Video processing method and video processing device

Abstract

A method for performing video processing by a video processor includes receiving a first syntax element in a coded video bitstream. The first syntax element may be a high-level syntax element and indicates whether a height of each of a plurality of pictures in a video sequence of the coded video bitstream is equal to or greater than a width of a corresponding picture in the video sequence of the coded video bitstream. Processing a picture in the video sequence of the coded video in an orientation determined according to the first syntax element indicating whether a height of each of a plurality of pictures in the video sequence of the coded video is guaranteed to be equal to or greater than a width of a corresponding picture in the video sequence.

Description

[0001] Cross-references

[0002] This application claims the benefit of priority to U.S. Patent Application No. 17 / 499,700, filed on October 12, 2021, entitled “Improvements in Parallel Processing in Video Coding” (which claims the benefit of priority to U.S. Provisional Application No. 63 / 164,633, filed on March 23, 2021, entitled “Improvements in Parallel Processing”). The disclosures of these prior applications are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure describes embodiments generally related to video encoding. Background Art

[0004] The background description provided herein is for the purpose of presenting the content of the present disclosure in general. To the extent that the work of the presently named inventors described in this background section and in various aspects of this specification is performed, it is not intended that it is prior art at the time of filing this application, and it is never expressly or impliedly admitted that it is prior art of the present disclosure.

[0005] Video encoding and decoding can be performed using inter-picture prediction with motion compensation. Uncompressed digital video can include a series of pictures, each picture having a spatial scale of, for example, 1920×1080 luma samples and associated chroma samples. The series of pictures can have a fixed or variable picture rate (also informally referred to as frame rate) of, for example, 60 pictures per second or 60 Hz. Uncompressed video has specific bit rate requirements. For example, 1080p604:2:0 video with 8 bits per sample (1920×1080 luma sample resolution at 60 Hz frame rate) requires close to 1.5 Gbit / s bandwidth. One hour of such video requires more than 600 GB of storage space.

[0006] One purpose of video encoding and decoding can be to reduce redundancy in the input video signal through compression. Compression can help reduce the above-mentioned bandwidth or storage space requirements, in some cases by two orders of magnitude or more. Lossless compression and lossy compression, as well as combinations thereof, can be used. Lossless compression refers to techniques that can reconstruct an exact copy of the original signal from the compressed original signal. When lossy compression is used, the reconstructed signal may be different from the original signal, but the distortion between the original signal and the reconstructed signal is small enough to make the reconstructed signal usable for the intended application. In the case of video, lossy compression is widely used. The amount of tolerable distortion depends on the application, for example, users of some consumer streaming applications can tolerate higher distortion than users of television distribution applications. The achievable compression rate can reflect that higher allowable / acceptable distortion can produce higher compression rates.

[0007] Video encoders and decoders may utilize techniques from several broad categories including, for example, motion compensation, transforms, quantization, and entropy coding.

[0008] Video coding techniques may include techniques 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, pictures are spatially subdivided into sample blocks. When all sample blocks are encoded in intra-mode, the picture may be an intra-picture. Intra-pictures and their derivatives (e.g., independent decoder refresh pictures) may be used to reset the decoder state, and may therefore be used as the first picture in an encoded video bitstream and video session, or as a still image. Samples of intra-blocks may be exposed to transformation, and transform coefficients may be quantized before entropy coding. Intra-prediction may be a technique for minimizing sample values ​​in the pre-transform domain. In some cases, the smaller the DC value after the transformation and the smaller the AC coefficient, the fewer bits are required to represent the block after entropy coding at a given quantization step size.

[0009] Conventional intra-frame coding (e.g., as known from, for example, MPEG-2 generation coding techniques) does not use intra-frame prediction. However, some newer video compression techniques include techniques that attempt to do so from, for example, surrounding sample data and / or metadata obtained during encoding / decoding of spatially adjacent and preceding data blocks in decoding order. Such techniques are hereinafter referred to as "intra-frame prediction" techniques. It should be noted that, in at least some cases, intra-frame prediction uses only reference data from the current picture being reconstructed, and not reference data from reference pictures.

[0010] There can be many different forms of intra-frame prediction. When more than one such technique is available in a given video coding technique, the technique used can be encoded in an intra-frame prediction mode. In some cases, a mode can have sub-modes and / or parameters, and the mode can be encoded separately or included in a mode codeword. Which codeword is used for a given mode / sub-mode / parameter combination may have an impact on the coding efficiency gain through intra-frame prediction, and entropy coding techniques can also be used to convert the codewords into a bitstream.

[0011] Certain intra prediction modes were introduced with H.264, improved in H.265, and further improved in newer coding techniques such as the Joint Detection Model (JEM), Next Generation Video Coding (VVC), and Benchmark Set (BMS). The predictor block can be formed using neighboring sample values ​​belonging to existing available samples. Sample values ​​of neighboring samples are copied into the predictor block according to the direction. A reference to the direction in use can be encoded in the bitstream or can be predicted itself.

[0012] refer to Figure 1 , depicted at the bottom right is a subset of 9 predictor directions known from the 33 possible predictor directions of H.265 (corresponding to the 33 angular modes of the 35 intra modes). The point (101) where the arrows converge represents the sample being predicted. The arrows represent the direction used to predict the sample. 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 to 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 to the horizontal.

[0013] Still reference Figure 1 , a square block (104) of 4×4 samples is depicted at the upper left (indicated by the dashed thick line). The square block (104) includes 16 samples, each sample marked with "S" to indicate 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 in the Y dimension (starting from the top) and the first sample in the X dimension (starting from the left). Similarly, sample S44 is the fourth sample in both the Y dimension and the X dimension in block (104). Since the size of the block is 4×4 samples, S44 is located at the lower right. Reference samples are further shown that follow a similar numbering scheme. The reference samples are marked with R to indicate their Y position (e.g., row index) and X position (column index) relative to the block (104). In H.264 and H.265, the prediction samples are adjacent to the block being reconstructed; therefore, negative values ​​do not need to be used.

[0014] Intra-picture prediction can work by copying reference sample values ​​from neighboring samples, as appropriate for the signaled prediction direction. For example, assume that the encoded video bitstream includes signaling that, for this block, indicates a prediction direction consistent with arrow (102) - that is, predicting samples from one or more prediction samples to the upper right at a 45 degree angle to the horizontal. In this case, samples S41, S32, S23, and S14 are predicted from the same reference sample R05. Sample S44 is then predicted from reference sample R08.

[0015] In some cases, the values ​​of multiple reference samples may be combined, such as by interpolation, to calculate the reference sample; particularly when the direction is not evenly divisible by 45 degrees.

[0016] As video coding technology has developed, the number of possible directions has increased. In H.264 (2003), 9 different directions could be represented. This increased to 33 directions in H.265 (2013), and up to 65 directions were supported when JEM / VVC / BMS was disclosed. Experiments have been conducted to identify the most likely directions and use certain techniques in entropy coding to represent those possible directions with a small number of bits, thereby accepting a certain penalty for less likely directions. Further, the direction itself can sometimes be predicted from the neighboring directions used in adjacent, decoded blocks.

[0017] Figure 2 A schematic diagram (201) depicting 65 intra prediction directions according to JEM is shown to illustrate that the number of prediction directions increases over time.

[0018] The mapping of intra-prediction direction bits representing directions in the coded video bitstream can vary from one video coding technique to another; and can range, for example, from a simple direct mapping of prediction directions to intra-prediction modes, to codewords, to complex adaptive schemes involving most probable modes, and similar techniques. However, in all cases, there may be certain directions that are statistically less likely to occur in the video content than certain other directions. Since the goal of video compression is to reduce redundancy, in a well-working video coding technique, those less likely directions will be represented by more bits than bits for more likely directions.

[0019] Motion compensation may involve a technique where a block of sample data from a previously reconstructed picture or portion thereof (reference picture) is used to predict a newly reconstructed picture or picture portion 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, the third dimension indicating the reference picture being used (the latter may indirectly be the temporal dimension).

[0020] In some video compression techniques, the MV applicable to a region of sample data can be predicted based on other MVs, for example, based on an MV related to another region of sample data that is spatially adjacent to the region being reconstructed and that precedes the MV in decoding order. Doing so can greatly reduce the amount of data required to encode the MV, thereby eliminating redundancy and increasing the compression rate. MV prediction can work effectively, for example, because when encoding an input video signal obtained from a camera (called natural video), there is a statistical possibility that a larger area than the area for which a single MV is applicable moves in a similar direction, so in some cases, similar motion vectors derived from MVs of adjacent areas can be used to predict the larger area. This makes the MV found for a given area similar or identical to the MV predicted from the surrounding MVs, and then after entropy coding, the MV found for the given area can be represented with fewer bits than the number of bits used when the MV is directly encoded. In some cases, MV prediction can be an example of lossless compression of a signal (i.e., MV) derived from the original signal (i.e., sample stream). In other cases, MV prediction itself can be lossy, for example due to rounding errors when calculating predicted values ​​based on multiple surrounding MVs.

[0021] Various MV prediction mechanisms are described in H.265 / HEVC (ITU-T Recommendation H.265, "High Efficiency Video Coding", December 2016). In addition to the multiple MV prediction mechanisms provided by H.265, H.265 provides a technique called "spatial merging". In spatial merging, the current block includes samples that have been discovered by the encoder during the motion search process, which are predictable based on the previous block of the same size that has been spatially shifted. Instead of directly encoding the MV, the MV can be derived from metadata associated with one or more reference pictures, for example, from the nearest (in decoding order) reference picture, using the MV associated with any of several merge candidate positions. In H.265, MV prediction is able to use the predictor of the same reference picture that is being used by neighboring blocks. Summary of the invention

[0022] Aspects of the present disclosure provide a video processing method performed by a video processor. The method includes receiving a first syntax element in a coded video bitstream. The first syntax element may be a high-level syntax element, and the first syntax element is used to indicate whether the height of each of a plurality of pictures in a video sequence of the coded video bitstream is guaranteed to be equal to or greater than the width of a corresponding picture in the video sequence of the coded video bitstream. The pictures in the video sequence of the coded video are processed in an orientation determined according to the first syntax element indicating whether the height of each of a plurality of pictures in the video sequence of the coded video is equal to or greater than the width of the corresponding picture in the video sequence.

[0023] In an embodiment, the first syntax element is transmitted in a supplemental enhancement information (SEI) message, a video usability information (VUI) parameter set, or a sequence parameter set (SPS). In an embodiment, a first value of the first syntax element indicates that a width of each of the pictures in the video sequence is less than a height of a corresponding picture in the video sequence. A second value of the first syntax element indicates that a width of the picture in the video sequence can be less than or not less than a height of the picture in the video sequence. When the first syntax element is not signaled in the bitstream, the first syntax element is inferred to have the second value.

[0024] In an embodiment, an input video sequence corresponding to a video sequence of an encoded video bitstream at an encoder has a height less than a width. The height of the input video sequence is encoded as the width of a picture in the video sequence of the encoded video bitstream, and the width of the input video sequence is encoded as the height of the picture in the video sequence of the encoded video bitstream.

[0025] Embodiments of the method may also include receiving a second syntax element indicating the width of a picture in the video sequence; and receiving a third syntax element indicating the difference between the height of the picture in the video sequence and the width of the picture in the video sequence, the difference being an unsigned integer. For example, the height of the picture in the video sequence may be determined as the sum of the value of the width indicated by the second syntax element and the unsigned integer.

[0026] In an embodiment, in response to a first syntax element indicating that a height of each picture in a video sequence of an encoded video bitstream is equal to or greater than a width of each picture in the video sequence, one or more pictures in the video sequence may be processed using wavefront parallel processing (WPP).

[0027] In an embodiment, a fourth syntax element may be received that is signaled at a slice level in a coded video bitstream. The fourth syntax element may indicate a coding tree unit (CTU) size of a slice in a video sequence. In an embodiment, a plurality of fourth syntax elements may be received, each of the plurality of fourth syntax elements may be associated with a corresponding slice in a plurality of slices in a video sequence. The plurality of fourth syntax elements may indicate different CTU sizes for respective slices of different types. In an embodiment, among the plurality of slices, a type I slice has a smaller CTU size than other slice types.

[0028] In an embodiment, a fifth syntax element may be received in a coded video bitstream, signaled at a picture level. The fifth syntax element may indicate a CTU size of one of the pictures in the video sequence. In an embodiment, a sixth syntax element may be received, included in a sequence parameter set (SPS) in the coded video bitstream, and indicating a first CTU size of the video sequence. A seventh syntax element may be received, signaled at a picture level or a slice level, and indicating a second CTU size of a corresponding picture or a corresponding slice in the video sequence. For example, the first CTU size is a maximum CTU size of the video sequence, and the second CTU size is less than the maximum CTU size.

[0029] Aspects of the present disclosure provide a video processing apparatus. The apparatus includes a circuit configured to receive a first syntax element in a coded video bitstream. The first syntax element may be a high-level syntax element and the first syntax element is used to indicate whether the height of each of a plurality of pictures in a video sequence of the coded video bitstream is guaranteed to be equal to or greater than the width of a corresponding picture in the video sequence of the coded video bitstream. The picture in the video sequence of the coded video is processed in an orientation determined according to the first syntax element indicating whether the height of each of a plurality of pictures in the video sequence of the coded video is equal to or greater than the width of the corresponding picture in the video sequence.

[0030] Aspects of the present disclosure also provide another method of video processing performed by a video processor. The method includes: including a first syntax element in a coded video bitstream, the first syntax element being a high-level syntax element, and the first syntax element being used to indicate whether the height of each of a plurality of pictures in a video sequence of the coded video bitstream is guaranteed to be equal to or greater than the width of a corresponding picture in the video sequence of the coded video bitstream. Processing the pictures in the video sequence of the coded video in an orientation determined by the first syntax element indicating whether the height of each of a plurality of pictures in the video sequence of the coded video is equal to or greater than the width of the corresponding picture in the video sequence. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other features, properties and various advantages of the disclosed subject matter will become more apparent from the following detailed description and the accompanying drawings, in which:

[0032] Figure 1 is a schematic diagram of an exemplary subset of intra prediction modes.

[0033] Figure 2 is a schematic diagram of exemplary intra prediction directions.

[0034] Figure 3 is a schematic diagram of a simplified block diagram of a communication system (300) according to an embodiment.

[0035] Figure 4 is a schematic diagram of a simplified block diagram of a communication system (400) according to an embodiment.

[0036] Figure 5 is a schematic diagram of a simplified block diagram of a decoder according to an embodiment.

[0037] Figure 6 is a schematic diagram of a simplified block diagram of an encoder according to an embodiment.

[0038] Figure 7 A block diagram of an encoder according to another embodiment is shown.

[0039] Figure 8 A block diagram of a decoder according to another embodiment is shown.

[0040] Fig. 9 An example of wavefront parallel processing (WPP) with a delay of two coding tree units (CTUs) is shown.

[0041] Fig.10 Another example of WPP with a delay of one CTU is shown.

[0042] Fig.11 A flow chart of an overview process (1100) according to an embodiment of the present disclosure is shown.

[0043] Fig.12 is a schematic diagram of a computer system according to an embodiment. DETAILED DESCRIPTION

[0044] I. Encoder and Decoder Systems

[0045] Figure 3 A simplified block diagram of a communication system (300) according to an embodiment of the present disclosure is shown. The communication system (300) includes a plurality of terminal devices that can communicate with each other, for example, via a network (350). For example, the communication system (300) includes a pair of terminal devices (310) and terminal devices (320) interconnected via the network (350). Figure 3In the example of , a first pair of terminal devices (310) and a terminal device (320) perform unidirectional transmission of data. For example, the terminal device (310) can encode video data (e.g., a video picture stream captured by the terminal device (310)) for transmission to another terminal device (320) via a network (350). The encoded video data can be transmitted in the form of one or more encoded video bitstreams. The terminal device (320) can receive the encoded video data from the network (350), decode the encoded video data to restore the video picture, and display the video picture based on the restored video data. Unidirectional data transmission may be common in media service applications, etc.

[0046] In another example, the communication system (300) includes a second pair of terminal devices (330) and terminal devices (340) that perform bidirectional transmission of encoded video data, which bidirectional transmission may occur, for example, during a video conference. For bidirectional data transmission, in one example, each of the terminal devices (330) and the terminal devices (340) may encode video data (e.g., a video picture stream collected by the terminal device) for transmission to the other of the terminal devices (330) and the terminal devices (340) via a network (350). Each of the terminal devices (330) and the terminal devices (340) may also receive the encoded video data transmitted by the other of the terminal devices (330) and the terminal devices (340), and may decode the encoded video data to restore the video picture, and may display the video picture on an accessible display device based on the restored video data.

[0047] exist Figure 3 In the example of , terminal device (330) and terminal device (340) may be shown as a server, a personal computer, and a smart phone, but the principles of the present disclosure may not be limited to this. Embodiments of the present disclosure are applicable to laptop computers, tablet computers, media players, and / or dedicated video conferencing equipment. Network (350) represents any number of networks that transmit encoded video data between terminal devices (310), (320), (330), and (340), including, for example, wired (wired) and / or wireless communication networks. The communication network (350) can exchange data in circuit switching and / or packet switching channels. Representative networks include telecommunication networks, local area networks, wide area networks, and / or the Internet. For the purposes of this discussion, unless explained below, the architecture and topology of the network (350) may not be important to the operation of the present disclosure.

[0048] As examples of applications of the disclosed subject matter, Figure 4The placement of the video encoder and video decoder in a streaming environment is shown. The disclosed subject matter is equally applicable to other video-enabled applications including, for example, video conferencing, digital TV, storing compressed video on digital media including CDs, DVDs, memory sticks, etc., and the like.

[0049] The streaming system may include an acquisition subsystem (413) that may include a video source (401), such as a digital camera, that creates, for example, an uncompressed video picture stream (402). In an example, the video picture stream (402) includes samples captured by a digital camera. The video picture stream (402), depicted as thick lines to emphasize the high amount of data compared to the encoded video data (404) (or the encoded 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 of hardware and software to implement or implement various aspects of the disclosed subject matter as described in more detail below. The encoded video data (404) (or the encoded video bitstream (404)), depicted as thin lines to emphasize the lower amount of data compared to the video picture stream (402), may be stored on a streaming server (405) for future use. One or more streaming client subsystems, such as, Figure 4 A client subsystem (406) and a client subsystem (408) in a streaming server (405) may access a streaming server (405) to retrieve a copy (407) and a copy (409) of the encoded video data (404). The client subsystem (406) may include a video decoder (410), for example, in an electronic device (430). The video decoder (410) decodes the incoming copy (407) of the encoded video data and generates an output video picture stream (411) that can be presented on a display (412) (e.g., a display screen) or another presentation device (not depicted). In some streaming systems, the encoded video data (404), the encoded video data (407), and the encoded video data (409) (e.g., a video bitstream) may be encoded according to certain video encoding / compression standards. Examples of these standards include ITU-T Recommendation H.265. In the example, the video coding standard under development is informally referred to as Versatile Video Coding (VVC). The disclosed subject matter may be used in the context of VVC.

[0050] It is understood that the electronic device (420) and the electronic device (430) may include other components (not shown). For example, the electronic device (420) may include a video decoder (not shown), and the electronic device (430) may include a video encoder (not shown).

[0051] Figure 5 A block diagram of a video decoder (510) according to an embodiment of the present disclosure is shown. 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 to replace Figure 4 A video decoder (410) is shown in an example.

[0052] The receiver (531) may receive one or more encoded video sequences to be decoded by the video decoder (510); in the same or another embodiment, one encoded video sequence is received at a time, wherein the decoding of each encoded video sequence is independent of the decoding of the other encoded video sequences. The encoded video sequence may be received from a channel (501), which may be a hardware / software link to a storage device storing the encoded video data. The receiver (531) may receive the encoded video data and other data, such as encoded audio data and / or auxiliary data streams, which may be forwarded to their respective consuming entities (not depicted). The receiver (531) may separate the encoded video sequence from the other data. To prevent network jitter, a buffer memory (515) may be coupled between the receiver (531) and the entropy decoder / parser (520) (hereinafter referred to as "parser (520)"). In some applications, the buffer memory (515) is part of the video decoder (510). In other cases, the buffer memory (515) may be provided external to the video decoder (510) (not depicted). In other cases, a buffer memory (not depicted) may be provided external to the video decoder (510) to, for example, prevent network jitter, and another buffer memory (515) may be configured internally to the video decoder (510) to, for example, handle playout timing. When the receiver (531) receives data from a storage / forward device with sufficient bandwidth and controllability or from an isochronous network, the buffer memory (515) may not be required, or may be made smaller. For use on a traffic packet network such as the Internet, a buffer memory (515) may be required, which may be relatively large and may advantageously have an adaptive size, and may be implemented at least partially in an operating system or similar element (not depicted) external to the video decoder (510).

[0053] The video decoder (510) may include a parser (520) to reconstruct symbols (521) from the encoded video sequence. The types of symbols include information for managing the operation of the video decoder (510) and potential information for controlling a display device such as a display device (512) (e.g., a display screen) that is not an integral part of the electronic device (530) but can be coupled to the electronic device (530), such as Figure 5As shown in . The control information for one (or more) display devices may be in the form of a parameter set fragment (not depicted) of Supplemental Enhancement Information (SEI message) or Video Usability Information (VUI). The parser (520) may parse / entropy decode the received coded video sequence. The encoding of the coded video sequence may be performed according to a video coding technique or standard, and may follow various principles, including variable length coding, Huffman coding, arithmetic coding with or without context sensitivity, and the like. The parser (520) may extract a subgroup parameter set for at least one subgroup 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 subgroup may include a Group of Pictures (GOP), a picture, a tile, a slice, a macroblock, a Coding Unit (CU), a block, a Transform Unit (TU), a Prediction Unit (PU), and the like. The parser (520) may also extract information from the encoded video sequence, such as transform coefficients, quantizer parameter values, motion vectors, and so on.

[0054] The parser (520) may perform entropy decoding / parsing operations on the video sequence received from the buffer memory (515), thereby creating symbols (521).

[0055] Depending on the type of coded video picture or part of coded video picture (e.g., inter-picture and intra-picture, inter-block and intra-block) and other factors, the reconstruction of symbol (521) may involve multiple different units. Which units are involved and how they are involved may be controlled by subgroup control information parsed by parser (520) from the coded video sequence. For the sake of brevity, such subgroup control information flow between parser (520) and the multiple units below is not depicted.

[0056] In addition to the functional blocks already mentioned, the video decoder (510) can be conceptually subdivided into several functional units as described below. In a practical implementation operating under commercial constraints, many of these units interact closely with each other and may be at least partially integrated with each other. However, for the purpose of describing the disclosed subject matter, the conceptual subdivision into the following functional units is appropriate.

[0057] The first unit is a sealer / inverse transform unit (551). The sealer / inverse transform unit (551) receives quantized transform coefficients as symbols (521) from the parser (520) and control information, including which transform method to use, block size, quantization factor, quantization scaling matrix, etc. The sealer / inverse transform unit (551) can output a block including sample values, which can be input into the aggregator (555).

[0058] In some cases, the output samples of the sealer / inverse transform (551) may belong to an intra-coded block; that is, a block that does not use predictive information from a previously reconstructed picture, but may use predictive 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 reconstructed information extracted from a current picture buffer (558). For example, the current picture buffer (558) buffers a partially reconstructed current picture and / or a fully reconstructed current picture. In some cases, the aggregator (555) adds the prediction information generated by the intra-prediction unit (552) to the output sample information provided by the sealer / inverse transform unit (551) on a per-sample basis.

[0059] In other cases, the output samples of the scaler / inverse transform unit (551) may belong to an inter-frame coded and potentially motion compensated block. In this case, the motion compensated prediction unit (553) may access the reference picture memory (557) to extract samples for prediction. After the extracted samples are motion compensated according to the symbols (521) belonging to the block, these samples may be added to the output of the scaler / inverse transform unit (551) (in this case referred to as residual samples or residual signals) by the aggregator (555), thereby generating output sample information. The acquisition of the predicted samples by the motion compensated prediction unit (553) from the address in the reference picture memory (557) may be controlled by a motion vector, and the motion vector is provided to the motion compensated prediction unit (553) in the form of a symbol (521), which may have, for example, X, Y and reference picture components. Motion compensation may also include interpolation of sample values ​​extracted from the reference picture memory (557) when sub-sample accurate motion vectors are used, motion vector prediction mechanisms, etc.

[0060] The output samples of the aggregator (555) may be subjected to various loop filtering techniques in a loop filter unit (556). The video compression techniques may include in-loop filter techniques controlled by parameters included in the coded video sequence (also referred to as the coded video code bitstream) and available to the loop filter unit (556) as symbols (521) from the parser (520), however, the video compression techniques may also be responsive to meta-information obtained during decoding of a coded picture or a previous (in decoding order) portion of the coded video sequence, as well as to previously reconstructed and loop filtered sample values.

[0061] The output of the loop filter unit (556) may be a sample stream that may be output to a rendering device (512) and stored in a reference picture memory (557) for subsequent inter-picture prediction.

[0062] Once fully reconstructed, certain coded pictures may be used as reference pictures for future prediction. For example, once the coded picture corresponding to the current picture is fully reconstructed, and the coded picture is identified as a reference picture (e.g., by the parser (520)), the current picture buffer (558) may become part of the reference picture memory (557), and a new current picture buffer may be reallocated before starting to reconstruct a subsequent coded picture.

[0063] The video decoder (510) may perform decoding operations according to a predetermined video compression technique in, for example, the ITU-T H.265 Recommendation standard. H.265 means that the coded video sequence may conform to the syntax specified by the video compression technology or standard used in the sense that the coded video sequence follows the syntax of the video compression technology or standard and the profile recorded in the video compression technology or standard. Specifically, the profile may select certain tools from all the tools available in the video compression technology or standard as the only tools available for use under the profile. For compliance, the complexity of the coded video sequence may also be required to be within the range defined by the hierarchy of the video compression technology or standard. In some cases, the hierarchy limits the maximum picture size, the maximum frame rate, the maximum reconstruction sampling rate (measured in, for example, mega samples per second), the maximum reference picture size, etc. In some cases, the limits set by the hierarchy may be further limited by the Hypothetical Reference Decoder (HRD) specification and metadata of the HRD buffer management signaled in the coded video sequence.

[0064] In one embodiment, the receiver (531) may receive additional (redundant) data along with the encoded video. The additional data may be included as part of the encoded video sequence. The additional data may be used by the video decoder (510) to properly decode the data and / or more accurately reconstruct the original video data. The additional data may be in the form of, for example, temporal, spatial or signal-to-noise ratio (SNR) enhancement layers, redundant slices, redundant pictures, forward error correction codes, etc.

[0065] Figure 6 A block diagram of a video encoder (603) according to an embodiment of the present disclosure is shown. 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 to replace Figure 4 The video encoder (403) in the example.

[0066] The video encoder (603) can be used to obtain the video source (601) (not Figure 6 In another example, the video source (601) is a part of the electronic device (620) to receive video samples, and the video source can capture video images to be encoded by the video encoder (603). In another example, the video source (601) is a part of the electronic device (620).

[0067] The video source (601) may provide a source video sequence in the form of a digital video sample stream to be encoded by the video encoder (603), which may have 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 service system, the video source (601) may be a storage device storing previously prepared videos. In a video conferencing system, the video source (601) may be a camera that captures local image information as a video sequence. The video data may be provided as a plurality of separate pictures that are given motion when viewed sequentially. The pictures themselves may be constructed as a spatial pixel array, where each pixel may include one or more samples depending on the sampling structure, color space, etc. used. The relationship between pixels and samples may be easily understood by those skilled in the art. The following description focuses on samples.

[0068] According to one embodiment, the video encoder (603) can encode and compress pictures of the source video sequence into an encoded video sequence (643) in real time or under any other time constraints required by the application. Implementing an appropriate encoding speed is a function of the controller (650). In some embodiments, the controller (650) controls other functional units as described below and is functionally coupled to the other functional units. For the sake of simplicity, the coupling is not depicted in the figure. The parameters set by the controller (650) may include rate control related parameters (picture skipping, quantizer, lambda value of rate distortion optimization technology, etc.), picture size, group of pictures (GOP) layout, maximum motion vector search range, etc. The controller (650) can be configured to have other suitable functions that are related to the video encoder (603) optimized for a certain system design.

[0069] In some embodiments, the video encoder (603) is configured to operate in an encoding loop. As a simple description, in an example, the encoding loop may include a source encoder (630) (e.g., responsible for creating symbols, such as a symbol stream, based on an input picture to be encoded and one (or more) reference pictures) and 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 how the (remote) decoder can also create sample data (because in the video compression technology considered by the disclosed subject matter, any compression between the symbols and the encoded video bitstream is lossless). The reconstructed sample stream (sample data) is input to a reference picture memory (634). Since the decoding of the symbol stream produces bit-accurate results that are independent of the decoder location (local or remote), the contents of the reference picture memory (634) are also bit-accurately corresponding between the local encoder and the remote encoder. In other words, the reference picture samples "seen" by the prediction part of the encoder are exactly the same as the sample values ​​that the decoder will "see" when using the prediction during decoding. This basic principle of reference picture synchronization (and the drift that occurs when synchronization cannot be maintained, eg due to channel errors) is also used in some related techniques.

[0070] The operation of the "local" decoder (633) can be combined with the above Figure 5 The operation of the "remote" decoder of the video decoder (510) described in detail is identical. However, additional brief reference is made to Figure 5 , when symbols are available and the entropy encoder (645) and parser (520) may be able to losslessly encode / decode the symbols into an encoded video sequence, 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).

[0071] At this point it can be observed that any decoder techniques other than parsing / entropy decoding present in the decoder must also be present in the corresponding encoder in substantially the same functional form. For this reason, the disclosed subject matter focuses on decoder operation. The description of encoder techniques can be simplified because encoder techniques are mutually inverse to the decoder techniques described comprehensively. A more detailed description is only required in certain areas and is provided below.

[0072] During operation, in some examples, the source encoder (630) may perform motion compensated predictive coding that predictively encodes an input picture with reference to one or more previously encoded pictures from a video sequence designated as "reference pictures." In this manner, the encoding engine (632) encodes the differences between pixel blocks of an input picture and pixel blocks of one (or more) reference pictures that may be selected as prediction references for the input picture.

[0073] The local video decoder (633) can decode the encoded video data of the picture that can be designated as the reference picture based on the symbol created by the source encoder (630). The operation of the encoding engine (632) can advantageously be a lossy process. When the encoded video data is available at the video decoder ( Figure 6 When the video encoder (603) is decoded at a remote location (not shown), the reconstructed video sequence may typically be a copy of the source video sequence with some errors. The local video decoder (633) replicates the decoding process that may be performed by the video decoder on the reference picture and may cause the reconstructed reference picture to be stored in the reference picture cache (634). In this way, the video encoder (603) may locally store a copy of the reconstructed reference picture that has common content (absent transmission errors) with the reconstructed reference picture that will be obtained by the remote video decoder.

[0074] The predictor (635) may perform a prediction search for the encoding engine (632). That is, for a new picture to be encoded, the predictor (635) may search the reference picture memory (634) for sample data (as candidate reference pixel blocks) or certain metadata, such as reference picture motion vectors, block shapes, etc., that may serve as appropriate prediction references for the new picture. The predictor (635) may operate on a pixel block by pixel block basis to find a suitable prediction reference. In some cases, as determined by the search results obtained by the predictor (635), the input picture may have prediction references taken from multiple reference pictures stored in the reference picture memory (634).

[0075] The controller (650) can manage the encoding operations of the source encoder (630), including, for example, setting parameters and subgroup parameters for encoding video data.

[0076] The outputs of all the above functional units may be entropy encoded in an entropy encoder (645). The entropy encoder (645) performs lossless compression on the symbols generated by the various functional units according to techniques such as Huffman coding, variable length coding, arithmetic coding, etc., thereby transforming the symbols into a coded video sequence.

[0077] The transmitter (640) may buffer the encoded video sequence created by the entropy encoder (645) in preparation for transmission over a communication channel (660), which may be a hardware / software link to a storage device where the encoded video data will be stored. The transmitter (640) may combine the encoded video data from the video encoder (603) with other data to be transmitted, such as encoded audio data and / or ancillary data streams (source not shown).

[0078] The controller (650) can manage the operation of the video encoder (603). During encoding, the controller (650) can assign a certain coded picture type to each coded picture, but this may affect the coding techniques that can be applied to the corresponding picture. For example, a picture can generally be assigned to any of the following picture types:

[0079] An intra picture (I picture) may be a picture that can be encoded and decoded without using any other picture in the sequence as a prediction source. Some video codecs allow different types of intra pictures, including, for example, Independent Decoder Refresh ("IDR") pictures. Those skilled in the art are aware of the variations of I pictures and their corresponding applications and features.

[0080] A predictive picture (P picture) may be a picture that can be encoded and decoded using intra prediction or inter prediction, which uses at most one motion vector and a reference index to predict sample values ​​for each block.

[0081] Bidirectional predictive pictures (B pictures), which can be pictures that can be encoded and decoded using intra prediction or inter prediction, which uses up to two motion vectors and reference indices to predict the sample values ​​of each block. Similarly, multiple predictive pictures can use more than two reference pictures and associated metadata for reconstructing a single block.

[0082] The source picture may typically be spatially subdivided into blocks of samples (e.g., blocks of 4×4, 8×8, 4×8, or 16×16 samples), and coded block by block. These blocks may be predictively coded with reference to other (already coded) blocks, which are determined by the coding allocation applied to the block's corresponding picture. For example, a block of an I picture may be non-predictively coded, or the block may be predictively coded (spatial prediction or intra prediction) with reference to already coded blocks of the same picture. A block of a P picture may be predictively coded by spatial prediction with reference to one previously coded reference picture or by temporal prediction. A block of a B picture may be predictively coded by spatial prediction with reference to one or two previously coded reference pictures or by temporal prediction.

[0083] The video encoder (603) may perform encoding operations according to a predetermined video encoding technique or standard, such as ITU-T H.265 Recommendation. In operation, the video encoder (603) may perform various compression operations, including predictive encoding operations that exploit temporal and spatial redundancy in an input video sequence. Thus, the encoded video data may conform to the syntax specified by the video encoding technique or standard used.

[0084] In one embodiment, the transmitter (640) may transmit additional data when transmitting the encoded video. The source encoder (630) may include such data as part of the encoded video sequence. The additional data may include other forms of redundant data such as temporal / spatial / SNR enhancement layers, redundant pictures and slices, SEI messages, VUI parameter set fragments, etc.

[0085] Video may be captured as multiple source pictures (video pictures) in a temporal sequence. Intra-picture prediction (often simplified to intra-prediction) exploits spatial correlations in a given picture, while inter-picture prediction exploits (temporal or other) correlations between pictures. In an example, a particular picture being encoded / decoded is partitioned into blocks, and the particular picture being encoded / decoded is referred to as the current picture. When a block in the current picture is similar to a reference block in a reference picture that was previously encoded in the video and is still buffered, the block in the current picture may be encoded by a vector called a motion vector. The motion vector points to a reference block in a reference picture, and in the case where multiple reference pictures are used, the motion vector may have a third dimension that identifies the reference picture.

[0086] In some embodiments, bidirectional prediction techniques may be used in inter-picture prediction. According to the bidirectional prediction technique, two reference pictures are used, for example, a first reference picture and a second reference picture that are both before the current picture in the video in decoding order (but may be in the past and future in display order, respectively). A block in the current picture may be encoded by a first motion vector pointing to a first reference block in the first reference picture and a second motion vector pointing to a second reference block in the second reference picture. The block may be predicted by a combination of the first reference block and the second reference block.

[0087] In addition, merge mode technology can be used in inter-picture prediction to improve coding efficiency.

[0088] According to some embodiments of the present disclosure, predictions such as inter-picture prediction and intra-picture prediction are performed in units of blocks. For example, according to the HEVC standard, a picture in a video picture sequence is divided into coding tree units (CTUs) for compression, and the CTUs in the 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), which are a luminance CTB and two chrominance CTBs. Each CTU can be recursively split into one or more coding units (CUs) using a quadtree. For example, a 64×64 pixel CTU can be split into a 64×64 pixel CU, or 4 32×32 pixel CUs, or 16 16×16 pixel CUs. In the example, each CU is analyzed to determine a prediction type for the CU, such as an inter-prediction type or an intra-prediction type. Depending on temporal and / or spatial predictability, the CU is split into one or more prediction units (PUs). Typically, each PU includes a luma prediction block (PB) and two chroma PBs. In an embodiment, the prediction operation in encoding (encoding / decoding) is performed in units of prediction blocks. Taking the luma prediction block as an example of a prediction block, the prediction block includes a matrix of values ​​(e.g., luma values) for pixels, such as 8×8 pixels, 16×16 pixels, 8×16 pixels, 16×8 pixels, and the like.

[0089] Figure 7 A diagram of a video encoder (703) according to another embodiment of the present disclosure is shown. The video encoder (703) is configured to receive a processed block (e.g., a prediction block) of sample values ​​within a current video picture in a sequence of video pictures and encode the processed block into an encoded picture that is part of an encoded video sequence. In an example, the video encoder (703) is used instead of Figure 4 The video encoder (403) in the example.

[0090] In the HEVC example, the video encoder (703) receives a matrix of sample values ​​for a processing block, such as a prediction block of 8×8 samples. The video encoder (703) uses, for example, rate-distortion (RD) optimization to determine whether to use intra mode, inter mode, or bidirectional prediction mode to best encode the processing block. When encoding the processing block in intra mode, the video encoder (703) may use intra prediction techniques to encode the processing block into an encoded picture; and when encoding the processing block in inter mode or bidirectional prediction mode, the video encoder (703) may use inter prediction or bidirectional prediction techniques to encode the processing block into an encoded picture, respectively. In some video coding techniques, the merge mode may be an inter-picture prediction submode, in which motion vectors are derived from one or more motion vector predictors without the aid of encoded motion vector components external to the predictor. In some other video coding techniques, there may be motion vector components applicable to the subject block. In the example, the video encoder (703) includes other components, such as a mode decision module (not shown) for determining the mode of the processing block.

[0091] exist Figure 7 In the example of FIG. 7 , the video encoder ( 703 ) includes Figure 7 Shown are an inter-frame encoder (730), an intra-frame encoder (722), a residual calculator (723), a switch (726), a residual encoder (724), a general controller (721), and an entropy encoder (725) coupled together.

[0092] The inter-frame encoder (730) is configured to receive samples of a current block (e.g., a processing block), compare the block with one or more reference blocks in a reference picture (e.g., blocks in a previous picture and a subsequent picture), generate inter-frame prediction information (e.g., redundant information description according to an inter-frame coding technique, motion vectors, merge mode information), and calculate an inter-frame prediction result (e.g., a predicted block) based on the inter-frame prediction information using any suitable technique. In some examples, the reference picture is a decoded reference picture decoded based on the encoded video information.

[0093] The intra encoder (722) is configured to receive samples of a current block (e.g., a processing block), compare the block with an encoded block in the same picture in some cases, generate quantization coefficients after transformation, and in some cases also generate intra prediction information (e.g., intra prediction direction information according to one or more intra coding techniques). In an example, the intra encoder (722) also calculates an intra prediction result (e.g., a predicted block) based on the intra prediction information and a reference block in the same picture.

[0094] The general controller (721) is configured to determine general control data and control other components of the video encoder (703) based on the general control data. In an example, the general 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 intra mode, the general controller (721) controls the switch (726) to select the 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 inter mode, the general controller (721) controls the switch (726) to select the inter prediction result for use by the residual calculator (723), and controls the entropy encoder (725) to select the inter prediction information and include the inter prediction information in the bitstream.

[0095] The residual calculator (723) is configured to calculate the difference (residual data) between the received block and the prediction result selected from the intra-frame encoder (722) or the inter-frame encoder (730). The residual encoder (724) is configured to operate based on the residual data to encode the residual data to generate transform coefficients. In an example, the residual encoder (724) is configured to convert the residual data from the spatial domain to the frequency domain and generate transform coefficients. The transform coefficients are then subjected to quantization 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 appropriately by the intra-frame encoder (722) and the inter-frame encoder (730). For example, the inter encoder (730) can generate a decoded block based on the decoded residual data and the inter prediction information, and the intra encoder (722) can generate a decoded block based on the decoded residual data and the intra prediction information. The decoded blocks are appropriately processed to generate a decoded picture, and in some examples, the decoded picture can be buffered in a memory circuit (not shown) and used as a reference picture.

[0096] The entropy encoder (725) is configured to format the bitstream to produce an encoded block. The entropy encoder (725) is configured to generate various information according to a suitable standard, such as the HEVC standard. In an example, the entropy encoder (725) is configured to include general control data, selected prediction information (such as intra-frame prediction information or inter-frame prediction information), residual information, and other suitable information in the bitstream. It should be noted that according to the disclosed subject matter, when the block is encoded in the inter-frame mode or the merge sub-mode of the bidirectional prediction mode, there is no residual information.

[0097] Figure 8A diagram of a video decoder (810) according to another embodiment of the present disclosure is shown. The video decoder (810) is configured to receive an encoded picture as part of an encoded video sequence and decode the encoded picture to generate a reconstructed picture. In an example, the video decoder (810) is used instead of Figure 4 A video decoder (410) is shown in an example.

[0098] exist Figure 8 In this example, the video decoder (810) includes Figure 8 Shown are an entropy decoder (871), an inter-frame decoder (880), a residual decoder (873), a reconstruction module (874), and an intra-frame decoder (872) coupled together.

[0099] The entropy decoder (871) may be configured to reconstruct certain symbols from the encoded picture, the symbols representing the syntax elements constituting the encoded picture. Such symbols may include, for example, a mode for encoding the block (e.g., intra mode, inter mode, bidirectional prediction mode, a merged sub-mode of the latter two, or another sub-mode), prediction information (e.g., intra prediction information or inter prediction information) that can identify certain samples or metadata for prediction by the intra decoder (872) or the inter decoder (880), respectively, residual information in the form of, for example, quantized transform coefficients, and the like. In one example, when the prediction mode is inter or bidirectional prediction 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 be subjected to inverse quantization and provided to the residual decoder (873).

[0100] The inter-frame decoder (880) is configured to receive inter-frame prediction information and generate an inter-frame prediction result based on the inter-frame prediction information.

[0101] The intra decoder (872) is configured to receive intra prediction information and generate a prediction result based on the intra prediction information.

[0102] 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)), and this information may be provided by the entropy decoder (871) (data path not depicted as this is only low-volume control information).

[0103] The reconstruction module (874) is configured to combine the residual output by the residual decoder (873) with the prediction result (which may be output by the inter-frame prediction module or the intra-frame prediction module as the case may be) in the spatial domain to form a reconstructed block, which may be part of a reconstructed picture, which in turn may be part of a reconstructed video. It should be noted that other suitable operations such as deblocking operations may be performed to improve visual quality.

[0104] It should be noted that the video encoder (403), video encoder (603) and video encoder (703) and video decoder (410), video decoder (510) and video decoder (810) may be implemented using any suitable technology. In one embodiment, the video encoder (403), video encoder (603) and video encoder (703) and video decoder (410), video decoder (510) and video decoder (810) may be implemented using one or more integrated circuits. In another embodiment, the video encoder (403), video encoder (603) and video encoder (603) and video decoder (410), video decoder (510) and video decoder (810) may be implemented using one or more processors that execute software instructions.

[0105] II. Wavefront Parallel Processing

[0106] In some embodiments, wavefront parallel processing (WPP) is used for parallelization. WPP enables the creation of picture partitions that can be processed in parallel without incurring high coding losses. Fig. 9 An example of WPP is shown. A picture (or slice or tile) (900) can be divided into, for example, 4 rows of CTUs. Each row of CTUs can be processed in parallel with a delay of two CTUs. After decoding the adjacent blocks (left, top, top left, top right), the CTU (901) can be decoded. Therefore, intra-picture prediction between adjacent CTU rows can be used. For example, as shown by arrow (902), the decoding of blocks within the CTU (901) can refer to adjacent blocks within the left, top, top left, and top right CTUs.

[0107] In addition, as shown by arrow (903), at the beginning of each CTU row, the context based on context adaptive binary arithmetic code (CABAC) context is reset using the context at the end of the upper right CTU. Therefore, compared with other parallel coding tools, for example, based on tile or slice partitioning, the coding dependency between adjacent CTU rows (intra-picture prediction and CABAC context modeling) can be preserved. Therefore, higher coding efficiency can be achieved.

[0108] In some embodiments, larger CTU sizes are allowed, for example, 128x128 pixels. WPP with one CTU delay can be used. For larger CTU sizes, since the number of pixels processed in a 128x128 CTU is greater than the number of pixels processed in two 64x64 CTUs, one CTU is sufficient for CABAC learning. Fig.10 Another example of WPP with one CTU delay is shown. Fig. 9 Similar to the example of , a picture (or slice or tile) (1000) can be divided into, for example, 4 rows of CTUs. Each row of CTUs can be processed in parallel with a delay of one CTU. After decoding the adjacent blocks (left, top, and top-left), the CTU (1001) can be decoded. As shown by the crossed arrows (1002), the blocks in the top-right CTU cannot be referenced. When processing the first CTU in each row of CTUs after the first row of CTUs, the CABAC probability can be inherited from the CTU above the first CTU, as shown by the arrow (1003).

[0109] III. Problems in WPP

[0110] There is a downside to using larger CTU sizes in WPP. For pictures of a certain resolution, using larger CTU sizes will reduce parallel processing performance. For example, a larger CTU size will result in fewer CTU rows, which in turn will result in fewer processing threads that can be parallelized. In addition, due to the larger CTU size, the pipeline latency of WPP may be longer. In addition, a larger CTU size can have a larger variance in the processing time to process (e.g., encode / decode) a CTU, resulting in increased latency in parallel processing.

[0111] WPP is handled at CTU row level.In some embodiments, the CTU size is signaled at the sequence level, for example contained in a sequence parameter set (SPS), which means there is no flexibility to adapt the CTU size at picture level or slice level.

[0112] When the height of a picture is smaller than its width, the size of the picture line buffer is relatively large since the picture line buffer depends on the number of horizontal pixels and the associated side information.

[0113] IV. Improvements to WPP

[0114] 1. Make sure the image is taller than it is wide

[0115] To solve the above problem, in some embodiments, the encoder can be configured to encode the picture with the longer picture side as the height and the shorter picture side as the width in the process of encoding the video sequence. In this way, each picture in the video sequence can be divided into more CTU rows than the case where the shorter picture side is high. Therefore, when WPP is enabled, more parallel threads can be used to obtain better parallel processing performance. In addition, due to the shorter picture width, the process may produce a smaller line buffer size.

[0116] The decision to encode the video sequence in the above coding mode can be based on certain conditions, such as knowledge of the decoder capabilities. For example, when the target decoder is configured with a multi-core CPU and is sufficient for parallel processing (possibly WPP), the above coding mode can be enabled.

[0117] When the above coding mode is enabled, a syntax element may be signaled to inform the decoder that the pictures in the coded video sequence are guaranteed to have a width greater than (or equal to) the height. For example, the syntax element indicates that each picture in the coded video sequence has a width greater than the height. Based on the signal, the decoder may decode subsequent syntax elements accordingly or determine whether WPP is available for decoding the coded video sequence.

[0118] In some embodiments, a high-level syntax element is used to indicate whether to ensure that the height of a picture in an encoded video sequence is not less than the width of the picture in the encoded video sequence. For example, a high-level syntax element can be used to ensure that the height of a picture in a video sequence is greater than or equal to the width of the picture.

[0119] The high-level syntax elements may be generated at the video encoder and signaled to the decoder. In an example, the high-level syntax elements are signaled in a Supplemental Enhancement Information (SEI) message. In an example, the high-level syntax elements are signaled as part of a Video Usability Information (VUI) parameter set.

[0120] For example, exemplary syntax and semantics of SEI messages and VUI parameters may be defined by the Versatile Supplemental Enhancement Information Messages for Coded Video Bitstreams (Draft 5) standard (JVET-S2007-v7, JVET of ITU-TSG 16WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11, 18th Meeting: Remote Meeting Held from April 15 to 24, 2020). The entire contents of this draft standard are incorporated herein by reference. For example, the VUI parameters and SEI messages defined in the above draft standard may be transmitted in a coded video bitstream in a manner specified in a video coding specification, or may be transmitted in other ways determined by the specifications of a system using such a coded video bitstream. For example, SEI messages and VUI parameters may be used with coded video bitstreams specified by Rec.ITU-T H.266, ISO / IEC 23090-3, or other types of coded video bitstreams.

[0121] In an example, the high-level syntax elements are signaled at a video sequence level, such as in an SPS contained in a coded video bitstream. In an example, the high-level syntax elements are signaled at a picture level, such as in a PPS. In various examples, the high-level syntax elements may be signaled as any type of high-level syntax element that may be referenced when decoding a picture.

[0122] In some embodiments, the high-level syntax element is a flag denoted as width_smaller_than_height_flag. The flag may be signaled at any level of the coded video bitstream or outside the coded video bitstream. In an example, when the flag has a first value, such as a value of 1, the flag may indicate that the video sequence or a picture referring to the flag has a picture width that is less than the picture height. When the flag has a second value, such as a value of 0, the flag may indicate that the video sequence or a picture referring to the flag may or may not have a picture width that is less than the picture height. For example, the second value may indicate that it is not known from the decoder's perspective whether the picture width is less than the picture height.

[0123] In an example, when the flag is not signaled in the coded video bitstream, the decoder may infer that the flag has a certain value. In one example, the flag may be inferred to have a value indicating that the video sequence or a picture that references the flag may or may not have a picture width that is less than the picture height. In another example, when the flag is not signaled in the coded video bitstream, the decoder may infer that the flag has a value indicating that the video sequence or a picture that references the flag has a picture width that is less than the picture height.

[0124] In an example, width_smaller_than_height_flag may be signaled in the SPS as shown in Table 1 below.

[0125] Table 1

[0126]

[0127] In some embodiments, after receiving or inferring width_smaller_than_height_flag, the decoder may decode the video sequence or picture accordingly with reference to the flag. For example, based on the value of width_smaller_than_height_flag, the decoder may decode the syntax element to determine the width and height of the video sequence or picture.

[0128] In an embodiment, when width_smaller_than_height_flag has a value indicating that the picture width is guaranteed to be less than the picture height of the video sequence (or picture), the picture width may be signaled with a first syntax element (e.g., in an SPS or PPS), and the difference between the picture height and the picture width may be signaled with a second syntax element (e.g., in an SPS or PPS). Since the picture height is always greater than (or equal to) the picture width, and the sign of the difference is not required, the second syntax element may be signaled as an unsigned integer. In an example, the first syntax element is signaled before the second syntax element in the coded video bitstream. In an example, the second syntax element is signaled before the first syntax element. In some examples, the first syntax element is used to represent the picture height instead of the picture width, and the second syntax element is still used to represent the difference.

[0129] Assuming the above-mentioned configuration of sending the signal of the first and second syntax elements, based on the predefined semantics of the first and second syntax elements, in response to receiving a width_smaller_than_height_flag having a value indicating that the guaranteed picture width is smaller than the picture height of the video sequence (or picture), the decoder can correctly interpret the first and second syntax elements accordingly.

[0130] In an embodiment, when width_smaller_than_height_flag has a value indicating that the picture width may be smaller or not smaller than the picture height of the video sequence (or picture) referring to the flag, the picture width and the picture height may be signaled using different syntax elements, respectively. For example, the picture width is indicated by a first syntax element, and the picture height is indicated by a second syntax element. Thus, the decoder may decode these two syntax elements to determine the picture width and the picture height upon receiving the flag.

[0131] In an example, after receiving or inferring width_smaller_than_height_flag, the decoder can determine which parallel processing encoding method to use to decode the video sequence or picture based on the value of width_smaller_than_height_flag. For example, candidate encoding methods for parallel processing may include tiles, WPP, slices, sub-pictures, etc. In an embodiment, when the flag indicates that the picture height is guaranteed to be greater than the picture width, the decoder can determine that WPP will be used to decode the video sequence. Other factors (e.g., CTU size) can be considered in conjunction with width_smaller_than_height_flag to make the above selection. In one embodiment, when width_smaller_than_height_flag is sent with a signal, syntax elements indicating the enablement of certain parallel processing methods other than WPP may not be sent with a signal, and may be inferred by the decoder to save coded bits.

[0132] In some embodiments, when the height of the input video sequence at the encoder is less than the width, preprocessing can be performed on the input video sequence to ensure that the width of the preprocessed video sequence is greater than the height. For example, as a result of the preprocessing, the orientation can be changed, and the width and height of the input video sequence become the height and width of the preprocessed video sequence.

[0133] In an example, a rotation operation can be performed on an input video sequence to generate a preprocessed video sequence. For example, the input video sequence can be rotated 90 degrees clockwise or counterclockwise. When rotating 90 degrees clockwise, the pixels on the left side of the picture in the input video sequence will move to the top of the picture in the preprocessed video sequence. When rotating 90 degrees counterclockwise, the pixels on the left side of the picture in the input video sequence will move to the bottom of the picture in the preprocessed video sequence. In either case, the width and height of the input video sequence become the height and width of the preprocessed video sequence.

[0134] Corresponding to the above-mentioned preprocessed video sequence, the width information can be first signaled, for example, in the SPS. Then, the difference between the height and the width can be signaled, for example, in the SPS as an unsigned integer. Thus, bits for signaling the encoding of the height and the width can be saved.

[0135] In an example, in the encoded video bitstream corresponding to the pre-processed video sequence, there is no signal as to whether the rotation operation occurred at the encoder. In another example, syntax indicating whether the rotation operation was performed may be signaled in the encoded video bitstream corresponding to the pre-processed video sequence.

[0136] In some embodiments, in conjunction with preprocessing to ensure that the picture width is less than the picture height of the encoded video sequence, the above-mentioned high-level syntax element (e.g., width_smaller_than_height_flag) can be signaled to indicate whether the height is guaranteed to be no less than the width in the encoded video sequence. Corresponding to preprocessing, the high-level syntax element can be set to a value such as 1. For example, regardless of whether preprocessing (e.g., rotation operation) is performed (depending on the length of the height and width of the input video sequence), the high-level syntax element can be signaled to indicate that the height is guaranteed to be no less than the width in the encoded video sequence.

[0137] Conversely, when preprocessing is not enabled at the encoder, a high-level syntax element may be signaled to indicate that the width can be less than or not less than the height in the encoded video sequence. Alternatively, the high-level syntax element is not signaled and may be inferred by the decoder to have a value indicating that the width can be less than or not less than the height.

[0138] In an example, in preprocessing to ensure that the picture height is greater than the picture width of the encoded video sequence, no high-level syntax elements are signaled to indicate whether the height is guaranteed to be no less than the width in the encoded video sequence. For example, preprocessing can be specified in a video coding standard (e.g., VVC). Therefore, the decoder and the encoder can have the same understanding that the height is guaranteed to be no less than the width. Therefore, the decoder can decode some syntax elements, for example, to obtain the picture width and height assuming that the picture height is greater than the picture width, or to decide how to select a suitable parallel processing method from multiple candidate parallel processing methods.

[0139] 2. Flexible CTU size

[0140] As described above, in some embodiments, the CTU size can affect the WPP coding performance and can be signaled, for example, in the SPS. In order to achieve better WPP coding performance for a specific picture or area in a picture, in some embodiments, the CTU size can be signaled at the picture level or slice level instead of at the sequence level. For example, the CTU size can be signaled in the PPS or slice header. Therefore, different pictures or slices can have different CTU sizes, resulting in different numbers of CTU rows. In this way, WPP of different granularities can be achieved.

[0141] In some examples, different types of slices may use different CTU sizes. In some embodiments, there may be three types of slices: I slices, P slices, and B slices. I slices use intra prediction, P slices may use intra prediction and inter prediction with one reference picture list, and B slices may use intra prediction and inter prediction with two reference picture lists. In an example, a smaller CTU size may be used for intra-coded slices (I slices), so that more WPP threads may be used to speed up the processing speed of intra-coded slices. In an example, a larger CTU size is used for other types of slices (such as P slices or B slices) with a higher temporal level so that fewer WPP threads are required. In some cases, the processing complexity of I slices is higher than that of B or P slices. In some examples, applying different CTU sizes (different numbers of threads) to different types of slices may balance the processing time (or workload) for different slices, thereby making the overall processing time of pictures including these slices shorter.

[0142] In some examples, the CTU size may be signaled at a tile level or a sub-picture level so that different tiles or sub-pictures may have different CTU sizes and, thus, different CTU rows and WPP threads.

[0143] In some embodiments, signaling CTU size at the picture level (PPS level) and slice level can be combined with signaling CTU size at the sequence level (SPS level). In an example, the maximum CTU size can be signaled at the SPS level, and at other levels, such as the picture level and / or slice level, a smaller CTU size can be further signaled to enable more WPP threads at that level. For pictures or slices that use the maximum CTU size signaled at the SPS level, the CTU size for these pictures or slices may not be signaled to save coded bits.

[0144] In an example, the CTU size is signaled at the sequence level, and at other levels, such as the picture level and / or slice level, a smaller or larger CTU size may be further signaled to enable more or fewer WPP threads at that level. Similarly, for pictures or slices of the same CTU size as signaled at the sequence level, the CTU size may not be signaled.

[0145] V. Ensure that the image width is smaller than the image height

[0146] Fig.11 A flow chart of an overview process (1100) according to an embodiment of the present disclosure is shown. The process (1100) can be used for reconstruction of a block. In various embodiments, the process (1100) is performed by a processing circuit, for example, a processing circuit in a terminal device (310), (320), (330) and (340), such as a processing circuit that performs video processing functions in a video decoder (410), a processing circuit that performs functions of a video decoder (510), etc. In some embodiments, the process (1100) is implemented in software instructions, so when the processing circuit executes the software instructions, the processing circuit performs the process (1100). The process starts at (S1101) and proceeds to (S1110).

[0147] At (S1110), a first syntax element may be received in a coded video bitstream. The first syntax element may indicate whether the height of each of a plurality of pictures in a video sequence of the coded video bitstream is equal to or greater than the width of a corresponding picture in the video sequence. The first syntax element may be transmitted as a high-level syntax element. For example, the first syntax element may be transmitted in an SEI message, a VUI parameter set (or referred to as a VUI syntax structure), an SPS, etc.

[0148] In an example, a first value of the first syntax element indicates that a width of each of the pictures in the video sequence is less than a height of the corresponding picture in the video sequence, and a second value of the first syntax element indicates that the width of the picture in the video sequence can be less than or not less than the height of the picture in the video sequence. In an embodiment, the first syntax element is not signaled in the bitstream. The decoder may infer that the value of the first syntax element is the second value.

[0149] In an embodiment, an input video sequence corresponding to a video sequence of an encoded video bitstream at an encoder has a height that is less than a width. The height of the input video sequence is encoded as the width of a picture in the video sequence of the encoded video bitstream, and the width of the input video sequence is encoded as the height of the picture in the video sequence of the encoded video bitstream. For example, a rotation preprocessing may be performed at the encoder to convert the height and width of the picture in the input video sequence.

[0150] In an embodiment, a second syntax element indicating the width of a picture in a video sequence may also be received. A third syntax element indicating the difference between the height of a picture in a video sequence and the width of a picture in the video sequence may also be received. The difference may be an unsigned integer. For example, when the first syntax element indicates that the video sequence of the encoded video ensures that the height of the picture in the video sequence is equal to or greater than the width of the picture in the video sequence, the second syntax and the third syntax may be signaled in the bitstream.

[0151] In an embodiment, a plurality of fourth syntax elements may be received in a coded video bitstream. Each of the plurality of fourth syntax elements may be associated with a corresponding slice of a plurality of slices in a video sequence. The plurality of fourth syntax elements may indicate different CTU sizes of corresponding slices of different types. For example, among the plurality of slices, an I-type slice has a smaller CTU size than other slice types.

[0152] In an embodiment, a fifth syntax element may be received. The fifth syntax element may be signaled at a picture level in a coded video bitstream. The fifth syntax element may indicate a CTU size of one of the pictures in the video sequence. In an example, both the fourth syntax element and the fifth syntax element are transmitted for the video sequence. In an example, for use of the fourth and fifth syntax elements, only the fourth syntax element or only the fifth syntax is transmitted for the video sequence.

[0153] In some embodiments, the signaling of the CTU size in the sequence level and the signaling of the CTU size in the picture or slice level can be combined so that different pictures or slices can use different CTU sizes. For example, a sixth syntax element can be received. The sixth element can be included in the SPS in the bitstream and indicates a first CTU size of the video sequence. A seventh syntax element signaled at the picture level or slice level can be received together with the sixth syntax element. The seventh syntax can indicate a second CTU size of the corresponding picture or the corresponding slice in the video sequence. For example, the first CTU size is the maximum CTU size of the video sequence, and the second CTU size is less than the maximum CTU size.

[0154] At (S1120), pictures in a video sequence of the encoded video are processed at an orientation determined according to a first syntax element indicating whether a height of each of a plurality of pictures in the video sequence of the encoded video is equal to or greater than a width of a corresponding picture in the video sequence.

[0155] For example, when the first syntax element has or is inferred to have a value indicating that there is no guarantee that the height of a picture in the video sequence is equal to or greater than the width of the picture in the video sequence, the decoder may continue to decode the video sequence in a manner similar to that specified in the current HEVC or VVC standard.

[0156] When the first syntax element has or is inferred to have a value indicating that the height of the picture in the video sequence is guaranteed to be equal to or greater than the width of the picture in the video sequence, the decoder can determine the width and height of the picture based on the second and third syntax elements. In addition, based on the first syntax element and optional other factors, the decoder can determine to select WPP from multiple candidate parallel processing methods to process the picture in the video sequence.

[0157] The decoder may also determine the CTU size of the picture or slice based on the fourth and fifth syntax elements or the sixth and seventh syntax elements. Subsequently, the decoder may determine the number of threads used to process the picture or slice. The decoder may configure software or hardware resources accordingly to process the picture or slice using the WPP method. Thus, a reconstructed picture corresponding to the video sequence may be generated. The process (1100) may proceed to (S1199) and terminate at (S1199).

[0158] VI. Computer System

[0159] The above techniques may be implemented as computer software using computer-readable instructions and physically stored in one or more computer-readable media. Fig.12 A computer system (1200) suitable for implementing certain embodiments of the disclosed subject matter is shown.

[0160] Computer software may be encoded using any suitable machine code or computer language that may be subjected to assembly, compilation, linking or similar mechanisms to create code comprising instructions that may be executed directly by one or more computer central processing units (CPUs), graphics processing units (GPUs), etc., or through interpretation, microcode, etc.

[0161] The instructions may be executed on various types of computers or components thereof, including, for example, personal computers, tablet computers, servers, smart phones, gaming devices, IoT devices, etc.

[0162] Fig.12 The components of the computer system (1200) shown in the example are exemplary in nature and are not intended to suggest any limitation on the scope of use or functionality of computer software implementing embodiments of the present disclosure. Nor should the configuration of components be interpreted as having any dependency or requirement relating to any one or combination of components shown in the exemplary embodiment of the computer system (1200).

[0163] The computer system (1200) may include certain human-machine interface input devices. Such human-machine interface input devices may respond to input from 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), olfactory input (not depicted). The human-machine interface device may also be used to capture certain media that are not necessarily directly related to human conscious input, such as audio (e.g., voice, music, ambient sound), images (e.g., scanned images, photographic images obtained from a still image camera), video (e.g., two-dimensional video, three-dimensional video including stereoscopic video), etc.

[0164] The input human-machine interface device may include one or more of the following (only one of each is shown): keyboard (1201), mouse (1202), touchpad (1203), touch screen (1210), data gloves (not shown), joystick (1205), microphone (1206), scanner (1207), camera (1208).

[0165] The computer system (1200) may include certain human-machine interface output devices. Such human-machine interface output devices may stimulate one or more human user senses, for example, through tactile output, sound, light, and smell / taste. Such human-machine interface output devices may include tactile output devices (e.g., tactile feedback of a touch screen (1210), a data glove (not shown), or a joystick (1205), but may also be a tactile feedback device that is not an input device), audio output devices (e.g., speakers (1209), headphones (not depicted)), visual output devices (e.g., screens (1210) including CRT screens, LCD screens, plasma screens, OLED screens, each with or without touch screen input capabilities, each with or without tactile feedback capabilities - some of which are capable of outputting two-dimensional visual outputs or outputs in more than three dimensions through devices such as stereoscopic image output, virtual reality glasses (not depicted), holographic displays and smoke boxes (not depicted), and printers (not depicted).

[0166] The computer system (1200) may also include human-accessible storage devices and their associated media, such as optical media including CD / DVD ROM / RW (1220) with CD / DVD and other media (1221), thumb drives (1222), removable hard drives or solid-state drives (1223), traditional magnetic media such as tapes and floppy disks (not depicted), dedicated ROM / ASIC / PLD-based devices such as security dongles (not depicted), etc.

[0167] Those skilled in the art should also understand that the term "computer-readable media" used in connection with the presently disclosed subject matter does not encompass transmission media, carrier waves, or other transitory signals.

[0168] The computer system (1200) may also include an interface (1254) to one or more communication networks (1255). The network may be, for example, a wireless network, a wired network, an optical network. The network may also be a local network, a wide area network, a metropolitan area network, a vehicle and industrial network, a real-time network, a delay-tolerant network, etc. Examples of networks include local area networks such as Ethernet, wireless LANs, cellular networks including GSM, 3G, 4G, 5G, LTE, etc., television wired or wireless wide area digital networks including cable television, satellite television, and terrestrial broadcast television, vehicle and industrial television including CANBus, etc. Some networks typically require an external network interface adapter connected to some common data port or peripheral bus (1249) (e.g., a USB port of the computer system (1200)); as described below, other network interfaces are typically integrated into the kernel of the computer system (1200) by connecting to the system bus (e.g., connecting to an Ethernet interface in a PC computer system or connecting to a cellular network interface in a smartphone computer system). The computer system (1200) can use any of these networks to communicate with other entities. Such communications may be one-way receive only (e.g., broadcast television), one-way send only (e.g., a CANbus connected to certain CANbus devices), or bidirectional, for example, using a LAN or WAN digital network to connect to other computer systems. As described above, certain protocols and protocol stacks may be used on each of those networks and network interfaces.

[0169] The above-mentioned human-machine interface device, human-machine accessible storage device, and network interface may be attached to the kernel (1240) of the computer system (1200).

[0170] The core (1240) may include one or more central processing units (CPUs) (1241), graphics processing units (GPUs) (1242), dedicated programmable processing units in the form of field programmable gate arrays (FPGAs) (1243), hardware accelerators (1244) for certain tasks, graphics adapters (1250), etc. These devices as well as read-only memory (ROM) (1245), random access memory (1246), internal mass storage (1247) such as internal non-user accessible hard drives, SSDs, etc., may be connected via a system bus (1248). In some computer systems, the system bus (1248) may be accessed in the form of one or more physical plugs to enable expansion by additional CPUs, GPUs, etc. Peripheral devices may be connected directly to the core's system bus (1248) or to the core's system bus (1848) via a peripheral bus (1249). In one example, a screen (1210) may be connected to a graphics adapter (1250). The architecture of the peripheral bus includes PCI, USB, etc.

[0171] The CPU (1241), GPU (1242), FPGA (1243) and accelerator (1244) can execute certain instructions, which can be combined to form the above-mentioned computer code. The computer code can be stored in ROM (1245) or RAM (1246). Transition data can also be stored in RAM (1246), while permanent data can be stored, for example, in internal mass storage (1247). Fast storage and retrieval to any storage device can be performed by using a cache, which can be closely associated with the following: one or more CPUs (1241), GPUs (1242), mass storage (1247), ROM (1245), RAM (1246), etc.

[0172] The computer readable medium may have thereon computer codes for performing various computer-implemented operations. The medium and computer codes may be those specially designed and constructed for the purposes of the present disclosure, or the medium and computer codes may be of a type well known and available to those skilled in the art of computer software.

[0173] As a non-limiting example, a computer system having an architecture (1200), particularly a kernel (1240), can provide functionality due to one or more processors (including CPUs, GPUs, FPGAs, accelerators, etc.) executing software contained in one or more tangible computer-readable media. Such computer-readable media can be media associated with user-accessible mass storage as described above, as well as certain non-temporary memories of the kernel (1240), such as kernel internal mass storage (1247) or ROM (1245). Software implementing the various embodiments of the present disclosure can be stored in such devices and executed by the kernel (1240). Depending on specific needs, the computer-readable medium may include one or more memory devices or chips. The software can cause the kernel (1240), particularly the processors therein (including CPUs, GPUs, FPGAs, etc.), to perform specific processes or specific parts of specific processes described herein, including defining data structures stored in RAM (1246) and modifying such data structures according to processes defined by the software. Additionally or alternatively, the computer system may provide functionality due to logic hardwired or otherwise embodied in circuitry (e.g., accelerator (1244)) that may replace software or operate in conjunction with software to perform specific processes or specific portions of specific processes described herein. Where appropriate, references to portions of software may include logic and vice versa. Where appropriate, references to portions of computer-readable media may include circuitry (e.g., integrated circuits (ICs)) storing software for execution, circuitry embodying logic for execution, or both. The present disclosure includes any suitable combination of hardware and software.

[0174] Appendix: Acronyms

[0175] JEM: Joint Exploration Model

[0176] VVC: Versatile Video Coding

[0177] BMS: Benchmark Set

[0178] MV: Motion Vector

[0179] HEVC: High Efficiency Video Coding

[0180] SEI: Supplemental Enhancement Information

[0181] VUI: Video Availability Information

[0182] GOP: Group of Pictures

[0183] TU: Transform Unit

[0184] PU: prediction unit

[0185] CTU: Coding Tree Unit

[0186] CTB: Coding Tree Block

[0187] PB: prediction block

[0188] HRD: Hypothetical Reference Decoder

[0189] SNR: Signal to Noise Ratio

[0190] CPU: Central Processing Unit

[0191] GPU: Graphics Processing Unit

[0192] CRT: cathode ray tube

[0193] LCD: Liquid Crystal Display

[0194] OLED: Organic Light Emitting Diode

[0195] CD: compact disc

[0196] DVD: Digital Video Disc

[0197] ROM: Read Only Memory

[0198] RAM: Random Access Memory

[0199] ASIC: Application-Specific Integrated Circuit

[0200] PLD: Programmable Logic Device

[0201] LAN: Local Area Network

[0202] GSM: Global System for Mobile Communications

[0203] LTE: Long Term Evolution

[0204] CANBus: Controller Area Network Bus

[0205] USB: Universal Serial Bus

[0206] PCI: Peripheral Component Interconnect

[0207] FPGA: Field Programmable Gate Array

[0208] SSD: Solid State Drive

[0209] IC: Integrated Circuit

[0210] CU: Coding Unit

[0211] Although the present disclosure has described a number of exemplary embodiments, there are modifications, permutations, and various replacement equivalents that fall within the scope of the present disclosure. Therefore, it should be understood that those skilled in the art will be able to design many systems and methods that, although not explicitly shown or described herein, embody the principles of the present disclosure and therefore fall within the spirit and scope of the present disclosure.

Claims

1. A video processing method, characterized in that: The method comprises: Receiving a first syntax element in a coded video bitstream, the first syntax element being a high-level syntax element, and the first syntax element being used to indicate whether a height of each of a plurality of pictures in a video sequence of the coded video bitstream is equal to or greater than a width; and In response to the first syntax element indicating that a height of each picture in a video sequence of the encoded video bitstream is greater than or equal to a width, at least one picture in the pictures in the video sequence is processed using wavefront parallel processing (WPP).

2. The method according to claim 1, characterized in that The first syntax element is transmitted in a supplemental enhancement information SEI message, a video usability information VUI parameter set or a sequence parameter set SPS.

3. The method according to claim 1, characterized in that A first value of the first syntax element indicates that a width of each of the pictures in the video sequence is smaller than a height of a corresponding picture in the video sequence.

4. The method according to claim 3, characterized in that The second value of the first syntax element indicates whether the width of a picture in the video sequence is allowed or not allowed to be smaller than the height of a picture in the video sequence.

5. The method according to claim 4, characterized in that The method further comprises: When the first syntax element is not signaled in the bitstream, the first syntax element is inferred to have the second value.

6. The method according to claim 1, characterized in that A picture in an input video sequence has a height smaller than a width, wherein the input video sequence corresponds to the video sequence of the encoded video bitstream at an encoder; and The height of the picture in the input video sequence is encoded as the width of the picture in the video sequence of the encoded video bitstream, and the width of the picture in the input video sequence is encoded as the height of the picture in the video sequence of the encoded video bitstream.

7. The method according to claim 1, characterized in that The method further comprises: receiving a second syntax element indicating a width of a picture in the video sequence; as well as A third syntax element is received that indicates a difference between a height and a width of a picture in the video sequence, the difference being an unsigned integer.

8. The method according to claim 7, characterized in that The method further comprises: A height of a picture in the video sequence is determined as a sum of a value of the width indicated by the second syntax element and the unsigned integer.

9. The method according to any one of claims 1 to 8, characterized in that: The method further comprises: A fourth syntax element is received, signaled in the coded video bitstream at a slice level, the fourth syntax element indicating a coding tree unit (CTU) size of a slice in the video sequence.

10. The method according to any one of claims 1 to 8, characterized in that: The method further comprises: A plurality of fourth syntax elements are received, wherein each fourth syntax element is associated with a respective slice of a plurality of slices in the video sequence, the plurality of fourth syntax elements indicating different CTU sizes for respective slices of different types.

11. The method according to claim 10, characterized in that Among the plurality of slices, type I slices have a smaller CTU size than other slice types.

12. The method according to any one of claims 1 to 8, characterized in that: The method further comprises: A fifth syntax element is received, signaled in the coded video bitstream at a picture level, the fifth syntax element indicating a CTU size of a picture of a plurality of pictures in the video sequence.

13. The method according to any one of claims 1 to 8, characterized in that: The method further comprises: receiving a sixth syntax element, the sixth syntax element being included in a sequence parameter set (SPS) of the coded video bitstream and indicating a first CTU size of the video sequence; as well as A seventh syntax element is received, the seventh syntax element being signaled at a picture level or a slice level and indicating a second CTU size of a corresponding picture or a corresponding slice in the video sequence.

14. The method according to claim 13, characterized in that The first CTU size is a maximum CTU size of the video sequence, and the second CTU size is smaller than the maximum CTU size.

15. A video processing device, characterized in that: The apparatus comprises a circuit configured to execute the video processing method according to any one of claims 1-14.

16. A method for video encoding, characterized in that The method comprises: A first syntax element is included in a coded video bitstream, the first syntax element being a high-level syntax element, and the first syntax element indicates whether a height of each of a plurality of pictures in a video sequence of the coded video bitstream is guaranteed to be equal to or greater than a width; wherein, The pictures in the video sequence of the coded video bitstream are processed using wavefront parallel processing (WPP) according to the first syntax element indicating that the height of each picture of the plurality of pictures is equal to or greater than the width.

17. A video encoding device, characterized in that: The apparatus comprises circuitry configured to perform the method of claim 16 .

18. A method for processing a video bitstream, characterized in that: The video bit stream is decoded based on the method according to any one of claims 1 to 14, or is generated based on the method according to claim 16.

Images