Method, device and medium for encoding video bitstream

Abstract

A method, device and computer-readable medium for encoding a video bitstream, the method comprising: determining whether reference picture resampling is enabled; determining a reference picture size of a reference picture; determining a current picture size of a current picture; determining whether the reference picture size is equal to the current picture size; disabling surround motion compensation when it is determined that the reference picture size is not equal to the current picture size; when the surround motion compensation is disabled, encoding the current picture without using the surround motion compensation; and generating an encoded video bitstream based on the encoded current picture.

Description

[0001] Priority information

[0002] This application claims priority to U.S. Provisional Application No. 62 / 958,486, filed on January 8, 2020, and U.S. Application No. 17 / 070,376, filed on October 14, 2020, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to video encoding and decoding technology, and more particularly, to a method, device, and medium for encoding a video bitstream. Background Art

[0004] The use of inter-picture prediction with motion compensation for video encoding and decoding is well known. An uncompressed digital video may comprise a series of pictures, each picture having spatial dimensions of, for example, 1920×1080 luma samples and associated chroma samples. The series of pictures has a fixed or variable picture rate (also informally referred to as a frame rate), for example, 60 pictures per second or 60 Hz. Uncompressed video has very large bitrate requirements. For example, 1080p60 4:2:0 video (1920x1080 luma sample resolution, 60 Hz frame rate) with 8 bits per sample requires nearly 1.5 Gbit / s of bandwidth. One hour of such video would require over 600 GB of storage space.

[0005] One goal of video encoding and decoding is to reduce redundant information in the input video signal through compression. Video compression can help reduce the bandwidth or storage space requirements mentioned above, in some cases by two or more orders of magnitude. Both lossless and lossy compression, as well as combinations of the two, can be used. Lossless compression refers to techniques that reconstruct an exact replica of the original signal from a compressed original. When lossy compression is used, the reconstructed signal may not be exactly the same as the original, but the distortion between the original and the reconstructed signal is small enough that the reconstructed signal is usable for the intended application. Lossy compression is widely used in video. The amount of distortion allowed depends on the application. For example, users of some consumer streaming applications may be able to tolerate higher distortion than users of television applications. The achievable compression ratio reflects the fact that higher allowed / tolerable distortion results in higher compression ratios.

[0006] Video encoders and decoders can utilize several broad categories of techniques, including, for example, motion compensation, transforms, quantization, and entropy coding, some of which are described below.

[0007] Historically, video encoders and decoders have tended to operate on a given picture size, which in most cases is defined and remains constant for a coded video sequence (CVS), group of pictures (GOP), or similar multi-picture temporal frame. For example, in MPEG-2, system designs are known to change the horizontal resolution (and therefore the picture size) only at the I-picture based on factors such as scene activity, and are therefore commonly used for GOPs. For example, from Annex P of ITU-T Rec. H.263, it is known to resample reference pictures using different resolutions within a CVS. However, here the picture size is not changed, only the reference pictures are resampled, which may result in only part of the picture canvas being used (in the case of downsampling) or only part of the scene being captured (in the case of upsampling). Further, Annex Q of H.263 allows individual macroblocks to be resampled up or down by a factor of two (in each dimension). Again, the picture size remains constant. The size of the macroblock is fixed in H.263, so no signaling is required.

[0008] In modern video codecs, changes in picture size in predicted pictures have become mainstream. For example, VP9 allows for resampling of reference pictures and changing the resolution of the entire picture. Similarly, certain proposals for Versatile Video Coding (VVC) (including, for example, Hendry et al., "On adaptive resolution change (ARC) for VVC", Joint Video Team document JVET-M0135-v1, January 9-19, 2019, which is incorporated herein in its entirety) allow for resampling of the entire reference picture to a different (higher or lower) resolution. In this document, it is proposed that the different candidate resolutions be encoded in a sequence parameter set and referenced by each picture syntax element in the picture parameter set.

[0009] Wrap-around motion compensation is a useful feature for encoding and decoding 360° projection images using the equirectangular projection (ERP) format. It can reduce some visual artifacts at seam lines and improve codec gain. In the current VVC draft specification, JVET-P2001 (edited and updated by JVET-Q0041), sps_ref_wraparound_offset_minus1 in the sequence parameter set (SPS) specifies the offset used to calculate the horizontal wrap position. The problem is that the wrap offset is determined relative to the picture width. If the picture width of the reference picture differs from the current picture width, the wrap offset should change proportionally to the scaling ratio between the current and reference pictures. However, in practice, this can significantly increase the implementation and computational complexity of adjusting the offset according to the picture width of each reference picture, compared to the advantages of wrap motion compensation. Inter-layer prediction with different picture sizes and reference picture resampling (RPR) will result in various combinations of different picture resolutions across layers and temporal pictures being generated in an undesirable manner. Summary of the Invention

[0010] In order to solve the above problems, embodiments of the present application provide a method, apparatus, device, and computer-readable medium for encoding a video bitstream.

[0011] In an embodiment, a method for encoding a video bitstream is provided, the method comprising: determining whether reference picture resampling is enabled; determining a reference picture size of a reference picture; determining a current picture size of a current picture; determining whether the reference picture size is equal to the current picture size; when it is determined that the reference picture size is not equal to the current picture size, disabling surround motion compensation; when the surround motion compensation is disabled, not using the surround motion compensation to encode the current picture; and generating an encoded video bitstream based on the encoded current picture.

[0012] In an embodiment, a device for encoding a video bitstream is provided, the device comprising: at least one memory for storing program code; and at least one processor for reading the program code and operating according to instructions of the program code to implement the method for encoding a video bitstream.

[0013] In an embodiment, a device for encoding a video bitstream is provided, the device comprising: a first determination module for determining whether reference picture resampling is enabled; a second determination module for determining a reference picture size of a reference picture; a third determination module for determining a current picture size of a current picture; a fourth determination module for determining whether the reference picture size is equal to the current picture size; a disabling module for disabling surround motion compensation when it is determined that the reference picture size is not equal to the current picture size; an encoding module for not using the surround motion compensation to encode the current picture when the surround motion compensation is disabled; and a generation module for generating an encoded video bitstream based on the encoded current picture.

[0014] In an embodiment, a non-volatile computer-readable medium is provided for storing instructions, the instructions comprising one or more instructions that, when executed by one or more processors of a device for encoding a video bitstream, cause the one or more processors to perform the method for encoding a video bitstream.

[0015] In an embodiment of the present application, when it is determined that the reference picture size is not equal to the current picture size, surround motion compensation is disabled, instead of adopting a scheme in which the surround offset is changed proportionally with the scaling ratio between the current picture and the reference picture when the reference picture size is different from the current picture size, thereby reducing computational complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features, properties, and various advantages of the disclosed subject matter will become more apparent from the following detailed description and accompanying drawings, in which

[0017] Figure 1 is a schematic diagram of a simplified block diagram of a communication system according to an embodiment;

[0018] Figure 2 is a schematic diagram of a simplified block diagram of a streaming system according to an embodiment;

[0019] Figure 3 is a schematic diagram of a simplified block diagram of a decoder according to an embodiment;

[0020] Figure 4 is a schematic diagram of a simplified block diagram of an encoder according to an embodiment;

[0021] Figure 5 is a schematic diagram of options for signaling ARC parameters according to an embodiment;

[0022] Figures 6A-6B is a schematic diagram of an example of a syntax table according to an embodiment;

[0023] Figure 7is a diagram illustrating signaling surround motion compensation syntax in a PPS according to an embodiment;

[0024] Figure 8 is a flowchart of an example process for encoding a video bitstream according to an embodiment;

[0025] Figure 9 is a schematic diagram of a computer system according to an embodiment. DETAILED DESCRIPTION

[0026] Figure 1 The present invention is a simplified block diagram of a communication system (100) according to an embodiment disclosed in the present application. The communication system (100) includes at least two terminal devices (110, 120), which can communicate with each other via a network (150). For one-way data transmission, a first terminal device (110) can encode video data at a local location for transmission to a second terminal device (120) via the network (150). The second terminal device (120) can receive encoded video data from another terminal on the network (150), decode the encoded video data to recover the video data, and display the recovered video data. One-way data transmission is common in applications such as media services.

[0027] Figure 1 A second pair of terminal devices (130, 140) supporting bidirectional transmission of encoded video is shown, which can occur, for example, during a video conference. For bidirectional data transmission, each of the third terminal device (130) and the fourth terminal device (140) can encode video data collected at a local location for transmission to the other of the third terminal device (130) and the fourth terminal device (140) via a network (150). Each of the third terminal device (130) and the fourth terminal device (140) can also receive the encoded video data transmitted by the other of the third terminal device (130) and the fourth terminal device (140), and can decode the encoded video data and display the recovered video data on a local display device.

[0028] exist Figure 1In the embodiment, the first terminal device (110), the second terminal device (120), the third terminal device (130) and the fourth terminal device (140) may be servers, personal computers and smart phones, but the principles disclosed in the present application may not be limited thereto. The embodiments disclosed in the present application are applicable to laptop computers, tablet computers, media players and / or dedicated video conferencing equipment. The network (150) represents any number of networks that transmit encoded video data between the first terminal device (110), the second terminal device (120), the third terminal device (130) and the fourth terminal device (140), including, for example, wired and / or wireless communication networks. The communication network (150) may exchange data in circuit switching and / or packet switching channels. The network may include a telecommunications network, a local area network, a wide area network and / or the Internet. For the purposes of this application, unless explained below, the architecture and topology of the network (150) may be irrelevant to the operations disclosed in the present application.

[0029] As an application example of the disclosed subject matter, Figure 2 The placement of the video decoder and encoder in a streaming environment is shown. The subject matter disclosed in this application 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.

[0030] The streaming system may include an acquisition subsystem (213), which may include a video source (201), such as a digital camera, that creates, for example, an uncompressed video sample stream (202). The video sample stream (202) is depicted as a thick line compared to an encoded video bitstream to emphasize that it is a video sample stream with a higher data volume, and the video sample stream (202) may be processed by an encoder (203) coupled to the camera (201). The encoder (203) 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 bitstream (204) is depicted as a thin line compared to the video sample stream (202) to emphasize the lower data volume of the encoded video bitstream, which may be stored on a streaming server (205) for future use. One or more streaming clients (206, 208) may access a streaming server (205) to retrieve a copy (207) and a copy (209) of an encoded video bitstream (204). The client (206) may include a video decoder (210). The video decoder (210) decodes the incoming copy (207) of the encoded video bitstream and produces an output video sample stream (211) that can be presented on a display (212) or another presentation device (not shown). In some streaming systems, the video bitstreams (204, 207, 209) may be encoded according to certain video codec / compression standards. Examples of such standards include ITU-T Recommendation H.265. The video codec standard under development is informally referred to as the Versatile Video Codec (VVC). The disclosed subject matter may be used in the context of VVC.

[0031] Figure 3 is a functional block diagram of a video decoder (210) according to an embodiment disclosed in this application.

[0032] A receiver (310) may receive one or more encoded video sequences to be decoded by a video decoder (210); in the same or another embodiment, one encoded video sequence at a time, wherein each encoded video sequence is decoded independently of the other encoded video sequences. The encoded video sequence may be received from a channel (312), which may be a hardware / software link to a storage device storing the encoded video data. The receiver (310) may receive the encoded video data as well as other data, such as encoded audio data and / or auxiliary data streams, which may be forwarded to their respective consuming entities (not shown). The receiver (310) may separate the encoded video sequence from the other data. To prevent network jitter, a buffer memory (315) may be coupled between the receiver (310) and an entropy decoder / parser (320) (hereinafter referred to as the "parser"). When the receiver (310) receives data from a store / forward device with sufficient bandwidth and controllability or from an isochronous network, the buffer memory (315) may not be required or may be made smaller. Of course, in order to be used on a traffic packet network such as the Internet, a buffer memory (315) may also be required, and the buffer memory may be relatively large and may have an adaptive size.

[0033] The video decoder (210) may include a parser (320) to reconstruct symbols (321) from an entropy coded video sequence. These symbols may include information for managing the operation of the video decoder (210) and potentially information for controlling a display device such as display 212 that is not part of the decoder but may be coupled to the decoder, such as Figure 3. The control information for the display device may be a parameter set fragment (not shown) of Supplementary Enhancement Information (SEI message) or Video Usability Information (VUI). The parser (320) may parse / entropy decode the received coded video sequence. The coding of the coded video sequence may be performed according to a video coding technique or standard and may follow principles known to those skilled in the art, including variable length coding, Huffman coding, arithmetic coding with or without context sensitivity, and the like. The parser (320) 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. Subgroups may include Group of Pictures (GOP), pictures, sub-pictures, tiles, slices, brick macroblocks, Coding Tree Units (CTU), Coding Units (CU), blocks, Transform Units (TU), Prediction Units (PU), and the like. A tile may indicate a rectangular area of ​​a CU / CTU within a specific tile column and row in a picture. A brick may indicate a rectangular area of ​​a CU / CTU row within a specific tile. A slice may indicate one or more tiles of a picture, which are contained in a NAL unit. A sub-picture may indicate a rectangular area of ​​one or more slices in a picture. The entropy decoder / parser may also extract information such as transform coefficients, quantizer parameter values, motion vectors, and the like from the encoded video sequence.

[0034] The parser (320) may perform entropy decoding / parsing operations on the video sequence received from the buffer memory (315), thereby creating symbols (321).

[0035] Depending on the type of coded video picture or portion of a coded video picture (e.g., inter- and intra-pictures, inter- and intra-blocks), and other factors, the reconstruction of the symbol (321) may involve a plurality of different units. Which units are involved and how they are involved may be controlled by subgroup control information parsed from the coded video sequence by the parser (320). For the sake of brevity, the flow of such subgroup control information between the parser (320) and the various units described below is not described.

[0036] In addition to the functional blocks already mentioned, the video decoder (210) can be conceptually broken down into several functional units as described below. In practical embodiments operating under commercial constraints, many of these units interact closely with each other and may be integrated with each other. However, for the purposes of describing the disclosed subject matter, the conceptual breakdown into the following functional units is appropriate.

[0037] The first unit may be a scaler / inverse transform unit (351). The scaler / inverse transform unit (351) may receive quantized transform coefficients as symbols (321) and control information from the parser (320), including which transform mode to use, block size, quantization factor, quantization scaling matrix, etc. The scaler / inverse transform unit (351) may output a block including sample values, which may be input to an aggregator (355).

[0038] In some cases, the output samples of the scaler / inverse transform unit (351) 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 predictive information may be provided by the intra-picture prediction unit (352). In some cases, the intra-picture prediction unit (352) uses reconstructed information extracted from the (partially reconstructed) current picture (358) to generate surrounding blocks of the same size and shape as the block being reconstructed. In some cases, the aggregator (355) adds the prediction information generated by the intra-prediction unit (352) to the output sample information provided by the scaler / inverse transform unit (351) on a per-sample basis.

[0039] In other cases, the output samples of the scaler / inverse transform unit (351) may belong to inter-frame coded and potentially motion compensated blocks. In this case, the motion compensated prediction unit (353) may access the reference picture memory (357) to extract samples for prediction. After the extracted samples are motion compensated according to the symbols (321), these samples may be added to the output of the scaler / inverse transform unit (351) (in this case referred to as residual samples or residual signal) by the aggregator (355) to generate output sample information. The retrieval of the prediction samples by the motion compensated prediction unit (353) from the address in the reference picture memory (357) may be controlled by a motion vector, and the motion vector is provided to the motion compensated prediction unit (353) in the form of the symbols (321), for example, including X, Y and reference picture components. Motion compensation may also include interpolation of sample values ​​extracted from the reference picture memory (357) when using sub-sample accurate motion vectors, motion vector prediction mechanisms, etc.

[0040] The output samples of the aggregator (355) may be used by various loop filtering techniques in a loop filter unit (356). The video compression techniques may include in-loop filtering techniques that are controlled by parameters included in the coded video bitstream and made available to the loop filter unit (356) as symbols (321) from the parser (320). However, in other embodiments, the video compression techniques may also be responsive to meta-information obtained during decoding of a previous (in decoding order) portion of a coded picture or coded video sequence, as well as to previously reconstructed and loop-filtered sample values.

[0041] The output of the loop filter unit (356) may be a sample stream that may be output to a display device (212) and stored in a reference picture memory (357) for subsequent inter-picture prediction.

[0042] Once fully reconstructed, certain coded pictures can be used as reference pictures for future prediction. Once a coded picture is fully reconstructed and the coded picture is identified as a reference picture (e.g., by a parser (320)), a current picture (358) can become part of a reference picture memory (357) and new current picture memory can be reallocated before starting reconstruction of a subsequent coded picture.

[0043] The video decoder (210) may perform decoding operations according to a predetermined video compression technique, such as that documented in the ITU-T H.265 standard. The coded video sequence may conform to the syntax specified by the video compression technique or standard used, in the sense that the coded video sequence follows the syntax of the video compression technique or standard as specified in the video compression technology document or standard, particularly in a profile. Compliance may also require that the complexity of the coded video sequence be within the limits defined by the hierarchy of the video compression technique or standard. In some cases, the hierarchy limits the maximum picture size, maximum frame rate, maximum reconstruction sampling rate (measured in, for example, megasamples per second), maximum reference picture size, etc. In some cases, the limits set by the hierarchy may be further defined by the Hypothetical Reference Decoder (HRD) specification and metadata for HRD buffer management signaled in the coded video sequence.

[0044] In an embodiment, a receiver (310) may receive additional (redundant) data along with the encoded video. The additional data may be part of the encoded video sequence. The additional data may be used by the video decoder (210) 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, and the like.

[0045] Figure 4 It is a functional block diagram of a video encoder (203) according to an embodiment disclosed in this application.

[0046] The video encoder (203) may receive video samples from a video source (201) (not part of the decoder), which may capture video images to be encoded by the video encoder (203).

[0047] The video source (201) may provide a source video sequence in the form of a stream of digital video samples to be encoded by the video encoder (203), wherein the stream of digital video samples 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 serving system, the video source (201) may be a storage device storing previously prepared videos. In a video conferencing system, the video source (201) may be a camera that captures local image information as a video sequence. The video data may be provided as a plurality of individual pictures that are given motion when viewed sequentially. The pictures themselves may be constructed as a spatial array of pixels, 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 readily understood by those skilled in the art. The following description focuses on samples.

[0048] According to an embodiment, the video encoder (203) can encode and compress pictures of a source video sequence into an encoded video sequence (443) in real time or under any other time constraints required by the application. Implementing an appropriate encoding speed is a function of the controller (450). The controller (450) controls other functional units as described below and is functionally coupled to these units. For the sake of simplicity, the coupling is not shown in the figure. The parameters set by the controller (450) may include rate control related parameters (e.g., picture skipping, quantizer, lambda value of rate-distortion optimization technology, etc.), picture size, group of pictures (GOP) layout, maximum motion vector search range, etc. Those skilled in the art can easily identify other functions of the controller (450) because these functions relate to the video encoder (203) optimized for a certain system design.

[0049] Some video encoders operate in what one skilled in the art will readily recognize as a "coding loop." As a simplified description, the coding loop may include an encoding portion of an encoder (430) (hereinafter referred to as a "source encoder," which is responsible for creating symbols based on the input picture to be encoded and a reference picture), and a (local) decoder (433) embedded in the video encoder (203). The "local" decoder (433) reconstructs the symbols to create sample data in a manner similar to how the (remote) decoder creates sample data (because, in the video compression techniques considered in this application, any compression between the symbols and the encoded video stream is lossless). The reconstructed sample stream is input to a reference picture memory (434). Since the decoding of the symbol stream produces bit-accurate results independent of the decoder's location (local or remote), the contents of the reference picture memory also correspond bit-accurately between the local encoder and the remote encoder. In other words, the reference picture samples "seen" by the prediction portion of the encoder are exactly the same sample values ​​that the decoder will "see" when using prediction during decoding. This basic principle of reference picture synchronization (and the resulting drift when synchronization cannot be maintained, eg due to channel errors) is well known to those skilled in the art.

[0050] The operation of the "local" decoder (433) can be combined with the operation of Figure 3 The "remote" decoder of the video decoder (210) is described in detail. However, additional brief reference is made to Figure 4 , when symbols are available and the entropy encoder (445) and parser (320) are capable of losslessly encoding / decoding the symbols into an encoded video sequence, the entropy decoding portion of the video decoder (210), including the channel (312), the receiver (310), the buffer memory (315), and the parser (320), may not be fully implemented in the local decoder (433).

[0051] At this point, it can be observed that any decoder technology other than parsing / entropy decoding present in the decoder must also be present in essentially the same functional form in the corresponding encoder. For this reason, the disclosed subject matter focuses on decoder operation. The description of encoder techniques may be abbreviated, as they are reciprocal to the fully described decoder techniques. A more detailed description is required only in certain areas and is provided below.

[0052] As part of its operation, the source encoder (430) may perform motion-compensated predictive coding. The motion-compensated predictive coding predictively encodes an input frame with reference to one or more previously encoded frames from a video sequence, designated as "reference frames." In this manner, the encoding engine (432) encodes the differences between pixel blocks of the input frame and pixel blocks of a reference frame that may be selected as a prediction reference for the input frame.

[0053] The local video decoder (433) may decode the encoded video data of a frame that may be designated as a reference frame based on the symbols created by the source encoder (430). The operation of the encoding engine (432) may be a lossy process. When the encoded video data is available at the video decoder ( Figure 4 When 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 (433) replicates the decoding process that the video decoder may perform on the reference frame and may cause the reconstructed reference frame to be stored in the reference picture memory (434). In this way, the encoder (203) may locally store a copy of the reconstructed reference frame that has common content (absent transmission errors) with the reconstructed reference frame that will be obtained by the remote video decoder.

[0054] The predictor (435) may perform a prediction search for the encoding engine (432). That is, for a new frame to be encoded, the predictor (435) may search the reference picture memory (434) for sample data (as candidate reference pixel blocks) or certain metadata, such as reference picture motion vectors, block shapes, etc., that may serve as suitable prediction references for the new frame. The predictor (435) may operate on a pixel-by-pixel-block basis based on sample blocks to find a suitable prediction reference. In some cases, based on the search results obtained by the predictor (435), it may be determined that the input picture may have prediction references taken from multiple reference pictures stored in the reference picture memory (434).

[0055] The controller (450) may manage encoding operations of the source encoder (430), including, for example, setting parameters and subgroup parameters for encoding video data.

[0056] The outputs of all the above functional units may be entropy coded in an entropy encoder (445). The entropy encoder (445) may perform lossless compression on the symbols generated by the various functional units using techniques known to those skilled in the art, such as Huffman coding, variable length coding, arithmetic coding, etc., thereby converting the symbols into a coded video sequence.

[0057] The transmitter (440) can buffer the encoded video sequence created by the entropy encoder (445) in preparation for transmission over a communication channel (460), which can be a hardware / software link to a storage device where the encoded video data will be stored. The transmitter (440) can combine the encoded video data from the source encoder (430) with other data to be transmitted, such as encoded audio data and / or an auxiliary data stream (source not shown).

[0058] The controller (450) can manage the operation of the video encoder (203). During encoding, the controller (450) 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:

[0059] An intra picture (I picture) can be a picture that can be encoded and decoded without using any other frame 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.

[0060] 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.

[0061] Bidirectionally predictive pictures (B pictures) can be encoded and decoded using intra prediction or inter prediction, which uses up to two motion vectors and reference indices to predict sample values ​​for each block. Similarly, multiple predictive pictures can use more than two reference pictures and associated metadata to reconstruct a single block.

[0062] A source picture is typically 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, determined according to the coding allocation applied to the block's corresponding picture. For example, blocks of an I picture may be non-predictively coded, or they may be predictively coded (spatial or intra-predicted) with reference to already coded blocks of the same picture. Pixel blocks of a P picture may be predictively coded using spatial prediction with reference to one previously coded reference picture or using temporal prediction. Blocks of a B picture may be predictively coded using spatial prediction with reference to one or two previously coded reference pictures or using temporal prediction.

[0063] The video encoder (203) may perform encoding operations according to a predetermined video coding technique or standard, such as ITU-T Recommendation H.265. In operation, the video encoder (203) may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancy in the input video sequence. Thus, the encoded video data may conform to the syntax specified by the video coding technique or standard used.

[0064] In an embodiment, the transmitter (440) may transmit additional data along with the encoded video. The source encoder (430) may include such data as a portion of the encoded video sequence. The additional data may include temporal / spatial / SNR enhancement layers, redundant pictures and slices, and other forms of redundant data, SEI messages, VUI parameter set fragments, and the like.

[0065] Recently, there has been some interest in the compression domain aggregation or extraction of multiple semantically independent picture parts into a single video picture. Specifically, in the context of, for example, 360° codecs or certain surveillance applications, multiple semantically independent source pictures (e.g., the six cube surfaces of a cube-projected 360° scene, or the input of a single camera in the case of a multi-camera surveillance setup) may require separate adaptive resolution settings to handle different scene activities at a given point in time. In other words, the encoder can choose to use different resampling factors for the different semantically independent pictures that make up the entire 360° or surveillance scene at a given point in time. This in turn requires that reference picture resampling be performed on a portion of the coded picture when combined into a single picture, and that adaptive resolution codec signaling is available.

[0066] Below, some terms are introduced that will be referred to in the rest of this specification.

[0067] In some cases, a sub-picture may refer to a rectangular arrangement of samples, blocks, macroblocks, coding units, or similar entities that are semantically grouped and can be independently encoded with varying resolutions. One or more sub-pictures may form a picture. One or more encoded sub-pictures may form a coded picture. One or more sub-pictures may be combined into a picture, and one or more sub-pictures may be extracted from a picture. In some circumstances, one or more coded sub-pictures may be assembled in a compressed domain without transcoding to the sample level to form a coded picture, and in the same or other circumstances, one or more coded sub-pictures may be extracted from a coded picture in the compressed domain.

[0068] Reference picture resampling (RPR) or adaptive resolution change (ARC) refers to a mechanism that allows the resolution of pictures or sub-pictures in a coded video sequence to be changed, for example, by resampling reference pictures. RPR / ARC parameters, hereinafter referred to as the control information required to perform adaptive resolution change, may include, for example, filter parameters, scaling factors, output and / or reference picture resolutions, various control flags, etc.

[0069] In an embodiment, encoding and decoding can be performed on a single, semantically independent coded video picture. Before describing the implications of encoding / decoding multiple sub-pictures with independent RPR / ARC parameters and the additional complexity they imply, the options for signaling RPR / ARC parameters will be described.

[0070] refer to Figure 5 , which shows several embodiments for signaling RPR / ARC parameters. As pointed out in each embodiment, these embodiments may have certain advantages and disadvantages from the perspective of codec efficiency, complexity and architecture. Video codec standards or technologies can select one or more of these embodiments, or select options known in the relevant art, to signal RPR / ARC parameters. These embodiments are not mutually exclusive and can be interchanged based on application requirements, the standard technologies involved, or the selection of encoders.

[0071] Categories of RPR / ARC parameters can include:

[0072] - Upsampling factor / downsampling factor, which are separated or combined in the X and Y dimensions;

[0073] - upsampling factor / downsampling factor, which together with the time dimension represents a constant speed enlargement / reduction of a given number of pictures;

[0074] - Either of the above two cases may involve encoding or decoding one or more short syntax elements, which may point to a table containing one or more factors.

[0075] - The combined or individual resolutions of the input picture, output picture, reference picture, or coded picture in the X or Y dimension, in units of samples, blocks, macroblocks, coding units (CUs), or any other suitable granularity. If there is more than one resolution (e.g., one for the input picture and another for the reference picture), then in some cases one set of values ​​can be inferred from another. This can be controlled, for example, by using flags (gates). See below for more detailed examples.

[0076] - "Warping" coordinates similar to those used in H.263 Annex P, also at the appropriate granularity described above. H.263 Annex P defines an efficient way to encode and decode such warped coordinates, but other, potentially more efficient, ways are also contemplated. For example, the variable-length reversible "Huffman" format encoding of the warped coordinates of Annex P could be replaced by a binary encoding of appropriate length, where the length of the binary codewords could be derived, for example, from the maximum picture size, possibly multiplied by a factor and offset by a value to allow "warping" outside the boundaries of the maximum picture size.

[0077] - Upsampling filter parameters or downsampling filter parameters. In embodiments, there may be only a single filter for upsampling and / or downsampling. However, in embodiments, it may be desirable to allow greater flexibility in filter design, and this may require signaling of the filter parameters. Such parameters may be selected by an index into a list of possible filter designs, the filter may be fully specified (e.g., by a list of filter coefficients, using a suitable entropy coding technique), the filter may be implicitly selected by the upsampling / downsampling ratio and then signaled according to any of the mechanisms described above, and so on.

[0078] Hereinafter, this specification assumes a codec that specifies a finite set of upsampling factors / downsampling factors (using the same factor in both the X and Y dimensions) indicated by a codeword. The codeword can be variable length encoded, for example using Ext-Golomb codes common to certain syntax elements in video codec specifications (e.g., H.264 and H.265). For example, according to Table 1, the values ​​can be appropriately mapped to the upsampling factors / downsampling factors.

[0079] Table 1

[0080]

[0081]

[0082] Many similar mappings can be devised, depending on the needs of the application and the capabilities of the upscaling and downscaling mechanisms available in the video compression technology or standard. The table can be extended to include more values. These values ​​can also be represented by entropy coding mechanisms other than Ext-Golomb codes, for example using binary codecs. This can have certain advantages when the resampling factors are of interest outside the video processing engine (most importantly the encoder and decoder) itself (for example, via a MANE). It should be noted that for cases where no resolution change is required, a shorter Ext-Golomb code can be chosen. In the table above, this is only one bit. This can have the advantage of improving codec efficiency compared to using binary codes in most cases.

[0083] The number of entries in the table and their semantics are fully or partially configurable. For example, the basic outline of the table may be conveyed in a "high" parameter set, such as a sequence or decoder parameter set. In an embodiment, one or more such tables may be defined in a video codec or standard and may be selected, for example, by a decoder or sequence parameter set.

[0084] The following describes how to include the encoded upsampling factor / downsampling factor (ARC information) described above in a video codec or standard syntax. Similar considerations can be applied to one or more codewords that control the upsampling filter / downsampling filter. When the filter or other data structure requires relatively large amounts of data, see the discussion below.

[0085] like Figure 5 As shown, H.263 Annex P includes ARC information (502) in the form of four warp coordinates in the picture header (501), specifically in the H.263PLUSPTYPE (503) header extension. This may be a reasonable design choice when picture headers are available and the ARC information is expected to change frequently. However, when signaling in the H.263 format is used, the overhead may be very high, and since picture headers may be transient in nature, the scaling factors may not be applied to picture boundaries.

[0086] In the same or another embodiment, signaling of ARC parameters may follow Figures 6A-6B A detailed example is outlined in . Figures 6A-6B A syntax diagram is depicted using a notation that roughly follows C-style programming, such as that used in video codec standards since at least 1993. Bold lines indicate syntax elements present in the bitstream; non-bold lines typically indicate control flow or the setting of variables.

[0087] like Figure 6AAs shown in FIG. 6 , as an example syntax structure for a header applicable to a (possibly rectangular) portion of a picture, a tile group header ( 601 ) may conditionally contain a variable-length, Exp-Golomb coded syntax element, Dec_pic_size_idx ( 602 ) (shown in bold). The presence of this syntax element in the tile group header may be controlled using adaptive resolution ( 603 ) (here, the flag's value is not in bold), meaning that the flag appears in the bitstream at the point where it appears in the syntax diagram. Whether adaptive resolution is applied to the picture or portion of the picture may be signaled in any high-level syntax structure, either internal or external to the bitstream. In the example shown, it is signaled in a sequence parameter set as described below.

[0088] refer to Figure 6B , which also shows an excerpt from a sequence parameter set (610). The first syntax element shown is adaptive_pic_resolution_change_flag (611). When true, this flag may indicate the use of adaptive resolution, which in turn may require certain control information. In this example, the value of the flag is based on an if statement in the parameter set (612) and the tile group header (601), and such control information appears conditionally based on the value of the flag.

[0089] In this example, when adaptive resolution is used, the output resolution in samples (613) is encoded. Reference numeral 613 refers to output_pic_width_in_luma_sample and output_pic_height_in_luma_sample, which together define the resolution of the output picture. Elsewhere in the video codec technology or standard, certain restrictions on any value may be defined. For example, the level definition may limit the number of total output samples, which may be the product of the values ​​of these two syntax elements. In addition, certain video codec technologies or standards, or external technologies or standards (e.g., system standards) may restrict the number range (e.g., one or both dimensions must be divisible by an integer power of 2) or the aspect ratio (e.g., the width and height must have a relationship such as 4:3 or 16:9). Such restrictions may be introduced to facilitate hardware implementation or for other reasons.

[0090] In some applications, it is recommended that the encoder instruct the decoder to use a certain reference picture size, rather than implicitly assuming that size as the output picture size. In this example, the syntax element reference_pic_size_present_flag (614) controls the conditional presence of the reference picture size (615) (again, this number refers to width and height).

[0091] Finally, a table of possible decoded picture widths and heights is shown. Such a table can be represented, for example, by a table indication (num_dec_pic_size_in_luma_samples_minus1) (616). "Minus1" refers to the interpretation of the value of this syntax element. For example, if the encoded value is 0, there is one table entry. If the value is 5, there are six table entries. For each "line" in the table, the width and height of the decoded picture are included in the syntax (617).

[0092] The presented table entries (617) can be indexed using the syntax element dec_pic_size_idx (602) in the tile group header, allowing each tile group to have a different decode size (effectively a scaling factor).

[0093] In an embodiment, a combination of surround offset and reference picture resampling (RPR) in VVC can be implemented. For example, according to an embodiment, the surround offset syntax element can be moved from the SPS to the picture parameter set (PPS). For another example, according to an embodiment, motion compensation with surround offset can be disabled only when the width of the reference picture is not equal to the width of the current picture.

[0094] The embodiments described above can solve the problem that the value of the surround offset is based on the width of the current picture, but when RPR is used, the offset is used for a reference picture that may have a different picture size from the current picture.

[0095] As a result, surround motion compensation can be used with RPR when the picture width between the current picture and the reference picture is the same.

[0096] That is, before encoding the current picture, the picture sizes of the reference picture and the current picture need to be determined. If it is determined that the size of the reference picture is not equal to the size of the current picture, surround motion compensation is disabled, and the current picture is not encoded using surround motion compensation. If it is determined that the size of the reference picture is equal to the size of the current picture, for example, if the picture widths of the current picture and the reference picture are the same, surround motion compensation is enabled and the current picture is encoded using surround motion compensation. Subsequently, a coded video bitstream can be generated based on the coded current picture.

[0097] In one embodiment, reference Figure 7, the pps_ref_wraparound_enabled_flag can be signaled in the PPS. The pps_ref_wraparound_enabled_flag can be called a first flag. When the pps_ref_wraparound_enabled_flag is equal to 1, it can be specified that horizontal wrap motion compensation is applied in inter-frame prediction. For example, when it is determined that the size of the reference picture is equal to the size of the current picture, the first flag included in the PPS of the encoded video bitstream is set to 1. At this time, horizontal wrap motion compensation is applied in inter-frame prediction, and the wrap offset is signaled in the PPS. When the pps_ref_wraparound_enabled_flag is equal to 0, it can be specified that horizontal wrap motion compensation is not applied. For example, when it is determined that the size of the reference picture is not equal to the size of the current picture, the first flag included in the PPS of the encoded video bitstream is set to 0. At this time, horizontal wrap motion compensation is not applied. For example, when the value of (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSizeY-1), the value of pps_ref_wraparound_enabled_flag may be equal to 0. When the value of sps_ref_wraparound_enabled_flag is equal to 0, the value of pps_ref_wraparound_enabled_flag equal to 0 may be a requirement for bitstream conformance. sps_ref_wraparound_enabled_flag may be referred to as a second flag. That is, when the second flag included in the sequence parameter set SPS referenced by the PPS is set to 0, the first flag is also set to 0, which may satisfy the bitstream conformance requirement.

[0098] In one embodiment, still referring to Figure 7 , pps_ref_wraparound_offset_minus1 can be signaled in the PPS. pps_ref_wraparound_offset_minus1 plus 1 can specify the offset used to calculate the horizontal wrap position in units of MinCbSizeY luma samples, that is, the wrap offset is taken as the number of luma samples and signaled in the PPS. The value of pps_ref_wraparound_offset_minus1 can be in the range of (CtbSizeY / MinCbSizeY)+1 to (pic_width_in_luma_samples / MinCbSizeY)-1 (inclusive).

[0099] In an embodiment, the size of the current picture is signaled in the PPS.

[0100] Figure 8 is a flow chart of an example process 800 for decoding an encoded video bitstream. In some embodiments, Figure 8 One or more steps of may be performed by the decoder 210. In some embodiments, Figure 8 One or more steps of may be performed by another device or a group of devices, such as encoder 203, separate from or including decoder 210.

[0101] like Figure 8 As shown, process 800 may include determining that reference picture resampling is enabled (step 810).

[0102] like Figure 8 As further shown, process 800 may include determining a reference picture size for the reference picture (step 820).

[0103] like Figure 8 As further shown, process 800 may include determining a current picture size for the current picture (step 830).

[0104] like Figure 8 As further shown, process 800 may include determining whether the reference picture size is equal to the current picture size (step 840).

[0105] When it is determined that the reference picture size is not equal to the current picture size ("No" in step 840), process 800 may perform step 850, and then perform steps 860 and 870. In step 850, process 800 may include disabling surround motion compensation; in step 860, process 800 may include encoding the current picture without using the surround motion compensation.

[0106] When it is determined that the reference picture size is equal to the current picture size ("yes" in step 840), process 800 may perform step 870, and then perform steps 880 and 890. In step 870, process 800 may include enabling the surround motion compensation; in step 880, process 800 may include encoding the current picture using the surround motion compensation.

[0107] like Figure 8 As further shown, process 800 may include generating an encoded video stream based on the encoded current picture (step 890).

[0108] In one embodiment, when it is determined that the reference picture size is equal to the current picture size, a first flag included in a picture parameter set (PPS) of the coded video bitstream may be set to 1. The first flag may correspond to, for example, pps_ref_wraparound_enabled_flag.

[0109] In one embodiment, the wraparound offset may be signaled in the PPS when the first flag is set to 1. The wraparound offset may correspond to, for example, pps_ref_wraparound_offset_minus1.

[0110] In one embodiment, the surround offset may be signaled as the number of luma samples.

[0111] In one embodiment, when it is determined that the reference picture size is not equal to the current picture size, a first flag included in the PPS of the encoded video bitstream may be set to 0.

[0112] In one embodiment, when it is determined that the second flag included in a sequence parameter set (SPS) referenced by the PPS is set to 0, the first flag may be set to 0. The second flag may correspond to, for example, sps_ref_wraparound_enabled_flag.

[0113] In one embodiment, the current picture size may be signaled in the PPS.

[0114] Although Figure 8 Example blocks of process 800 are shown, but in some implementations, process 800 may include more Figure 8 More blocks, fewer blocks, different blocks, or a different arrangement of blocks than shown in . Additionally or alternatively, two or more blocks of process 800 can be executed in parallel.

[0115] In an embodiment, a device for encoding a video bitstream is provided, the device comprising: a first determination module for determining whether reference picture resampling is enabled; a second determination module for determining a reference picture size of a reference picture; a third determination module for determining a current picture size of a current picture; a fourth determination module for determining whether the reference picture size is equal to the current picture size; a disabling module for disabling surround motion compensation when it is determined that the reference picture size is not equal to the current picture size; an encoding module for not using the surround motion compensation to encode the current picture when the surround motion compensation is disabled; and a generation module for generating an encoded video bitstream based on the encoded current picture.

[0116] Furthermore, the proposed method may be implemented by a processing circuit (e.g., one or more processors or one or more integrated circuits). In one example, one or more processors of a device for encoding a video bitstream execute a program (including one or more instructions) stored in a non-transitory computer-readable medium to perform one or more of the proposed methods.

[0117] The above techniques can be implemented as computer software through computer-readable instructions and physically stored in one or more computer-readable media. For example, Figure 9 A computer system 900 is shown that is suitable for implementing certain embodiments of the disclosed subject matter.

[0118] The computer software may be encoded in any suitable machine code or computer language, and may be assembled, compiled, linked, or other mechanisms to create code comprising instructions, which may be directly executed by one or more computer central processing units (CPUs), graphics processing units (GPUs), or the like, or executed through decoding, microcode, or the like.

[0119] The instructions may be executed on various types of computers or components thereof, including, for example, personal computers, tablets, servers, smartphones, gaming devices, IoT devices, and the like.

[0120] Figure 9 The components shown for computer system 900 are exemplary in nature and are not intended to limit the scope of use or functionality of computer software implementing embodiments of the present application. Nor should the configuration of components be interpreted as having any dependency or requirement on any component or combination of components shown in the exemplary embodiment of computer system 900.

[0121] Computer system 900 may include certain human-computer interface input devices. Such human-computer interface input devices may respond to input from one or more human users via tactile input (e.g., keyboard input, swipe gestures, data glove movements), audio input (e.g., voice, applause), visual input (e.g., gestures), or olfactory input (not shown). The human-computer interface devices may also be used to capture media that is not necessarily directly related to conscious human input, such as audio (e.g., speech, music, ambient sounds), images (e.g., scanned images, photographic images obtained from a still camera), and video (e.g., two-dimensional video, three-dimensional video including stereoscopic video).

[0122] The human interface input devices may include one or more of the following (only one of which is depicted): keyboard 901, mouse 902, touchpad 903, touch screen 910 and associated graphics adapter 950, data gloves, joystick 905, microphone 906, scanner 907, camera 908.

[0123] The computer system 900 may also include certain human-computer interface output devices. Such human-computer interface output devices can stimulate one or more human user senses through, for example, tactile output, sound, light, and smell / taste. Such human-computer interface output devices may include tactile output devices (e.g., tactile feedback through touch screen 910, data gloves, or joystick 905, but tactile feedback devices that do not function as input devices may also be present), audio output devices (e.g., speakers 909, headphones (not shown)), visual output devices (e.g., screens 910 including cathode ray tube (CRT) screens, liquid crystal (LCD) screens, plasma screens, organic light emitting diode (OLED) screens, each with or without touch screen input capabilities, each with or without tactile feedback capabilities—some of which can output two-dimensional visual output or output in three or more dimensions through means such as stereoscopic image output; virtual reality glasses (not shown), holographic displays, and cigarette boxes (not shown)), and printers (not shown).

[0124] The computer system 900 may also include human-accessible storage devices and their associated media, such as optical media including high-density read-only / rewritable optical disks (CD / DVD ROM / RW) 920 with CD / DVD or similar media 921, a thumb drive 922, a removable hard drive or solid state drive 923, traditional magnetic media such as magnetic tapes and floppy disks (not shown), dedicated ROM / ASIC / PLD-based devices such as security software dongles (not shown), and the like.

[0125] Those skilled in the art will also understand that the term "computer-readable media" used in connection with the disclosed subject matter does not include transmission media, carrier waves, or other transient signals.

[0126] The computer system 900 may also include an interface to one or more communication networks (955). For example, the network may be wireless, wired, or optical. The network may also be a local area network, a wide area network, a metropolitan area network, an in-vehicle network, an industrial network, a real-time network, a delay-tolerant network, and the like. The network also includes local area networks such as Ethernet, wireless local area networks, cellular networks (Global System for Mobile Communications (GSM), third generation (3G), fourth generation (4G), fifth generation (5G), long term evolution (LTE), etc.), television wired or wireless wide area digital networks (including cable television, satellite television, and terrestrial broadcast television), in-vehicle and industrial networks (including CANBus), and the like. Some networks typically require an external network interface adapter (954) for connecting to some universal data port or peripheral bus (949) (e.g., a universal serial bus (USB) port of the computer system 900); other systems are typically integrated into the core of the computer system 900 by connecting to a system bus as described below (e.g., an Ethernet interface integrated into a PC computer system or a cellular network interface integrated into a smartphone computer system). As an example, the network 955 can be connected to the peripheral bus 949 via the network interface 954. By using any of these networks, the computer system 900 can communicate with other entities. The communication can be one-way, only for receiving (e.g., wireless television), one-way only for sending (e.g., CAN bus to certain CAN bus devices), or two-way, such as to other computer systems via a local or wide area digital network. Each of the above-mentioned networks and network interfaces (954) can use certain protocols and protocol stacks.

[0127] The aforementioned human-machine interface devices, human-accessible storage devices, and network interfaces may be connected to the core 940 of the computer system 900 .

[0128] The core 940 may include one or more central processing units (CPUs) 941, graphics processing units (GPUs) 942, specialized programmable processing units in the form of field programmable gate arrays (FPGAs) 943, hardware accelerators 944 for specific tasks, and the like. These devices, as well as read-only memory (ROM) 945, random access memory (RAM) 946, and internal mass storage (e.g., an internal non-user accessible hard drive, solid-state drive (SSD), etc.) 947, may be connected via a system bus 948. In some computer systems, the system bus 948 may be accessible in the form of one or more physical plugs to allow expansion with additional central processing units, graphics processing units, and the like. Peripheral devices may be attached directly to the core's system bus 948 or connected via a peripheral bus 949. Peripheral bus architectures include peripheral bus interconnects (PCI), universal serial buses (USB), and the like.

[0129] The CPU 941, GPU 942, FPGA 943, and accelerator 944 can execute certain instructions, which, when combined, can constitute the aforementioned computer code. This computer code can be stored in ROM 945 or RAM 946. Transient data can also be stored in RAM 946, while permanent data can be stored, for example, in internal mass storage 947. Fast storage and retrieval from any memory device can be achieved through the use of cache memory, which can be closely associated with one or more of the CPU 941, GPU 942, mass storage 947, ROM 945, RAM 946, and the like.

[0130] The computer readable medium may have computer code thereon for performing various computer-implemented operations. The medium and computer code may be specially designed and constructed for the purposes of this application, or may be medium and code well known and available to those skilled in the art of computer software.

[0131] As an example and not a limitation, a computer system having architecture 900, in particular core 940, can provide functionality as a processor (including a CPU, GPU, FPGA, accelerator, etc.) to execute software contained in one or more tangible computer-readable media. Such computer-readable media can be media associated with the aforementioned user-accessible mass storage, as well as specific memories of the core 940 that are non-volatile, such as core internal mass storage 947 or ROM 945. Software that implements various embodiments of the present application can be stored in such a device and executed by the core 940. Depending on specific needs, the computer-readable medium may include one or more storage devices or chips. The software can enable the core 940, in particular the processor therein (including a CPU, GPU, FPGA, etc.) to perform a specific process or a specific part of a specific process described herein, including defining a data structure stored in RAM 946 and modifying such a data structure according to a software-defined process. Additionally or alternatively, the computer system can provide functionality that is logically hardwired or otherwise contained in a circuit (e.g., accelerator 944), which can replace the software or run together with the software to perform a specific process or a specific part of a specific process described herein. Where appropriate, references to software may include logic, and vice versa. Where appropriate, references to computer-readable media may include circuitry (such as an integrated circuit (IC)) storing the software, circuitry containing the logic, or both. This application includes any suitable combination of hardware and software.

[0132] Although this application has described a number of exemplary embodiments, various modifications, permutations, and equivalent substitutions of the embodiments are within the scope of this application. Therefore, it should be understood that those skilled in the art will be able to design a variety of systems and methods that, although not explicitly shown or described herein, embody the principles of this application and are therefore within the spirit and scope of this application.

Claims

1. A method for encoding a video bit stream, characterized in that: The method comprises: Make sure reference picture resampling is enabled; determining a reference picture size for the reference picture; Determine the current picture size of the current picture; Determining whether the reference picture size is equal to the current picture size; disabling surround motion compensation when it is determined that the reference picture size is not equal to the current picture size; When the surround motion compensation is disabled, encoding the current picture without using the surround motion compensation; and generating a coded video bitstream based on the coded current picture; When the value of (CtbSizeY / MinCbSizeY+1) is less than the value of (pic_width_in_luma_samples / MinCbSizeY-1), the value of pps_ref_wraparound_enabled_flag in the picture parameter set PPS of the coded video bitstream is set to 0.

2. The method according to claim 1, characterized in that Further including: When it is determined that the reference picture size is equal to the current picture size, enabling the surround motion compensation; as well as When the surround motion compensation is enabled, the current picture is encoded using the surround motion compensation.

3. The method according to claim 1 or 2, characterized in that Further including: When it is determined that the reference picture size is equal to the current picture size, the value of the pps_ref_wraparound_enabled_flag is set to 1.

4. The method according to claim 3, characterized in that Further including: When the value of the pps_ref_wraparound_enabled_flag is set to 1, the wraparound offset is signaled in the PPS.

5. The method according to claim 4, characterized in that Further including: The surround offset is signaled as the number of luma samples.

6. The method according to claim 1, characterized in that Further including: When it is determined that the value of sps_ref_wraparound_enabled_flag included in the sequence parameter set SPS referenced by the PPS is set to 0, the value of the pps_ref_wraparound_enabled_flag is set to 0.

7. The method according to any one of claims 1-2 and 4-6, characterized in that Further including: The current picture size is signaled in the PPS.

8. A device for encoding a video bit stream, characterized in that The device comprises: at least one memory for storing program code; and At least one processor is configured to read the program code and operate according to instructions of the program code to implement the method according to any one of claims 1 to 7.

9. A device for encoding a video bit stream, characterized in that The device comprises: A first determining module, configured to determine whether reference picture resampling is enabled; a second determining module, configured to determine a reference picture size of the reference picture; A third determining module is used to determine the current picture size of the current picture; a fourth determining module, configured to determine whether the reference picture size is equal to the current picture size; a disabling module, configured to disable surround motion compensation when it is determined that the reference picture size is not equal to the current picture size; an encoding module, configured to encode the current picture without using the surround motion compensation when the surround motion compensation is disabled; and A generation module, configured to generate an encoded video bitstream based on the encoded current picture; When the value of (CtbSizeY / MinCbSizeY+1) is less than the value of (pic_width_in_luma_samples / MinCbSizeY-1), the value of pps_ref_wraparound_enabled_flag in the picture parameter set PPS of the coded video bitstream is set to 0.

10. A non-volatile computer-readable medium, characterized in that Used to store instructions, the instructions comprising one or more instructions, when the one or more instructions are executed by one or more processors of a device for encoding a video bitstream, enable the one or more processors to perform the method according to any one of claims 1 to 7.

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