Method for indicating parameter set in video streaming

Abstract

The present disclosure generally relates to video coding, and in particular to video file encapsulation and parameter signaling. For example, a method for processing video data is disclosed, which may include receiving a bitstream including at least one video sample, the at least one video sample including a current video sample and a previous video sample, each video sample including at least one video frame, and each video sample being associated with a serving SPS for decoding each of the at least one video sample, determining a serving SPS of the current video sample as one of a previous SPS already parsed from the bitstream and used to decode the previous video sample, a current SPS encapsulated in the current video sample, and an SPS in a list of candidate SPSs, and decoding the current video sample based on the serving SPS of the current video sample.

Description

[Technical field]

[0001] Incorporation by Reference This application claims the benefit of priority to U.S. Provisional Application No. 63 / 323,846, entitled "METHOD AND APPARATUS FOR PARAMETER SET INDICATION IN VIDEO STREAMING," filed on March 25, 2022, which claims the benefit of priority to U.S. Non-provisional Application No. 17 / 973,986, entitled "METHODS OF PARAMETER SET INDICATION IN VIDEO STREAMING," filed on October 26, 2022, which is incorporated by reference in its entirety herein.

[0002] This disclosure describes a set of advanced video coding techniques. More specifically, the disclosed techniques include implementations and enhancements of video file encapsulation for video bitstreams, and decoding parameter signaling. [Background technology]

[0003] The discussion of the background art provided herein is intended to generally present the context of the present disclosure. The inventors' work is not admitted expressly or implicitly as prior art to the present disclosure, to the extent that that work is described in this background section, together with aspects of the description that may not otherwise be admitted as prior art at the time of filing of this application.

[0004] A multimedia system may include modules that support the following procedures: video capture, video coding, video file encapsulation, file transport, file deencapsulation, video decoding, and video rendering. Among these procedures, file encapsulation is used to organize the original video bitstream with essential metadata information to optimize the transport and decoding procedures. During file encapsulation, video frames in the bitstream are usually redefined as samples (or video samples) in a file, and typically a sample can be considered as a video frame with additional metadata such as frame size, presentation time, etc.

[0005] Video coding and video decoding can be performed using inter-picture prediction with motion compensation. Uncompressed digital video can include a sequence of pictures, each having spatial dimensions of, for example, 1920x1080 luminance samples and associated full-sampled or sub-sampled chrominance samples. The sequence of pictures can have a fixed or variable picture rate (alternatively called frame rate), for example, 60 pictures per second or 60 frames per second. Uncompressed video has specific bit rate requirements for streaming or data processing. For example, a video with a pixel resolution of 1920x1080, a frame rate of 60 frames / second, and 4:2:0 chroma subsampling with 8 bits per pixel per color channel requires a bandwidth approaching 1.5 Gbit / s. One hour of such video requires more than 600 GByte of storage space.

[0006] One objective of video coding and video decoding may be the reduction of redundancy in an uncompressed input video signal through compression. Compression may help reduce the aforementioned bandwidth and / or storage space requirements, in some cases by more than two orders of magnitude. Both lossless and lossy compression, as well as combinations thereof, may be employed. Lossless compression refers to techniques where an exact copy of an original signal can be reconstructed from a compressed original signal through a decoding process. Lossy compression refers to a coding / decoding process where the original video information is not fully preserved when coding and cannot be fully restored when decoding. When using lossy compression, the reconstructed signal may not be identical to the original signal, but the distortion between the original signal and the reconstructed signal is small enough to make the reconstructed signal useful for its intended application, even with some information loss. For video, lossy compression is widely adopted in many applications. The amount of distortion that can be tolerated depends on the application. For example, a user of a particular consumer video streaming application may tolerate higher distortion than a user of a movie or television broadcast application. The compression ratio achievable by a particular coding algorithm can be selected or adjusted to reflect different distortion tolerances; that is, in general, the higher the tolerable distortion, the more coding algorithms that result in higher losses and higher compression ratios are possible.

[0007] Video encoders and decoders can utilize techniques from a number of broad categories and steps, including, for example, motion compensation, Fourier transform, quantization, and entropy coding. Summary of the Invention [Means for solving the problem]

[0008] Aspects of the present disclosure relate generally to video encoding and decoding, and more particularly to implementations and enhancements of video file encapsulation for video bitstreams and decoding parameter signaling.

[0009] An aspect of the present disclosure provides a method for processing video data, the method including: receiving a bitstream including at least one video sample, the at least one video sample including a current video sample and a previous video sample, each of the at least one video sample including at least one video frame, each of the at least one video sample being associated with a serving sequence parameter set (SPS) for decoding each of the at least one video sample; determining a serving SPS for the current video sample as one of a previous SPS already parsed from the bitstream and used to decode the previous video sample, a current SPS encapsulated in the current video sample, and an SPS in a list of candidate SPSs; and decoding the current video sample based on the serving SPS for the current video sample.

[0010] Aspects of the present disclosure also provide a video encoding or decoding device or apparatus that includes circuitry configured to perform any of the above method implementations.

[0011] Aspects of the present disclosure also provide a non-transitory computer-readable medium storing instructions that, when executed by a computer, cause the computer to perform a method for video decoding and / or video encoding.

[0012] Further features, nature and various advantages of the disclosed subject matter will become more apparent from the following detailed description and the accompanying drawings. [Brief description of the drawings]

[0013] [Figure 1] 1 shows a diagram of an exemplary application environment of a video encoding / decoding method. [Diagram 2] 4 shows various exemplary video samples. [Diagram 3] 1 illustrates a simplified block diagram schematic of a communication system (300) in accordance with an exemplary embodiment. [Figure 4] 4 shows a simplified block diagram schematic of a communication system (400) according to an exemplary embodiment. [Diagram 5] 1 shows a schematic diagram of a simplified block diagram of a video decoder according to an exemplary embodiment; [Figure 6] 1 shows a schematic diagram of a simplified block diagram of a video encoder according to an example embodiment; [Figure 7] 4 shows a block diagram of a video encoder according to another example embodiment. [Figure 8] 4 shows a block diagram of a video decoder according to another exemplary embodiment. [Figure 9] 1 illustrates a flowchart of a method according to an exemplary embodiment of the present disclosure. [Figure 10] 1 shows a schematic diagram of a computer system according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will now be described in detail below with reference to the accompanying drawings, which form a part hereof, and which show by way of illustration specific examples of embodiments. It should be noted, however, that the present invention may be embodied in a variety of different forms, and thus it is intended that the subject matter encompassed or claimed be construed as not being limited to any of the embodiments described below. It should also be noted that the present invention may be embodied as a method, device, component, or system. Thus, embodiments of the present invention may take the form of, for example, hardware, software, firmware, or any combination thereof.

[0015] Throughout this specification and the claims, terms may have subtle meanings that are suggested or implied in the context beyond the meaning explicitly stated. The phrases "in one embodiment" or "in some embodiments" used herein do not necessarily refer to the same embodiment, and the phrases "in another embodiment" or "in other embodiments" used herein do not necessarily refer to different embodiments. Similarly, the phrases "in one implementation" or "in some implementations" used herein do not necessarily refer to the same implementation, and the phrases "in another implementation" or "in other implementations" used herein do not necessarily refer to different implementations. For example, the claimed subject matter is intended to include all or part of the exemplary embodiments / implementations.

[0016] Generally, terms may be understood at least in part from their usage in context. For example, terms such as "and", "or", or "and / or" as used herein may include various meanings that may depend at least in part on the context in which such terms are used. Typically, "or" when used to relate a list such as A, B, or C is intended to mean A, B, and C, which are used herein in an inclusive sense, as well as A, B, or C, which are used herein in an exclusive sense. In addition, the terms "one or more" or "at least one" as used herein may be used to describe any feature, structure, or characteristic in a singular sense, or may be used to describe a combination of features, structures, or characteristics in a plural sense, depending at least in part on the context. Similarly, terms such as "a", "an", or "the" may also be understood to convey a singular usage or a plural usage, depending at least in part on the context. In addition, the terms "based on" or "determined by" may be understood as not necessarily intended to convey an exclusive set of factors, but instead may allow for the existence of additional factors not necessarily expressly recited, also depending at least in part on the context.

[0017] FIG. 1 is a diagram of an application environment of a video processing (encoding / decoding) method according to an embodiment. Referring to FIG. 1, the video processing method is applied to a video processing system. The video processing system includes a terminal 110 and a server 120. The terminal 110 is connected to the server 120 by a network. The terminal 110 may be, but is not limited to, a desktop terminal or a mobile terminal, and the mobile terminal may specifically be at least one of a mobile phone, a tablet computer, a notebook computer, etc., and no limitation is imposed in this application. The server 120 may be implemented by using an independent server or a server cluster including multiple servers. The terminal may also be called a client.

[0018] The video encoding method and the video decoding method may be implemented in the terminal 110 and / or the server 120. The terminal 110 may encode a current frame by using the video encoding method, then send the encoded video frame to the server 120, or receive encoded data (e.g., a bitstream) from the server 120, decode the encoded data by using the video decoding method, and then generate a reconstructed video frame. The server 120 may perform transcoding on the code stream during storage. In this case, the video encoding method is completed on the server. If the server 120 needs to decode the code stream, the video decoding method is completed on the server. It should be understood that the encoding end and the decoding end may be the same end or different ends. A computing device, such as a terminal or a server, may be an encoding end, a decoding end, or both an encoding end and a decoding end.

[0019] Referring to FIG. 1, the terminal 110 or the server 120 may perform video encoding by using an encoder or may perform video decoding by using a decoder. The terminal 110 or the server 120 may also perform video encoding by using a processor that executes a video encoding program or may perform video decoding by using a processor that executes a video decoding program. For example, after receiving the encoded data sent by the terminal 110 through the input interface, the server 120 may directly transfer the encoded data to the processor for decoding, or may store the encoded data in a database for later decoding. After obtaining the encoded data by encoding the original video frame by the processor, the server 120 may directly transmit the encoded data to the terminal 110 through the output interface, or may store the encoded data in a database for later transfer.

[0020] In an exemplary implementation, the video encoding method and the video decoding method provided in this disclosure may be applied to applications such as video on demand and video streaming. In such applications, as an example, a terminal may send a request to a server to play a video. The server may fetch source data from a database, and the video source may be pre-encoded video data, or the server may encode the video source in real time to obtain encoded video data, for example, to meet specific service requirements and / or transmission bandwidth. The server may then send the encoded video data to the terminal via a bitstream. The terminal may also support multiple playback modes, such as fast forward, rewind, or jump (e.g., by clicking a new time point in the timeline or dragging the playhead in the timeline to a new time point). Jump playback includes a random access function, which will be described in detail in a later section.

[0021] In an exemplary implementation, the video encoding method and the video decoding method provided in the present disclosure may be applied to an application having a video call function. The application may include a social application or an instant messaging application. During a video call between two terminals installed with an embodiment of the present application, the first terminal obtains a video frame by using a camera, encodes the video frame by using a video encoding function of the application to obtain encoded data, and transmits the encoded data to a background server of the application. The background server transfers the encoded data to the second terminal. After receiving the encoded data, the second terminal decodes the encoded data by using a video decoding function of the application, and performs reconstruction to obtain the video frame in order to display the video frame. Similarly, the second terminal may transmit the encoded data obtained by encoding to the first terminal by using a background server, and the first terminal performs decoding and displaying, thereby realizing a video call between the two parties.

[0022] In an exemplary implementation, the video encoding method and the video decoding method provided in this application may be applied to an application having a video playback function. For example, the application may include a video live streaming application, a short video application, or a video playback application. A terminal on which an embodiment of the application is installed may obtain video frames by using a camera, encode the video frames by using a video encoding function of the application to obtain encoded data, and send the encoded data to a background server of the application. When another terminal requests to watch a video, the background server sends the encoded data of the video to the other terminal. The application on the other terminal decodes the encoded data and plays the video.

[0023] The above several possible application scenarios are only used for illustrative purposes. The video encoding and decoding methods provided in various embodiments of the present disclosure may be further applied to any scenario requiring video encoding and video decoding.

[0024] 2 illustrates an exemplary high-level video bitstream structure. The bitstream may include n video samples (202). Each video sample is formed by at least one video frame. In one implementation, the number of video frames in each video sample may be variable. In one implementation, the number of video frames in each video sample may be fixed (e.g., each video sample may include one video frame, each video sample may include two video frames, etc.). In one implementation, each video sample may be encapsulated in one data packet (e.g., an Internet Protocol (IP) packet) for transmission. In one implementation, each video frame may be encapsulated in one data packet.

[0025] In an exemplary implementation, multiple adjacent video samples sharing the same sequence parameter set (SPS, also referred to as sequence level parameter set) may form a video sequence (or sequence, coded video sequence). With reference to FIG. 2, video sample 1 and video sample 2 may form a sequence, and the sequence includes all frames in both video samples. Video frame n-1 and video frame n may form another sequence. A video sample may further encapsulate an SPS that may be used to decode a video sample in the same sequence. An SPS may be encapsulated in only one video sample in a sequence, such as the start video sample in the sequence. An SPS may also be encapsulated in all video samples in the sequence. Detailed implementations are described in a later section. In this disclosure, decoding a video sample includes decoding all frames in the video sample. As an example, a bitstream may include n video samples, where n is a positive integer, and each video sample may include one video frame, and the n video samples may form multiple sequences.

[0026] In this disclosure, a video sequence may be formed by a single video sample.

[0027] FIG. 3 illustrates a simplified block diagram of a communication system (300) according to an embodiment of the present disclosure. The communication system (300) includes a plurality of terminal devices that can communicate with each other, for example, via a network (350). For example, the communication system (300) includes a first pair of terminal devices (310) and (320) interconnected via the network (350). In the example of FIG. 3, the first pair of terminal devices (310) and (320) may perform unidirectional transmission of data. For example, the terminal device (310) may code video data (e.g., of a stream of video pictures captured by the terminal device (310)) for transmission to the other terminal device (320) via the network (350). The encoded video data may be transmitted in the form of one or more coded video bitstreams. The terminal device (320) may receive the coded video data from the network (350), decode the coded video data to reconstruct the video pictures, and display the video pictures according to the reconstructed video data. One-way data transmission may be implemented in media serving applications, etc. It should be noted that the terminal device (310) may also retrieve pre-encoded video data directly from an internal / external storage and / or an internal / external database. In this case, the encoding process may be skipped, and the terminal device (310) may directly transmit the video bitstream to the terminal device (320).

[0028] In another example, the communication system (300) includes a second pair of terminal devices (330) and (340) for bidirectional transmission of coded video data, which may be implemented, for example, during video conferencing applications. In the case of bidirectional transmission of data, in one example, each of the terminal devices (330) and (340) may code video data (e.g., of a stream of video pictures captured by the terminal device) for transmission to the other of the terminal devices (330) and (340) over the network (350). Each of the terminal devices (330) and (340) may also receive coded video data transmitted by the other of the terminal devices (330) and (340), decode the coded video data to recover the video pictures, and display the video pictures on an accessible display device according to the recovered video data.

[0029] In the example of FIG. 3, the terminal devices (310), (320), (330), and (340) may be implemented as a server, a personal computer, and a smartphone, although the applicability of the principles underlying the present disclosure is not so limited. The embodiments of the present disclosure may be implemented in desktop computers, laptop computers, tablet computers, media players, wearable computers, dedicated video conferencing equipment, and the like. The network (350) represents any number or type of network that conveys coded video data between the terminal devices (310), (320), (330), and (340), including, for example, wired (wired connection) and / or wireless communication networks. The communication network (350) may exchange data over circuit-switched channels, packet-switched channels, and / or other types of channels. Representative networks include telecommunications networks, local area networks, wide area networks, and / or the Internet. For purposes of this discussion, the architecture and topology of the network (350) may not be important to the operation of the present disclosure unless explicitly described herein.

[0030] 4 illustrates an arrangement of video encoders and video decoders in a video streaming environment as an example of an application for the disclosed subject matter. The disclosed subject matter may be equally applicable to other video applications including, for example, video conferencing, digital television broadcasting, gaming, virtual reality, storage of compressed video on digital media including CDs, DVDs, memory sticks, etc.

[0031] A video streaming system may include a video source (401) for creating a stream of uncompressed video pictures or images (402), a video capture subsystem (413) that may include, for example, a digital camera. In one example, the stream of video pictures (402) includes samples recorded by the digital camera of the video source 401. The stream of video pictures (402) is illustrated as a bold line to emphasize its high amount of data compared to the encoded video data (404) (or coded video bitstream), and may be processed by an electronic device (420) that includes a video encoder (403) coupled to the video source (401). The video encoder (403) may include hardware, software, or a combination thereof to enable or implement aspects of the disclosed subject matter, as described in more detail below. The encoded video data (404) (or encoded video bitstream (404)), shown as thin lines to emphasize its low amount of data compared to the stream of uncompressed video pictures (402), can be stored on the streaming server (405) or directly on a downstream video device (not shown) for future use. One or more streaming client subsystems, such as the client subsystems (406) and (408) of FIG. 4, can access the streaming server (405) to retrieve copies (407) and (409) of the encoded video data (404). The client subsystem (406) can include, for example, a video decoder (410) in the electronic device (430). The video decoder (410) decodes the input copy of the encoded video data (407) and creates an output stream of video pictures (411) that is uncompressed and can be rendered on a display (412) (e.g., a display screen) or other rendering device (not shown). The video decoder 410 may be configured to perform some or all of the various functions described in this disclosure.In some streaming systems, the encoded video data (404), (407), and (409) (e.g., video bitstreams) may be encoded according to a particular video coding / compression standard. Examples of such standards include ITU-T Recommendation H.265. In one example, a video coding standard under development is informally known as Versatile Video Coding (VVC). The disclosed subject matter may be used in the context of VVC, as well as other video coding standards.

[0032] It should be noted that the electronic devices (420) and (430) may include other components (not shown). For example, the electronic device (420) may also include a video decoder (not shown), and the electronic device (430) may also include a video encoder (not shown).

[0033] 5 shows a block diagram of a video decoder (510) according to any of the following embodiments of the present disclosure. The video decoder (510) can be included in an electronic device (530). The electronic device (530) can include a receiver (531) (e.g., a receiving circuit). The video decoder (510) can be used in place of the video decoder (410) of the example of FIG. 4.

[0034] The receiver (531) may receive one or more coded video sequences to be decoded by the video decoder (510). In the same or another embodiment, one coded video sequence may be decoded at a time, with the decoding of each coded video sequence being independent of the other coded video sequences. Each video sequence may be associated with multiple video frames or video images. The coded video sequences may be received from a channel (501), which may be a hardware / software link to a storage device that stores the encoded video data, or a streaming source that transmits the encoded video data. The receiver (531) may receive the encoded video data along with other data, such as coded audio data and / or auxiliary data streams, which may be forwarded to respective processing circuits (not shown). The receiver (531) may separate the coded video sequences from the other data. A buffer memory (515) may be placed between the receiver (531) and the entropy decoder / parser (520) (hereafter "parser (520)") to combat network jitter. In certain applications, the buffer memory (515) may be implemented as part of the video decoder (510). In other applications, the buffer memory (515) may be external to the video decoder (510) and separate from the video decoder (510) (not shown). In still other applications, there may be a buffer memory (not shown) external to the video decoder (510), for example to combat network jitter, and there may be another additional buffer memory (515) internal to the video decoder (510), for example to handle playback timing. When the receiver (531) is receiving data from a storage / forwarding device with sufficient bandwidth and controllability, or from an isosynchronous network, the buffer memory (515) may be unnecessary or may be small.For use with best-effort packet networks such as the Internet, a buffer memory of sufficient size (515) may be required, which may be relatively large in size. Such a buffer memory may be implemented with an adaptive size and may be implemented at least in part in an operating system or similar element (not shown) external to the video decoder (510).

[0035] The video decoder (510) may include a parser (520) for reconstructing symbols (521) from the coded video sequence. These categories of symbols include information used to manage the operation of the video decoder (510) and information for controlling a rendering device such as a display (512) (e.g., a display screen) that may or may not be an integral part of the electronic device (530) but may potentially be coupled to the electronic device (530) as shown in FIG. 5. The control information for the rendering device(s) may be in the form of a supplemental enhancement information (SEI message) or a video usability information (VUI) parameter set fragment (not shown). The parser (520) may parse / entropy decode the coded video sequence received by the parser (520). The entropy coding of the coded video sequence may be in accordance with a video coding technique or standard and may follow various principles including variable length coding, Huffman coding, arithmetic coding with or without context sensitivity, etc. The parser (520) may extract from the coded video sequence a set of subgroup parameters for at least one of the subgroups of pixels in the video decoder based on at least one parameter corresponding to the subgroup. The subgroups may include Group of Pictures (GOPs), pictures, tiles, slices, macroblocks, coding units (CUs), blocks, transform units (TUs), prediction units (PUs), etc. The parser (520) may also extract information from the coded video sequence, such as transform coefficients (e.g., Fourier transform coefficients), quantization parameter values, motion vectors, etc.

[0036] The parser (520) may perform an entropy decoding / parsing operation on the video sequence received from the buffer memory (515) to produce symbols (521).

[0037] The reconstruction of the symbols (521) may involve a number of different processing or functional units, depending on the type of video picture or portion thereof being coded (inter-picture and intra-picture, inter-block and intra-block, etc.), as well as other factors. The units that are included and how they are included may be controlled by subgroup control information parsed from the coded video sequence by the parser (520). The flow of such subgroup control information between the parser (520) and the following processing or functional units is not shown for the sake of simplicity.

[0038] Besides the functional blocks already mentioned, the video decoder (510) may be conceptually subdivided into several functional units, as described below. In an actual implementation operating under commercial constraints, many of these functional units may closely interact with each other and may be, at least in part, integrated with each other. However, for the purpose of clearly describing the various functions of the disclosed subject matter, a conceptual subdivision into functional units is adopted in the following disclosure.

[0039] The first unit may include a scalar / inverse transform unit (551), which may receive quantized transform coefficients as well as control information from the parser (520) including information indicating which type of inverse transform to use, block size, quantization coefficients / parameters, quantization scaling matrices, etc. The scalar / inverse transform unit (551) may output a block including sample values ​​that may be input to an aggregator (555).

[0040] In some cases, the output samples of the scaler / inverse transform (551) may relate to intra-coded blocks, i.e., blocks that do not use prediction information from a previously reconstructed picture, but may use prediction information from a previously reconstructed portion of the current picture. Such prediction information may be provided by an intra-picture prediction unit (552). In some cases, the intra-picture prediction unit (552) may generate a block of the same size and shape as the block being reconstructed using information of surrounding blocks already reconstructed and stored in the current picture buffer (558). The current picture buffer (558) buffers, for example, a partially reconstructed current picture and / or a fully reconstructed current picture. The aggregator (555) may add, on a sample-by-sample basis, the prediction information generated by the intra-prediction unit (552) to the output sample information provided by the scaler / inverse transform unit (551), in some implementations.

[0041] In other cases, the output samples of the scalar / inverse transform unit (551) may relate to an inter-coded, potentially motion-compensated block. In such cases, the motion compensated prediction unit (553) may access the reference picture memory (557) to fetch samples used for inter-picture prediction. After motion compensating the fetched samples according to the symbols (521) related to the block, these samples may be added to the output of the scalar / inverse transform unit (551) by the aggregator (555) to generate output sample information (the output of unit 551 may be referred to as a residual sample or residual signal). The address in the reference picture memory (557) from which the motion compensated prediction unit (553) fetches the prediction sample may be controlled by a motion vector available to the motion compensated prediction unit (553) in the form of a symbol (521) that may have, for example, an X component, a Y component (shift), and a reference picture component (time). Motion compensation may also include interpolation of sample values ​​fetched from a reference picture memory (557) when sub-sample accurate motion vectors are used, and may be associated with a motion vector prediction mechanism, etc.

[0042] The output samples of the aggregator (555) may be subjected to various loop filtering techniques in the loop filter unit (556). The video compression techniques may include in-loop filter techniques controlled by parameters included in the coded video sequence (also called the coded video bitstream) and provided to the loop filter unit (556) as symbols (521) from the parser (520), but may also be responsive to meta-information obtained during decoding of a previous portion (in decoding order) of the coded picture or coded video sequence, or to previously reconstructed and loop filtered sample values. As described in more detail below, several types of loop filters may be included as part of the loop filter unit 556 in various orders.

[0043] The output of the loop filter unit (556) may be a sample stream that can be output to a rendering device (512) or stored in a reference picture memory (557) for use in future inter-picture prediction.

[0044] Once a particular coded picture is fully reconstructed, it can be used as a reference picture for future inter-picture prediction. For example, once a coded picture corresponding to a current picture is fully reconstructed and the coded picture is identified as a reference picture (e.g., by the parser (520)), the current picture buffer (558) can become part of the reference picture memory (557), and a new current picture buffer can be reallocated before beginning reconstruction of a subsequent coded picture.

[0045] The video decoder (510) may perform decoding operations according to a given video compression technique adopted in a standard such as ITU-T Recommendation H.265. The coded video sequence may conform to the syntax specified by the video compression technique or standard used in the sense that the coded video sequence adheres to both the syntax of the video compression technique or standard and to the profile documented in the video compression technique or standard. Specifically, the profile may select certain tools from all tools available in the video compression technique or standard as limited tools that can be used under that profile. To conform to a standard, the complexity of the coded video sequence may be within a range defined by a level of the video compression technique or standard. In some cases, the level limits a maximum picture size, a maximum frame rate, a maximum reconstruction sample rate (e.g., measured in megasamples per second), a maximum reference picture size, etc. The limits set by the level may be further constrained in some cases by the specification of a hypothetical reference decoder (HRD) and metadata for HRD buffer management signaled within the coded video sequence.

[0046] In some example embodiments, the receiver (531) may receive additional (redundant) data along with the encoded video. The additional data may be included as part of the coded video sequence(s). The additional data may be used by the video decoder (510) to properly decode the data and / or to more accurately reconstruct the original video data. The additional data may be in the form of, for example, temporal, spatial, or signal-to-noise ratio (SNR) enhancement layers, redundant slices, redundant pictures, forward error correction codes, etc.

[0047] 6 shows a block diagram of a video encoder (603) according to an exemplary embodiment of the present disclosure. The video encoder (603) may be included in an electronic device (620). The electronic device (620) may further include a transmitter (640) (e.g., a transmitting circuit). The video encoder (603) may be used in place of the video encoder (403) of the example of FIG. 4.

[0048] The video encoder (603) may receive video samples from a video source (601) (which is not part of the electronic device (620) in the example of FIG. 6) that may capture the video image(s) to be coded by the video encoder (603). In another example, the video source (601) may be implemented as part of the electronic device (620).

[0049] The video source (601) may provide a source video sequence to be coded by the video encoder (603) in the form of a digital video sample stream that may be of any suitable bit depth (e.g., 8-bit, 10-bit, 12-bit, ...), any color space (e.g., BT.601 YCrCb, RGB, XYZ ...), and any suitable sampling structure (e.g., YCrCb 4:2:0, YCrCb 4:4:4). In a media serving system, the video source (601) may be a storage device capable of storing previously prepared video. In a video conferencing system, the video source (601) may be a camera that captures local image information as a video sequence. The video data may be provided as a number of individual pictures or images that give motion when viewed in sequence. The picture itself may be organized as a spatial array of pixels, each pixel may contain one or more samples depending on the sampling structure, color space, etc. being used. Those skilled in the art can easily understand the relationship between pixels and samples. The following description focuses on samples.

[0050] According to some example embodiments, the video encoder (603) may code and compress pictures of a source video sequence into a coded video sequence (643) in real-time or under any other time constraint required by the application. Enforcing an appropriate coding rate constitutes one function of the controller (650). In some embodiments, the controller (650) may be operatively coupled to and control other functional units as described below. For simplicity, coupling is not shown. Parameters set by the controller (650) may include rate control related parameters (picture skip, quantizer, lambda value for rate distortion optimization techniques, ...), picture size, Group of Pictures (GOP) layout, maximum motion vector search range, etc. The controller (650) may be configured to have other appropriate functions related to the video encoder (603) optimized for a particular system design.

[0051] In some example embodiments, the video encoder (603) may be configured to operate in a coding loop. As an oversimplified explanation, in one example, the coding loop may include a source coder (630) (responsible for creating symbols, such as a symbol stream, based on an input picture to be coded and a reference picture, for example) and a (local) decoder (633) embedded in the video encoder (603). The decoder (633) reconstructs the symbols to create sample data in a similar manner as a (remote) decoder would create them (even though the embedded decoder 633 processes the coded video stream by the source coder 630 without entropy coding, since any compression between the symbols and the coded video bitstream may be lossless in the video compression techniques contemplated by the disclosed subject matter). The reconstructed sample stream (sample data) is input to a reference picture memory (634). Since decoding of the symbol stream produces bit-exact results regardless of the location of the decoder (local or remote), the contents in the reference picture memory (634) are also bit-exact between the local and remote encoders. In other words, the predictive part of the encoder "sees" exactly the same sample values ​​as the reference picture samples that the decoder will "see" when using prediction during decoding. This basic principle of reference picture synchrony (and the resulting drift when synchrony cannot be maintained, e.g., due to channel errors) is used to improve coding quality.

[0052] The operation of the "local" decoder (633) may be the same as the operation of a "remote" decoder, such as the video decoder (510), already described in detail above in conjunction with Figure 5. Referring also briefly to Figure 5, however, because symbols are available and the encoding / decoding of the symbol-pair coded video sequence by the entropy coder (645) and parser (520) may be lossless, the entropy decoding portion of the video decoder (510), including the buffer memory (515) and parser (520), may not be fully implemented in the local decoder (633) within the encoder.

[0053] At this point, it can be said that any decoder technology, except for parsing / entropy decoding, which may only exist in the decoder, may also necessarily need to exist in the corresponding encoder in substantially the same functional form. For this reason, the subject matter of the disclosure may focus on the decoder operation, which is similar to the decoding part of the encoder. Thus, the description of the encoder technology may be omitted, since it is the reverse of the decoder technology described in general. Only in certain areas or aspects, a more detailed description of the encoder is provided below.

[0054] In operation, in some example implementations, the source coder (630) may perform motion-compensated predictive coding, predictively coding an input picture with reference to one or more previously coded pictures from a video sequence designated as "reference pictures." In this manner, the coding engine (632) codes color channel differences (or residuals) between pixel blocks of the input picture and pixel blocks of the reference picture(s) that may be selected as the predictive reference(s) to the input picture. The terms "residual" and its adjective form "residual" may be used interchangeably.

[0055] The local video decoder (633) may decode the coded video data of pictures that may be designated as reference pictures based on the symbols created by the source coder (630). The operation of the coding engine (632) may advantageously be a lossy process. If the coded video data may be decoded in a video decoder (not shown in FIG. 6), the reconstructed video sequence may typically be a copy of the source video sequence with some errors. The local video decoder (633) may replicate the decoding process that may be performed by the video decoder on the reference pictures and store the reconstructed reference pictures in a reference picture cache (634). In this way, the video encoder (603) may locally store copies of reconstructed reference pictures that have common content with reconstructed reference pictures obtained by a far-end (remote) video decoder (without transmission errors).

[0056] The predictor (635) may perform a prediction search for the coding engine (632). That is, for a new picture to be coded, the predictor (635) may search the reference picture memory (634) for sample data (as candidate reference pixel blocks) or specific metadata such as reference picture motion vectors, block shapes, etc., that may serve as suitable prediction references for the new picture. The predictor (635) may operate pixel block by pixel block to find a suitable prediction reference. In some cases, as determined by the search results obtained by the predictor (635), the input picture may have a prediction reference chosen from multiple reference pictures stored in the reference picture memory (634).

[0057] The controller (650) may manage the coding operations of the source coder (630), including, for example, setting the parameters and subgroup parameters used to encode the video data.

[0058] The output of all the aforementioned functional units may be entropy coded in an entropy coder (645), which converts the symbols produced by the various functional units into a coded video sequence by lossless compression of the symbols through techniques such as Huffman coding, variable length coding, arithmetic coding, etc.

[0059] The transmitter (640) may buffer the coded video sequence(s) created by the entropy coder (645) for transmission over a communication channel (660), which may be a hardware / software link to a storage device that stores the encoded video data. The transmitter (640) may merge the coded video data from the video coder (603) with other data to be transmitted, such as coded audio data and / or auxiliary data streams (sources not shown).

[0060] The controller (650) may manage the operation of the video encoder (603). The controller (650) may assign a particular coded picture type to each coded picture during coding, which may affect the coding technique that may be applied to the respective picture. For example, pictures may often be assigned as one of the following picture types:

[0061] An intra picture (I-picture) may be a picture that can be coded and decoded without using other pictures in a sequence as a source of prediction. Some video codecs allow different types of intra pictures, including, for example, independent decoder refresh ("IDR") pictures. Those skilled in the art are aware of these variations of I-pictures, as well as their respective uses and characteristics.

[0062] A predictive picture (P picture) may be a picture that can be coded and decoded using intra- or inter-prediction, which predicts sample values ​​for each block using at most one motion vector and reference index.

[0063] A bidirectionally predicted picture (B-picture) may be a picture that can be coded and decoded using intra- or inter-prediction, which predicts sample values ​​for each block using at most two motion vectors and reference indexes. Similarly, a multi-predictive picture can use more than two reference pictures and associated metadata for the reconstruction of a single block.

[0064] A source picture may generally be spatially subdivided into multiple sample coding blocks (e.g., blocks of 4x4, 8x8, 4x8, or 16x16 samples each) and coded block by block. A block may be predictively coded with reference to other (already coded) blocks as determined by a coding assignment applied to the block's respective picture. For example, a block of an I picture may be non-predictively coded or predictively coded with reference to already coded blocks of the same picture (spatial or intra prediction). A pixel block of a P picture may be predictively coded via spatial prediction or via temporal prediction with reference to one previously coded reference picture. A block of a B picture may be predictively coded via spatial prediction or via temporal prediction with reference to one or two previously coded reference pictures. A source picture or an intermediate processed picture may be subdivided into other types of blocks for other purposes. The division of coding blocks and other types of blocks may or may not follow the same manner, as described in more detail below.

[0065] The video encoder (603) may perform coding operations in accordance with a given video coding technique or standard, such as ITU-T Recommendation H.265. In so doing, the video encoder (603) may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancy in the input video sequence. The coded video data may accordingly conform to a syntax specified by the video coding technique or standard being used.

[0066] In some example embodiments, the transmitter (640) may transmit additional data along with the encoded video. The source coder (630) may include such data as part of the coded video sequence. The additional data may include temporal / spatial / SNR enhancement layers, other forms of redundant data such as redundant pictures and slices, SEI messages, VUI parameter set fragments, etc.

[0067] Video may be captured in a time sequence as multiple source pictures (video pictures). Intra-picture prediction (often abbreviated as intra prediction) exploits spatial correlation in a given picture, while inter-picture prediction exploits temporal or other correlation between pictures. For example, a particular picture being encoded / decoded, called the current picture, may be divided into blocks. If a block in the current picture is similar to a reference block in a previously coded and still buffered reference picture in the video, it may be coded by a vector, called a motion vector. A motion vector points to a reference block in a reference picture and may have a third dimension that identifies the reference picture if multiple reference pictures are used.

[0068] In some exemplary embodiments, bi-prediction techniques can be used for inter-picture prediction. According to such bi-prediction techniques, two reference pictures, such as a first reference picture and a second reference picture, both of which are before the current picture in the video in decoding order (but may be past or future, respectively, in display order), are used. A block in the current picture can be coded by a first motion vector that points to a first reference block in the first reference picture and a second motion vector that points to a second reference block in the second reference picture. A block can be jointly predicted by a combination of the first reference block and the second reference block.

[0069] Additionally, merge mode techniques may be used to improve coding efficiency in inter-picture prediction.

[0070] According to some exemplary embodiments of the present disclosure, prediction, such as inter-picture prediction and intra-picture prediction, is performed on a block-by-block basis. For example, a picture in a sequence of video pictures is divided into coding tree units (CTUs) for compression, and the CTUs in a picture may have the same size, such as 128×128 pixels, 64×64 pixels, 32×32 pixels, or 16×16 pixels. In general, a CTU may include three parallel coding tree blocks (CTBs), i.e., one luma CTB and two chroma CTBs. Each CTU may be recursively quadtree partitioned into one or more coding units (CUs). For example, a CTU of 64×64 pixels may be partitioned into one CU of 64×64 pixels, or four CUs of 32×32 pixels. Each of one or more of the 32×32 blocks may be further partitioned into four CUs of 16×16 pixels. In some exemplary embodiments, each CU may be analyzed during encoding to determine its prediction type among various prediction types, such as inter prediction type and intra prediction type. A CU may be divided into one or more prediction units (PUs) according to temporal and / or spatial predictability. In general, each PU includes one luma prediction block (PB) and two chroma PBs. In one embodiment, prediction operations in coding (encoding / decoding) are performed on a prediction block basis. The division of a CU into PUs (or PBs of different color channels) may be performed in various spatial patterns. A luma PB or a chroma PB may include a matrix of sample values ​​(e.g., luma values), for example, 8×8 pixels, 16×16 pixels, 8×16 pixels, 16×8 samples, etc.

[0071] 7 shows a diagram of a video encoder (703) according to another exemplary embodiment of the present disclosure. The video encoder (703) is configured to receive a processed block (e.g., a predictive block) of sample values ​​in a current video picture in a sequence of video pictures and to encode the processed block into a coded picture that is part of a coded video sequence. The exemplary video encoder (703) may be used in place of the example video encoder (403) of FIG. 4.

[0072] For example, the video encoder (703) receives a matrix of sample values ​​for a processing block, such as a predictive block of 8×8 samples. The video encoder (703) then determines whether the processing block is best coded using intra-mode, inter-mode, or bi-predictive mode, for example using rate-distortion optimization (RDO). If it is determined that the processing block is coded in intra-mode, the video encoder (703) may encode the processing block into a coded picture using intra-prediction techniques, and if it is determined that the processing block is coded in inter-mode or bi-predictive mode, the video encoder (703) may encode the processing block into a coded picture using inter-prediction techniques or bi-prediction techniques, respectively. In some exemplary embodiments, a merge mode, in which a motion vector is derived from one or more motion vector predictors without the benefit of coded motion vector components outside the predictors, may be used as a sub-mode of inter-picture prediction. In some other exemplary embodiments, there may be motion vector components applicable to the current block. Thus, the video encoder (703) may include components not explicitly shown in FIG. 7, such as a mode decision module, to determine the prediction mode of a processing block.

[0073] In the example of FIG. 7, the video encoder (703) includes an inter-encoder (730), an intra-encoder (722), a residual calculator (723), a switch (726), a residual encoder (724), a general-purpose controller (721), and an entropy encoder (725), coupled to each other as shown in the exemplary arrangement of FIG.

[0074] The inter-encoder (730) is configured to receive samples of a current block (e.g., a processing block), compare the block to one or more reference blocks in a reference picture (e.g., blocks in previous and subsequent pictures in display order), generate inter-prediction information (e.g., a description of redundancy information, motion vectors, merge mode information according to an inter-encoding technique), and calculate an inter-prediction result (e.g., a predicted block) based on the inter-prediction information using any suitable technique. In some examples, the reference picture is a decoded reference picture that has been decoded based on the encoded video information using a decoding unit 633 incorporated in the example encoder 620 of FIG. 6 (shown as a residual decoder 728 of FIG. 7, as described in further detail below).

[0075] The intra encoder (722) is configured to receive samples of a current block (e.g., a processing block), compare the block to already coded blocks in the same picture, generate transformed quantized coefficients, and possibly also generate intra prediction information (e.g., intra prediction direction information according to one or more intra encoding techniques). The intra encoder (722) may calculate an intra prediction result (e.g., a prediction block) based on the intra prediction information and reference blocks in the same picture.

[0076] The generic controller (721) may be configured to determine generic control data and control other components of the video encoder (703) based on the generic control data. In one example, the generic controller (721) determines a prediction mode of the block and provides a control signal to the switch (726) based on the prediction mode. For example, if the prediction mode is an intra mode, the generic controller (721) controls the switch (726) to select an intra mode result for use by the residual calculator (723) and controls the entropy encoder (725) to select intra prediction information and include the intra prediction information in the bitstream, and if the prediction mode of the block is an inter mode, the generic controller (721) controls the switch (726) to select an inter prediction result for use by the residual calculator (723) and controls the entropy encoder (725) to select inter prediction information and include the inter prediction information in the bitstream.

[0077] The residual calculator (723) may be configured to calculate a difference (residual data) between a received block and a prediction result for a block selected from the intra-encoder (722) or the inter-encoder (730). The residual encoder (724) may be configured to encode the residual data to generate transform coefficients. For example, the residual encoder (724) may be configured to transform the residual data from the spatial domain to the frequency domain to generate transform coefficients. The transform coefficients then undergo a quantization process to obtain quantized transform coefficients. In various exemplary embodiments, the video encoder (703) also includes a residual decoder (728). The residual decoder (728) is configured to perform an inverse transform and generate decoded residual data. The decoded residual data can be used appropriately by the intra-encoder (722) and the inter-encoder (730). For example, the inter-encoder (730) can generate decoded blocks based on the decoded residual data and the inter-prediction information, and the intra-encoder (722) can generate decoded blocks based on the decoded residual data and the intra-prediction information. The decoded blocks are appropriately processed to generate decoded pictures, which can be buffered in a memory circuit (not shown) and used as reference pictures.

[0078] The entropy encoder (725) may be configured to format a bitstream to include the encoded block and perform entropy coding. The entropy encoder (725) may be configured to include various information in the bitstream. For example, the entropy encoder (725) may be configured to include general control data, selected prediction information (e.g., intra-prediction information or inter-prediction information), residual information, and other suitable information in the bitstream. When coding a block in a merged sub-mode of either an inter mode or a bi-prediction mode, the residual information may not be present.

[0079] 8 shows a diagram of an example video decoder (810) according to another embodiment of the present disclosure. The video decoder (810) is configured to receive coded pictures that are part of a coded video sequence and decode the coded pictures to generate reconstructed pictures. In one example, the video decoder (810) may be used in place of the example video decoder (410) of FIG. 4.

[0080] In the example of FIG. 8, the video decoder (810) includes an entropy decoder (871), an inter-decoder (880), a residual decoder (873), a reconstruction module (874), and an intra-decoder (872), coupled to each other as shown in the exemplary arrangement of FIG. 8.

[0081] The entropy decoder (871) may be configured to reconstruct from the coded picture certain symbols that represent syntax elements of which the coded picture is composed. Such symbols may include, for example, prediction information (e.g., intra- or inter-prediction information) that may identify the mode in which the block is coded (e.g., intra-mode, inter-mode, bi-prediction mode, merged submode, or another submode), certain samples or metadata used for prediction by the intra-decoder (872) or inter-decoder (880), residual information in the form of, for example, quantized transform coefficients, etc. In one example, if the prediction mode is an inter-prediction mode or a bi-prediction mode, the inter-prediction information is provided to the inter-decoder (880), and if the prediction type is an intra-prediction type, the intra-prediction information is provided to the intra-decoder (872). The residual information may undergo inverse quantization and is provided to the residual decoder (873).

[0082] The inter decoder (880) may be configured to receive the inter prediction information and generate inter prediction results based on the inter prediction information.

[0083] The intra decoder (872) may be configured to receive intra prediction information and generate a prediction result based on the intra prediction information.

[0084] The residual decoder (873) may be configured to perform inverse quantization to extract inverse quantized transform coefficients and process the inverse quantized transform coefficients to transform the residual from the frequency domain to the spatial domain. The residual decoder (873) may also utilize certain control information that may be provided by the entropy decoder (871) (to include a quantization parameter (QP)) (data path not shown as this may be only low amount of control information).

[0085] The reconstruction module (874) may be configured to combine, in the spatial domain, the residual as output by the residual decoder (873) and the prediction result (possibly as output by an inter prediction module or an intra prediction module) to form a reconstructed block that forms part of a reconstructed picture as part of the reconstructed video. It should be noted that other suitable operations, such as a deblocking operation, may be performed to improve visual quality.

[0086] It should be noted that the video encoders (403), (603), and (703) and the video decoders (410), (510), and (810) can be implemented using any suitable technology. In some exemplary embodiments, the video encoders (403), (603), and (703) and the video decoders (410), (510), and (810) can be implemented using one or more integrated circuits. In another embodiment, the video encoders (403), (603), and (603) and the video decoders (410), (510), and (810) can be implemented using one or more processors executing software instructions.

[0087] Turning to block partitioning for coding and decoding, a general partitioning may start from a base block and follow a predefined set of rules, a specific pattern, a partitioning tree, or any partitioning structure or scheme. The partitioning may be hierarchical and recursive. After dividing or partitioning the base block according to any of the exemplary partitioning procedures described below or other procedures, or combinations thereof, a final set of partitions or coding blocks may be obtained. Each of these partitions may be at one of various partitioning levels in the partitioning hierarchy and may be of various shapes. Each of the partitions may be referred to as a coding block (CB). In various exemplary partitioning implementations described further below, each resulting CB may be of any of the allowed sizes and partitioning levels. Such partitions are referred to as coding blocks because they may form the units for which some basic coding / decoding decisions are made and coding / decoding parameters may be optimized, determined, and signaled in the encoded video bitstream. The highest or deepest level in the final partition represents the depth of the coding block partitioning tree structure. The coding blocks may be luma coding blocks or chroma coding blocks. The CB tree structure for each color is sometimes called a coding block tree (CBT).

[0088] The coding blocks of all color channels may be collectively referred to as a coding unit (CU). The hierarchical structure of all color channels may be collectively referred to as a coding tree unit (CTU). The partitioning pattern or partitioning structure of various color channels within a CTU may or may not be the same.

[0089] In some implementations, the partition tree scheme or structure used for the luma channel and the chroma channel may not be the same. In other words, the luma channel and the chroma channel may have separate coding tree structures or patterns. Furthermore, whether the luma channel and the chroma channel use the same coding partition tree structure or different coding partition tree structures, and the actual coding partition tree structure to be used, may depend on whether the slice being coded is a P slice, a B slice, or an I slice. For example, for an I slice, the chroma channel and the luma channel may have separate coding partition tree structures or coding partition tree structure modes, while for a P slice or a B slice, the luma channel and the chroma channel may share the same coding partition tree scheme. When separate coding partition tree structures or modes are applied, the luma channel may be partitioned into CB by one coding partition tree structure, and the chroma channel may be partitioned into chroma CB by another coding partition tree structure.

[0090] Returning to FIG. 2, each frame in the same sequence may have some common characteristics or properties. For example, each frame in a sequence may share the same profile, the same chroma format, the same level, etc. Thus, for decoding purposes, all frames in a sequence may share a parameter set at the sequence level, and such a parameter set is called a sequence parameter set (SPS, or sequence-level parameter set). On the decoder side, the decoder may refer to the SPS for various decoding tasks, including initializing decoding parameters, parsing the bitstream, performing memory management, etc.

[0091] In an example implementation, the SPS may include at least the following parameters: Profile, Level value, Tier value, Chroma format, Bit depth, Picture width, Picture height, Entropy coding mode, or Conversion mode.

[0092] The SPS set may be applicable to a variety of video technologies and standards, including but not limited to HEVC, VVC, AV1, AV2, AVS, AVS2, AVS3, and future generation video standards.

[0093] During the decoding process, it is important that the decoder uses the correct SPS to decode a sequence of frames, otherwise the sequence may not be decoded correctly. Various performance overheads may be introduced by the SPS. For example, the transmission of the SPS in the bitstream requires transmission bandwidth. On the decoder side, effort is required to parse the SPS from the raw data bits and to store / activate the parsed SPS for later use.

[0094] In this disclosure, various embodiments are described that aim to improve SPS implementation. In one aspect, some embodiments may improve SPS signaling efficiency. For example, the SPS may be signaled only when necessary, and the currently activated SPS (also known as the serving SPS) may be reused for subsequent video samples in the same sequence. In another aspect, some embodiments may improve the flexibility of SPS determination. For example, the SPS may be made available to the decoder (e.g., by encapsulating the SPS in the bitstream), but the decoder may determine whether an SPS update is necessary and has the flexibility to ignore the signaled SPS or update the SPS base based on the signaled SPS. In another aspect, for the same video source transmitted in different sessions, the encoder may choose to signal different SPS for the same sequence based on, for example, transmission conditions, quality of service agreements, etc. In yet another aspect, over the duration of the video streaming, the SPS applied to a video sequence may be dynamically updated to adapt to different types of decoders and / or different transmission conditions, etc., to achieve, for example, better compression ratios and / or better video quality.

[0095] In some example implementations, the serving SPS is a particular SPS used to decode the current video frame. In some scenarios, the serving SPS may be the same as the SPS used to decode a video frame previous to the current video frame, e.g., if the previous and current video frames are in the same sequence. In this case, the decoder may directly reuse the previously used SPS (e.g., the serving SPS is already stored in memory). In some scenarios, the serving SPS may be different from the SPS used to decode the previous video frame, e.g., if the previous and current video frames are in different sequences. In this case, the decoder may obtain the serving SPS, e.g., by parsing SPS-related syntax in the video bitstream.

[0096] In some example implementations, referring to FIG. 2, in each video sample, a flag may be signaled to indicate whether the current video sample encapsulates / carries an SPS. For example, in video sample 1, a flag may be signaled as true to indicate that there is an SPS1 being carried in video sample 1. Meanwhile, in video sample 2, a flag may be signaled as false to indicate that there is no SPS being carried in video sample 2. If a video sample is indicated as carrying an SPS, position information such as the length of the SPS may be further signaled. The starting position of the SPS within the video sample may be a fixed or predefined position or may be signaled. The starting position may include an offset from a particular reference point such as the start of the video frame or the start of the flag. In these implementations, the SPS may be signaled as needed when the SPS needs to be updated for a current video sample, such as video sample 1. This may be done when a new sequence is started. When a decoder processes video sample 1, it may need to parse the bitstream to retrieve the encapsulated SPS, activate the retrieved SPS, and use it to decode the video sequence in video sample 1. However, for video sample 2, the SPS is unchanged from the SPS signaled in video sample 1, so the decoder may reuse the already activated SPS1 to decode video sample 2. The activated SPS for decoding a video sample may be referred to as the serving SPS.

[0097] In some example implementations, the SPS is signaled in each video sample whether the SPS is updated or not. Referring to FIG. 2, the SPS2 is signaled in video sample n even if the same SPS2 is signaled in video sample n-1. A flag may be further signaled to indicate the SPS update status. If the flag indicates that the SPS is updated, the decoder needs to parse the bitstream to retrieve the updated SPS. Otherwise, the flag may indicate that the SPS is not updated from the previous video sample, and the decoder may have different options. In one option, the decoder may skip parsing the content of the SPS carried in the current video sample and directly use the previous SPS that has already been parsed (used for the previous video sample and stored for later use). This option is useful when the video streaming is played continuously (i.e., frames are displayed according to a timeline sequence) because it saves the SPS parsing cost. In another option, even if the flag indicates no SPS update, the decoder may nevertheless need to parse the contents of the SPS carried in the current video sample and use the newly parsed / retrieved SPS to decode the current video sample. This option is useful when the current video sample is the starting point of a random access playback, since the previously used SPS may in this case be the SPS of a random video sample and is no longer valid for the current video sample, and therefore a forced refresh on the SPS may be desirable. In these implementations, the SPS and the next frame to be displayed are encapsulated in the same video sample, so the SPS is always available to the decoder. The SPS position information may be signaled similarly to the previous implementations.

[0098] In the above exemplary implementation, whether the video streaming is in-order (following the frame timeline) or random access is transparent to the server / encoder, which encapsulates the SPS into each video sample regardless. The logic for selecting the SPS only needs to be implemented on the terminal / decoder side.

[0099] In some example implementations, an SPS update flag may be signaled to indicate the SPS update status, and the SPS is signaled with a video sample only if the SPS is updated and is different from the SPS used for the previous video sample. If the SPS update flag indicates that the SPS has been updated, the decoder may parse the bitstream to obtain the updated SPS, store / save the updated SPS, for example, in a local or on-chip memory, and continue to use the updated SPS for subsequent video samples until the SPS update flag indicates that the SPS has been updated again. On the other hand, if the SPS update flag indicates that there is no SPS update, the decoder may use the stored previous SPS without expending the effort of SPS parsing and processing. It should be noted that if the SPS update flag indicates that the SPS has been updated, position information such as the length of the SPS may be further signaled. The starting position of the SPS within the video sample may be a fixed or predefined position or may be signaled. The starting position may include an offset from a particular reference point, such as the start of the video frame or the position of the SPS update flag.

[0100] In some example implementations, a syntax element may be signaled for each video sample to indicate the length of the SPS associated with the video sample. When this length is equal to 0, it implicitly indicates that the current video sample does not carry an SPS, and thus the contents of the subsequent SPS do not need to be parsed. In this case, the decoder uses the previous SPS (for decoding the previous video sample) for proper decoding. When this length is not equal to 0, it indicates that the SPS is signaled, for example, immediately after the length information field or starting from a predefined position. The decoder parses and uses the SPS signaled / encapsulated in the current video sample.

[0101] In some example implementations, from the server side, the server or encoder may determine a list of SPSs to be used in a video streaming session and signal the list of SPSs to the terminal (decoder) when the video streaming session starts, and each SPS in the list of SPSs is identifiable by an SPS id (identifier). Then, in each video frame, the SPS id may be signaled to inform the decoder which SPS should be selected from the list of SPSs and applied when decoding the video frame. The detailed SPS content does not need to be signaled anymore. Thus, the SPS signaling overhead may be reduced, and the SPS parsing effort on the decoder is also eliminated. Furthermore, a special SPS id, such as 0, a negative number, or the maximum number supported by the SPS id field (such as 0xff, the SPS id is one byte long), may be used to indicate that there is no SPS update and the decoder may directly use the previous SPS. These implementations may be particularly useful for random access scenarios.

[0102] In some example implementations, instead of the server / encoder signaling the list of SPSs as described in the above implementations, the terminal / decoder receiving the video streaming may collect and maintain the list of SPSs. For example, the SPS may be signaled in the video sample, and the SPS may include an id. The decoder may maintain the list of SPSs by adding any new SPS received (indicated by its id) to the list. For each video sample, the decoder may first perform a search to check whether the SPS indicated by the SPS id (e.g., carried in the video sample) is already present in the list of SPSs. If the decoder can find a particular SPS from the list of SPSs, parsing the content of the SPS from the bitstream may be skipped. In one implementation, the list of SPSs may be implemented by a circular buffer to avoid excessive memory usage.

[0103] In some example implementations, if the current video sample includes a random video sequence resulting from a random access request, the encoder may make a determination as to whether the SPS of the random video sequence is the same as the SPS used for the last video sample provided to the receiving terminal (e.g., a decoder). For example, as shown in FIG. 2, if the last played sequence is in video sample 1 and the next sequence is a random sequence in video sample n (i.e., the video jumps from video sample 1 to video sample n), there is an SPS update (from SPS1 to SPS2), so the bitstream signals an SPS update flag indicating the SPS update. The decoder correspondingly retrieves the updated SPS. However, when jumping to video sample n, if the last played sequence also uses SPS2, the SPS update flag indicates that there is no update to the SPS, and no SPS is signaled in video sample n. Thus, even if the current video sample is a random access starting point, the decoder may still reuse the previous SPS.

[0104] 9 illustrates an example method 900 for processing video data. The method includes the following steps: step 910, receiving a bitstream including at least one video sample, the at least one video sample including a current video sample and a previous video sample, each of the at least one video sample including at least one video frame, each of the at least one video sample being associated with a serving sequence parameter set (SPS) for decoding each of the at least one video sample; and step 920, determining a serving SPS for the current video sample based on the serving SPS. the previous SPS, already parsed from the bitstream and used to decode the previous video sample, The current SPS encapsulated in the current video sample, and An SPS in the list of candidate SPSs, and step 930, decoding the current video sample based on the serving SPS for the current video sample.

[0105] In the embodiments and implementations of the present disclosure, any steps and / or operations may be combined or arranged in any quantity or order as desired. Two or more of the steps and / or operations may be performed in parallel. The embodiments and implementations of the present disclosure may be used separately or combined in any order. Furthermore, each of the methods (or embodiments), the encoder, and the decoder may be implemented by processing circuitry (e.g., one or more processors or one or more integrated circuits). In one example, the one or more processors execute a program stored on a non-transitory computer-readable medium.

[0106] The techniques described above can be implemented as computer software using computer readable instructions and physically stored on one or more computer readable media. For example, Figure 10 illustrates a computer system (2800) suitable for implementing certain embodiments of the disclosed subject matter.

[0107] Computer software can be coded using any suitable machine code or computer language that can be subjected to mechanisms such as assembly, compilation, linking, etc. to produce code containing instructions that can be executed directly, or via interpretation, microcode execution, etc., by one or more computer central processing units (CPUs), graphics processing units (GPUs), etc.

[0108] The instructions may be executed on various types of computers or computer components including, for example, personal computers, tablet computers, servers, smartphones, gaming consoles, Internet of Things devices, and the like.

[0109] 10 for the computer system (2800) are exemplary in nature and are not intended to suggest any limitation as to the scope of use or functionality of the computer software implementing the embodiments of the present disclosure. The arrangement of components should not be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the exemplary embodiment of the computer system (2800).

[0110] The computer system (2800) may include certain human interface input devices. Such human interface input devices may be responsive to input by one or more human users, for example, via tactile input (keystrokes, swipes, data glove movements, etc.), audio input (voice, clapping, etc.), visual input (gestures, etc.), and olfactory input (not shown). Human interface devices may also be used to capture certain media not necessarily directly associated with conscious human input, such as audio (voice, music, ambient sounds, etc.), images (scanned images, photographic images still images captured from a camera, etc.), and video (two-dimensional video, three-dimensional video including stereoscopic video, etc.).

[0111] The input human interface devices may include one or more (only one of each shown) of a keyboard (2801), a mouse (2802), a trackpad (2803), a touch screen (2810), a data glove (not shown), a joystick (2805), a microphone (2806), a scanner (2807), and a camera (2808).

[0112] The computer system (2800) may also include certain human interface output devices. Such human interface output devices may stimulate one or more of the human user's senses, for example, by haptic output, sound, light, and smell / taste. Such human interface output devices may include haptic output devices (e.g., haptic feedback via a touch screen (2810), data gloves (not shown), or joystick (2805), although there may also be haptic feedback devices that do not function as input devices), audio output devices (speakers (2809), headphones (not shown), etc.), visual output devices (e.g., screens (2810) including CRT screens, LCD screens, plasma screens, OLED screens, virtual reality glasses (not shown), holographic displays, and smoke tanks (not shown), each with or without touch screen input capability, each with or without haptic feedback capability, some of which may be capable of outputting output in more than three dimensions by means of two-dimensional visual output or stereoscopic output, etc.), and printers (not shown).

[0113] The computer system (2800) may also include human accessible storage devices and their associated media, such as optical media, including CD / DVD ROM / RW (2820) with CD / DVD or similar media (2821), thumb drives (2822), removable hard drives or solid state drives (2823), legacy magnetic media such as tape or floppy disks (not shown), and dedicated ROM / ASIC / PLD based devices such as security dongles (not shown).

[0114] Those skilled in the art will also understand that the term "computer-readable medium" as used in connection with the subject matter of this disclosure does not encompass transmission media, carrier waves, or other transitory signals.

[0115] The computer system (2800) may also include an interface (2854) to one or more communication networks (2855). The networks may be, for example, wireless, wired, optical. The networks may further be local, wide area, metropolitan, vehicular and industrial, real-time, delay tolerant, etc. Examples of networks include local area networks such as Ethernet, cellular networks including wireless LAN, GSM, 3G, 4G, 5G, LTE, etc., television wired or wireless wide area digital networks including cable television, satellite television and terrestrial television, vehicular and industrial including CAN bus, etc. Certain networks generally require an external network interface adapter connected to a particular general-purpose data port or peripheral bus (2849) (e.g., a USB port of the computer system (2800)), while other networks are generally integrated into the core of the computer system (2800) by connecting to a system bus (e.g., an Ethernet interface to a PC computer system, a cellular network interface to a smartphone computer system), as described below. Using any of these networks, the computer system (2800) can communicate with other entities. Such communications can be one-way receive only (e.g., television broadcast), one-way transmit only (e.g., a CANbus to a particular CANbus device), or two-way to other computer systems using, for example, local or wide area digital networks. Specific protocols and protocol stacks can be used in each of these networks and network interfaces, as described above.

[0116] The aforementioned human interface devices, human accessible storage devices, and network interfaces may be attached to the core (2840) of the computer system (2800).

[0117] The cores (2840) may include one or more central processing units (CPUs) (2841), graphics processing units (GPUs) (2842), dedicated programmable processing units in the form of field programmable gate areas (FPGAs) (2843), hardware accelerators for specific tasks (2844), graphics adapters (2850), and the like. These devices may be connected via a system bus (2848), along with read only memory (ROM) (2845), random access memory (2846), internal mass storage (2847), such as an internal non-user accessible hard drive, SSD, and the like. In some computer systems, the system bus (2848) may be accessible in the form of one or more physical plugs to allow expansion with additional CPUs, GPUs, and the like. Peripheral devices may be attached directly to the core's system bus (2848) or via a peripheral bus (2849). In one example, a screen (2810) may be connected to the graphics adapter (2850). Peripheral bus architectures include PCI, USB, and the like.

[0118] The CPU (2841), GPU (2842), FPGA (2843), and accelerator (2844) can combine to execute certain instructions that may constitute the aforementioned computer code. The computer code can be stored in ROM (2845) or RAM (2846). Persistent data can be stored, for example, in internal mass storage (2847), while temporary data can also be stored in RAM (2846). Rapid storage and retrieval in any of the memory devices can be made possible by the use of cache memory, which can be closely associated with one or more of the CPU (2841), GPU (2842), mass storage (2847), ROM (2845), RAM (2846), etc.

[0119] The computer-readable medium can bear computer code for performing various computer-implemented operations. The medium and computer code can be those specially designed and constructed for the purposes of the present disclosure, or they can be of the available kind well known to those skilled in the computer software arts.

[0120] As a non-limiting example, a computer system (2800) having an architecture, and specifically a core (2840), can provide functionality as a result of a processor (or processors) (including CPUs, GPUs, FPGAs, accelerators, etc.) executing software embodied in one or more tangible computer-readable media. Such computer-readable media can be user-accessible mass storage as introduced above, as well as media associated with a particular storage of the core (2840) that is non-transitory in nature, such as mass storage (2847) internal to the core or ROM (2845). Software implementing various embodiments of the present disclosure can be stored in such devices and executed by the core (2840). The computer-readable media can include one or more memory devices or chips, depending on the particular need. The software can cause the core (2840), and in particular the processors therein (including CPUs, GPUs, FPGAs, etc.), to execute certain processes or certain portions of certain processes described herein, including defining data structures stored in RAM (2846) and modifying such data structures according to processes defined by the software. Additionally or alternatively, the computer system can provide functionality as a result of logic hardwired or otherwise embodied in circuitry (e.g., accelerators (2844)) that can operate to execute certain processes or certain portions of certain processes described herein in place of or in conjunction with software. References to software can encompass logic, and vice versa, where appropriate. References to computer-readable media can encompass circuitry (such as integrated circuits (ICs)) that store software for execution, circuitry that embodies logic for execution, or both, where appropriate. The present disclosure encompasses any appropriate combination of hardware and software.

[0121] Although this disclosure uses visual media as an example, the proposed embodiments may be used in other similar scenarios, such as audio or other types of media content.

[0122] While this disclosure describes several exemplary embodiments, there exist modifications, substitutions, and various alternative equivalents, which fall within the scope of this disclosure. Thus, it will be appreciated that those skilled in the art can devise numerous systems and methods that, although not explicitly shown or described herein, embody the principles of this disclosure and are therefore within the spirit and scope of this disclosure.

[0123] Appendix A: Acronyms IBC: Intra-Block Copy IntraBC: Intra-Block Copy JEM: Joint exploration model VVC: versatile video coding BMS: Benchmark set MV: Motion Vector HEVC: High Efficiency Video Coding SEI: Supplementary Enhancement Information VUI: Video Usability Information GOP: Group of Pictures TU: Transform Units PU: Prediction Units CTU: Coding Tree Units CTB: Coding Tree Blocks PB: Prediction Blocks HRD: Hypothetical Reference Decoder SNR: Signal Noise Ratio CPU: Central Processing Units GPU: Graphics Processing Units CRT: Cathode Ray Tube LCD: Liquid Crystal Display OLED: Organic Light-Emitting Diode CD: Compact Disc DVD: Digital Video Disc ROM: Read-Only Memory RAM: Random Access Memory ASIC: Application-Specific Integrated Circuit PLD: Programmable Logic Device LAN: Local Area Network GSM: Global System for Mobile communications LTE: Long-Term Evolution CANBus: Controller Area Network Bus USB: Universal Serial Bus PCI: Peripheral Component Interconnect FPGA: Field Programmable Gate Areas SSD: Solid-state drive IC: Integrated Circuit HDR: High dynamic range SDR: standard dynamic range JVET: Joint Video Exploration Team MPM: Most probable mode WAIP: Wide-Angle Intra Prediction CU: Coding Unit PU: Prediction Unit TU: Transform Unit CTU: Coding Tree Unit PDPC: Position Dependent Prediction Combination ISP: Intra Sub-Partitions SPS: Sequence Parameter Setting PPS: Picture Parameter Set APS: Adaptation Parameter Set VPS: Video Parameter Set DPS: Decoding Parameter Set ALF: Adaptive Loop Filter SAO: Sample Adaptive Offset CC-ALF: Cross-Component Adaptive Loop Filter CDEF: Constrained Directional Enhancement Filter CCSO: Cross-Component Sample Offset LSO: Local Sample Offset LR: Loop Restoration Filter AV1:AOMedia Video 1 AV2:AOMedia Video 2 AVS: Audio and Video Coding Standard AVS2: The Second Generation AVS Standard AVS3: The Third Generation AVS Standard DASH: Dynamic Adaptive Streaming over HTTP ISO BMFF: ISO Base Media File Format VOD: Video on Demand RPS: Reference Picture Set [Explanation of symbols]

[0124] 1 video sample, 2 video sample, 110 terminal, 120 server, 202 video sample, 300 communication system, 310 terminal device, 320 terminal device, 330 terminal device, 340 terminal device, 350 network, 400 communication system, 401 video source, 402 stream of video pictures, 403 video encoder, 404 encoded video data, encoded video bitstream, 405 streaming server, 406 client subsystem, 407 copy of encoded video data, 408 client subsystem, 409 copy of encoded video data, 410 video decoder, 411 output stream of video pictures, 412 display, 413 video capture subsystem, 420 electronic device, 430 electronic device, 501 channel, 510 video decoder, 512 rendering device, display, 515 buffer memory, 520 parser, 521 symbols, 531 receiver, 551 Scaler / inverse transform unit, 552 Intra picture prediction unit, 553 Motion compensation prediction unit, 555 Aggregator, 556 Loop filter, 557 Reference picture memory, 558 Current picture buffer, 601 Video source, 603 Video encoder, video coder, 620 Electronic device, 630 Source coder, 632 Coding engine, 633 Local video decoder, decoding unit, 634 Reference picture memory, reference picture cache, 635 Predictor, 640 Transmitter, 643 Coded video sequence, 645 Entropy coder, 650 Controller, 660 Communication channel, 703 Video encoder, 721 General controller, 722 Intra encoder, 723 Residual calculator, 724 Residual encoder, 725 Entropy encoder, 726 Switch, 728 Residual decoder, 730 Inter encoder, 810 Video decoder, 871 Entropy decoder, 872 Intra decoder, 873 Residual decoder, 874 Reconstruction module, 880 Inter decoder, 900 Method for processing video data, 2800 Computer system, 2801keyboard, 2802 mouse, 2803 track pad, 2805 joystick, 2806 microphone, 2807 scanner, 2808 camera, 2809 audio output device speaker, 2810 touch screen, 2820 CD / DVD ROM / RW, 2821 CD / DVD or similar medium, 2822 thumb drive, 2823 removable hard drive or solid state drive, 2840 core, 2841 central processing unit, CPU, 2842 graphics processing unit, GPU, 2843 field programmable gate area, FPGA, 2844 hardware accelerator, 2845 read only memory, ROM, 2846 random access memory, 2847 internal mass storage, 2848 system bus, 2849 peripheral bus, 2850 graphics adapter, 2854 interface, 2855 communication network

Claims

1. 1. A method for video processing, the method comprising: receiving a bitstream including at least one video sample, the at least one video sample including a current video sample and a previous video sample, each of the at least one video sample including at least one video frame, each of the at least one video sample being associated with a serving sequence parameter set (SPS) for decoding the each of the at least one video sample; The serving SPS for the current video sample may be of the following types: a previous SPS that has already been parsed from the bitstream and used to decode the previous video sample; the current SPS encapsulated in said current video sample, and An SPS in the list of candidate SPSs, and determining the first criterion as one of and decoding the current video sample based on the serving SPS for the current video sample and the determined type of the serving SPS. The SPS has the following parameters: Profile, Level value, Tier value, Chroma format, Bit depth, Picture width, Picture height, Entropy coding mode, and A method comprising:

2. The step of determining the serving SPS for the current video sample comprises: extracting from the bitstream an SPS present flag indicating whether the current video sample encapsulates the current SPS; in response to the SPS present flag indicating that the current video sample encapsulates the current SPS, extracting position information of the current SPS from the bitstream; parsing the bitstream based on the position information to obtain the current SPS; and determining the current SPS as the serving SPS for the current video sample.

3. The method of claim 2 , further comprising: determining the previous SPS as the serving SPS for the current video sample in response to the SPS present flag indicating that the current video sample does not encapsulate the current SPS.

4. said each of said at least one video sample encapsulates an SPS; the SPS encapsulated in the current video sample is the current SPS; The step of determining the serving SPS for the current video sample comprises: extracting from the bitstream an SPS update status flag indicating whether the serving SPS has been updated since the previous SPS used to decode the previous video sample; determining the current SPS as the serving SPS according to the SPS update status flag indicating that the serving SPS has been updated from the previous SPS; in response to the SPS update status flag indicating that the serving SPS has not been updated from the previous SPS, ignoring the current SPS in the current video sample and skipping parsing, and determining the previous SPS as the serving SPS for the current video sample. The method of claim 1.

5. The method of claim 1 , wherein the current SPS is encapsulated in the current video sample in response to the current video sample being a starting point of a random access request.

6. The step of determining the serving SPS for the current video sample comprises: The method of claim 5 , comprising: determining the current SPS as the serving SPS for the current video sample in response to the current video sample being a starting point of a random access request.

7. storing the serving SPS for the current video sample; receiving a next video sample from the bitstream that follows the current video sample; determining that the serving SPS for the next video sample has not been updated from the serving SPS for the current video sample; decoding the next video sample based on the serving SPS for the current video sample; The method of claim 1, further comprising:

8. The method further comprises, prior to receiving the bitstream including the at least one video sample, receiving the list of candidate SPSs from the bitstream; The step of determining the serving SPS for the current video sample comprises: extracting from the bitstream an SPS identifier that identifies an SPS in the list of candidate SPSs associated with the current video sample; determining the SPS in the list of candidate SPSs identified by the SPS identifier as the serving SPS for the current video sample. The method of claim 1.

9. the current video sample encapsulates the current SPS, The method further includes determining whether the current SPS is in the list of candidate SPSs; The step of determining the serving SPS for the current video sample comprises: In response to the current SPS not being within the list of candidate SPSs, parsing the current video sample to obtain the current SPS; adding the current SPS to the list of candidate SPSs; determining the current SPS as the serving SPS for the current video sample; In response to the current SPS being in the list of candidate SPSs, retrieving the current SPS from the list of candidate SPSs; determining the current SPS as the serving SPS for the current video sample. The method of claim 1.

10. The step of determining the serving SPS for the current video sample comprises: extracting from the bitstream an SPS length indicator associated with the current video sample, the SPS length indicator indicating a length of the current SPS encapsulated in the current video sample; determining, in response to the length of the current SPS indicated by the SPS length indicator being zero, that the serving SPS is the previous SPS used to decode the previous video sample; In response to the length of the current SPS indicated by the SPS length indicator being not zero, extracting position information of the current SPS from the bitstream; parsing the bitstream based on the position information to obtain the current SPS; and determining the current SPS as the serving SPS for the current video sample.

11. A device for video processing, the device comprising a memory for storing computer instructions and a processor in communication with the memory, the processor being configured, when the processor executes the computer instructions, to cause the device to perform a method according to any one of claims 1 to 10.

12. A computer program product which, when executed by a processor in a device for video processing, causes said processor to perform the method according to any one of claims 1 to 10.

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