Subpicture division and scaling window information

Abstract

Aspects of the present disclosure provide a method, an apparatus, and a non-transitory computer-readable storage medium for video decoding. The apparatus includes a processing circuit configured to decode at least one of a first flag or a second flag in a syntax structure for a first picture in a coded video sequence (CVS). The first flag may indicate whether first sub-picture partition information of the first picture is signaled in the syntax structure. The second flag may indicate whether first sub-picture scaling window information for a first sub-picture included in the first picture is signaled in the syntax structure. The processing circuit reconstructs the first sub-picture based on at least one of the first flag indicating that the first sub-picture partition information of the first picture is signaled in the syntax structure or the second flag indicating that the first sub-picture scaling window information for the first sub-picture is signaled in the syntax structure.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Application No. 63 / 215,937, entitled "Techniques for subpicture-wise reference picture resampling and scalability for video streaming," filed June 28, 2021, which claims the benefit of priority to U.S. Provisional Application No. 17 / 850,608, entitled "SUBPICTURE PARTITIONING AND SCALING WINDOW INFORMATION," filed June 27, 2022. The disclosures of the prior applications are incorporated herein by reference in their entireties.

[0002] This disclosure generally describes embodiments related to video coding. [Background technology]

[0003] The discussion of the background art provided herein is intended to provide a general context for the present disclosure. The work of the inventors named herein is not admitted, expressly or impliedly, as prior art to the present disclosure to the extent that their work is described in this Background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing.

[0004] Image and / or video coding and decoding can be performed using inter-picture prediction with motion compensation. Uncompressed digital images and / or videos can include a sequence of pictures, each having spatial dimensions of, for example, 1920x1080 luma samples and associated chroma samples. The sequence of pictures can have a fixed or variable (also informally known as frame rate) picture rate of, for example, 60 pictures per second or 60 Hz. Uncompressed images and / or videos have specific bitrate requirements. For example, 1080p60 4:2:0 video (1920x1080 luma sample resolution at a frame rate of 60 Hz) at 8 bits per sample requires a bandwidth approaching 1.5 Gbit / s. One hour of such video requires more than 600 Gbytes of storage space.

[0005] One objective of image and / or video coding and decoding may be to reduce redundancy in the input image and / or video signal through compression. Compression may help reduce the aforementioned bandwidth and / or storage space requirements, in some cases by more than one order of magnitude. In the description herein, video encoding / decoding is used as an illustrative example, but similar schemes may be applied to image encoding / decoding without departing from the spirit of this disclosure. Both lossless and lossy compression may be employed, as well as combinations thereof. Lossless compression refers to techniques that can reconstruct an exact copy of an original signal from a compressed original signal. With lossy compression, the reconstructed signal may not be identical to the original signal, but the distortion between the original and reconstructed signals is small enough to make the reconstructed signal useful for the intended application. For video, lossy compression is widely adopted. The amount of acceptable distortion depends on the application, e.g., a user of a particular consumer streaming application may tolerate higher distortion than a user of a television distribution application. The achievable compression ratio may reflect that a higher acceptable / tolerable distortion may result in a higher compression ratio.

[0006] Video encoders and decoders may utilize techniques from a number of broad categories, including, for example, motion compensation, transform, quantization, and entropy coding.

[0007] Video codec techniques may include a technique known as intra-coding. In intra-coding, sample values ​​are represented without reference to samples or other data from previously reconstructed reference pictures. In some video codecs, a picture is spatially subdivided into blocks of samples. When all blocks of samples are intra-mode decoded, the picture may be an intra picture. Intra pictures, and their derivatives, such as independent decoder refresh pictures, may be used to reset the decoder state, and therefore may be used as the first picture in a coded video bitstream and video session, or as still images. Samples of an intra block may be subjected to a transform, and the transform coefficients may be quantized before entropy coding. Intra prediction may be a technique that minimizes sample values ​​in the pre-transform domain. In some cases, the smaller the DC value after the transform and the smaller the AC coefficients, the fewer bits are needed at a given quantization step size to represent the block after entropy coding.

[0008] Conventional intra-coding, for example as known from MPEG-2 generation coding techniques, does not use intra-prediction. However, some newer video compression techniques include techniques that attempt to predict from surrounding sample data and / or metadata obtained during encoding and / or decoding of a data block that is, for example, spatially adjacent and preceding in decoding order. Such techniques are hereafter referred to as "intra-prediction" techniques. It should be noted that, at least in some cases, intra-prediction uses only reference data from the current picture being reconstructed, and not from a reference picture.

[0009] There may be many different forms of intra-prediction. When two or more of such techniques may be used in a given video coding technique, the technique in use may be coded in intra-prediction mode. In certain cases, a mode may have sub-modes and / or parameters that may be coded separately or included in the codeword of the mode. Which codeword is used for a given mode, sub-mode, and / or parameter combination may affect the coding efficiency gains via intra-prediction, and thus may also affect the entropy coding technique used to convert the codeword into a bitstream.

[0010] A particular mode of intra prediction was introduced in H.264, improved in H.265, and further improved in newer coding techniques such as the joint exploration model (JEM), versatile video coding (VVC) and benchmark set (BMS). A predictor block can be formed using neighboring sample values ​​belonging to already available samples. The sample values ​​of the neighboring samples are copied to the predictor block according to the direction. The reference to the direction in use can be coded in the bitstream or it can be predicted itself.

[0011] Referring to FIG. 1A, depicted at the bottom right is a subset of 9 predictor directions known from the 33 possible predictor directions (corresponding to the 33 angle modes of the 35 intra modes) of H.265. The point (101) where the arrows converge represents the sample being predicted. The arrows represent the direction from which the sample is predicted. For example, arrow (102) indicates that sample (101) is predicted from one or more samples to the upper right at an angle of 45 degrees from the horizontal. Similarly, arrow (103) indicates that sample (101) is predicted from one or more samples to the lower left of sample (101) at an angle of 22.5 degrees from the horizontal.

[0012] 1A, at the top left is depicted a square block (104) of 4x4 samples (indicated by a thick dashed line). The square block (104) contains 16 samples, each labeled with "S", its position in the Y dimension (e.g., row index) and its position in the X dimension (e.g., column index). For example, sample S21 is the second sample (from the top) in the Y dimension and the first sample (from the left) in the X dimension. Similarly, sample S44 is the fourth sample in both the Y and X dimensions in the block (104). Since the block is 4x4 samples in size, S44 is at the bottom right. Also shown are reference samples that follow a similar numbering scheme. The reference samples are labeled R, their Y position (e.g., row index) and X position (column index) relative to the block (104). In both H.264 and H.265, the predicted samples are adjacent to the block being reconstructed, so negative values ​​do not need to be used.

[0013] Intra-picture prediction may work by copying reference sample values ​​from adjacent samples as assigned by the signaled prediction direction. For example, assume that the coded video bitstream includes signaling for this block indicating a prediction direction that coincides with the arrow (102), i.e., the sample is predicted from one or more prediction samples located to the upper right at an angle of 45 degrees from the horizontal. In that case, samples S41, S32, S23, and S14 are predicted from the same reference sample R05. Then, sample S44 is predicted from reference sample R08.

[0014] In certain cases, especially when the orientation is not evenly divisible by 45 degrees, the values ​​of multiple reference samples may be combined, for example by interpolation, to calculate the reference sample.

[0015] The number of possible directions is increasing as video coding techniques develop. In H.264 (2003), nine different directions could be represented. In H.265 (2013), this increased to 33, and at the time of this disclosure, JEM / VVC / BMS can support up to 65 directions. Experiments have been performed to identify the most likely directions, and certain techniques of entropy coding are used to represent those likely directions with a small number of bits, accepting a certain penalty for less likely directions. Furthermore, the direction itself may be predicted from neighboring directions used in adjacent already decoded blocks.

[0016] FIG. 1B shows a schematic diagram (110) depicting 65 intra prediction directions with JEM to illustrate the increasing number of prediction directions over time.

[0017] The mapping of intra-prediction direction bits in a coded video bitstream that represent the directions may vary from one video coding technique to another, ranging, for example, from a simple direct mapping of prediction directions to intra-prediction modes, to complex adaptation schemes involving codewords, most likely modes, and similar techniques. In all cases, however, there may be certain directions that are statistically less likely to occur in the video content than certain other directions. Because the goal of video compression is to reduce redundancy, these less likely directions are represented by more bits than more likely directions in well-performing video coding techniques.

[0018] Motion compensation may be a lossy compression technique, and may refer to a technique in which blocks of sample data from a previously reconstructed picture or part thereof (reference picture) are used to predict a newly reconstructed picture or part of a picture after being spatially shifted in a direction indicated by a motion vector (hereafter MV). In some cases, the reference picture may be the same as the picture currently being reconstructed. The MV may have two dimensions X and Y, or three dimensions, with the third dimension being an indication of the reference picture in use (the latter may indirectly be a temporal dimension).

[0019] In some video compression techniques, the MV applicable to a particular region of sample data may be predicted from other MVs, e.g., from an MV associated with another region of sample data that is spatially adjacent to the region being reconstructed and precedes that MV in decoding order. Doing so may significantly reduce the amount of data required to code the MV, thereby eliminating redundancy and increasing the compression ratio. For example, when coding an input video signal derived from a camera (known as natural video), MV prediction may work effectively since there exists a statistical possibility that a region larger than the region to which a single MV is applicable moves in a similar direction, and thus, in some cases, may be predicted using similar motion vectors derived from MVs of neighboring regions. As a result, the detected MV for a given region is similar or the same as the MV predicted from the surrounding MVs, and after entropy coding, may be represented with fewer bits than would be used when coding the MV directly. In some cases, MV prediction may be an example of lossless compression of a signal (i.e., MV) derived from the original signal (i.e., sample stream). In other cases, the MV prediction itself may be lossy, e.g., due to rounding errors when computing a predictor from several surrounding MVs.

[0020] Various MV prediction mechanisms are described in H.265 / HEVC (ITU-T Rec. H.265, "High Efficiency Video Coding", December 2016). Among the many MV prediction mechanisms that H.265 offers, the one described herein is a technique hereafter referred to as "spatial merging".

[0021] Referring to Figure 2, a current block (201) contains samples that the encoder found during the motion search process to be predictable from a previous block of the same size but spatially shifted. Instead of coding its MV directly, the MV can be derived from metadata associated with one or more reference pictures, e.g., from the most recent reference picture (in decoding order), using MVs associated with any one of five surrounding samples, denoted A0, A1, and B0, B1, B2 (202-206, respectively). In H.265, MV prediction can use predictors from the same reference picture that neighboring blocks use. Summary of the Invention [Means for solving the problem]

[0022] Aspects of the present disclosure provide a method and apparatus for video encoding and video decoding. In some examples, the apparatus for video decoding includes a processing circuit. The processing circuit is configured to decode at least one of a first flag or a second flag in a syntax structure for a first picture in a coded video sequence (CVS). The first picture includes a first sub-picture. The first flag can indicate whether first sub-picture partition information of the first picture is signaled in the syntax structure. The second flag can indicate whether first sub-picture scaling window information for the first sub-picture is signaled in the syntax structure. The processing circuit can reconstruct the first sub-picture based on at least one of the first flag indicating that the first sub-picture partition information of the first picture is signaled in the syntax structure or the second flag indicating that the first sub-picture scaling window information for the first sub-picture is signaled in the syntax structure.

[0023] In one embodiment, the syntax structure is a first picture parameter set (PPS) syntax structure.

[0024] In one embodiment, at least one of the first flag and the second flag includes a first flag, the first flag indicating that first sub-picture split information for the first picture is signaled in the syntax structure.

[0025] In one embodiment, the first picture includes a plurality of sub-pictures, the plurality of sub-pictures including a first sub-picture, and the processing circuitry can determine a first sub-picture layout of the plurality of sub-pictures in the first picture based on the first sub-picture partition information, the first sub-picture layout including a size and a position of each of the plurality of sub-pictures in the first picture.

[0026] In one embodiment, a sub-picture identifier (ID) for each sub-picture in the first picture may be determined based on the first sub-picture partition information in the syntax structure.

[0027] In one embodiment, the syntax structure is a first picture parameter set (PPS) syntax structure. The processing circuit can decode second sub-picture partition information signaled in the second PPS syntax structure for the second picture in the CVS. The processing circuit can reconstruct a second sub-picture in the second picture based on the second sub-picture partition information. The second sub-picture layout of the second picture may be different from the first sub-picture layout of the first picture.

[0028] In one embodiment, the first picture is in a first layer in the CVS. The processing circuit can decode second sub-picture partition information signaled in another syntax structure for a second picture in a second layer in the CVS. The second sub-picture partition information can be different from the first sub-picture partition information. The processing circuit can reconstruct a second sub-picture in the second picture based on the second sub-picture partition information.

[0029] In one embodiment, at least one of the first flag and the second flag includes a second flag, where the second flag indicates that first sub-picture scaling window information of the first sub-picture is signaled in the syntax structure.

[0030] In one embodiment, the processing circuit decodes the first sub-picture scaling window information of the first sub-picture based on the syntax structure. The processing circuit can reconstruct the first sub-picture using per-sub-picture reference picture resampling based on the first sub-picture scaling window information of the first sub-picture.

[0031] In one embodiment, at least one of the first flag and the second flag further includes a first flag. The first flag indicates that the first sub-picture partition information is signaled in the syntax structure. The processing circuit can decode the first sub-picture scaling window information of the first sub-picture based on the syntax structure. The processing circuit can determine the first sub-picture dimension information and the position information based on the first sub-picture partition information. The processing circuit can reconstruct the first sub-picture based on the first sub-picture scaling window information of the first sub-picture, the first sub-picture dimension information, and the first sub-picture position information.

[0032] Aspects of the present disclosure also provide a non-transitory computer-readable storage medium, the non-transitory computer-readable storage medium storing a program executable by at least one processor to perform a method for video decoding.

[0033] 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]

[0034] [Figure 1A] FIG. 2 is a schematic diagram of an example subset of intra-prediction modes. [Figure 1B] FIG. 2 is a diagram of an example intra-prediction direction. [Diagram 2] FIG. 2 illustrates a current block (201) and surrounding samples according to one embodiment. [Diagram 3] 1 is a schematic diagram of a simplified block diagram of a communication system (300), according to one embodiment. [Figure 4] FIG. 4 is a schematic diagram of a simplified block diagram of a communication system (400) according to one embodiment. [Diagram 5] FIG. 2 is a schematic diagram of a simplified block diagram of a decoder according to one embodiment. [Figure 6]FIG. 2 is a schematic diagram of a simplified block diagram of an encoder according to one embodiment. [Figure 7] FIG. 4 is a block diagram illustrating an encoder according to another embodiment. [Figure 8] FIG. 4 is a block diagram illustrating a decoder according to another embodiment. [Figure 9] 1 illustrates an example of a slice header that includes references to a picture parameter set (PPS), a sequence parameter set (SPS), and a video parameter set (VPS), according to one embodiment of the present disclosure. [Figure 10] 1 illustrates an exemplary image including multiple picture-in-pictures, according to one embodiment of the present disclosure. [Figure 11] 1 illustrates an example of enhanced display of local regions according to one embodiment of the present disclosure. [Figure 12] 1 illustrates an exemplary architectural design involving sub-pictures and multi-layers, according to one embodiment of the present disclosure. [Figure 13] 1 illustrates an example of a reference sub-picture scaling window within a reference picture and a sub-picture scaling window within a sub-picture, according to one embodiment of the present disclosure. [Figure 14A] 1 illustrates an exemplary sub-picture layout update process in a coded video sequence (CVS), according to one embodiment of the present disclosure. [Figure 14B] 1 illustrates an exemplary sub-picture layout update process in a CVS, according to one embodiment of the present disclosure. [Figure 15] 1 illustrates an exemplary sub-picture layout in different layers in a CVS, according to one embodiment of the present disclosure. [Figure 16] 1 shows a flowchart outlining an encoding process according to one embodiment of the present disclosure. [Figure 17] 1 shows a flowchart outlining a decoding process according to one embodiment of the present disclosure. [Figure 18] 1 is a schematic diagram of a computer system, according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] FIG. 3 illustrates a simplified block diagram of a communication system (300) according to one embodiment of the present disclosure. The communication system (300) includes, for example, a plurality of terminal devices that can communicate with each other 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) perform unidirectional transmission of data. For example, the terminal device (310) can code video data (e.g., a stream of video pictures captured by the terminal device (310)) for transmission to another terminal device (320) via the network (350). The encoded video data can be transmitted in the form of one or more coded video bitstreams. The terminal device (320) can 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. Unidirectional data transmission may be common, such as in media serving applications.

[0036] In another example, the communication system (300) includes a second pair of terminal devices (330) and (340) performing a bidirectional transmission of coded video data, such as may occur during a video conference. In the case of a bidirectional transmission of data, in one example, each of the terminal devices (330) and (340) can code video data (e.g., 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) can also receive coded video data transmitted by the other of the terminal devices (330) and (340), can decode the coded video data to recover the video pictures, and can display the video pictures on an accessible display device according to the recovered video data.

[0037] In the example of FIG. 3, the terminal devices (310), (320), (330), and (340) may be depicted as a server, a personal computer, and a smartphone, although the principles of the present disclosure may not be so limited. Embodiments of the present disclosure find application with laptop computers, tablet computers, media players, and / or dedicated video conferencing equipment. The network (350) represents any number of networks that convey coded video data between the terminal devices (310), (320), (330), and (340), including, for example, wired and / or wireless communication networks. The communication network (350) may exchange data over circuit-switched and / or packet-switched channels. Representative networks include telecommunications networks, local area networks, wide area networks, and / or the Internet. For purposes of this description, the architecture and topology of the network (350) may not be important to the operation of the present disclosure, unless otherwise described herein below.

[0038] 4 shows an arrangement of a video encoder and a video decoder in a streaming environment as one example for application of the disclosed subject matter. The disclosed subject matter may be equally applicable to other video-enabled applications including, for example, video conferencing, digital television, storage of compressed video on digital media including CDs, DVDs, memory sticks, etc.

[0039] The streaming system may include a video source (401), e.g., a capture subsystem (413) that may include a digital camera, for example, that creates a stream of uncompressed video pictures (402). In one example, the stream of video pictures (402) includes samples taken by a digital camera. The stream of video pictures (402), depicted as thick lines to emphasize the large amount of data when compared to the encoded video data (404) (or coded video bitstream), 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 coded video bitstream), depicted as thin lines to emphasize the small amount of data when compared to the stream of video pictures (402), may be stored in a streaming server (405) 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 an electronic device (430). The video decoder (410) decodes an input copy (407) of the encoded video data and creates an output stream (411) of video pictures that can be rendered on a display (412) (e.g., a display screen) or other rendering device (not depicted). In some streaming systems, the encoded video data (404), (407), and (409) (e.g., a video bitstream) can be encoded according to a particular video coding / compression standard.Examples of those 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.

[0040] It should be noted that the electronic devices (420) and (430) can include other components (not shown). For example, the electronic device (420) can include a video decoder (not shown), and the electronic device (430) can also include a video encoder (not shown).

[0041] 5 shows a block diagram of a video decoder (510) according to one embodiment of the present disclosure. The video decoder (510) may be included in an electronic device (530). The electronic device (530) may include a receiver (531) (e.g., a receiving circuit). The video decoder (510) may be used in place of the video decoder (410) of the example of FIG. 4.

[0042] The receiver (531) may receive one or more coded video sequences to be decoded by the video decoder (510), one coded video sequence at a time in the same or another embodiment, with the decoding of each coded video sequence being independent of the other coded video sequences. 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. The receiver (531) may receive the encoded video data together with other data, e.g., coded audio data and / or auxiliary data streams, that may be forwarded to their respective using entities (not depicted). The receiver (531) may separate the coded video sequences from the other data. To combat network jitter, a buffer memory (515) may be coupled between the receiver (531) and the entropy decoder / parser (520) (hereinafter "parser (520)"). In certain applications, the buffer memory (515) is part of the video decoder (510). In other applications, it may be outside the video decoder (510) (not depicted). In still other applications, there may be a buffer memory (not depicted) outside the video decoder (510), e.g., to combat network jitter, plus another buffer memory (515) inside the video decoder (510), e.g., to handle playout timing. When the receiver (531) is receiving data from a store / forward device of sufficient bandwidth and controllability, or from an isosynchronous network, the buffer memory (515) may not be needed or may be small.For use in a best effort packet network such as the Internet, the buffer memory (515) may be required, may be relatively large, and preferably may be of adaptive size, and may be implemented at least in part in an operating system or similar element (not depicted) outside the video decoder (510).

[0043] The video decoder (510) may include a parser (520) to reconstruct symbols (521) from the coded video sequence. These categories of symbols include information used to manage the operation of the video decoder (510) and potentially information for controlling a rendering device such as a rendering device (512) (e.g., a display screen) that is not an integral part of the electronic device (530) but may be coupled to the electronic device (530) as shown in FIG. 5. The control information for the rendering device may be in the form of a supplemental enhancement information (SEI message) or a video usability information (VUI) parameter set fragment (not depicted). The parser (520) may parse / entropy decode the received coded video sequence. The coding of the coded video sequence may follow a video coding technique or standard and may follow a variety of principles including variable length coding, Huffman coding, arithmetic coding, with or without context sensitivity, etc. The parser (520) can extract a set of subgroup parameters for at least one of the subgroups of pixels in the video decoder from the coded video sequence based on at least one parameter corresponding to the group. The subgroups can include groups of pictures (GOPs), pictures, tiles, slices, macroblocks, coding units (CUs), blocks, transform units (TUs), prediction units (PUs), etc. The parser (520) can also extract information from the coded video sequence, such as transform coefficients, quantizer parameter values, motion vectors, etc.

[0044] The parser (520) can perform entropy decoding / parsing operations on the video sequence received from the buffer memory (515) to create symbols (521).

[0045] The reconstruction of the symbols (521) can involve a number of different units, depending on the type of coded video picture or part thereof (interpicture and intrapicture, interblock and intrablock, etc.) and other factors. Which units are involved and how can 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 units is not depicted for the sake of clarity.

[0046] Beyond 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 units may interact closely with each other and may be at least partially integrated with each other. However, for purposes of describing the disclosed subject matter, the following conceptual subdivision into functional units is appropriate.

[0047] The first unit is a scalar / inverse transform unit (551), which receives quantized transform coefficients as well as control information from the parser (520) including which transform to use, block size, quantization coefficients, quantization scaling matrices, etc. as symbols (521). The scalar / inverse transform unit (551) can output blocks containing sample values ​​that can be input to an aggregator (555).

[0048] In some cases, the output samples of the scaler / inverse transform unit (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) generates a block of the same size and shape as the block being reconstructed using surrounding already reconstructed information fetched from a 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) adds, possibly 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).

[0049] 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 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 (in this case referred to as residual samples or residual signals). The addresses in the reference picture memory (557) from which the motion compensated prediction unit (553) fetches the prediction samples may be controlled by motion vectors available to the motion compensated prediction unit (553) in the form of symbols (521), which may have, for example, X, Y, and reference picture components. Motion compensation may also include interpolation of sample values ​​fetched from the reference picture memory (557) when sub-sample accurate motion vectors are used, motion vector prediction mechanisms, etc.

[0050] The output samples of the aggregator (555) may be subjected to various loop filtering techniques in a loop filter unit (556). Video compression techniques may include in-loop filter techniques that are controlled by parameters contained in the coded video sequence (also called the coded video bitstream) and made available to the loop filter unit (556) as symbols (521) from the parser (520), but may also be responsive to previously reconstructed and loop filtered sample values ​​as well as to meta-information obtained during decoding of a coded picture or previous portion (in decoding order) of the coded video sequence.

[0051] The output of the loop filter unit (556) may be a sample stream that can be stored in a reference picture memory (557) for use in future inter-picture prediction as well as output to a rendering device (512).

[0052] Once fully reconstructed, a particular coded picture may be used as a reference picture for future prediction. For example, once a coded picture corresponding to a current picture is fully reconstructed and the coded picture is identified (e.g., by the parser (520)) as a reference picture, the current picture buffer (558) can become part of the reference picture memory (557), and any unused current picture buffer can be reallocated before beginning reconstruction of the next coded picture.

[0053] The video decoder (510) may perform decoding operations according to a given video compression technique in a standard such as ITU-T Rec. H.265. The coded video sequence may conform to the syntax specified by the video compression technique or standard being used, in the sense that the coded video sequence adheres to both the syntax of the video compression technique or standard and the profile documented in the video compression technique. In particular, the profile may select some tools from all tools available in the video compression technique or standard as the only tools available for use under that profile. Also, what is required for compliance may be that the complexity of the coded video sequence is within a range defined by the level of the video compression technique or standard. In some cases, the level limits the maximum picture size, maximum frame rate, maximum reconstruction sample rate (e.g., measured in megasamples per second), maximum reference picture size, etc. The limits set by the level may in some cases be further limited by a Hypothetical Reference Decoder (HRD) specification and metadata for HRD buffer management signaled in the coded video sequence.

[0054] In one embodiment, the receiver (531) can receive additional (redundant) data along with the encoded video. The additional data may be included as part of the coded video sequence. 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 noise ratio (SNR) enhancement layers, redundant slices, redundant pictures, forward error correction codes, etc.

[0055] 6 shows a block diagram of a video encoder (603) according to one embodiment of the present disclosure. The video encoder (603) is included in an electronic device (620). The electronic device (620) includes a transmitter (640) (e.g., a transmission circuit). The video encoder (603) can be used in place of the video encoder (403) of the example of FIG. 4.

[0056] The video encoder (603) can receive video samples from a video source (601) (which is not part of the electronic device (620) in the example of FIG. 6) that can capture video images to be coded by the video encoder (603). In another example, the video source (601) is part of the electronic device (620).

[0057] 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 Y CrCB, RGB, ...) and any suitable sampling structure (e.g., Y CrCb 4:2:0, Y CrCb 4:4:4). In a media serving system, the video source (601) may be a storage device that stores 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 multiple individual pictures that convey motion when viewed in sequence. The pictures themselves 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. in use. Those skilled in the art can easily understand the relationship between pixels and samples. The following description focuses on samples.

[0058] According to one embodiment, the video encoder (603) can 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 is one function of the controller (650). In some embodiments, the controller (650) controls and is operatively coupled to other functional units described below. For clarity, coupling is not depicted. Parameters set by the controller (650) can 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) can be configured to have other appropriate functions associated with the video encoder (603) optimized for a particular system design.

[0059] In some embodiments, the video encoder (603) is configured to operate in a coding loop. As an oversimplified explanation, in one example, the coding loop can include a source coder (630) (e.g., responsible for creating symbols, such as a symbol stream, based on an input picture to be coded and a reference picture) as well as a (local) decoder (633) embedded in the video encoder (603). The decoder (633) reconstructs the symbols to create sample data in a manner similar to that which the (remote) decoder also does (since any compression between the symbols and the coded video bitstream is lossless in the video compression techniques contemplated in the disclosed subject matter). The reconstructed sample stream (sample data) is input to a reference picture memory (634). Since decoding of the symbol stream leads to a bit-exact result regardless of the location of the decoder (local or remote), the content in the reference picture memory (634) is also bit-exact between the local and remote encoders. In other words, the prediction part of the encoder "sees" exactly the same sample values ​​as the reference picture samples that the decoder "sees" 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 also used in several related technologies.

[0060] 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. However, and with brief reference again to Figure 5, because symbols are available and the encoding / decoding of symbols into a 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 the parser (520), may not be fully implemented in the local decoder (633).

[0061] In one embodiment, the decoder techniques, except for parsing / entropy decoding, present in the decoder are present in the same or substantially the same functional form in the corresponding encoder. Thus, the disclosed subject matter focuses on the operation of the decoder. A description of the encoder techniques can be omitted, since they are the inverse of the decoder techniques described generically. In certain areas, more detailed descriptions are provided below.

[0062] In operation, in some examples, the source coder (630) may perform motion-compensated predictive coding, which predictively codes 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 differences between pixel blocks of the input picture and pixel blocks of reference pictures that may be selected as predictive references for the input picture.

[0063] 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 preferably be a lossy process. When the coded video data may be decoded in a video decoder (not shown in FIG. 6), the reconstructed video sequence may be a replica of the source video sequence, usually 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, such that the reconstructed reference pictures are stored in the reference picture memory (634). In this way, the video encoder (603) may locally store copies of reconstructed reference pictures that have common content as reconstructed reference pictures obtained by a far-end video decoder (without transmission errors).

[0064] The predictor (635) may perform a prediction search for the coding engine (632). That is, for a coded new picture, 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 on sample blocks on a pixel block by pixel block basis to find suitable prediction references. In some cases, as determined by the search results obtained by the predictor (635), the input picture may have prediction references drawn from multiple reference pictures stored in the reference picture memory (634).

[0065] The controller (650) can manage the coding operations of the source coder (630), including, for example, setting the parameters and subgroup parameters used to encode the video data.

[0066] The output of all the aforementioned functional units may undergo entropy coding in an entropy coder (645), which converts the symbols produced by the various functional units into a coded video sequence by losslessly compressing the symbols according to techniques such as Huffman coding, variable length coding, arithmetic coding, etc.

[0067] The transmitter (640) can buffer the coded video sequence created by the entropy coder (645) and prepare it 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) can merge the coded video data from the video encoder (603) with other data to be transmitted, such as coded audio data and / or auxiliary data streams (sources not shown).

[0068] The controller (650) can manage the operation of the video encoder (603). During coding, the controller (650) can assign a particular coded picture type to each coded picture, which may affect the coding techniques that may be applied to the respective picture. For example, pictures are often assigned as one of the following picture types:

[0069] An intra picture (I-picture) may be one that can be coded and decoded without using any other picture in a sequence as a prediction source. Some video codecs allow various 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 and their respective uses and characteristics.

[0070] A predictive picture (P picture) may be a picture that can be coded and decoded using intra- or inter-prediction, which uses at most one motion vector and reference index to predict the sample values ​​of each block.

[0071] A bidirectionally predicted picture (B-picture) may be a picture that can be coded and decoded using intra- or inter-prediction that uses at most two motion vectors and reference indices to predict the sample values ​​of each block. Similarly, a multi-prediction picture may use more than two reference pictures and associated metadata for the reconstruction of a single block.

[0072] A source picture is generally spatially subdivided into multiple sample blocks (e.g., blocks of 4x4, 8x8, 4x8, or 16x16 samples each) and may be coded block by block. Blocks may be predictively coded with reference to other (already coded) blocks as determined by the coding assignment applied to the respective picture of the block. For example, blocks of an I-picture may be non-predictively coded, or they may be predictively coded with reference to already coded blocks of the same picture (spatial or intra prediction). Pixel blocks of a P-picture may be predictively coded via spatial prediction or via temporal prediction with reference to one previously coded reference picture. Blocks 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.

[0073] The video encoder (603) may perform coding operations in accordance with a given video coding technique or standard, such as ITU-T Rec. H.265. In its operations, the video encoder (603) may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancy in the input video sequence. Thus, the coded video data may conform to a syntax specified by the video coding technique or standard being used.

[0074] In one embodiment, the transmitter (640) can 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.

[0075] A video may be captured in time sequence as multiple source pictures (video pictures). Intra-picture prediction (often abbreviated as intra-prediction) exploits spatial correlation within a given picture, while inter-picture prediction exploits correlation (temporal or other) between pictures. In one example, a particular picture being encoded / decoded, called the current picture, is divided into blocks. When a block in the current picture is similar to a reference block in a reference picture that was previously coded and is still buffered in the video, the block in the current picture 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.

[0076] In some embodiments, bi-prediction techniques may be used in inter-picture prediction. According to bi-prediction techniques, two reference pictures, such as a first reference picture and a second reference picture, both of which are earlier in decoding order than the current picture in the video (but may be past and future in display order, respectively), are used. A block in the current picture may 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 may be predicted by a combination of the first reference block and the second reference block.

[0077] Furthermore, in inter-picture prediction, merge mode techniques may be used to improve coding efficiency.

[0078] According to some embodiments of the present disclosure, predictions such as inter-picture prediction and intra-picture prediction are performed on a block-by-block basis. For example, according to the HEVC standard, a picture in a sequence of video pictures is divided into coding tree units (CTUs) for compression, and the CTUs in a picture have the same size, such as 64×64 pixels, 32×32 pixels, or 16×16 pixels. In general, a CTU includes three coding tree blocks (CTBs), one luma CTB and two chroma CTBs. Each CTU can be recursively quadtree partitioned into one or more coding units (CUs). For example, a 64×64 pixel CTU can be partitioned into one 64×64 pixel CU, or four 32×32 pixel CUs, or sixteen 16×16 pixel CUs. In one example, each CU is analyzed to determine the prediction type of the CU, such as an inter prediction type or an intra prediction type. A CU is 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 in units of prediction blocks. Taking a luma prediction block as an example of a prediction block, the prediction block includes a matrix of pixel values ​​(e.g., luma values) of 8×8 pixels, 16×16 pixels, 8×16 pixels, 16×8 pixels, etc.

[0079] 7 shows a diagram of a video encoder (703) according to another 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. In one example, the video encoder (703) is used in place of the video encoder (403) of the example of FIG. 4.

[0080] In an HEVC 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) determines whether the processing block is best coded using intra-mode, inter-mode, or bi-predictive mode, e.g., using rate-distortion optimization. When the processing block is coded in intra-mode, the video encoder (703) can encode the processing block into a coded picture using intra-prediction techniques, and when the processing block is coded in inter-mode or bi-predictive mode, the video encoder (703) can encode the processing block into a coded picture using inter-prediction techniques or bi-prediction techniques, respectively. In certain video coding techniques, the merge mode can be an inter-picture prediction sub-mode in which motion vectors are derived from one or more motion vector predictors without the benefit of coded motion vector components outside the predictors. In certain other video coding techniques, there may be motion vector components applicable to the current block. In one example, the video encoder (703) includes other components, such as a mode decision module (not shown), to determine the mode of the processing block.

[0081] 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 controller (721), and an entropy encoder (725) coupled together as shown in FIG.

[0082] 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 a previous picture and a subsequent picture), generate inter-prediction information (e.g., a description of redundancy information, motion vectors, merge mode information from an inter-encoding technique), and calculate an inter-prediction result (e.g., a prediction block) based on the inter-prediction information using any suitable technique. In some examples, the reference picture is a decoded reference picture that is decoded based on the encoded video information.

[0083] The intra encoder (722) is configured to receive samples of a current block (e.g., a processing block), possibly compare the block with already coded blocks in the same picture, generate quantized coefficients after transformation, and possibly also generate intra prediction information (e.g., intra prediction direction information according to one or more intra encoding techniques). In one example, the intra encoder (722) also calculates intra prediction results (e.g., a prediction block) based on the intra prediction information and reference blocks in the same picture.

[0084] The generic controller (721) is 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 the mode of the block and provides a control signal to the switch (726) based on the mode. For example, when the 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 when the mode 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.

[0085] The residual calculator (723) is configured to calculate a difference (residual data) between the received block and a prediction result selected from the intra-encoder (722) or the inter-encoder (730). The residual encoder (724) is configured to operate on the residual data to encode the residual data to generate transform coefficients. In one example, the residual encoder (724) is 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 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 by the intra-encoder (722) and the inter-encoder (730) as appropriate. For example, the inter-encoder (730) may generate decoded blocks based on the decoded residual data and the inter-prediction information, and the intra-encoder (722) may generate decoded blocks based on the decoded residual data and the intra-prediction information. In some examples, the decoded blocks are suitably processed to generate decoded pictures, which may be buffered in a memory circuit (not shown) and used as reference pictures.

[0086] The entropy encoder (725) is configured to format a bitstream to include the encoded block. The entropy encoder (725) is configured to include various information in accordance with an appropriate standard, such as the HEVC standard. In one example, the entropy encoder (725) is configured to include in the bitstream general control data, selected prediction information (e.g., intra-prediction information or inter-prediction information), residual information, and other appropriate information. It should be noted that, according to the disclosed subject matter, when coding a block in a merged sub-mode of either an inter mode or a bi-prediction mode, no residual information is present.

[0087] 8 shows a diagram of a 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 to decode the coded pictures to generate reconstructed pictures. In one example, the video decoder (810) is used in place of the video decoder (410) of the example of FIG. 4.

[0088] 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 together as shown in FIG. 8.

[0089] 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 prediction information or inter prediction information) that may identify the mode in which the block is coded (e.g., intra mode, inter mode, bi-predictive mode, merged sub-mode, or another sub-mode, the latter two of which), certain samples or metadata used for prediction by the intra decoder (872) or inter decoder (880), respectively, such as residual information in the form of quantized transform coefficients. In one example, when the prediction mode is an inter mode or bi-predictive mode, the inter prediction information is provided to the inter decoder (880), and when 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).

[0090] The inter decoder (880) is configured to receive the inter prediction information and to generate inter prediction results based on the inter prediction information.

[0091] The intra decoder (872) is configured to receive the intra prediction information and to generate a prediction result based on the intra prediction information.

[0092] The residual decoder (873) is configured to perform inverse quantization to extract dequantized transform coefficients, and process the dequantized transform coefficients to transform the residual from the frequency domain to the spatial domain. The residual decoder (873) may also require certain control information (to include quantizer parameters (QP)), which may be provided by the entropy decoder (871) (this may be only a small amount of control information, so the data path is not depicted).

[0093] The reconstruction module (874) is configured to combine, in the spatial domain, the residual output by the residual decoder (873) with a prediction result (possibly output by an inter-prediction module or an intra-prediction module) to form a reconstructed block, which may be part of a reconstructed picture, which may be part of a reconstructed video. It should be noted that other suitable operations, such as a deblocking operation, may be performed to improve visual quality.

[0094] It should be noted that the video encoders (403), (603), and (703) and the video decoders (410), (510), and (810) may be implemented using any suitable technique. In one embodiment, the video encoders (403), (603), and (703) and the video decoders (410), (510), and (810) may 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) may be implemented using one or more processors executing software instructions.

[0095] According to an embodiment of the present disclosure, a bitstream may include one or more coded video sequences (CVSs). A CVS may be coded independently of other CVSs. Each CVS may include one or more layers, where each layer may be a representation of a video with a particular quality (e.g., spatial resolution) or a particular component interpretation property, such as a depth map, a transparency map, or a perspective view. In the temporal dimension, each CVS may include one or more access units (AUs). Each AU may include one or more pictures of different layers corresponding to the same time instance. A coded layered video sequence (CLVS) is a per-layer CVS that may include a sequence of picture units in the same layer. If there are multiple layers in a bitstream, the CVS in the bitstream may have one or more CLVSs per layer.

[0096] In one embodiment, the CVS includes a sequence of AUs, where the sequence of AUs includes an Intra Random Access Point (IRAP) AU in decoding order, followed by zero or more AUs that are not IRAP AUs. In one example, the zero or more AUs include all subsequent AUs up to and including any subsequent AU that is an IRAP AU. In one example, the CLVS includes a sequence of pictures and associated non-video coding layer (VCL) network abstraction layer (NAL) units of a base layer of the CVS.

[0097] The parameter sets may be part of the video bitstream or may be received at the decoder through other means (including out-of-band transmission using a reliable channel, hard-coding at the encoder and decoder, etc.) The parameter sets may include, but are not limited to, a video parameter set (VPS), a sequence parameter set (SPS), a picture parameter set (PPS), etc.

[0098] High level syntax structures may include a VPS, SPS, PPS, supplemental enhancement information (SEI) message, slice header, picture header, tile group header, etc.

[0099] A VPS can contain information that is applicable to multiple layers and sub-layers. In one example, each layer of a video sequence references the same VPS.

[0100] An SPS may contain information that applies to slices of a coded video sequence. An SPS may include one or more of the following: 1) a self-reference or identifier (ID), 2) decoder operation point related information (e.g., profile, level, picture size, number of sub-layers), 3) enablement flags for specific tools in the profile and associated coding tool parameters if the tool is enabled, 4) information that limits the flexibility of coding of structure and transform coefficients, 5) temporal scalability control, and 6) visual usability information (VUI).

[0101] The PPS may include syntax elements that apply to zero or more entire coded pictures, for example as determined by syntax elements found in a slice header. The PPS may include information that may change from picture to picture. The PPS may include one or more of the following: 1) a self-reference or ID, 2) initial picture control information, such as an initial quantization parameter (QP), a number of flags indicating the use or presence of certain tools, or control information in the slice header, and 3) tiling information.

[0102] Slice headers can contain information that may vary from slice to slice, as well as picture-related information that is relatively small or relevant only to a particular slice or picture type.

[0103] 9 illustrates an example of a slice header that includes references to a PPS, an SPS, and a VPS, according to one embodiment of the present disclosure. The slice header references a PPS (e.g., pps_id:4). The PPS (e.g., pps_id:4) may include a reference to an SPS (e.g., sps_id:1). The SPS (e.g., sps_id:1) may include a reference to a VPS (e.g., vps_id:0).

[0104] Each type of parameter set can include an extension mechanism, allowing the parameter sets to be extended to future versions of a video coding technology or standard.

[0105] A sub-picture in a picture may refer to a rectangular arrangement of samples, blocks, macroblocks, CUs, or similar entities that are semantically grouped and may be coded separately at a modified resolution. One or more sub-pictures may form a picture. One or more coded sub-pictures may form a coded picture. One or more sub-pictures may be assembled into a picture, and one or more sub-pictures may be extracted from a picture. In certain circumstances, one or more coded sub-pictures may be assembled in the compressed domain without transcoding into a sample-level coded picture. In one embodiment, one or more coded sub-pictures may be extracted from a coded picture in the compressed domain.

[0106] In one embodiment, a picture includes one or more sub-pictures. Each sub-picture may cover a local area or the entire area of ​​the picture. The area supported by a sub-picture may or may not overlap with another area supported by another sub-picture. The area covered by one or more sub-pictures may or may not cover the entire area of ​​the picture. If a picture includes sub-pictures, the area supported by the sub-pictures may be the same as the area supported by the picture.

[0107] Sub-pictures may be coded by coding methods similar to those used for coded pictures as described in this disclosure. Sub-pictures may be coded independently or dependent on other sub-pictures or coded pictures. Sub-pictures may or may not have analysis dependencies from other sub-pictures or coded pictures.

[0108] A coded sub-picture may be included in one or more layers. The coded sub-pictures within a layer may have different spatial resolutions. An original sub-picture may be spatially resampled (e.g., upsampled or downsampled) and coded with different spatial resolution parameters and included in a bitstream corresponding to a layer.

[0109] A subpicture having dimensions (W, H), where W and H denote the width and height of the subpicture, respectively, may be coded and included in the coded bitstream corresponding to layer 0. An upsampled (or downsampled) subpicture from a subpicture having the original spatial resolution may be coded and included in the coded bitstream corresponding to layer k. The upsampled (or downsampled) subpicture may have dimensions W×S w,k Width and H×S h,kThe parameter S w,k and S. h,k indicate the horizontal and vertical resampling rates, respectively.

[0110] A coded subpicture within a layer may have a different visual quality than a coded subpicture within another layer within the same subpicture or a different subpicture.

[0111] A coded sub-picture in a layer may be independently decodable without analysis or decoding dependency from a coded sub-picture in another layer of the same local region. A sub-picture layer that may be independently decodable without reference to another sub-picture layer of the same local region may be an independent sub-picture layer. A coded sub-picture in an independent sub-picture layer may or may not have a decoding or analysis dependency from a previously coded sub-picture in the same sub-picture layer, but the coded sub-picture may have no dependency from a coded picture in another sub-picture layer.

[0112] A coded subpicture in a layer may be dependently decodable due to parsing or decoding dependency from a coded subpicture in another layer of the same local region. A subpicture layer that may be dependently decodable with reference to another subpicture layer of the same local region may be a dependent subpicture layer. A coded subpicture in a dependent subpicture may refer to a coded subpicture in the same subpicture, a previously coded subpicture in the same subpicture layer, or both reference subpictures.

[0113] A coded subpicture may include one or more independent subpicture layers and one or more dependent subpicture layers. There may be at least one independent subpicture layer for a coded subpicture. The value of a layer identifier (e.g., layer_id) of an independent subpicture layer, which may be present in a NAL unit header or another high-level syntax structure, may be equal to 0. A subpicture layer with layer_id equal to 0 may be a base subpicture layer.

[0114] A picture may include one or more foreground subpictures and one background subpicture. The area supported by the background subpicture may be equal to the area of ​​the picture. The area supported by the foreground subpicture may overlap with the area supported by the background subpicture. The background subpicture may be a base subpicture layer, and the foreground subpicture may be a non-base (e.g., enhanced) subpicture layer. One or more non-base subpicture layers may reference the same base layer for decoding. Each non-base subpicture layer with a first layer_id may reference a non-base subpicture layer with a second layer_id, the first layer_id being greater than the second layer_id.

[0115] A picture can contain one or more foreground subpictures, with or without background subpictures. Each subpicture can have its own base subpicture layer and one or more non-base (e.g., enhancement) layers. Each base subpicture layer can be referenced by one or more non-base subpicture layers.

[0116] Each coded subpicture in a base or non-base subpicture layer may be referenced by one or more non-base layer subpictures that belong to the same subpicture and by one or more non-base layer subpictures that are not in the same subpicture.

[0117] A CVS may contain a group of coded pictures. A CVS may contain one or more Coded Sub-Picture Sequences (CSPS), which may contain a group of coded sub-pictures covering the same local area of ​​a picture. The temporal resolution of a CSPS may be the same as or different from the temporal resolution of the CVS.

[0118] A CSPS may be coded and included in one or more layers. A CSPS may include one or more CSPS layers. Decoding one or more CSPS layers corresponding to a CSPS can reconstruct a sequence of sub-pictures corresponding to the same local region.

[0119] This disclosure includes techniques for sub-picture-by-subpicture reference picture resampling and scalability for video streaming.

[0120] Image / video coding technologies such as VVC are being developed for a variety of applications, including ultra-high definition (UHD) video streaming, immersive media solutions (e.g., 360-degree video, point cloud, 6 degrees of freedom), gaming, and / or e-sports. E-sports can be used for live broadcast and / or real-time streaming events. In one example, e-sports as an online application includes competitive video games in which multiple players, e.g., in teams, play against each other. Matches can be live-streamed to fans. Cloud-based game streaming solutions (e.g., Tencent's Start) allow e-sports to enable professional gamers to play matches remotely and simultaneously. Gameplay along with the video and audio of the commentators can be broadcast to viewers in real-time.

[0121] Computer-generated (CG) test sequences, including mobile game content such as multiplayer online battle arena (MOBA) games (e.g., Arena of Valor) developed for mobile devices, have been studied. CG content may have unique characteristics that differ from natural images captured by a camera. Specific coding tools (e.g., IBC) specialized for game content sequences have been developed and adopted. Convenience functions and system interfaces with advanced syntax design have been developed.

[0122] According to one embodiment of the present disclosure, local enhancement of visual quality or resolution may be employed.

[0123] A viewer can view and view live video of a particular E-Sports match, including images of commentators, players, scoreboards, and game screens. Multiple windows for picture-in-picture (PIP) can be advantageous for E-Sports broadcasting to simultaneously display multiple images on the player's screen. Figure 10 shows an example image (or picture) (1000) including multiple PIPs in an E-Sports broadcasting, according to one embodiment of the present disclosure.

[0124] An E-Sport broadcasting system can mix and / or switch between multiple video inputs. The multiple video inputs can include video inputs associated with team players, commentators, and game videos. A main broadcast image (or main video) that mixes a subset (e.g., the most interesting input images) or the entire set of multiple video inputs into a video sequence can be encoded as a main bitstream and streamed to a remote audience (e.g., all remote viewers). The main bitstream can include general input videos. The visual quality of each input video can be relatively low depending on the respective picture resolution or bitrate.

[0125] Each input video can be encoded at a higher quality and / or resolution and optionally transmitted to the viewer as a separate bitstream. Each video can be dependently encoded by referencing a main video, where the main video can include each video as a PIP. In one example, each video can be encoded as an enhancement layer (e.g., a base layer) of a local region of the main video by referencing a decoded picture(s) in the main video. In one example, the enhancement layer is independently encoded without any decoding dependency on the main video and transmitted as a simulcast.

[0126] 11 shows an example of a highlighted display of a local region according to an embodiment of the present disclosure. From a user experience perspective, when a client or viewer (user or viewer) receives a main video (1101) and one or more enhanced videos of local regions, the viewer can select one of the main videos and one or more enhanced videos of the local regions. Referring to FIG. 11, the local regions may include region 0 covered by PIP 0, region 1 covered by PIP 1, region 2 covered by PIP 2, and region 3 covered by PIP 3. The one or more enhanced videos of the local region may include enhanced video of PIP 0 in region 0 in Enhancement Layer 1 (or Enhancement Layer 1 in PIP 0), enhanced video of PIP 1 in region 1 in Enhancement Layer 1 (or Enhancement Layer 1 in PIP 1), enhanced video of PIP 1 in region 1 in Enhancement Layer 2 (or Enhancement Layer 2 in PIP 1), enhanced video of PIP 2 in region 2 in Enhancement Layer 1 (or Enhancement Layer 1 in PIP 2), enhanced video of PIP 2 in region 2 in Enhancement Layer 2 (or Enhancement Layer 2 in PIP 2), enhanced video of PIP 3 in region 3 in Enhancement Layer 1 (or Enhancement Layer 1 in PIP 3), enhanced video of PIP 3 in region 3 in Enhancement Layer 2 (or Enhancement Layer 2 in PIP 3), and enhanced video of PIP 3 in region 3 in Enhancement Layer 3 (or Enhancement Layer 3 in PIP 3).

[0127] When a viewer selects the main video (1101), the PIPs, such as PIPs 0-3 (e.g., all PIPs), may be displayed in the background picture. When a viewer selects a particular PIP (e.g., one of one or more enhanced videos, such as Enhancement Layer 3 of PIP 3), the PIP (e.g., PIP 3) may be enlarged and displayed with enhanced visual quality compared to the corresponding decoded region of the main video (1101). In one example, Enhancement Layer 3 of PIP 3 is selected by the viewer to be displayed with a higher spatial resolution than the spatial resolution of PIP 3 in the main video, the spatial resolution of Enhancement Layer 1 of PIP 3, and the spatial resolution of Enhancement Layer 2 of PIP 3.

[0128] The above description regarding the PIP in FIG. 11 can be applied when the PIP in FIG. 11 is replaced by the respective sub-pictures. For example, a local region may be covered by a respective sub-picture. The main video may include the sub-picture in the base layer. One or more enhanced videos of a local region may be included in the bitstream. An example of an enhanced video of a local region is the enhanced video of a sub-picture of region 0 of enhancement layer 1.

[0129] FIG. 12 illustrates an exemplary systematic design with sub-pictures and multi-layers according to one embodiment of the present disclosure. Multiple input videos (e.g., input videos 0-3) can be mixed or combined into a main video (1200) by a video composer (1210). A region (e.g., a rectangular region) of the main video (1200) corresponding to an input video (e.g., input video 0) can be encoded as a sub-picture, such as sub-picture 0 (e.g., a VVC sub-picture coded based on VVC). Referring to FIG. 12, sub-pictures 0-3 correspond to input videos 0-3, respectively.

[0130] The coded bitstream of the main video (1200) may include multiple sub-pictures (e.g., sub-pictures 0-3). The coded bitstream of the main video (1200) may include multiple sub-bitstreams corresponding to the sub-pictures (e.g., sub-pictures 0-3). For example, sub-bitstreams 0-3 correspond to sub-pictures 0-3, respectively. The sub-bitstreams corresponding to the sub-pictures may be extractable from the main bitstream and may be independently decodable. Each sub-bitstream may include one or more layers having different qualities (e.g., different spatial resolutions or visual qualities). A sub-bitstream may be referenced by another sub-bitstream including a sub-picture layer having a higher resolution. Referring to FIG. 12, sub-bitstream 3 corresponding to sub-picture 3 (1222) may be referenced by enhanced sub-bitstream 3 corresponding to sub-picture 3 (1220) having an enhanced resolution (e.g., higher resolution). For example, sub-picture 3 (1220) in an enhancement layer (eg, layer 1) is predicted based on sub-picture 3 (1222) in the base layer using inter-layer prediction.

[0131] If the spatial resolution of a subpicture varies within a CVS, the subpicture may be decoded by performing per-subpicture reference picture resampling. FIG. 13 shows an example of a reference subpicture scaling window (1302) within a reference subpicture (1301) and a subpicture scaling window (1312) within a subpicture (1311) according to one embodiment of the present disclosure. The subpicture (1311) may be one of the subpictures within a picture, as described in FIG. 11-FIG. 12. In one example, the subpicture to be decoded (e.g., subpicture (1311)) has a different spatial resolution or a different size than the reference subpicture (e.g., reference subpicture (1301)). Per-subpicture reference picture resampling may be performed to match the spatial resolution or size of the subpicture and the reference subpicture. The reference subpicture may be resampled based on the size of the subpicture and the reference subpicture.

[0132] In one example, the reference subpicture is resampled based on the sizes of the subpicture and the reference subpicture, and the subpicture scaling window information of the subpicture and / or the reference subpicture scaling window information of the reference subpicture. With reference to Figure 13, the subpicture scaling window information of the subpicture (1311) may indicate dimension information and / or position information of the subpicture scaling window (1312). In one example, the subpicture scaling window information of the subpicture (1311) may indicate the left offset O of the subpicture scaling window (1312) relative to the subpicture (1311). L , right offset O R , Top offset O T , and lower offset O B The size and position of the sub-picture scaling window (1312) can be determined based on the first offset.

[0133] 13, the reference subpicture scaling window information of the reference subpicture (1301) may indicate size information and / or position information of the reference subpicture scaling window (1302). In one example, the reference subpicture scaling window information of the reference subpicture (1301) may indicate the reference left offset O of the reference subpicture scaling window (1302) relative to the reference subpicture (1301). REF,L , reference right offset O REF,R , offset on reference O REF,T , and the reference offset O REF,B The dimensions and position of the reference sub-picture scaling window (1302) can be determined based on the second offset.

[0134] According to an embodiment of the present disclosure, sub-picture scaling window information of a sub-picture scaling window of a sub-picture may be signaled, for example, when there are multiple sub-pictures in a picture. The sub-picture scaling window information may be signaled. The sub-picture scaling window information may be signaled in a syntax structure (e.g., a high-level syntax structure), such as a high-level syntax structure (e.g., a PPS) in a CVS. In one example, the sub-picture scaling window information of the sub-picture scaling window of each sub-picture may be signaled. In case of per-sub-picture reference picture resampling within a layer or between layers, the sub-picture scaling window information for each sub-picture that has a different scaling ratio from the respective reference sub-picture may be signaled, for example, in a high-level syntax structure (e.g., a PPS).

[0135] The layout of the video may be customized. In a collaborative and interactive game, multiple players may play simultaneously. At the same time, multiple viewers may follow the game in real time. An observer may see a combination of views from favored players, observer views, and / or physical camera views, for example, according to certain selection criteria. In some examples, the server may generate and transmit multiple layouts of multiple input videos according to a director's cut. The layout information may be represented by sub-picture partition information such as SPS, or may be further delivered as metadata in a file format. When each viewer selects one of the layouts according to his / her preference, or further customizes the layout according to his / her preference, local regions of the decoded picture (e.g., each local region) may be relocated in the displayed picture according to the selected layout information. After decoding and reorganizing the main video and one or more enhancement videos, a customized video may be generated, for example, in the cloud. Such a reorganization process for video customization may be processed in the cloud server, for example, using network-based media processing (NBMP). The combined video may be streamed to the client. The layout information may be generated by a user or a client. Layout information can be shared with other users to enjoy the same experience.

[0136] In some examples, each local region can be mapped to a respective sub-picture. The sub-picture layout can be signaled in the SPS. In certain video coding standards (e.g., VVC version 1), the sub-picture layout can only be updated at the beginning of a CVS. In some embodiments, the same sub-picture layout is applied throughout the CVS. For example, the sub-picture layout is not updated within a CVS. Because the same sub-picture layout is used within the same CVS, some applications may limit flexible layout expression for gaming and e-sports content composition.

[0137] To allow more flexible configuration of output images or pictures in the CVS, it may be desirable to update subpicture layouts on the fly. According to an embodiment of the present disclosure, subpicture layout information (or subpicture partition information) indicating subpicture layouts (or subpicture partition layouts) in a picture may be updated in the CVS. Updating subpicture partition information may be applied to various applications, such as games, e-sports, and immersive media.

[0138] A sub-picture layout (or sub-picture partition layout) may be signaled. For example, a sub-picture layout may be indicated by sub-picture partition information of a high-level syntax structure that applies to a picture(s) in the CVS. The sub-picture partition information or sub-picture layout may indicate the position(s), spatial resolution(s), and / or sub-picture ID(s) of the sub-picture(s) within the picture(s) in the CVS. A sub-picture layout may be updated (e.g., changed) in the CVS. For example, a first subset of pictures in the CVS that are covered by a first syntax structure (e.g., a first high-level syntax structure) has a first sub-picture layout. The first sub-picture layout is specified by a first sub-picture partition information in the first high-level syntax structure. A second subset of pictures in the CVS that are covered by a second syntax structure (e.g., a second high-level syntax structure) has a second sub-picture layout. The second sub-picture layout is specified by second sub-picture partition information in a second high-level syntax structure.

[0139] In one example, the first subpicture layout is different from the second subpicture layout. A first number of subpictures in the first subpicture layout may be different from a second number of subpictures in the second subpicture layout. In one example, a subpicture in the first subpicture layout is not included in the second subpicture layout. Two subpictures with the same subpicture ID in the first and second subpicture layouts may have different spatial resolutions and / or positions.

[0140] In one example, the first sub-picture layout is identical to the second sub-picture layout.

[0141] FIG. 14A illustrates an exemplary sub-picture layout update process (1400A) in a CVS according to one embodiment of this disclosure.

[0142] The sub-picture layout (1401) may be indicated (e.g., specified) by a first sub-picture partition information in a first PPS (e.g., PPS ID is 0). The first sub-picture partition information or sub-picture layout (1401) may indicate the location(s), spatial resolution(s), and / or sub-picture ID(s) of the sub-picture(s) in one or more pictures in the first PPS. The sub-picture IDs of the sub-pictures in the sub-picture layout (1401) are 0 through 3, respectively, and the sub-pictures are referred to as sub-pictures 0 through 3.

[0143] The subpicture layer (1401) may be updated to a subpicture layout (1402) by the second PPS. The subpicture layout (1402) may be indicated (e.g., specified) by second subpicture partition information in the second PPS (e.g., PPS ID is 1). The second subpicture partition information or subpicture layout (1402) may indicate the location(s), spatial resolution(s), and / or subpicture ID(s) of the subpicture(s) in one or more pictures in the second PPS. The subpicture IDs of the subpictures in the subpicture layout (1402) are subpictures 0-3. The subpicture layout (1402) is different from the subpicture layout (1401). For example, the spatial resolution of subpictures 0 to 3 in the subpicture layout (1402) is different from the spatial resolution of subpictures 0 to 3 in the subpicture layout (1401), respectively. The spatial resolution of subpicture 0 (1421) in the subpicture layout (1402) is higher than the spatial resolution of subpicture 0 (1411) in the subpicture layout (1401).

[0144] The subpicture layer (1402) can be updated to a subpicture layout (1403) with a third PPS, similar to that described above. The subpicture IDs of the subpictures in the subpicture layout (1403) are subpictures 0 through 3. The third PPS can be different from the second PPS and / or the first PPS. In one example, the subpicture layout (1403) is different from the subpicture layout (1402). In one example, the subpicture layout (1403) is identical to a previous subpicture layout used in the CVS, such as the subpicture layout (1401). In one example, the PPS ID of the third PPS is 2. In one example, the PPS ID of the third PPS is 0.

[0145] A sub-picture layout update process (1400A) may be performed within a CVS to update a sub-picture layout of a picture (e.g., indicated by a first syntax structure, such as a first PPS) within the CVS to generate a different sub-picture layout (e.g., indicated by a second syntax structure, such as a second PPS) for another picture within the CVS.

[0146] The sub-picture layout update process (1400A) performed within the CVS can enable configuration layout changes without delay or coding gain loss. Sub-picture layouts can be updated at the picture level, for example, by signaling sub-picture layout and / or sub-picture ID mapping information within the CVS (e.g., within the PPS). To minimize loss of coding efficiency when the sub-picture layout is updated or changed, motion compensation prediction can be enabled within the same sub-picture, for example, using a sub-picture specific scaling window as described in FIG. 13.

[0147] In one embodiment, updated sub-picture split information can be signaled in the PPS. Optionally, sub-picture split information can be signaled in the PPS to allow picture-level updates of the sub-picture split information. When the sub-picture split information is updated, one or more sub-pictures with respective sub-picture IDs can be displayed or hidden. FIG. 14B illustrates an example sub-picture layout update process (1400B) in the CVS according to one embodiment of the present disclosure. The sub-picture layout (1401) illustrated by the first PPS and sub-pictures 0-3 in FIG. 14B is described in FIG. 14A.

[0148] In the sub-picture layout update process (1400B), the sub-picture layer (1401) is updated to a sub-picture layout (1404) by the fourth PPS. The sub-picture layout (1404) may be indicated (e.g., specified) by a fourth sub-picture partition information in the fourth PPS (e.g., PPS ID is 3). The fourth sub-picture partition information or sub-picture layout (1404) may indicate the location(s), spatial resolution(s), and / or sub-picture ID(s) of the sub-picture(s) in one or more pictures in the fourth PPS. The sub-picture IDs of the sub-pictures in the sub-picture layout (1404) are sub-pictures 0-2. The sub-picture layout (1404) is different from the sub-picture layout (1401). For example, the spatial resolution of subpictures 0 to 2 in the subpicture layout (1404) is different from the spatial resolution of subpictures 0 to 2 in the subpicture layout (1401), respectively. Furthermore, the number of subpictures in the subpicture layout (1404) is three, which is different from the number of subpictures in the subpicture layout (1401) (e.g., four). Subpicture 3 in the subpicture layout (1401) is not in the subpicture layout (1404). Subpicture 3 in the subpicture layout (1401) disappears from the subpicture layout (1404).

[0149] The sub-picture layer (1404) is updated to a sub-picture layout (1405) by the fifth PPS (e.g., PPS ID is 4). In one example, the sub-picture layout (1405) is identical to the sub-picture layout (1401). The sub-picture layout (1405) is different from the sub-picture layout (1404). For example, sub-picture 3, which is not in the sub-picture layout (1404), is displayed in the sub-picture layout (1405).

[0150] When the sub-picture split information is updated, the dimensional information (eg, spatial resolution(s)) and / or position information (eg, vertical offset value and / or horizontal offset value) of each sub-picture may be changed.

[0151] In some examples of certain video coding technologies (e.g., VVC version 1), all layers belonging to the same dependency tree may have the same sub-picture partition layout. According to one embodiment of the present disclosure, the above constraint may be relaxed to support applications where different sub-picture layouts may be applied across different layers. In one embodiment, a first sub-picture layout of a first layer may be different from a second sub-picture layout of a second layer. In one example, each layer has a different sub-picture layout.

[0152] FIG. 15 illustrates exemplary subpicture layouts (1501) and (1502) in different layers in a CVS, according to one embodiment of the present disclosure. Subpicture layout (1501) and subpictures 0-3 in subpicture layout (1501) may be identical to subpicture layout (1401) and subpictures 0-3, respectively, described in FIG. 14A. Subpicture layout (1501) may be applied to picture(s) in layer 0 in the CVS. Subpicture layout (1502) may be applied to pictures in layer 1 in the CVS. Subpicture layout (1502) corresponding to layer 1 is different from subpicture layout (1501) corresponding to layer 0. For example, subpictures 1 and 3 disappear from subpicture layout (1502). Subpictures 0 and 2 in the subpicture layout (1502) have different spatial resolutions than subpictures 0 and 2 in the subpicture layout (1501), respectively.

[0153] In some examples of certain video coding technologies (e.g., VVC version 1), the combination of sub-picture partitioning and reference picture resampling is not supported. According to an embodiment of the present disclosure, the above constraints can be relaxed to support per-region quality and resolution enhancement. In an embodiment, sub-picture partitioning and per-sub-picture reference picture resampling can be combined. In one example, updating of sub-picture partitioning information in the CVS is combined with per-sub-picture reference picture resampling. For example, sub-picture partitioning information and sub-picture scaling window information of the sub-pictures are signaled within a high-level syntax structure, such as a PPS.

[0154] According to one embodiment of the present disclosure, a syntax structure (e.g., a high level syntax structure) such as a parameter set may include an extension such as a sub-picture reference picture resampling (RPR) extension indicating (i) sub-picture split information and / or (ii) sub-picture scaling window information for a sub-picture scaling window of a sub-picture. In one embodiment, the parameter set is a PPS and the extension is referred to as a PPS Sub-picture RPR Extension, as shown in Tables 1-2 below.

[0155] Table 1 illustrates a portion of an example syntax structure of a PPS, according to one embodiment of the present disclosure.

[0156] [Table 1]

[0157] Table 2 illustrates an example syntax structure extension of a PPS according to one embodiment of the present disclosure.

[0158] [Table 2]

[0159] A syntax element such as a flag (e.g., pps_subpic_rpr_extension_flag) may indicate whether a PPS subpicture RPR extension (e.g., the pps_subpic_rpr_extension() syntax structure of Table 2) is present in the PPS RBSP syntax structure. A syntax element (e.g., pps_subpic_rpr_extension_flag) equal to 1 may specify that the pps_subpic_rpr_extension() syntax structure is present in the PPS RBSP syntax structure. A syntax element (e.g., pps_subpic_rpr_extension_flag) equal to 0 may specify that the pps_subpic_rpr_extension() syntax structure is not present. If not present, the value of the syntax element (e.g., pps_subpic_rpr_extension_flag) may be inferred to be equal to 0.

[0160] If a syntax element (eg, pps_subpic_rpr_extension_flag) is equal to 1, then the pps_subpic_rpr_extension() syntax structure is present in the PPS RBSP syntax structure.

[0161] Table 2 shows an example PPS RBSP syntax structure. With reference to Table 2, a first syntax element, such as a first flag pps_subpic_update_info_present_flag, may indicate whether sub-picture partition information (or sub-picture partition layout information) is present in the PPS. A first syntax element (e.g., pps_subpic_update_info_present_flag) equal to 1 may specify that sub-picture partition layout information is present (e.g., signaled) in the PPS. A first syntax element (e.g., pps_subpic_update_info_present_flag) equal to 0 may specify that sub-picture partition layout information is not present in the PPS.

[0162] A second syntax element, such as a second flag pps_subpic_scaling_win_info_present_flag, may indicate whether per-subpicture scaling window information is present (e.g., signaled) in the PPS. A second syntax element (e.g., pps_subpic_scaling_win_info_present_flag) equal to 1 may specify that per-subpicture scaling window information is present in the PPS. A second syntax element (e.g., pps_subpic_scaling_win_info_present_flag) equal to 0 may specify that per-subpicture scaling window information is not present in the PPS.

[0163] The syntax element pps_updated_num_subpics_minus1+1 may specify the number of subpictures for each picture that references the PPS. The value of pps_updated_num_subpics_minus1 may range from 0 to MaxSlicesPerAu-1 (inclusive). In one example, MaxSlicesPerAu indicates the maximum number of slices per AU. If not present, the value of pps_updated_num_subpics_minus1 is inferred to be equal to sps_num_subpics_minus1.

[0164] The syntax element pps_independent_subpics_flag equal to 1 may specify that all subpicture boundaries of each picture that references the PPS are treated as picture boundaries and there is no loop filtering across subpicture boundaries. The syntax element pps_independent_subpics_flag equal to 0 imposes no such constraint. If not present, the value of pps_independent_subpics_flag is inferred to be equal to 1.

[0165] The syntax element pps_subpic_same_size_flag equal to 1 may specify that all subpictures of each picture referencing a PPS have the same width, specified by pps_subpic_width_minus1[0], and the same height, specified by pps_subpic_height_minus1[0]. The syntax element pps_subpic_same_size_flag equal to 0 does not impose such a constraint. If not present, the value of pps_subpic_same_size_flag is inferred to be equal to 0.

[0166] In one example, the variable tmpWidthVal is equal to (pps_pic_width_in_luma_samples+CtbSizeY-1) / CtbSizeY, and the variable tmpHeightVal is equal to (pps_pic_height_in_luma_samples+CtbSizeY-1) / CtbSizeY.

[0167] The syntax element pps_subpic_ctu_top_left_x[i] can specify the horizontal position of the top left CTU of the i-th subpicture in CtbSizeY units. The length of the syntax element is Ceil(Log2(tmpWidthVal)) bits.

[0168] If not present, the value of pps_subpic_ctu_top_left_x[i] can be inferred as follows: If pps_subpic_same_size_flag is equal to 0 or i is equal to 0, the value of pps_subpic_ctu_top_left_x[i] is inferred to be equal to 0. Otherwise, the value of pps_subpic_ctu_top_left_x[i] is inferred to be equal to (i%numSubpicCols)*(pps_subpic_width_minus1[0]+1).

[0169] When pps_subpic_same_size_flag is 1, the variable numSubpicCols, which specifies the number of subpicture columns in each picture of the CLVS, is derived as follows: numSubpicCols = tmpWidthVal / (pps_subpic_width_minus1[0] + 1).

[0170] If pps_subpic_same_size_flag is 1, the value of numSubpicCols*tmpHeightVal / (pps_subpic_height_minus1[0]+1)-1 may be equal to pps_updated_num_subpics_minus1.

[0171] The syntax element pps_subpic_ctu_top_left_y[i] can specify the vertical position of the top left CTU of the i-th subpicture in CtbSizeY units. The length of the syntax element is Ceil(Log2(tmpHeightVal)) bits.

[0172] If not present, the value of pps_subpic_ctu_top_left_y[i] can be inferred as follows: If pps_subpic_same_size_flag is equal to 0 or i is equal to 0, the value of pps_subpic_ctu_top_left_y[i] is inferred to be equal to 0. Otherwise, the value of pps_subpic_ctu_top_left_y[i] is inferred to be equal to (i / numSubpicCols)*(pps_subpic_height_minus1[0]+1).

[0173] The syntax element pps_subpic_width_minus1[i] plus 1 can specify the width of the i-th subpicture in units of CtbSizeY. The length of the syntax element is Ceil(Log2(tmpWidthVal)) bits.

[0174] If not present, the value of pps_subpic_width_minus1[i] is inferred as follows: If pps_subpic_same_size_flag is equal to 0 or i is equal to 0, the value of pps_subpic_width_minus1[i] is inferred to be equal to tmpWidthVal-pps_subpic_ctu_top_left_x[i]-1. Otherwise, the value of pps_subpic_width_minus1[i] is inferred to be equal to pps_subpic_width_minus1[0].

[0175] If pps_subpic_same_size_flag is equal to 1, the value of tmpWidthVal%(pps_subpic_width_minus1[0]+1) may be equal to 0.

[0176] The syntax element pps_subpic_height_minus1[i]+1 can specify the height of the i-th subpicture in units of CtbSizeY. The length of the syntax element is Ceil(Log2(tmpHeightVal)) bits.

[0177] If not present, the value of pps_subpic_height_minus1[i] can be inferred as follows: If pps_subpic_same_size_flag is equal to 0 or i is equal to 0, the value of pps_subpic_height_minus1[i] is inferred to be equal to tmpHeightVal-pps_subpic_ctu_top_left_y[i]-1. Otherwise, the value of pps_subpic_height_minus1[i] is inferred to be equal to pps_subpic_height_minus1[0].

[0178] If pps_subpic_same_size_flag is 1, the value of tmpHeightVal%(pps_subpic_height_minus1[0] + 1) is equal to 0.

[0179] In one example, it is a bitstream compliant requirement that the subpicture shape be such that when decoded, each subpicture can have its entire left border and its entire top border that either includes the picture boundary or includes the boundary of a previously decoded subpicture.

[0180] In one example, it is a bitstream compliance requirement that for each subpicture with subpicture index i in the range 0 to pps_num_subpics_minus1, all of the following conditions are true: ·The value of (pps_subpic_ctu_top_left_x[i]*CtbSizeY) must be less than (pps_pic_width_in_luma_samples-pps_conf_win_right_offset*SubWidthC). The value of ((pps_subpic_ctu_top_left_x[i]+pps_subpic_width_minus1[i]+1)*CtbSizeY) must be greater than (pps_conf_win_left_offset*SubWidthC). ·The value of (pps_subpic_ctu_top_left_y[i]*CtbSizeY) must be less than (pps_pic_height_in_luma_samples-pps_conf_win_bottom_offset*SubHeightC). The value of ((pps_subpic_ctu_top_left_y[i]+pps_subpic_height_minus1[i]+1)*CtbSizeY) must be greater than (pps_conf_win_top_offset*SubHeightC).

[0181] The syntax element pps_subpic_treated_as_pic_flag[i] equal to 1 may specify that the i-th subpicture of each coded picture that references the PPS is treated as a picture in the decoding process except for in-loop filtering operations. pps_subpic_treated_as_pic_flag[i] equal to 0 may specify that the i-th subpicture of each coded picture in the CLVS is not treated as a picture in the decoding process except for in-loop filtering operations. If not present, the value of pps_subpic_treated_as_pic_flag[i] is inferred to be equal to 1.

[0182] The syntax element pps_loop_filter_across_subpic_enabled_flag[i] equal to 1 may specify that in-loop filtering operations across subpicture boundaries are enabled and may be performed across the i-th subpicture boundary for each CLVS coded picture. pps_loop_filter_across_subpic_enabled_flag[i] equal to 0 may specify that in-loop filtering operations across subpicture boundaries are disabled and may not be performed across the i-th subpicture boundary for each CLVS coded picture. If not present, the value of pps_loop_filter_across_subpic_enabled_pic_flag[i] is inferred to be equal to 0.

[0183] The syntax element pps_updated_subpic_id_len_minus1 plus 1 may specify the number of bits used to represent the syntax element pps_updated_subpic_id[i] (if present) and optionally the syntax element sh_subpic_id (if present). The value of pps_updated_subpic_id_len_minus1 may be in the range 0 to 15 inclusive. The value of 1<<(pps_updated_subpic_id_len_minus1+1) may be greater than or equal to pps_updated_num_subpics_minus1+1.

[0184] The syntax element pps_updated_subpic_id_mapping_explicitly_signalled_flag equal to 1 may specify that subpicture ID mapping is explicitly signaled in the PPS referenced by the CLVS coded picture. pps_updated_subpic_id_mapping_explicitly_signalled_flag equal to 0 may specify that subpicture ID mapping is not explicitly signaled to the CLVS. If not present, the value of pps_updated_subpic_id_mapping_explicitly_signalled_flag is inferred to be equal to 0.

[0185] The syntax element pps_updated_subpic_id_mapping_present_flag equal to 1 may specify that subpicture ID mapping is signaled in the PPS if pps_updated_subpic_id_mapping_explicitly_signalled_flag is equal to 1. The syntax element pps_updated_subpic_id_mapping_present_flag equal to 0 may specify that subpicture ID mapping is signaled in the PPS referenced by the CLVS coded picture if pps_subpic_id_mapping_explicitly_signalled_flag is equal to 1.

[0186] The syntax element pps_updated_subpic_id[i] can specify the subpicture ID of the i-th subpicture. The length of the pps_updated_subpic_id[i] syntax element is pps_updated_subpic_id_len_minus1+1 bits.

[0187] The syntax elements pps_subpic_scaling_win_left_offset[i], pps_subpic_scaling_win_right_offset[i], pps_subpic_scaling_win_top_offset[i], and pps_subpic_scaling_win_bottom_offset[i] can specify an offset to be applied to the subpicture size of the i-th subpicture for the calculation of the scaling ratio. Referring to FIG. 13, the syntax elements pps_subpic_scaling_win_left_offset[i], pps_subpic_scaling_win_right_offset[i], pps_subpic_scaling_win_top_offset[i], and pps_subpic_scaling_win_bottom_offset[i] can specify an offset to be applied to the subpicture size of the i-th subpicture for the calculation of the scaling ratio. L , right offset OR , Top offset O T , and lower offset O B can be specified.

[0188] If not present, the values ​​of pps_subpic_scaling_win_left_offset[i], pps_subpic_scaling_win_right_offset[i], pps_subpic_scaling_win_top_offset[i], and pps_subpic_scaling_win_bottom_offset[i] are inferred to be equal to pps_scaling_win_left_offset, pps_scaling_win_right_offset, pps_scaling_win_top_offset, and pps_scaling_win_bottom_offset, respectively.

[0189] Depending on the values ​​of a first syntax element (or a first flag) and a second syntax element (or a second flag) in a syntax structure (e.g., a high-level syntax structure) such as the PPS in Table 2, various operations can be performed.

[0190] In one embodiment, the first flag indicates that sub-picture partition layout information for the picture is signaled. For example, when the first flag (e.g., pps_subpic_update_info_present_flag) is equal to 1, the first flag indicates that the sub-picture partition layout information is signaled within the PPS. In one example, the picture includes multiple sub-pictures. Based on the subpicture partition information (e.g., syntax elements pps_subpic_ctu_top_left_x[i], pps_subpic_ctu_top_left_y[i], pps_subpic_width_minus1[i], and pps_subpic_height_minus1[i]), a subpicture layout of multiple subpictures in a picture can be determined, including the size (e.g., the subpicture width W indicated by the syntax element pps_subpic_width_minus1[i] and the subpicture height H indicated by pps_subpic_height_minus1[i]) and position (e.g., syntax elements pps_subpic_ctu_top_left_x[i], pps_subpic_ctu_top_left_y[i]) of each of the multiple subpictures in the picture. In one example, a subpicture identifier (ID) of each subpicture in a picture is determined based on subpicture partition information in the PPS (e.g., syntax element pps_updated_subpic_id[i]). A first subpicture in a plurality of subpictures may be reconstructed based on the subpicture partition information, such as the size and position of the first subpicture. Subpicture partition layout information may be updated in the CVS, for example, from a picture referencing a first PPS to another picture referencing a second PPS.

[0191] In one example, the first sub-picture partition information is signaled in a first PPS, and the second sub-picture partition information is signaled in a second PPS, and the second sub-picture layout indicated by the second sub-picture partition information is different from the first sub-picture layout indicated by the first sub-picture partition information.

[0192] In one embodiment, the second flag indicates that sub-picture scaling window information for the sub-picture is signaled. For example, the second flag indicates that the sub-picture scaling window information is signaled in the PPS, for example, when a second syntax element (e.g., pps_subpic_scaling_win_info_present_flag) is equal to 1. The reference sub-picture of the sub-picture may have a different spatial resolution (or a different size) than the spatial resolution of the sub-picture.

[0193] In one example, the subpicture scaling window information of the subpicture (e.g., syntax elements pps_subpic_scaling_win_left_offset[i], pps_subpic_scaling_win_right_offset[i], pps_subpic_scaling_win_top_offset[i], and pps_subpic_scaling_win_bottom_offset[i] in Table 2) is decoded from the PPS. The subpictures can be reconstructed using per-subpicture reference picture resampling based on the subpicture's subpicture scaling window information.

[0194] For example, the syntax elements pps_subpic_scaling_win_left_offset[i], pps_subpic_scaling_win_right_offset[i], pps_subpic_scaling_win_top_offset[i], and pps_subpic_scaling_win_bottom_offset[i] represent the left offset O of the subpicture scaling window (1312). L , right offset O R , Top offset O T , and lower offset O B In one example, the width W of the subpicture scaling window (1312) is S is W S =W-(O L +OR ), where W is the width of the subpicture. In one example, the height H S is H S =H-(O T +O B ), where H is the height of the subpicture.

[0195] The scaling ratio associated with the reference subpicture (1301) and the subpicture (1311) may be determined based on the dimension information of the scaling window (e.g., 1312) of the subpicture (1311). Referring to Figure 13, the scaling ratio between the reference subpicture (1301) and the subpicture (1311) may be determined based on the dimension information of the scaling window (e.g., 1312) of the subpicture (1311). S and the height H of the subpicture scaling window (1312) S The per-subpicture reference picture resampling may be performed based on the determined scaling ratio associated with the reference subpicture (1301) and the subpicture (1311). In one example, a scaled reference subpicture that matches the spatial resolution (or size) of the subpicture is generated using per-subpicture reference picture resampling. The subpicture may be decoded by the scaled reference subpicture.

[0196] According to one embodiment, syntax elements indicating sub-picture split information and sub-picture scaling window information may be combined within a syntax structure (eg, a higher level syntax structure) such as a PPS.

[0197] In one embodiment, the first flag indicates that the sub-picture split information is signaled in the PPS. The second flag indicates that the sub-picture scaling window information for the sub-picture is signaled in the PPS. The sub-picture split information may be decoded based on the PPS. The sub-picture scaling window information of the sub-picture may be decoded based on the PPS. The dimension information of the sub-picture (e.g., the width W indicated by pps_subpic_width_minus1[i] and the height H indicated by pps_subpic_height_minus1[i]) and the position information of the sub-picture (e.g., the width W indicated by pps_subpic_width_minus1[i] and the height H indicated by pps_subpic_height_minus1[i]) may be determined based on the sub-picture split information, as described above. The subpicture may be reconstructed based on the subpicture's subpicture scaling window information (e.g., indicated by pps_subpic_scaling_win_left_offset[i], pps_subpic_scaling_win_right_offset[i], pps_subpic_scaling_win_top_offset[i], and pps_subpic_scaling_win_bottom_offset[i]), the subpicture's dimension information, and the subpicture's position information, as described above with reference to FIG. 13.

[0198] FIG. 16 shows a flow chart outlining an encoding process (1600) according to one embodiment of the present disclosure. In various embodiments, the process (1600) is performed by processing circuitry (e.g., processing circuitry within terminal devices (310), (320), (330), and (340), processing circuitry performing the functions of a video encoder (e.g., (403), (603), (703)), etc.). In some embodiments, the process (1600) is implemented with software instructions, and thus the processing circuitry performs the process (1600) when it executes the software instructions. The process begins at (S1601) and proceeds to (S1610).

[0199] At (S1610), at least one of a first flag or a second flag in a syntax structure (e.g., a high-level syntax structure) for a first picture in a coded video sequence may be determined. The first flag may indicate whether a first sub-picture partition information of the first picture is signaled in the syntax structure. The second flag may indicate whether a first sub-picture scaling window information for a first sub-picture in the first picture is signaled in the syntax structure. In one example, the syntax structure is a PPS as shown in Table 2. The first flag may be a first syntax element (e.g., pps_subpic_update_info_present_flag). The second flag may be a second syntax element (e.g., pps_subpic_scaling_win_info_present_flag).

[0200] In (S1620), a syntax element indicating the first sub-picture split information may be generated based on a first flag indicating that the first sub-picture split information is signaled in the syntax structure. In one example, the first flag indicates that the first sub-picture split information is signaled in the syntax structure (e.g., the value of pps_subpic_update_info_present_flag is 1). A syntax element indicating the first sub-picture split information, such as a syntax element indicating the size(s), position(s), and sub-picture ID(s) of the sub-picture in the first picture, may be generated.

[0201] In (S1630), a syntax element indicating the first sub-picture scaling window information may be generated based on a second flag indicating that the first sub-picture scaling window information is signaled in the syntax structure. In one example, the second flag indicates that the first sub-picture scaling window information is signaled in the syntax structure (e.g., the value of pps_subpic_scaling_win_info_present_flag is 1). A syntax element indicating the first sub-picture scaling window information, such as a syntax element indicating an offset of the sub-picture in the first picture, may be generated.

[0202] In (S1640), the first sub-picture may be encoded based on the first flag and the second flag. If the first flag indicates that the first sub-picture partition information is signaled in the syntax structure, the first sub-picture may be encoded based on the first sub-picture partition information.

[0203] If the second flag indicates that the first sub-picture scaling window information is signaled in the syntax structure, the first sub-picture may be encoded based on the first sub-picture scaling window information.

[0204] If the first flag indicates that the first sub-picture partition information is signaled in the syntax structure and the second flag indicates that the first sub-picture scaling window information is signaled in the syntax structure, the first sub-picture may be encoded based on the first sub-picture partition information and the first sub-picture scaling window information.

[0205] The process (1600) may be adapted appropriately to various scenarios, and the steps within the process (1600) may be adjusted accordingly. One or more of the steps within the process (1600) may be adapted, omitted, repeated, and / or combined. Any suitable order may be used to perform the process (1600). Additional step(s) may be added.

[0206] FIG. 17 shows a flow chart outlining a decoding process (1700) according to one embodiment of the present disclosure. In various embodiments, the process (1700) is performed by a processing circuit (e.g., a processing circuit in the terminal devices (310), (320), (330), and (340), a processing circuit performing the functions of a video encoder (403), a processing circuit performing the functions of a video decoder (410), a processing circuit performing the functions of a video decoder (510), a processing circuit performing the functions of a video encoder (603), etc.). In some embodiments, the process (1700) is implemented with software instructions, and thus the processing circuit performs the process (1700) as the processing circuit executes the software instructions. The process begins at (S1701) and proceeds to (S1710).

[0207] At (S1710), at least one of a first flag (e.g., pps_subpic_update_info_present_flag) or a second flag (e.g., pps_subpic_scaling_win_info_present_flag) in a syntax structure (e.g., a high-level syntax structure) for a first picture in a coded video sequence (CVS) may be decoded. The first picture may include a first sub-picture. The first flag may indicate whether first sub-picture partition information of the first picture is signaled in the syntax structure. The second flag may indicate whether first sub-picture scaling window information for the first sub-picture is signaled in the syntax structure. In one embodiment, the syntax element is a high-level syntax structure.

[0208] In one example, the syntax structure is a first picture parameter set (PPS) syntax structure.

[0209] At (S1720), the first subpicture can be reconstructed based on (i) a first flag indicating that the first subpicture partition information is signaled in the syntax structure, or (ii) a second flag indicating that the first subpicture scaling window information for the first subpicture is signaled in the syntax structure.

[0210] In one example, at least one of the first flag and the second flag includes a first flag, the first flag indicating that first sub-picture split information for the first picture is signaled within the syntax structure.

[0211] The first picture includes a plurality of sub-pictures, and the plurality of sub-pictures includes a first sub-picture. Based on the first sub-picture partition information, a first sub-picture layout of the plurality of sub-pictures in the first picture can be determined. The first sub-picture layout can indicate (e.g., include) a size and a position of each of the plurality of sub-pictures in the first picture, as described with reference to Table 2.

[0212] A sub-picture identifier (ID) for each sub-picture in the first picture can be determined based on the first sub-picture partition information in the syntax structure.

[0213] In one example, the syntax structure including the first sub-picture partition information is a first PPS. The second sub-picture partition information signaled in the second PPS syntax structure for the second picture in the CVS can be decoded. The second sub-picture in the second picture can be reconstructed based on the second sub-picture partition information. The second sub-picture layout of the second picture can be different from the first sub-picture layout of the first picture.

[0214] At least one of the first flag and the second flag may include a second flag. The second flag may indicate that the first sub-picture scaling window information of the first sub-picture is signaled in the syntax structure. The first sub-picture scaling window information of the first sub-picture may be decoded based on the syntax structure. The first sub-picture may be reconstructed using per-sub-picture reference picture resampling based on the first sub-picture scaling window information of the first sub-picture.

[0215] The process (1700) proceeds to (S1799) and ends.

[0216] The process (1700) may be adapted appropriately to various scenarios, and the steps within the process (1700) may be adjusted accordingly. One or more of the steps within the process (1700) may be adapted, omitted, repeated, and / or combined. Any suitable order may be used to perform the process (1700). Additional step(s) may be added.

[0217] In one example, a first picture is in a first layer in the CVS. Second sub-picture partition information signaled in another syntax structure for a second picture in a second layer in the CVS may be decoded. The second sub-picture partition information may be different from the first sub-picture partition information. A second sub-picture in the second picture may be reconstructed based on the second sub-picture partition information.

[0218] In an embodiment, at least one of the first flag and the second flag includes a first flag and a second flag. The first flag indicates that the first sub-picture partition information is signaled in the syntax structure. The second flag may indicate that the first sub-picture scaling window information of the first sub-picture is signaled in the syntax structure. The first sub-picture scaling window information of the first sub-picture may be decoded from the syntax structure. The first sub-picture dimension information and position information may be determined based on the first sub-picture partition information. The first sub-picture may be reconstructed based on the first sub-picture scaling window information of the first sub-picture, the first sub-picture dimension information, and the first sub-picture position information.

[0219] The embodiments 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 a processing circuit (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.

[0220] The techniques described above may be implemented as computer software using computer readable instructions and physically stored on one or more computer readable media. For example, Figure 18 illustrates a computer system (1800) suitable for implementing some embodiments of the disclosed subject matter.

[0221] The computer software may be coded using any suitable machine code or computer language that may be subject to assembly, compilation, linking, or similar mechanisms to generate code containing instructions that may be executed, such as by one or more computer central processing units (CPUs) and / or graphics processing units (GPUs), either directly, or through interpretation and execution of microcode.

[0222] The instructions may be executed in various types of computers or components thereof, including, for example, a personal computer, a tablet computer, a server, a smart phone, a gaming device, an Internet of Things device, and the like.

[0223] The components illustrated in Figure 18 of the computer system (1800) are of course exemplary 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. Moreover, the configuration 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 (1800).

[0224] The computer system (1800) may include a number of human interface input devices. Such human interface input devices may be responsive to input by one or more human users through, for example, tactile input (e.g., keystrokes, swipes, data glove movements), audio input (e.g., voice, clapping), visual input (e.g., gestures), and olfactory input (not shown). Human interface devices may be used to capture certain media that are not necessarily directly related to conscious human input, such as sound (e.g., speech, music, ambient sounds), images (e.g., scanned images, photographic images obtained from a still image camera), and video (e.g., two-dimensional video, three-dimensional video including stereoscopic video).

[0225] The input human interface devices may include one or more (only one of each is shown) of a keyboard (1801), a mouse (1802), a trackpad (1803), a touch screen (1810), a data glove (not shown), a joystick (1805), a microphone (1806), a scanner (1807), and a camera (1808).

[0226] The computer system (1800) may also include a number of human interface output devices. Such human interface output devices may stimulate one or more of the human user's senses, for example, through 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 (1810), data gloves (not shown), or joystick (1805), although there may also be haptic feedback devices that are not used as input devices), audio output devices (speakers (1809), headphones (not shown), etc.), visual output devices (such as screens (1810), including CRT screens, LCD screens, plasma screens, and OLED screens, each with or without touch screen input capability and with or without haptic feedback capability. Some of the above screens may be capable of outputting two-dimensional visual output, or three or more dimensional output through means such as stereoscopic graphic output. Virtual reality glasses (not shown), holographic displays, smoke generator tanks (not shown), and printers (not shown).

[0227] The computer system (1800) may also include storage devices and associated media that may be directly operated by a human, such as optical media (1821), including a CD / DVD ROM / RW (1820) using CD / DVD or similar media, thumb drives (1822), removable hard drives or solid state drives (1823), legacy magnetic media such as tapes or floppy disks (not shown), and specialized ROM / ASIC / PLD based devices (not shown) such as security dongles.

[0228] Those skilled in the art will also understand that the term "computer-readable medium" as used in connection with the presently disclosed subject matter does not encompass transmission media, carrier waves, or other transitory signals.

[0229] The computer system (1800) may also include an interface (1854) to one or more communication networks (1855). The networks may be, for example, wireless, wired, or optical. The networks may further be local, wide area, metropolitan, vehicular, and industrial, real-time, delay tolerant, and the like. Examples of networks include local area networks such as Ethernet, wireless LAN, and the like; cellular networks including GSM, 3G, 4G, 5G, LTE, and the like; television wired or wireless wide area digital networks including cable television, satellite television, and terrestrial broadcast television; vehicular and industrial including CANBus, and the like. Certain networks typically require an external network interface adapter that connects to a particular general-purpose data port or peripheral bus (1849) (e.g., a USB port on the computer system (1800) or the like), while others are typically integrated into the core of the computer system (1800) by connection to a system bus as described below (e.g., an Ethernet interface to a PC computer system or a cellular network interface to a smartphone computer system). Using any of these networks, computer system 1800 can communicate with other entities. Such communication can be one-way, receive-only (e.g., television broadcast), one-way transmit-only (e.g., from a CANbus to a particular CANbus device), or two-way, e.g., two-way communication to other computer systems using local or wide area digital networks. Specific protocols and protocol stacks may be used with each of these networks and network interfaces, as described above.

[0230] The above-mentioned human interface devices, memory devices that can be directly operated by humans, and network interfaces can be attached to the core (1840) of the computer system (1800).

[0231] The cores (1840) may include one or more central processing units (CPUs) (1841), graphics processing units (GPUs) (1842), specialized programmable processing units in the form of field programmable gate areas (FPGAs) (1843), hardware accelerators for specific tasks (1844), graphics adapters (1850), and the like. Such devices may be connected through a system bus (1848) along with read only memory (ROM) (1845), random access memory (1846), and internal mass storage (1847) such as hard drives, SSDs, etc. that are internal and not directly accessible to the user. In some computer systems, the system bus (1848) may be directly accessible in the form of one or more physical plugs that allow expansion with additional CPUs, GPUs, etc. Peripherals may be attached directly to the core's system bus (1848) or through a peripheral bus (1849). In one example, a screen (1810) may be connected to a graphics adapter (1850). Peripheral bus architectures include PCI, USB, and the like.

[0232] The CPU (1841), GPU (1842), FPGA (1843) and accelerator (1844) may execute a number of instructions that may combine to make up the above-mentioned computer code. The computer code may be stored in a ROM (1845) or a RAM (1846). Also, transient data may be stored in the RAM (1846), while persistent data may be stored, for example, in an internal mass storage (1847). A cache memory, which may be closely associated with one or more of the CPU (1841), GPU (1842), mass storage (1847), ROM (1845), RAM (1846), etc., may be used to enable fast storage and retrieval from any of the memory devices.

[0233] The computer-readable medium may bear computer code for performing various computer-implemented operations. The medium and computer code may be those specially designed and constructed for the purposes of the present disclosure, or they may be of the kind well known and available to those skilled in the computer software arts.

[0234] By way of example and not limitation, a computer system having the architecture (1800), and in particular the cores (1840), can provide functionality as a result of processors (including CPUs, GPUs, FPGAs, accelerators, etc.) executing software embodied in one or more tangible computer-readable media. Such computer-readable media can be the user-accessible mass storage introduced above, as well as media associated with specific storage of the cores (1840) that is non-transitory in nature, such as the core internal mass storage (1847) or ROM (1845). Software implementing various embodiments of the present disclosure can be stored on such devices and executed by the cores (1840). The computer-readable media can include one or more memory devices or chips, depending on the particular requirements. The software can cause the cores (1840), and in particular the processors (including CPUs, GPUs, FPGAs, etc.) therein, to perform certain processes or certain portions of certain processes described herein, including defining data structures stored in RAM (1846) and modifying such data structures according to the processes defined by the software. Additionally, or alternatively, a computer system may provide functionality as a result of circuit-hardened or otherwise embodied logic (e.g., accelerator (1844)) that may operate in place of or in conjunction with software to perform certain processes or portions of certain processes described herein. References to software may encompass logic, and vice versa, where appropriate. Where appropriate, references to computer-readable media may encompass circuitry (such as an integrated circuit (IC)) that stores software for execution, circuitry that embodies logic for execution, or both. The present disclosure encompasses any appropriate combination of hardware and software. Appendix A: Acronyms 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: conversion unit PU: Prediction Unit CTU: Coding Tree Unit CTB: coding tree block PB: Predicted block HRD: Hypothetical Reference Decoder SNR: Signal to Noise Ratio CPU: Central Processing Unit GPU: Graphics Processing Unit 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 Area SSD: Solid State Drive IC: Integrated Circuit CU: coding unit NIC: Neural Image Compression RD: Rate Distortion E2E: End-to-end ANN: Artificial Neural Network DNN: Deep Neural Network CNN: Convolutional Neural Network

[0235] While this disclosure has described several exemplary embodiments, there are modifications, substitutions, and various alternative equivalents that are within the scope of this disclosure. It will thus be appreciated that those skilled in the art will be able to devise numerous systems and methods that, although not explicitly shown or described herein, embody the principles of the present disclosure and are therefore within its spirit and scope. [Explanation of symbols]

[0236] 101 Samples 102 Arrow 103 Arrow 104 Square Block 110 Schematic diagram 201 Block 300 Communication Systems 310 Terminal Devices 320 Terminal Devices 330 Terminal Devices 340 Terminal Devices 350 Communication Network 400 Communication Systems 401 Video Source 402 Stream 403 Video Encoder 404 Video Data 405 Streaming Server 406 Client Subsystem 407 Copy video data 408 Client Subsystem 409 Copy of video data 410 Video Decoder 411 Output Stream 412 Display 413 Capture Subsystem 420 Electronic Devices 430 Electronic Devices 501 Channel 510 Video Decoder 512 Rendering Device 515 Buffer Memory 520 Parser 521 Symbols 530 Electronic Devices 531 Receiver 551 Reverse conversion unit 552 Intra picture prediction unit, intra prediction unit 553 Motion Compensation Prediction Unit 555 Aggregator 556 Loop Filter Unit 557 Reference Picture Memory 558 Current Picture Buffer 601 Video Sources 603 Video Encoder 620 Electronic Devices 630 Source Coder 632 Coding Engine 633 Local Video Decoder 634 Reference Picture Memory 635 Predictor 640 Transmitter 643 Video Sequences 645 Entropy Coder 650 Controller 660 Communication Channels 703 Video Encoder 721 General-purpose controller 722 Intra Encoder 723 Residual Calculator 724 Residual Encoder 725 Entropy Encoder 726 Switch 728 Residual Decoder 730 InterEncoder 810 Video Decoder 871 Entropy Decoder 872 Intra Decoder 873 Residual Decoder 874 Reconstruction Module 880 Interdecoder 1000 Pictures 1101 Main Video 1200 Main Video 1210 Video Composer 1220 Subpicture 3 1222 Subpicture 3 1301 Reference Subpicture 1302 Reference Subpicture Scaling Window 1311 Subpicture 1312 Subpicture Scaling Window 1400A Subpicture Layout Update Process 1400B Subpicture Layout Update Process 1401 Subpicture Layout, Subpicture Layer 1402 Subpicture Layout, Subpicture Layer 1403 Subpicture Layout 1404 Subpicture Layout, Subpicture Layer 1405 Subpicture Layout 1411 Subpicture 1421 Subpicture 1501 Subpicture Layout 1502 Subpicture Layout 1600 Encoding Process 1700 Decoding Process 1800 Computer Systems 1801 Keyboard 1802 Mouse 1803 Trackpad 1805 Joystick 1806 Mike 1807 Scanner 1808 Camera 1809 Audio output device speaker 1810 Touch Screen 1821 Optical media 1823 Solid State Drive 1840 Core 1841 Central Processing Unit, CPU 1842 Graphics Processing Unit, GPU 1843 Field Programmable Gate Area, FPGA 1844 Hardware Accelerator 1845 Read-Only Memory, ROM 1846 Random Access Memory, RAM 1847 core internal mass storage 1848 System Bus 1849 Peripheral Bus 1850 Graphics Adapter 1854 Interface 1855 Communication Network

Claims

1. 1. A method for video decoding in a video decoder, comprising: decoding at least one of a first flag or a second flag in a first picture parameter set (PPS) syntax structure based on a flag indicating whether a sub-picture reference picture resampling (RPR) extension is present in the syntax structure for a first picture in a coded video sequence (CVS), the syntax structure being a first PPS syntax structure, the first picture including one or more sub-pictures including a first sub-picture, the first flag indicating whether first sub-picture partition information of the first picture is signaled in the first PPS syntax structure, and the second flag indicating whether first sub-picture scaling window information for the first sub-picture is signaled in the first PPS syntax structure; based on at least one of the first flag indicating that the first sub-picture partition information of the first picture is signaled in the first PPS syntax structure or the second flag indicating that the first sub-picture scaling window information for the first sub-picture is signaled in the first PPS syntax structure; determining a first sub-picture layout of the plurality of sub-pictures in the first picture based on the first sub-picture partition information or the first sub-picture scaling window information, the first sub-picture partition information including a size, a position, a spatial resolution and / or a sub-picture ID of each of the plurality of sub-pictures in the first picture; reconstructing the first sub-picture based on the first sub-picture layout; decoding second sub-picture partition information or the first sub-picture scaling window information signaled in a second PPS syntax structure for a second picture in the CVS; determining a second sub-picture layout of the plurality of sub-pictures in the second picture based on the second sub-picture partition information or the first sub-picture scaling window information, the second sub-picture partition information including a size, a position, a spatial resolution and / or a sub-picture ID of each of the plurality of sub-pictures in the second picture; updating the first sub-pictures based on the second sub-picture layout to reconstruct second sub-pictures, wherein the second sub-picture layout differs from the first sub-picture layout in that at least one of a size, a position, a spatial resolution and / or a sub-picture ID of each of the plurality of sub-pictures in the second picture included in the second sub-picture layout is different from at least one of a size, a position, a spatial resolution and / or a sub-picture ID of each of the plurality of sub-pictures in the first picture included in the first sub-picture layout; The method includes:

2. the at least one of the first flag and the second flag includes the first flag; The method of claim 1 , wherein the first flag indicates that the first sub-picture split information for the first picture is signaled in the syntax structure.

3. The method of claim 2 , wherein the first picture includes a plurality of sub-pictures, the plurality of sub-pictures including the first sub-picture.

4. determining a sub-picture identifier (ID) for each sub-picture in the first picture based on the first sub-picture partition information in the syntax structure; 4. The method of claim 3, further comprising:

5. the first picture is in a first layer in the CVS; The method comprises: decoding second sub-picture partition information signaled in another syntax structure for a second picture in a second layer in the CVS, the second sub-picture partition information being different from the first sub-picture partition information; reconstructing a second sub-picture in the second picture based on the second sub-picture division information; The method of claim 1, further comprising:

6. the at least one of the first flag and the second flag includes the second flag; The method of claim 1 , wherein the second flag indicates that the first sub-picture scaling window information of the first sub-picture is signaled in the syntax structure.

7. The method further includes decoding the first sub-picture scaling window information of the first sub-picture based on the syntax structure; 7. The method of claim 6, wherein the step of reconstructing the first subpicture comprises reconstructing the first subpicture using per-subpicture reference picture resampling based on the first subpicture scaling window information of the first subpicture.

8. the at least one of the first flag and the second flag further includes the first flag; the first flag indicates that the first sub-picture split information is signaled in the syntax structure; The method comprises: decoding the first sub-picture scaling window information of the first sub-picture based on the syntax structure; determining size information and position information of the first sub-picture based on the first sub-picture division information; Further comprising:

7. The method of claim 6, wherein the step of reconstructing the first subpicture comprises the step of reconstructing the first subpicture based on the first subpicture scaling window information of the first subpicture, the dimension information of the first subpicture, and the position information of the first subpicture.

9. Apparatus configured to carry out the method according to any one of claims 1 to 8.

10. A program for causing a processor to carry out the method according to any one of claims 1 to 8.

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