleaving may be useless before reconstructing the point cloud.

[0150] An application (e.g., application 302) can dynamically receive scene and pose information and determine that not all portions of the point cloud are visible at a certain point in time. The application can use metadata information to map the visible 3D portions of the point cloud to a collection of patches and corresponding 2D regions. This information can be passed to a decoding instance (e.g., Figure 8The decoder instance 356, 358 and 360) can request to crop the output to the indicated 2D area. The decoder instance can further use this information to reduce the decoding process by limiting the decoding to the visible 2D area.

[0151] Fig.10 390. The device may determine whether two or more decoder instances are intended to be synchronized (390). For example, decoder platform control 352 of MVD 350 may determine whether a group identifier (ID) of each of the two or more decoder instances is the same. Having the same group ID may indicate an intention that the two or more decoder instances are to be synchronized. For example, application 302 may dispatch two or more decoder instances intended to be synchronized with the same group ID.

[0152] Based on the two or more decoder instances being intended to be synchronized, the two or more decoder instances are controlled so that decoded data from each of the two or more decoder instances can be presented at the same presentation time (392). For example, the MVD 350 can assign the same timestamp offset and unit to each of the two or more decoder instances. The same timestamp value can indicate that samples on each of the two or more decoder instances have the same presentation time. The MVD 350 can couple each of the two or more decoder instances to the same clock.

[0153] Additionally, in some examples, the MVD 350 may be configured to: Figure 8 The MVD 350 may buffer the outputs of the two or more decoder instances in an aggregation buffer 362 of the MVD 350. The aggregation buffer 362 may be configured to interleave decoded data output from each of the two or more decoder instances. In some examples, the MVD 350 may determine parameters of the aggregation buffer 362, for example, by reading instructions from the application 302. In some examples, the parameters include one or more of an indication of a sample format, an indication of a type of each component of a sample, an indication of a number of bytes between two consecutive samples of the output, an indication of a number of bytes between a first byte of a row of the output and a first byte of a next row of the output, or an indication of an offset at which an output frame should be written. In some examples, the MVD 350 may configure the aggregation buffer 362 based on these parameters.

[0154] In some examples, the group ID is a first group ID, and the MVD 350 may receive a request from the application to create a new decoder instance. The request may include a second group ID. The MVD 350 may determine whether the second group ID is the same as the first group ID. The MVD 350 may create a new decoder instance. The MVD 350 may control the new decoder instance based on the second group ID being the same as the first group ID so that the decoded data from the new decoder instance can be presented at the same presentation time as each of the two or more decoder instances. For example, the MVD 350 may assign the same timestamp offset and unit as each of the two or more decoder instances to the new decoder instance, couple the new decoder instance to the same clock as each of the two or more decoder instances, and / or buffer the output of the new decoder instance in the same aggregation buffer as the two or more decoder instances.

[0155] In some examples, the group ID is a first group ID, and the MVD 350 may receive a request from the application to create a new decoder instance. The request may include a second group ID. The MVD 350 may determine whether the second group ID is equal to 0. Based on the second group ID being 0, the MVD 350 may create a new decoder instance and assign the new decoder instance to the new group ID.

[0156] In some examples, the MVD 350 may determine parameters for the new decoder instance. For example, the MVD may read instructions from the application 302 to determine parameters for the new decoder instance. These parameters may include one or more of: an indication of whether output of a subframe is required, desired, or not allowed; an indication of a specific metadata type for which a callback function is set; an indication of whether only a portion of a decoded frame is required at output; or an indication of a maximum amount of time between successive executions of a decoder instance. In some examples, the MVD 350 may create a new decoder instance based on the parameters.

[0157] In some examples, MVD 350 may determine the current aggregate capabilities of the multi-video decoder. In some examples, MVD 350 may determine the current aggregate capabilities of the multi-video decoder in response to receiving a query from application 302. In some instances, MVD 350 may send an indication of the current aggregate capabilities of the multi-video decoder to application 302.

[0158] In some examples, the current aggregate capabilities include one or more of: an indication of a maximum number of decoder instances that can be instantiated for a provided decoder component when creating an indication of a maximum number of decoder instances that can be instantiated; an indication of a maximum available buffer size that can be allocated on the MVD for buffer exchange with components of the MVD when creating an indication of a maximum available buffer size that can be allocated; an indication of a maximum encoded bit rate that the queried component can handle when creating an indication of a maximum encoded bit rate that the queried component can handle; an indication of a maximum number of samples per unit time that the queried component can handle when creating an indication of a maximum number of samples per unit time that the queried component can handle; or an indication of a maximum performance point of a bitstream that can be decoded by the indicated component in a new instance of the decoder component.

[0159] In some examples, an indication of a maximum performance point of a bitstream that can be decoded by the indicated component includes an image rate of images per unit time of the maximum performance point, a height of luma samples of the maximum performance point, a width of luma samples of the maximum performance point, and a bit depth of luma samples of the maximum performance point.

[0160] In some examples, client device 40 includes a display device configured to display the point cloud.

[0161] In this way, an application may be able to query the MVD for current capabilities, multiple samples from different streams may be grouped to be decoded simultaneously by the MVD, and an application may be able to exert fine-grained control over the scheduling of different decoder instances of the MVD.

[0162] This disclosure includes the following examples.

[0163] Clause 1. A method for decoding media data, the method comprising:

[0164] A client device including multiple video decoders determines capabilities of multiple components of the client device; the client device controls access to the multiple video decoders or adjusts one or more of the decoding processes based on the capabilities of the multiple components; and the client device decodes media data based on controlling access or adjusting one or more of the decoding processes.

[0165] Clause 2. A method according to clause 1, wherein the determined capabilities include a maximum number of decoder instances that can be instantiated at one time for a first component among multiple components, a maximum buffer size that can be allocated when performing buffer exchanges with multiple components, a maximum encoded bit rate that the first component can handle, a maximum number of samples per unit time that the first component can process, or a maximum performance point of a bitstream that the first component can decode in a new decoder instance of the first component.

[0166] Clause 3. A method according to Clause 2, wherein the maximum performance point includes one or more of an image rate of images per unit time of the maximum performance point, a height of brightness samples of the maximum performance point, a width of brightness samples of the maximum performance point, or a bit depth of brightness samples of the maximum performance point.

[0167] Clause 4. A method according to Clause 3, wherein the maximum performance point includes an image rate of images per unit time of the maximum performance point, a height of brightness samples of the maximum performance point, a width of brightness samples of the maximum performance point, and a bit depth of brightness samples of the maximum performance point.

[0168] Clause 5. The method of any combination of clauses 1-4, further comprising: determining an identifier of the decoder instance and a group id of the decoder instance.

[0169] Clause 6. The method according to any combination of clauses 1-5, further comprising: determining a format of an output buffer.

[0170] Clause 7. A method according to clause 6, wherein the format of the output buffer includes one or more of the format of each sample, the type of each component of each sample, the number of bytes between two consecutive samples of the output, the number of bytes between the first byte of one line of the output and the first byte of the next line of the output, or the offset in the output buffer from which the output frame should start being written.

[0171] Clause 8. The method of clause 7, wherein the format of each sample comprises one of a scalar, a 2D vector, a 3D vector, or a 4D vector.

[0172] Clause 9. The method according to any combination of clauses 1-8, further comprising: determining a configuration of the decoder instance.

[0173] Clause 10. A method according to clause 9, wherein the configuration includes one or more of: indicating whether output of a subframe is required, expected, or not allowed; setting a callback function for a metadata type; indicating that only a portion of a frame is expected to be decoded at the output; or signaling a maximum amount of time per unit time between successive executions of a decoder instance.

[0174] Clause 11. The method of clause 10, wherein the list of supported metadata types is codec-dependent and is defined independently for each codec.

[0175] Clause 12. A client device for decoding media data, the client device comprising: a memory configured to store the media data; and one or more processors implemented in circuitry configured to: execute a multi-video decoder; and

[0176] Clause 13. The client device of Clause 12, further comprising a display configured to display the decoded media data.

[0177] Clause 14. A client device according to any combination of clauses 12-13, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0178] Clause 15. A client device according to any combination of clauses 12-14, further comprising a plurality of video decoders.

[0179] Clause 16. A client device according to any combination of clauses 12-15, further comprising a video encoder.

[0180] Clause 17. An apparatus for decoding media data, the apparatus comprising one or more means for performing any combination of clauses 1-11.

[0181] Clause 18. A computer-readable storage medium having stored thereon instructions that, when executed, cause a processor to: execute a multiple video decoder; and perform any combination of clauses 1-11.

[0182] 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 or transmitted on a computer-readable medium as one or more instructions or codes and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to tangible media such as data storage media, or communication media, including any media that facilitates the transfer of computer programs from one place to another, for example, according to a communication protocol. In this manner, computer-readable media may generally correspond to (1) tangible, non-temporary computer-readable storage media, or (2) communication media such as signals or carrier waves. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures for implementing the techniques described in the present disclosure. A computer program product may include a computer-readable medium.

[0183] As an example and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage devices, flash memory or any other medium that can be used to store the required program code in the form of instructions or data structures and can be accessed by a computer. Similarly, any connection is properly referred to as a computer-readable medium. For example, if a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technologies such as infrared, radio and microwaves are used to transmit instructions from a website, server or other remote source, then the coaxial cable, fiber optic cable, twisted pair, DSL or wireless technologies such as infrared, radio and microwaves are included in the definition of the medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals or other temporary media, but point to non-temporary tangible storage media. The disks and optical disks used here include compact disks (CDs), laser optical disks, optical disks, digital versatile disks (DVDs), floppy disks and blue-ray disks, where disks usually reproduce data magnetically, and optical disks reproduce data optically with lasers. The above combination should also be included in the scope of computer-readable media.

[0184] 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 circuits. Therefore, the term "processor" used herein may refer to any of the aforementioned structures or any other structure suitable for implementing the techniques described herein. In addition, in some aspects, the functions described herein may be provided in dedicated hardware and / or software modules configured for encoding and decoding, or may be incorporated in a combined codec. Similarly, these techniques may be implemented entirely in one or more circuits or logic elements.

[0185] The techniques of the present disclosure may be implemented in a variety of devices or equipment, including a wireless handset, an integrated circuit (IC), or a set of ICs (e.g., a chipset). Various components, modules, or units are described in the present disclosure to emphasize the functional aspects of a device configured to perform the disclosed techniques, but do not necessarily need to be implemented by different hardware units. Instead, as described above, the various units may be combined in a codec hardware unit in conjunction with appropriate software and / or firmware, or provided by a collection of interoperable hardware units, including one or more processors as described above.

[0186] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. A method for decoding media data, the method comprising: determining, by the client device, that two or more decoder instances are intended to be synchronized, wherein determining that the two or more decoder instances are intended to be synchronized comprises determining that a group identifier ID of each of the two or more decoder instances is the same; and Based on the group ID of each of the two or more decoder instances determined to be the same, it is determined that the two or more decoder instances are intended to be synchronized, and the two or more decoder instances are controlled so that decoded data from each of the two or more decoder instances can be presented at the same presentation time.

2. The method according to claim 1, wherein: The group ID is a first group ID, and the method further includes: receiving a request from an application to create a new decoder instance, the request including a second set of IDs; Determine that the second group ID is the same as the first group ID; Create a new decoder instance; and Based on the second group ID being the same as the first group ID, the new decoder instance is controlled to be able to present decoded data from the new decoder instance at the same presentation time as each of the two or more decoder instances.

3. The method according to claim 1, further comprising: receiving a request from an application to create a new decoder instance, the request including a second set of IDs; Determine that the second group ID is equal to 0; and Based on the second group ID being equal to 0, a new decoder instance is created and a new group ID is assigned to the new decoder instance.

4. The method according to claim 1, further comprising: A same timestamp offset and measurement unit are assigned to each of the two or more decoder instances, wherein the same timestamp offset and measurement unit indicate that samples on each of the two or more decoder instances have a same presentation time.

5. The method according to claim 4, wherein: Each of the two or more decoder instances is coupled to a same clock.

6. The method according to claim 1, further comprising: Outputs of the two or more decoder instances are buffered in an aggregation buffer, wherein the aggregation buffer is configured to interleave decoded data output from each of the two or more decoder instances.

7. The method according to claim 6, further comprising: Determine parameters of the aggregation buffer, where the parameters include one or more of the following: Instructions for sample formats; an indication of the type of each component of the sample; an indication of the number of bytes between two consecutive samples of the output of the decoder instance; an indication of the number of bytes between the first byte of one line and the first byte of the next line of the output of the decoder instance; or An indication of the offset from which the output frames of the decoder instance should be written.

8. The method according to claim 1, further comprising: Determine parameters of the new decoder instance, where the parameters include one or more of the following: an indication that an output subframe is required, desired, or not allowed; An indication of a specific metadata type for which to set a callback function; an indication that only a portion of the frame is desired to be decoded at the output; or An indication of the maximum amount of time between successive executions of new decoder instances.

9. The method according to claim 8, further comprising: Creates a new decoder instance based on the parameters.

10. The method according to claim 1, further comprising: Determine the current aggregation capabilities of the multiple video decoders.

11. The method according to claim 10, wherein: Determining a current aggregation capability of the multi-video decoder is responsive to receiving a query from an application; the method further comprising: Sends an indication of the current aggregation capabilities of the multi-video decoder to the application.

12. The method according to claim 10, wherein: Current aggregation capabilities include one or more of the following: an indication of the maximum number of decoder instances that can be instantiated for a provided decoder component when creating an indication of the maximum number of decoder instances that can be instantiated; an indication of a maximum available buffer size that can be allocated at a multi-video decoder (MVD) for buffer exchanges with components of the MVD when creating an indication of a maximum available buffer size that can be allocated; an indication of a maximum encoding bit rate that the queried component is capable of handling when creating the indication of a maximum encoding bit rate that the queried component is capable of handling; an indication of the maximum number of samples per unit time that the queried component is capable of processing when creating an indication of the maximum number of samples per unit time that the queried component is capable of processing; or An indication of a maximum performance point of the bitstream that can be decoded by the indicated component in the new instance of the decoder component.

13. The method according to claim 12, wherein: An indication of a maximum performance point of a bitstream that can be decoded by the indicated component includes: The image rate of images per unit time at the point of maximum performance; Brightness sample height at the maximum performance point; The luminance sample width at the point of maximum performance; and Luma sample bit depth at the point of maximum performance.

14. A device for decoding media data, the device comprising: a memory configured to store media data; and One or more processors implemented in circuitry and communicatively coupled to the memory, the one or more processors configured to: determining that two or more decoder instances are intended to be synchronized, wherein as part of determining that the two or more decoder instances are intended to be synchronized, the one or more processors are configured to determine that a group identifier ID of each of the two or more decoder instances is the same; and Based on the group ID of each of the two or more decoder instances determined to be the same, it is determined that the two or more decoder instances are intended to be synchronized, and the two or more decoder instances are controlled so that decoded data from each of the two or more decoder instances can be presented at the same presentation time.

15. The device according to claim 14, wherein: The group ID is a first group ID, and the one or more processors are further configured to: receiving a request from an application to create a new decoder instance, the request including a second set of IDs; Determine that the second group ID is the same as the first group ID; Create a new decoder instance; and Based on the second group ID being the same as the first group ID, the new decoder instance is controlled to be able to present decoded data from the new decoder instance at the same presentation time as each of the two or more decoder instances.

16. The apparatus according to claim 14, wherein: The one or more processors are further configured to: receiving a request from an application to create a new decoder instance, the request including a second set of IDs; Determine that the second group ID is equal to 0; and Based on the second group ID being equal to 0, a new decoder instance is created and a new group ID is assigned to the new decoder instance.

17. The apparatus according to claim 14, wherein: The one or more processors are further configured to: A same timestamp offset and measurement unit are assigned to each of the two or more decoder instances, wherein the same timestamp offset and measurement unit indicate that samples on each of the two or more decoder instances have a same presentation time.

18. The apparatus of claim 17, further comprising a clock communicatively coupled to each of the two or more decoder instances.

19. The apparatus of claim 14, further comprising: An aggregation buffer is communicatively coupled to the one or more processors, the aggregation buffer configured to interleave decoded data output from each of the two or more decoder instances.

20. The apparatus of claim 19, wherein: The one or more processors are further configured to: Determine parameters of the aggregation buffer, where the parameters include one or more of the following: Instructions for sample formats; an indication of the type of each component of the sample; an indication of the number of bytes between two consecutive samples of the output of the decoder instance; an indication of the number of bytes between the first byte of one line and the first byte of the next line of the output of the decoder instance; or An indication of the offset from which the output frames of the decoder instance should be written.

21. The apparatus according to claim 20, wherein: The one or more processors are further configured to configure an aggregation buffer based on the parameter.

22. The apparatus of claim 14, wherein: The one or more processors are further configured to: Determine parameters of the new decoder instance, where the parameters include one or more of the following: an indication that an output subframe is required, desired, or not allowed; An indication of a specific metadata type for which to set a callback function; an indication that only a portion of the frame is desired to be decoded at the output; or An indication of the maximum amount of time between successive executions of new decoder instances.

23. The apparatus of claim 22, wherein: The one or more processors are further configured to: Creates a new decoder instance based on the parameters.

24. The apparatus of claim 14, wherein: The one or more processors are further configured to: Determine the current aggregation capabilities of the multiple video decoders.

25. The apparatus of claim 24, wherein: The one or more processors determine a current aggregation capability of the multi-video decoder in response to receiving a query from an application, and wherein the one or more processors are further configured to: Sends an indication of the current aggregation capabilities of the multi-video decoder to the application.

26. The apparatus of claim 24, wherein: Current aggregation capabilities include one or more of the following: an indication of the maximum number of decoder instances that can be instantiated for a provided decoder component when creating an indication of the maximum number of decoder instances that can be instantiated; an indication of a maximum available buffer size that can be allocated at a multi-video decoder (MVD) for buffer exchanges with components of the MVD when creating an indication of a maximum available buffer size that can be allocated; an indication of a maximum encoding bit rate that the queried component is capable of handling when creating the indication of a maximum encoding bit rate that the queried component is capable of handling; an indication of the maximum number of samples per unit time that the queried component is capable of processing when creating an indication of the maximum number of samples per unit time that the queried component is capable of processing; or An indication of a maximum performance point of the bitstream that can be decoded by the indicated component in the new instance of the decoder component.

27. The apparatus of claim 26, wherein: An indication of a maximum performance point of a bitstream that can be decoded by the indicated component includes: The image rate of images per unit time at the point of maximum performance; Brightness sample height at the maximum performance point; The luminance sample width at the point of maximum performance; and Luma sample bit depth at the point of maximum performance.

28. The device of claim 14, further comprising a display device communicatively coupled to the one or more processors, the display device configured to display the point cloud.

29. A non-transitory computer-readable storage medium storing instructions that, when executed by one or more processors, cause the one or more processors to: determining that two or more decoder instances are intended to be synchronized, wherein as part of determining that the two or more decoder instances are intended to be synchronized, the one or more processors are configured to determine that a group identifier (ID) of each of the two or more decoder instances is the same; and Based on the group ID of each decoder instance among the two or more decoder instances determined to be the same, it is determined that the two or more decoder instances are intended to be synchronized, and the two or more decoder instances are controlled so that decoded data from each decoder instance among the two or more decoder instances can be presented at the same presentation time.

30. A device for decoding media data, the device comprising: means for determining that two or more decoder instances are intended to be synchronized, wherein as part of determining that the two or more decoder instances are intended to be synchronized, the one or more processors are configured to determine that a group identifier ID of each of the two or more decoder instances is the same; and A device for determining that the two or more decoder instances are intended to be synchronized based on the group ID of each decoder instance in the two or more decoder instances determined to be the same, and controlling the two or more decoder instances so that decoded data from each decoder instance in the two or more decoder instances can be presented at the same presentation time.

Images