RU2785364C1 - Method for cyclic motion compensation with oversampling of the reference image - Google Patents

Abstract

FIELD: imaging technology.

SUBSTANCE: invention relates to the field of encoding and decoding video data and, in particular, to enabling and disabling cyclic motion compensation. A method is proposed for generating a bit stream of encoded video data using at least one processor, including performing the first determination as to whether the current level of the current image is an independent level; performing a second determination as to whether oversampling of the reference image is enabled for the current level; based on the first determination and the second determination, disabling cyclic compensation for the current level and encoding the current level without cyclic compensation. Cyclic motion compensation can be a useful function for encoding, for example, a 360-degree image projected in an equirectangular projection (ERP) format and can reduce some visual artifacts on the “stitching” line.

EFFECT: increase in the efficiency of encoding and decoding.

17 cl, 16 dwg, 1 tbl

Description

Cross-reference to related application

[1] This application claims priority under U.S. Provisional Application No. 62/955,520, filed December 31, 2019, and U.S. Patent Application No. 17/064,172, filed October 6, 2020, the contents of which are incorporated herein in their entirety. .

Technical field

[2] The invention relates to encoding and decoding video data and, in particular, to enabling and disabling cyclic motion compensation.

Prerequisites for the creation of the invention

[3] Encoding and decoding of video data may be performed using motion-compensated inter-picture prediction. Uncompressed digital video may include a sequence of images, each of which has a spatial size of, for example, 1920×1080 luma samples and their associated chrominance samples. The image sequence may have a fixed or variable image rate (informally also referred to as frame rate), such as 60 images per second, or 60 Hz. Uncompressed video has significant bitrate requirements. For example, 1080p60 4:2:0 video with 8 bits per sample (resolution of 1920x1080 luminance samples at 60Hz frame rate) requires about 1.5Gbps of bandwidth. An hour of such video requires more than 600 GB of storage.

[4] One of the purposes of encoding and decoding video data may be to reduce redundancy in the input video signal by compressing. Compression can help to alleviate the aforementioned bandwidth or storage requirements, in some cases by two orders of magnitude or more. You can use both lossless and lossy compression, as well as a combination of both. Lossless compression refers to techniques for reconstructing an exact copy of the original signal from the compressed original signal. When lossy compression is used, the reconstructed signal may not be identical to the original signal, but the discrepancy between the original and reconstructed signals is small enough that the reconstructed signal can be used for the intended application. Lossy compression is widely used for video. The amount of distortion allowed depends on the application; for example, users of some custom streaming applications may tolerate more distortion than users of broadcast TV applications. Higher allowed/allowable distortion allows a higher compression ratio to be achieved.

[5] The video encoder and decoder may use techniques from several broad categories including, for example, motion compensation, transformation, quantization, and entropy coding, some of which will be presented below.

[6] Historically, video encoders and decoders have usually worked with a given image size, which in most cases was set and remained constant for a coded video sequence (CVS, coded video sequence), a group of pictures (GOP, Group of Pictures) or similar time frame with multiple images. For example, in MPEG-2, systems are known that change the horizontal resolution (and hence image size) depending on factors such as activity in the frame, but only in I-pictures, hence common for GOPs. Resampling of reference pictures to use different resolutions in CVS is known, for example, from ITU-T Rec. H.263, Annex P. However, here the image size does not change, only the reference pictures are resampled, with the result that only parts of the image can potentially be used (in the case of downsampling). sampling) or only parts of the captured frame (in the case of upsampling). In addition, H.263 Annex Q allows single macroblock resampling by a factor of 2 (in each dimension) in either the up or down direction. Again, the image size remains the same. The macroblock size in H.263 is fixed and therefore does not need to be signaled.

[7] Image resizing for predicted images has become widespread in modern video coding. For example, VP9 allows you to resample the reference image and change the resolution for the entire image. Likewise, some proposals made in relation to VVC (including, for example, Hendry, et. al, "On adaptive resolution change (ARC) for VVC", document JVET-M0135-vl, January 9-19, 2019, are in full included herein) allow entire reference pictures to be resampled at various higher or lower resolutions. This document proposes to encode the various possible resolutions in a sequence parameter set and refer to the syntax elements for each picture in the picture parameter set.

SUMMARY OF THE INVENTION

[8] In an embodiment of the invention, there is provided a method for generating a bitstream of encoded video data using at least one processor, including making a first determination as to whether the current level of the current image is an independent level; making a second determination as to whether resampling of the reference picture is enabled for the current layer; based on the first determination and the second determination, disabling cyclic compensation for the current level and encoding the current level without cyclic compensation.

[9] In an embodiment of the invention, an apparatus is provided for generating an encoded video data bitstream, comprising at least one memory configured to store program code and at least one processor configured to read the program code and operate in accordance with instructions of the program code, wherein the program code includes: a first determination code configured to allow at least one processor to perform a first determination as to whether the current level of the current image is an independent level; a second determination code configured to cause the at least one processor to perform a second determination as to whether reference picture resampling is enabled for the current layer; a disable code configured to provide at least one processor, based on the first determination and the second determination, disabling cyclic compensation for the current level, and an encoding code configured to provide at least one processor encoding the current level without cyclic compensation.

[10] In one embodiment of the invention, a computer-readable medium is provided on which instructions are stored, including one or more instructions, which, when executed by one or more processors of a device for generating an encoded video data bitstream, cause, by one or more processors, the following: making a first determination as to whether the current layer of the current image is an independent layer; making a second determination as to whether resampling of the reference picture is enabled for the current layer; based on the first determination and the second determination, disabling cyclic compensation for the current level, and encoding the current level without cyclic compensation.

Brief description of the drawings

[11] Additional features, nature and various advantages of the present invention will be apparent from the following detailed description and the accompanying drawings.

[12] FIG. 1 is a schematic illustration of a simplified block diagram of a communication system in accordance with an embodiment of the invention.

[13] FIG. 2 is a schematic illustration of a simplified block diagram of a communication system in accordance with an embodiment of the invention.

[14] FIG. 3 is a schematic illustration of a simplified block diagram of a decoder according to an embodiment of the invention.

[15] FIG. 4 is a schematic illustration of a simplified block diagram of an encoder in accordance with an embodiment of the invention.

[16] FIG. 5A-5E are schematic illustrations of options for ARC parameter signaling in accordance with an embodiment of the invention.

[17] FIG. 6A-6B are schematic illustrations of examples of syntax tables in accordance with an embodiment of the invention.

[18] FIG. 7 is a schematic illustration of an example of a syntax table in accordance with an embodiment of the invention.

[19] FIG. 8A-8C are flowcharts of examples of methods for generating an encoded video data bitstream in accordance with an embodiment of the invention.

[20] FIG. 9 is a schematic illustration of a computer system in accordance with an embodiment of the invention.

Detailed description of the invention

[21] FIG. 1 shows a simplified block diagram of a communication system (100) according to an embodiment of the present invention. The system (100) may include at least two terminals (110-120) interconnected via a network (150). For unidirectional data transmission, the first terminal (110) may encode video data at the local location for transmission to another terminal (120) via the network (150). The second terminal (120) may receive another terminal's encoded video data from the network (150), decode the encoded data, and display the recovered video data. One-way communication may be inherent in media service applications and the like.

[22] FIG. 1 illustrates a second pair of terminals (130, 140) supporting bidirectional transmission of coded video data, which may occur during video conferences, for example. For bi-directional data transmission, each terminal (130, 140) may encode video data captured at a local location for transmission to another terminal over a network (150). Each terminal (130, 140) can also receive the encoded video data transmitted by the other terminal, decode the encoded data, and display the recovered video data on a local display device.

[23] In the example shown in FIG. 1, terminals (110-140) can be illustrated as servers, personal computers, and smartphones, but this does not limit the principles of the present invention. Embodiments of the present invention find application in laptop computers, tablet computers, media players and/or equipment used for video conferencing. Network (150) represents any number of networks that carry encoded video data between terminals (110-140), including, for example, wired and/or wireless networks. The communication network (150) allows data to be exchanged in a circuit-switched and/or packet-switched mode. Examples of networks include telecommunications networks, local area networks, wide area networks and/or the Internet. For the purposes of this discussion, the architecture and topology of the network (150) may not be relevant to the present invention unless specifically noted below.

[24] FIG. 2 shows, as an example of the application of the present invention, the placement of a video encoder and a video decoder in a streaming environment. The present invention may be equally applicable to other video processing applications including, for example, videoconferencing, digital television, storage of compressed video on digital media such as CD, DVD, memory card, and the like.

[25] The streaming system may include a capture subsystem (213), which may include a source (201) of video data, such as a digital camera, creating, for example, an uncompressed stream (202) of video data samples. This stream (202) of samples, depicted with a thick line to emphasize the large amount of data compared to the bitstreams of encoded video data, can be processed by an encoder (203) connected to a camera (201). The encoder (203) may include hardware, software, or a combination thereof to provide or implement aspects of the present invention, as described in more detail below. The encoded video data bitstream (204), depicted as a thin line to emphasize the smaller amount of data compared to the sample stream, may be stored on the streaming server (205) for later use. One or more streaming clients (206, 208) can access the streaming server (205) to extract copies (207, 209) of the encoded video bitstream (204). The client (206) may include a video decoder (210) that decodes an incoming copy of the encoded video bitstream (207) and produces an outgoing stream (211) of video samples that can be displayed on a display (212) or other visualization device (not shown) . In some streaming systems, bitstreams (204, 207, 209) of video data may be encoded according to certain video coding/compression standards. Examples of these standards include ITU-T Rec. H.265. A video coding standard is under development, informally known as Universal Video Coding or VVC (Versatile Video Coding). The present invention can be used in the context of VVC.

[26] FIG. 3 shows a functional diagram of a video decoder (210) according to an embodiment of the present invention.

[27] The receiver (310) may receive one or more encoded video sequences for decoding by video decoder (210), in the same or another embodiment of the invention, one encoded video sequence at a time, with the decoding of each encoded video sequence independent of 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 where the encoded video data is stored. The receiver (310) may receive encoded video data with other data, such as encoded audio data and/or auxiliary data streams, which may be redirected to their respective utilizing entities (not shown). The receiver (310) may separate the encoded video sequence from other data. To combat network jitter, a buffer memory (315) can be connected between the receiver (310) and the entropy decoder/analyzer (320) (hereinafter "analyzer"). When the receiver (310) receives data from a storage/redirector with sufficient bandwidth and controllability, or from an isosynchronous network, the buffer memory (315) may not be needed or may be small. For use in best effort packet networks such as the Internet, a buffer (315) may be required, which may be relatively large and may preferably have an adaptive size.

[28] The video decoder (210) may include an analyzer (320) for reconstructing the symbols (321) from the entropy coded video sequence. The categories of these symbols include information used to control the operation of the decoder (210) and possibly information to control a visualization device such as a display (212) that is not an integral part of the decoder but may be connected to it, as shown in FIG. 3. The control information for the rendering device(s) may be Supplemental Enhancement Information (SEI) messages or Video Usability Information (VUI) parameter set fragments (not shown). The analyzer (320) may analyze/entropy decode the received encoded video sequence. The encoding of the video sequence may be in accordance with a video coding technology or standard and may follow principles known to those skilled in the art, including variable run length coding, Huffman coding, arithmetic coding with or without context sensitivity, and so on. The analyzer (320) can extract from the encoded video sequence a set of subgroup parameters for at least one of the subgroups of pixels in the video decoder based on at least one parameter corresponding to the group. Subgroups may include groups of pictures (GOP, Groups of Pictures), pictures, sub-images, tiles, slices, modules, macroblocks, coding tree units (CTU, Coding Tree Unit), coding units (CU, Coding Unit), blocks, transformation units ( TU, Transform Unit), prediction units (PU, Prediction Unit), etc. A tile can point to a rectangular area of a CU/CTU in a specific column and row of a tile in an image. A module can point to a rectangular area of CU/CTU rows within a specific tile. A slice may point to one or more image units that are contained in a NAL unit. A sub-image may point to a rectangular area of one or more slices in an image. The entropy decoder/analyzer can also extract information from the encoded video sequence, such as transform coefficients, quantizer parameter values, motion vectors, etc.

[29] The analyzer (320) may perform an entropy decoding/analysis operation of the video sequence obtained from the buffer (315) to create symbols (321).

[30] Several different modules can be used for symbol reconstruction (321) depending on the type of encoded video image or parts thereof (eg, intra- and outer-coded pictures, intra- and outer-coded blocks) and other factors. Which modules are used and how can be determined by the subgroup management information obtained from the encoded video sequence by the analyzer (320). The flow of such subgroup control information between the analyzer (320) and the modules is not shown hereinafter for simplicity.

[31] In addition to the previously mentioned functional blocks, video decoder 210 can be fundamentally divided into several functional modules, as described below. In practical implementation under commercial constraints, many of these modules interact closely with each other and can, at least partially, be built into one another. However, for the purpose of describing the present invention, a fundamental division into the following functional modules is appropriate.

[32] The first module is the scaling/inverse transform module (351). The scaling/inverse transform module (351) receives the quantized transform coefficient as well as control information including the transform used, block size, quantization factor, quantization scaling matrices, etc. as character(s) (321) from the analyzer (320). It can output blocks containing sample values that can be entered into the aggregator (355).

[33] In some cases, the output samples of the scaling / inverse transform module (351) may refer to an intra-coded block, that is, a block that does not use predicted information from previously reconstructed images, but can use predicted information from previously reconstructed parts of the current image . Such predicted information may be provided by the intra image prediction module (352). In some cases, the intra image prediction module (352) generates a block of the same size and shape as the block to be reconstructed using the already reconstructed environment information extracted from the current (partially reconstructed) image (358). The aggregator (355) in some cases adds, for each sample, the prediction information generated by the intra prediction module (352) to the output sample information provided by the scaling/inverse transform module (351).

[34] In other cases, the output samples of the scaling/inverse transform module (351) may refer to an intra-coded block, possibly with motion compensation. In such a case, the motion compensation prediction module (353) may access the reference picture memory (357) to retrieve samples used for prediction. After motion compensation has been applied to the extracted samples according to the symbols (321) associated with the block, these samples can be added by an aggregator (355) to the output of the scaler/demap module (in this case referred to as residual samples or residual signal) to generate output information. counts. Reference picture memory addresses from where the motion-compensated prediction module retrieves prediction samples may be driven by motion vectors available to the motion-compensated prediction module in the form of symbols (321), which may have, for example, X, Y, and reference picture components. . Motion compensation may also include interpolation of sample values retrieved from reference picture memory when accurate subsample motion vectors, motion vector prediction mechanisms, and so on are used.

[35] Various loop filtering methods can be applied to the aggregator (355) output samples in the loop filter module (356). The video data compression technologies may include loop filter technologies controlled by parameters included in the encoded video bitstream and available to the loop filter module (356) as symbols (321) from the analyzer (320), but may also be responsive to metainformation obtained during decoding previous (in decoding order) parts of the encoded image or encoded video sequence, as well as responding to previously reconstructed and contour filtered sample values.

[36] The loop filter module (356) can output a stream of samples that can be fed to the renderer (212) and also stored in the reference picture memory 557 for use in future inter-image prediction.

[37] Some encoded pictures, when fully reconstructed, can be used as reference pictures for future prediction. For example, when an encoded picture is fully reconstructed and identified as a reference picture (e.g., by analyzer (320)), the current reference picture (358) may become part of the reference picture buffer memory (357), and fresh memory for the current picture may be re-allocated prior to reconstruction. next encoded picture.

[38] Video decoder 210 may perform decoding operations according to a predetermined video data compression technology documented in a standard such as ITU-T Rec. H.265. The encoded video sequence may follow the syntax given by the video compression technology or standard used, in the sense that the encoded video sequence may follow the syntax of the video compression technology or standard specified in the video compression technology document or standard, and in particular in the profile document. . It may also be necessary for consistency that the complexity of the encoded video sequence remains within the limits set by the level of technology or video compression standard. In some cases, the levels limit the maximum image size, the maximum frame rate, the maximum sampling rate for reconstruction (measured in megasamples per second, for example), the maximum reference image size, and so on. The limits set by the levels, in some cases, may be further limited by the specifications of the Hypothetical Reference Decoder (HRD) and the metadata for managing the HRD buffer signaled in the encoded video sequence.

[39] According to an embodiment of the invention, the receiver (310) may receive additional (redundant) data with encoded video data. Additional data may be included as part of the encoded video sequence(s). 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 side data may be, for example, temporal enhancement levels, spatial enhancement levels or signal noise ratio (SNR) enhancement levels, redundant slices, redundant images, forward error correction codes, and so on.

[40] FIG. 4 is a functional diagram of a video encoder (203) according to an embodiment of the present invention.

[41] The encoder (203) may receive video data samples from a video data source (201) (which is not part of the encoder) that may capture the video image(s) to be encoded by the video encoder (203).

[42] The video source (201) may provide the source video sequence to be encoded by the video encoder (203) in the form of a digital video sample stream of any suitable bit depth (eg: 8 bits, 10 bits, 12 bits, ...), any color space (eg , VT.601 Y CrCB, RGB, …) and any suitable sampling structure (eg Y CrCb 4:2:0, Y CrCb 4:4:4). In a media service system, the source (201) of video data may be a storage device where previously prepared video is stored. In a videoconferencing system, the video data source (203) may be a camera that captures local image information as a video sequence. The video data may be provided as a plurality of individual images that give a sense of movement when viewed in sequence. The images themselves may be organized as a spatial array of pixels, where each pixel may contain one or more samples depending on the sampling structure used, color space, and so on. It is not difficult for a person skilled in the art to understand the relationship between pixels and samples. The following description is devoted to readings.

[43] According to an embodiment of the invention, the encoder (203) may encode and compress images of the source video sequence into the encoded video sequence (443) in real time or subject to any other time constraints imposed by the application. Setting the proper coding rate is one of the functions of the controller (450). The controller controls other functional modules as described below and is functionally connected to them. The connection is not shown for simplicity. The parameters set by the controller may include parameters related to frequency adjustment (picture skip, quantizer, lambda value used in rate-distortion optimization methods, etc.), image size, group of images (GOP, group of pictures), maximum motion vector search area, etc. One skilled in the art will appreciate that the controller (450) may have other suitable functions related to the video encoder (203) optimized for a particular system design.

[44] Some video encoders may operate in a "coding loop" as understood by one skilled in the art. As a very simplified description, for example, an encoding loop may include an encoder (430) encoding part (herein referred to as a "source encoder") (responsible for creating symbols, for example, a stream of symbols, based on the input image to be encoded and the reference image(s). (s)) and a (local) decoder (433) built into the encoder (203) that reconstructs the symbols to produce sample data as a (remote) decoder would (because any symbol compression into the encoded video bitstream is lossless in video compression technologies discussed in this description). The reconstructed stream of samples enters the memory (434) reference images. Since decoding a stream of symbols produces bit-accurate results that are independent of the position (local or remote) of the decoder, the contents of the reference picture buffer will also be the same bit-accuracy for the local encoder and the remote encoder. In other words, the prediction part of the encoder "sees" as reference picture samples exactly the same sample values as the decoder would "see" if using prediction during decoding. This fundamental principle of reference picture synchronism (and eventually drift if synchronism cannot be maintained due to, for example, channel errors) is well known to those skilled in the art.

[45] The "local" decoder (433) may operate in the same manner as the "remote" decoder (210) detailed above with reference to FIG. 3. However, again, referring to FIG. 4, since the symbols are available and the entropy encoder (445) and parser (320) can be losslessly encoded/decoded into the encoded video sequence, the entropy decoding parts of the decoder (210) including channel (312), receiver (310), buffer ( 315) and analyzer (320) may not be fully implemented in the local decoder (433).

[46] In doing so, it can be concluded that any decoding technology present in a decoder, with the exception of analysis/entropy decoding, must also necessarily be present in essentially identical functional form in the corresponding encoder. For this reason, the present invention is focused on the operation of the decoder. The description of the encoding technologies can be abbreviated as they are the inverse of the decoding technologies described in detail. Only in some areas a more detailed description is required, which is given below.

[47] In operation, the source encoder (430) may perform motion-compensated predictive coding in which an input frame is predictively encoded based on one or more previously encoded frames from the video sequence, referred to as "reference frames". Thus, the coding engine (432) encodes the differences between the pixel blocks of the input frame and the pixel blocks of the reference frame(s) that can be selected as the prediction reference(s) to the input frame.

[48] The local video decoder (433) may decode the encoded video data of the frames, which may be indicated as reference frames, based on the symbols generated by the source encoder (430). The operations of the encoding engine (432) may be predominantly lossy methods. When the encoded video data can be decoded in a video decoder (not shown in FIG. 4), the reconstructed video sequence can typically be a copy of the original video sequence with some errors. The local video decoder (433) duplicates the decoding processes that may be performed by the video decoder on the reference frames and may store the reconstructed reference frames in the reference picture cache (434). Thus, the encoder (203) can locally store copies of the reconstructed key frames having the same content as the reconstructed key frames that would be received by the remote video decoder (in the absence of transmission errors).

[49] The predictor (435) may perform prediction searches for the encoding engine (432). Thus, for a new frame to be encoded, the predictor (435) may search the reference picture memory (434) for sample data (as pixel reference block candidates) or specific metadata such as reference picture motion vectors, block shapes, etc. .d., which can serve as a proper reference for predicting new images. The predictor (435) may operate on a "blocks of samples×blocks of pixels" basis to find appropriate references for prediction. In some cases, according to the search results obtained by the predictor (435), the input picture may have prediction references extracted from the plurality of reference pictures stored in the reference picture memory (434).

[50] The controller (450) may control the encoding operations of the video encoder (430), including, for example, setting parameters as well as subgroup parameters used to encode video data.

[51] The output signal of all the above functional modules can be entropy encoded in an entropy encoder (445). The entropy encoder translates the symbols generated by the various functional units into an encoded video sequence by lossless symbol compression according to, for example, techniques known to one skilled in the art, such as Huffman coding, variable run length coding, arithmetic coding, and so on.

[52] The transmitter (440) may buffer the encoded video sequence(s) created by the entropy encoder (445) in preparation for transmission over a communication channel (460), which may be a hardware/software memory link. where the encoded video data is stored. The transmitter (440) may combine the encoded video data from the video encoder (430) with other data to be transmitted, such as encoded audio data and/or auxiliary data streams (sources not shown).

[53] The controller (450) may control the operation of the encoder (203). During encoding, the controller (450) may assign to each encoded picture one or another encoded picture type, which may determine the encoding methods applicable to the corresponding picture. For example, images can often be assigned the following types of frames.

[54] An intra-coded picture (I-picture) that can be encoded and decoded without using any other frame in the sequence as a source for prediction. Some video codecs allow different types of intra-coded images, including, for example, images in the Independent Decoder Refresh (IDR) format. One skilled in the art will be aware of the I-image varieties and their respective applications and features.

[55] A predictive picture (P-picture) that can be encoded and decoded using intra prediction or inter prediction using at most one motion vector and a reference index to predict sample values of each block.

[56] A bidirectional predictive picture (B-picture) that can be encoded and decoded using intra prediction or inter prediction using no more than two motion vectors and reference indices to predict sample values of each block. Likewise, multi-prediction pictures may use more than two reference pictures and associated metadata to reconstruct a single block.

[57] Source images typically allow for spatial division into multiple blocks of samples (eg, blocks of 4x4, 8x8, 4x8, or 16x16 samples each) and coding on a block-by-block basis. The blocks may be predictively encoded with reference to other (previously coded) blocks defined by the coding assignment applied to the respective images of those blocks. For example, blocks of I-pictures may be encoded without prediction or predictively with reference to previously encoded blocks of the same picture (with spatial prediction or intra prediction). The pixel blocks of P-pictures may be encoded without prediction, either by spatial prediction or temporal prediction with reference to one previously encoded reference picture. Blocks of B-pictures may be encoded without prediction, by spatial prediction or temporal prediction with reference to one or two previously encoded reference pictures.

[58] The video encoder (203) may perform encoding operations according to a predetermined video coding technology or standard, such as ITU-T Rec. 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. Therefore, the encoded video data may follow the syntax given by the technology used or the video coding standard used.

[59] According to an embodiment of the invention, the transmitter (440) may transmit additional data with encoded video data. The source video encoder (430) may include such data as part of the encoded video sequence. The additional data may comprise temporal/spatial/SNR enhancement levels, other forms of redundant data such as redundant images and slices, enhancement additional information (SEI) messages, video usability information (VUI) parameter set fragments, and so on.

[60] Recently, some attention has been paid to combining compressed regions or extracting several semantically independent parts of an image to form a single video image. In particular, in the context of e.g. 360-degree encoding or certain surveillance applications, multiple semantically independent source images (e.g., a six-facet surface of a 360-degree image projected onto a cube, or separate camera inputs in the case of a multi-camera surveillance setup) may require separate adaptive resolution settings to account for different activity for each image at a given time. In other words, encoders at a given time may use different resampling factors for different semantically independent images that make up the entire 360-degree image or scene of observation. When combined into a single picture, this in turn requires performing reference picture resampling and adaptive resolution coding signaling for parts of the encoded picture.

[61] Several terms will be introduced below and will be used in the rest of this description.

[62] A sub-image may refer, in some cases, to a rectangular organization of samples, blocks, macroblocks, coding units, or similar objects that are semantically grouped and can be independently encoded in a modified resolution. One or more sub-images may form an image. One or more encoded sub-images may form an encoded image. One or more sub-images may be assembled into an image, and one or more sub-images may be extracted from the image. In certain environments, one or more encoded sub-images may be assembled into an encoded image in the compression domain without being re-coded to a sample layer, and in the same or other cases, one or more encoded sub-images may be extracted from the encoded image in the compression domain.

[63] Adaptive Resolution Change (ARC) may refer to mechanisms that allow the resolution of an image or sub-images in an encoded video sequence to be changed, for example, by resampling a reference image. The ARC parameters hereinafter refer to control information that is necessary to perform adaptive resolution change and may include, for example, filter parameters, scaling factors, output and/or reference picture resolutions, various control flags, and so on.

[64] In embodiments of the invention, encoding and decoding may be performed on a single semantically independent encoded video image. Before describing the consequences of encoding/decoding multiple sub-pictures with independent ARC parameters and their expected additional complexity, options for signaling ARC parameters must be described.

[65] FIG. 5A-5E show several embodiments of the invention for signaling ARC parameters. As noted, in each of the embodiments of the invention, they may have certain advantages and certain disadvantages in terms of coding efficiency, complexity and architecture. A video coding standard or technology may choose one or more of these embodiments or options known in the art for signaling the ARC parameters. Embodiments of the invention may not be mutually exclusive and may possibly be interchangeable depending on the requirements of the application, the standards technology used, or the choice of encoder.

[66] ARC parameter classes may include:

[67] - upsampling/downsampling coefficients, singly or in combination in the X and Y dimensions,

[68] - upsampling/downsampling ratios with the addition of a temporal dimension, indicative of zooming in/out at a constant rate for a given number of images,

[69] - any of the above two classes may include the encoding of one or more supposedly short syntax elements, which may indicate a table containing coefficient(s),

[70] is the resolution, along the X or Y axis, in units of samples, blocks, macroblocks, coding units (CUs), or any other suitable granularity of the input picture, output picture, reference picture, encoded picture, considered in combination or separately. If there is more than one resolution (eg, one for the input image, one for the reference image), then in some cases one set of values may be derived from another set of values. This can be controlled, for example, with flags. A more detailed example is described below,

[71] - "warp" coordinates are similar to those used in Annex P of the H.263 standard, again with the appropriate degree of subdivision as mentioned above. Annex P of the H.263 standard defines an efficient way to encode such strain coordinates, but other, potentially more efficient ways may be devised. For example, the reversible Huffman-style variable-length encoding of warp coordinates from Annex P can be replaced by a suitable length binary encoding, where the length of the binary code word can be, for example, obtained from the maximum image size, perhaps multiplied by a certain factor and offset by a certain value, to allow "warping" beyond the bounds of the maximum image size,

[72] - upsampling/downsampling filter parameters. In embodiments of the invention, only one upsampling/downsampling filter may be present. However, in embodiments of the invention, it may be desirable to provide greater flexibility in filter design, and this may require filter parameter signaling. 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 suitable entropy coding techniques), the filter may be implicitly selected by upsampling/downsampling coefficients, which , in turn, are signaled according to any of the mechanisms mentioned above, and so on.

[73] The following description assumes encoding a finite set of upsampling/downsampling coefficients (the same coefficient is used in both the X dimension and the Y dimension) that are indicated by a codeword. This codeword may be encoded with variable length codes, for example using the Exponential Golomb code adopted for certain syntax elements in video coding specifications such as H.264 and H.265. A suitable conversion of values to upsampling/downsampling coefficients can, for example, follow Table 1:

[74] Many such transformations may be obtained according to the needs of the application and the capabilities of the upscaling and downscaling mechanisms available in the video compression technology or standard. The table could be expanded to more values. Values may also be represented by entropy encoding mechanisms other than Exponential Golomb codes, such as using binary encoding. This can have certain advantages when the oversampling factors are of interest outside of the video processing engines themselves (primarily the encoder and decoder), such as MANE. It should be noted that in situations where a change in resolution is not required, a short Exponential Golomb code can be chosen; in the above table, it is only one bit. This may have an advantage in coding efficiency over using binary codes in the most common case.

[75] The number of entries in the table, as well as their semantics, can be completely or partially customizable. For example, the underlying table data may be transmitted in a "high" parameter set, such as a sequence or decoder parameter set. In some embodiments of the invention, one or more such tables may be defined in a video coding technology or standard and may be selected, for example, by a set of decoder or sequence parameters.

[76] The following describes how the upsampling/downsampling ratio (ARC information) encoded as described above can be included in the syntax of a video coding technology or standard. A similar consideration may be applied to one or more codewords driving the upsampling/downsampling filters. The following is a discussion of the case where a filter or other data structure requires relatively large amounts of data.

[77] As shown in FIG. 5A, H.263 Annex P includes ARC information (502) in the form of four warp coordinates in the image header (501), namely the H.263 PLUSPTYPE header extension (503). This may be a reasonable design choice if a) there is an image header, and b) the ARC information is expected to change frequently. However, the overhead of using H.263 signaling can be quite high, and the scaling factors may not apply to picture boundaries because the picture header may be transient.

[78] As shown in FIG. 5B, JVCET-M135-v1 includes ARC reference information (505) (index) located in the set (504) of image parameters and pointing to a table (506) including target resolutions, which, in turn, is inside the set (507) sequence parameters. Placing a candidate resolution in a table (506) in a set (507) of sequence parameters, as claimed by the authors, may be justified by using the SPS for interoperability in capability exchange. The resolution can be changed from image to image within the limits set by the values in the table (506) by referring to the corresponding set (504) of image parameters.

[79] As shown in FIG. 5C-5E, the following embodiments of the invention may involve the transmission of ARC information in a video bitstream. Each of these options has certain advantages over the options described above. Embodiments of the invention can be simultaneously used in the same technology or the same video coding standard.

[80] In embodiments of the invention, for example, in the embodiment of the invention shown in FIG. 5C, ARC information (509) such as a resampling (scaling) factor may be present in a slice header, a GOP header, a tile header, or a tile group header. Fig. 5C illustrates an embodiment of the invention that uses a tile group header (508). This may be sufficient if the ARC information is small, such as a single variable length codeword ue(v) or a fixed length codeword of a small number of bits, such as shown above. Having the ARC information directly in the tile group header has the added benefit that the ARC information may be applicable to a sub-image represented by that tile group, for example, rather than to the entire image. See also the description below. In addition, even if a video compression technology or standard only provides for adaptive resizing of the entire image (as opposed to, for example, adaptive resizing based on a tile group), placing ARC information in the tile group header versus placing it in the image header in style H.263 has certain advantages in terms of error tolerance.

[81] In embodiments of the invention, such as the embodiment shown in FIG. 5D, the ARC information (512) itself may be present in a corresponding parameter set such as, for example, a picture parameter set, a header parameter set, a tile parameter set, an adaptation parameter set, and so on. Fig. 5D illustrates an embodiment of the invention that uses a set (511) of adaptation parameters. The scope of this set of parameters may preferably be no larger than the image, for example, may extend over a group of tiles. The ARC information is used implicitly by activating the appropriate set of options. For example, when a video coding technology or standard considers ARC based on an image only, then a set of image parameters or an equivalent set may be appropriate.

[82] In embodiments of the invention, for example, in the embodiment of the invention shown in FIG. 5E, the ARC reference information (513) may be present in a tile group header (514) or a similar data structure. This reference information (513) may refer to a subset of the ARC information (515) available in a parameter set (516) with a scope that extends beyond a single picture, such as in a sequence parameter set or a decoder parameter set.

[83] An extra layer of indirect PPS activation from a tile group header, PPS, SPS, as used in JVET-M0135-v1, seems unnecessary because image parameter sets, like sequence parameter sets, can (and should in certain standards such as RFC3984) be used to negotiate capabilities or declarations. If, however, the ARC information is to be applicable to a sub-image represented, for example, also by tile groups, a parameter set with an activation area limited by the tile group, such as an adaptation parameter set or a header parameter set, may be a more appropriate choice. Also, if the size of the ARC information is not small, such as containing filter control information such as multiple filter coefficients, then the parameter may be a better choice than using the (508) header directly from a coding efficiency point of view, since these settings can be reused for future images or subimages with reference to the same set of parameters.

[84] When using a sequence parameter set or other higher-level parameter set with a scope spanning multiple images, certain considerations may apply:

[85] 1. A parameter set for storing a table 516 with ARC information may in some cases be a sequence parameter set, but in other cases may preferably be a decoder parameter set. The decoder parameter set may have an activation area of several CVS video sequences, namely the encoded video data stream, ie all encoded video data bits from session start to session break. Such a scope may be more appropriate because the possible ARC coefficients may be a characteristic of the decoder, possibly implemented in hardware, and hardware functions are generally independent of the CVS video sequence (which, in at least some entertainment systems, is a group of pictures duration of one second or less). However, placing a table in a sequence parameter set is explicitly included in the placement options described here, in particular in connection with point 2 below.

[86] 2. The ARC reference information (513) may preferably be placed directly in the image/tile slice/GOP/tile group header, for example, in the tile group header (514), rather than in the picture parameter set as in JVCET-M0135 -v1. For example, when an encoder needs to change one value in a picture parameter set, such as the ARC reference information, for example, it must create a new PPS set and refer to this new PPS set. Assume that only the ARC reference information is changed, but other information, such as the quantization matrix information in PPS, for example, remains unchanged. Such information can be of considerable size and will need to be retransmitted to complete the new PPS set. Since the ARC reference information (513) may be a single codeword, such as an index in a table, and this will be the only value that changes, it would be cumbersome and wasteful to retransmit, for example, all of the quantization matrix information. In this regard, it may be significantly better, in terms of encoding efficiency, to avoid indirection via PPS, as proposed in JVET-M0135-v1. Likewise, placing the ARC reference information in the PPS has the additional disadvantage that the ARC information referred to by the ARC reference information (513) may apply to the entire image and not to a sub-image, since the activation area of the image parameter set is the image.

[87] In the same or another embodiment of the invention, ARC parameter signaling may follow the detailed example shown in FIG. 6A-6B. In FIG. 6A-6B are representational syntax diagrams using a notation that roughly corresponds to C-style programming used, for example, in video coding standards since at least 1993. Lines in bold indicate syntax elements present in the bitstream, lines without bold often indicate a control data stream or variable setting.

[88] As shown in FIG. 6A, a tile group header (601), as an example of a header syntax structure applicable to a (possibly rectangular) part of an image, may conventionally contain a dec_pic_size_idx (602) (in bold) variable length syntax element encoded in Exponential Golomb code. The presence of this syntax element in the tile group header may be due to the use of adaptive resolution (603) - here the flag value is not in bold, which means that the flag is present in the bitstream where it occurs in the syntax diagram. Whether adaptive resolution is being used for a given image or part of it can be signaled in any high-level syntactic structure inside or outside the bitstream. In the example shown, this is signaled in the sequence parameter set, as described below.

[89] FIG. 6B also shows a fragment of the set (610) of sequence parameters. The first syntax element shown is adaptive_pic_resolution_change_flag (611). If true, this flag may indicate the use of adaptive resolution, which in turn may require certain control information. In the example, such control information is conditionally present based on the value of the flag based on the if() construct in the parameter set (612) and the tile group header (601).

[90] When using adaptive resolution, this example encodes the output resolution in units of samples (613). The number 613 refers to both output_pic_width_in_luma_samples and output_pic_height_in_luma_samples, which together can set the resolution of the output image. Elsewhere in the video coding technology or standard, some restrictions may be defined for any of these values. For example, setting the level may limit the number of total output samples that can be the product of the value of these two syntax elements. In addition, certain video coding technologies or standards or external technologies or standards, such as systems standards, for example, may restrict the numbering range (for example, one or both dimensions must be a multiple of a power of 2) or aspect ratio (for example, the ratio width and height 4:3 or 16:9). Such restrictions may be introduced to facilitate hardware implementations or for other reasons and are well known in the art.

[91] In some applications, it may be desirable for the encoder to instruct the decoder to use a specific reference picture size instead of implicitly accepting that size as the output picture size. In this example, the reference_pic_size_present_flag syntax element (614) controls the conditional presence of the reference picture dimensions (615) (again, the figure refers to both width and height).

[92] Finally, a table of possible image width and height values during decoding is shown. Such a table may be expressed, for example, by specifying a table (num_dec_pic_size_in_luma_samples_minus1) (616). Here "minusl" may refer to the interpretation of the meaning of this syntax element. For example, if the encoded value is zero, then there is one table entry. If the value is five, then there are six records in the table. For each "row" in the table, the width and height of the decoded image are then included in the syntax (617).

[93] The rendered table entries (617) can be indexed using the dec_pic_size_idx (602) syntax element in the tile group header, which allows for different decoded sizes—essentially scaling factors—for each tile group.

[94] In prior art VVC implementations, a problem may arise in that circular motion compensation may not work correctly when the width of the reference image is different from the width of the current image. In embodiments of the invention, cyclic motion compensation may be disabled in the high-level syntax when the current picture level is a dependent level, or RPR resampling for the current level is enabled. In embodiments of the invention, looping may be disabled during the motion compensation interpolation process when the width of the reference image differs from the width of the current image.

[95] Cyclic motion compensation can be a useful feature for encoding, for example, a 360-degree image projected in equirectangular projection (ERP) format. It can reduce some of the visual artifacts at the "sewing" line, and also improve coding efficiency. In the current draft VVC specification JVET-P2001 (new revision JVET-Q0041), the sps_ref_wraparound_offset_minusl parameter in SPS specifies the offset used to calculate the horizontal position of the wraparound.

[96] There may be a problem that the wraparound offset value is determined depending on the width of the image. If the image width of the reference image is different from the width of the current image, the wraparound offset value must be changed in proportion to the scaling factor between the current image and the reference image. In practice, however, this can greatly increase the implementation and computational complexity for adjusting the offset value according to the image width of each reference image over the benefit of cyclic motion compensation. Inter-layer prediction with different picture sizes and reference picture resampling (RPR) can lead to very different combinations of different picture resolutions across levels and across temporal pictures.

[97] Embodiments of the invention can solve this problem. For example, in embodiments of the invention, circular motion compensation can be disabled by setting the sps_ref_wraparound_enabled_flag flag to 0 when the current picture layer is layer dependent or RPR resampling is enabled for the current layer. Thus, cyclic motion compensation can only be used when the current level is level independent and RPR is disabled. Under this condition, the size of the reference image must be equal to the size of the current image. Furthermore, in embodiments of the invention, the cyclic motion compensation process may be disabled during the interpolation process for motion compensation when the width of the reference image is different from the width of the current image.

[98] Embodiments of the invention can be used individually or combined in any order. In addition, each of the encoder and decoder methods (or embodiments) may be implemented by a processing circuit (eg, one or more processors or one or more integrated circuits). In one example, one or more processors execute a program that is stored on a computer-readable medium.

[99] FIG. 7 illustrates an example syntax table according to embodiments of the invention. In embodiments of the invention, the flag sps_ref_wraparound_enabled_flag (701) equal to 1 may indicate that horizontal cyclic motion compensation is applied in inter prediction. The sps_ref_wraparound_enabled_flag (701) flag of 0 may indicate that horizontal cyclic motion compensation is not applied. When the value of (CtbSizeY / MinCbSizeY+1) is less than or equal to (pic_width_in_luma_samples / MinCbSize Y-1), where pic_width_in_luma_samples is the value of pic_width_in_luma_samples in any PPS that relates to SPS, the value of sps_ref_wraparound_enabled_flag (701) may be 0. Bitstream conformance requirement may be that when the value of vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is 0, the value of sps_ref_wraparound_enabled_flag (701) should be 0. If it is absent, it may be inferred that the value of sps_ref_wraparound_enabled_flag (701) is 0.

[100] In embodiments of the invention, the value of refPicWidthInLumaSamples may be the value of pic_width_in_luma_samples of the current reference picture of the current picture. In embodiments of the invention, if the value of refPicWidthInLumaSamples is equal to the value of pic_width_in_luma_samples of the current image, the refWraparoundEnabledFlag flag may be set to sps_ref_wraparound_enabled_flag. Otherwise, the refWraparoundEnabledFlag flag can be set to 0.

[101] The location of brightness in units of full samples (xIniti, yInti) can be obtained as follows for i=0…1:

[102] If the value of subpic_treated_as_pic_flag[SubPicIdx] is 1, the following may apply:

[103] Otherwise (subpic_treated_as_pic_flag[SubPicIdx] is 0), the following may apply:

[104] The location of the brightness in units of full samples (xInt, yInt) can be obtained as follows:

[105] If the value of subpic_treated_as_pic_flag[SubPicIdx] is 1, the following applies:

[106] Otherwise, the following may apply:

[107] The predicted luminance sample value predSampleLXL can be obtained as follows: predSampleLXL=refPicLXL[xInit][yInt] <<shift3.

[108] Chromaticity positions in units of full samples (xIniti, yInti) can be obtained as follows for i=0…3:

[109] If the value of subpic_treated_as_pic_flag[SubPicIdx] is 1, the following may apply:

[110] Otherwise (subpic_treated_as_pic_flag[SubPicIdx] is 0), the following may apply:

[111] The arrangement of chromaticity in units of full samples (xIniti, yInti) can be further changed as follows for i=0…3:

[112] FIG. 8A-8C are flowcharts of examples of methods 800A, 800B, and 800C for generating an encoded video bitstream according to embodiments of the invention. In embodiments, any of the methods 800A, 800B, and 800C, or any parts of the methods 800A, 800B, and 800C, may be combined in any combination or permutation and in any order desired. In some implementations, one or more of the steps in the methods of FIG. 8A-8C may be performed by decoder 210. In some implementations, one or more of the steps of the methods of FIG. 8A-8C may be performed by another device or group of devices separate from or including decoder 210, such as encoder 203.

[113] As shown in FIG. 8A, method 800A may include making a first determination as to whether the current layer of the current picture is a layer independent (block 811).

[114] As shown in FIG. 8A, method 800A may include making a second determination as to whether reference picture resampling is enabled for the current layer (block 812).

[115] As shown in FIG. 8A, method 800A may include, based on the first determination and the second determination, turning off circular compensation for the current picture (block 813).

[116] As shown in FIG. 8A, method 800A may include encoding the current picture without circular compensation (block 814).

[117] In an embodiment, the first determination may be made based on the first flag signaled in the first syntax structure, and the second determination may be made based on the second flag signaled in the second syntax structure below the first syntax structure.

[118] In an embodiment of the invention, a first flag may be signaled in a video parameter set, and a second flag may be signaled in a sequence parameter set.

[119] In an embodiment of the invention, cyclic compensation may be disabled based on the absence of a second flag in the sequence parameter set.

[120] As shown in FIG. 8B, method 800B may include determining if the current layer of the current picture is a layer independent (block 821).

[121] As shown in FIG. 8B, if it is determined that the current layer is not an independent layer ("No" at 821), method 800B may proceed to 822 where cyclic motion compensation may be disabled.

[122] As shown in FIG. 8B, if the current layer is determined to be an independent layer ("Yes" at 821), method 800B may proceed to 823.

[123] As further shown in FIG. 8B, method 800B may include determining if reference picture resampling is enabled (block 823).

[124] As shown in FIG. 8B, if it is determined that reference picture resampling is enabled ("Yes" in step 823), method 800B may proceed to step 822 where cyclic motion compensation may be disabled.

[125] As shown in FIG. 8B, if it is determined that reference picture resampling is not enabled ("No" at 823), method 800B may proceed to 824 where circular motion compensation may be enabled.

[126] As shown in FIG. 8C, method 800C may include determining that the current layer of the current picture is a layer independent (block 831).

[127] As shown in FIG. 8C, method 800C may include determining that reference picture resampling is enabled (block 832).

[128] As shown in FIG. 8C, method 800C may include determining if the width of the current image is different from the width of the current reference image (block 833).

[129] As shown in FIG. 8C, if it is determined that the width of the current picture is different from the width of the current reference picture ("Yes" in step 833), method 800C may proceed to step 834 where circular motion compensation may be disabled.

[130] As shown in FIG. 8C, if it is determined that the width of the current picture is equal to the width of the current reference picture ("No" at step 821), method 800C may proceed to step 835, where circular motion compensation may be turned on.

[131] In an embodiment of the invention, step 833 may be performed during the interpolation process for motion compensation.

[132] Although FIG. 8A-8C show examples of steps in methods 800A, 800B, and 800C, in some embodiments, methods 800 may include additional steps, fewer steps, other steps, or steps arranged differently than shown in FIG. 8A-8C. Additionally or alternatively, two or more steps of methods 800A, 800B, and 800C may be performed in parallel.

[133] In addition, the proposed methods can be implemented using processing circuits (eg, one or more processors or one or more integrated circuits). In one example, one or more processors execute a program that is stored on a computer-readable medium to perform one or more of the proposed methods.

[134] The above methods may be implemented as computer software using computer-readable instructions and physically stored on one or more computer-readable media. For example, in FIG. 9 shows a computer system 900 suitable for practicing some embodiments of the invention.

[135] Computer software may be coded using any suitable machine code or computer language, which may be assembled, compiled, linked, or similarly processed to produce code containing instructions that can be executed directly or through interpretation, execution of microcode, etc. etc., computer central processing units (CPU, central processing units), graphic processors (GPU, Graphics Processing Units), etc.

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

[137] The components of the computer system 900 shown in FIG. 9 are illustrative in nature and are not intended to impose any limitation on the scope of application or functionality of computer software implementing embodiments of the present invention. The component configuration should also not be interpreted as having any dependency or requirement in connection with any component or combination of components shown in the exemplary computer system 900.

[138] Computer system 900 may include some human-machine interface input devices. Such an input device may be responsible for input by one or more users through, for example, tactile input (e.g., keystrokes, waving, glove movements), audio input (e.g., voice, claps), visual input (e.g., gestures), olfactory input (not shown). Interface devices may also be used to capture certain media not necessarily directly related to conscious human input, such as sound (e.g. speech, music, external sound), images (e.g. scanned images, photographic images received from a still camera), video (eg 2D video, 3D video including stereoscopic video).

[139] The input human-machine interface of the device may include one or more of the following (shown one at a time): keyboard 901, mouse 902, touch pad 903, touch screen 910 and associated graphics adapter 950, data glove, joystick 905, microphone 906, scanner 907 and camera 908.

[140] Computer system 900 may also include some human-machine interface output devices. Such output devices may stimulate the senses of one or more users through, for example, tactile output, sound, light, and smell/taste. Such output devices may include tactile output devices (for example, haptic feedback via the 910 touch screen, information glove, or 905 joystick, as well as haptic feedback devices that do not serve as input devices), audio output devices (for example: speakers 909, headphones ( not shown)), visual output devices (e.g., 910 screens, including cathode ray tube (CRT) screens), liquid-crystal display (LCD), plasma screens, organic light-emitting diode screens ( OLED, organic light-emitting diode), each with or without touch screen input capabilities, each with or without tactile feedback capabilities, some of them are capable of two-dimensional visual output or more than three-dimensional output through, for example, stereographic output, glasses virtual reality (not shown), holographic displays, smoke tanks (not shown) and printers (not shown). cauldrons).

[141] The computer system 900 may also include human accessible storage devices and associated media, such as optical media including CD/DVD ROM/RW 920 with CD/DVD media 921 and the like, flash memory cards 922, removable hard drive or solid state drive 923, traditional magnetic media such as tape and magnetic disk (not shown), dedicated ROM/ASIC/PLD based devices such as security dongles (not shown), etc.

[142] Those skilled in the art should also understand that the term "computer-readable media" as used in connection with the present invention does not encompass transmission media, carrier waves, or other time signals.

[143] Computer system 900 may also include interface(s) to one or more communication networks (955). Networks can be, for example, wireless, wired, optical. Networks can also be local, global, urban, transport and industrial, real-time, latency, etc. Examples of networks include local area networks such as Ethernet, wireless LANs, cellular networks, including global systems for mobile communications (GSM), 3G, 4G, and 5G generation networks, Long Term Evolution (LTE, Long Term Evolution) -Term Evolution), etc., global digital networks of wired or wireless television, including cable television, satellite television and terrestrial television broadcasting, transport and industrial networks, including CANBus, etc. Some networks typically require external network interface adapters (954) that are connected to some general purpose data ports or peripheral buses (949) (for example, computer system 900's USB universal serial bus ports); others are typically built into the core of computer system 900 by connecting to a system bus as described below (eg, an Ethernet interface to a PC computer system or a cellular network interface to a smartphone computer system). For example, network 955 may be connected to peripheral bus 949 using network interface 954. Using any of these networks, computer system 900 may communicate with other entities. Such communication may be unidirectional with receive-only capability (eg broadcast), unidirectional with transmit-only capability (eg CANbus to some CANbus devices), or bidirectional, eg to other computer systems using a local area network or a wide area digital network. Several protocols and protocol stacks may be used on each of these networks and the network interfaces described above (954).

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

[145] The core 940 may include one or more central processing units (CPUs) 941, graphics processing units (GPUs) 942, dedicated field programmable gate arrays (FPGAs) 943, hardware accelerators 944 for some tasks, etc. These devices, together with Read Only Memory (ROM) 945, Random Access Memory (RAM) 946, high-capacity internal storage such as user-inaccessible internal hard drives, solid-state drives (SSDs, solid-state drives), and the like. 947 may be connected via system bus 948. In some computer systems, system bus 948 may be available in the form of one or more physical connectors to allow for expansions with additional CPUs, GPUs, and the like. Peripherals can connect either directly to the core system bus 948 or via a peripheral bus 949. Peripheral bus architectures include a peripheral component interconnect (PCI) bus, USB, and the like.

[146] CPU 941, GPU 942, FPGA 943, and accelerators 944 may execute some instructions that together may constitute the aforementioned computer code. This computer code may be stored in ROM 945 or RAM 946. Temporary data may also be stored in RAM 946, while permanent data may be stored in, for example, internal high capacity data storage 947. Fast storage and retrieval from any storage device can be achieved through the use of a cache memory that can be tightly coupled to one or more CPU 941, GPU 942, mass storage 947, ROM 945, RAM 946, and the like.

[147] Computer-readable media may store computer code for performing various computer-executable operations. The media and computer code may be specially created for the purposes of the present invention or may be well known and available to those skilled in the art of computer software.

[148] By way of example, and not limitation of the invention, a computer system having architecture 900, and in particular core 940, can provide functionality by being executed by processor(s) (including(and) including CPU, GPU, FPGA, accelerators etc.) software embodied in one or more tangible computer-readable media. Such computer-readable media may be media associated with the user-accessible mass storage described above as well as some persistent storage of the kernel 940, such as internal mass storage 947 or ROM 945. Software implementing various embodiments of the present invention may stored in such devices and executed by the core 940. The computer-readable medium may include one or more storage devices or chips, as appropriate. The software may direct the core 940, and in particular its processors (including CPUs, GPUs, FPGAs, and the like), to perform specific methods or specific portions of the specific methods described herein, including setting data structures stored in RAM 946 and modifying such data structures according to the methods specified by the software. Additionally or alternatively, the computer system may provide functionality through logic hardwired or otherwise embodied in circuitry (e.g., accelerator 944) that may operate in place of, or in conjunction with software, to perform specific methods or specific portions of the specific methods described herein. A reference to software may cover logic, and vice versa when appropriate. Reference to computer-readable media may cover a circuit (eg, an integrated circuit (IC, integrated circuit)), where software is stored for execution, a circuit embodying logic for execution, or both circuits, when appropriate. The present invention encompasses any suitable combination of hardware and software.

[149] While some embodiments of the invention have been described herein, variations, permutations, and various equivalent substitutions are possible within the scope of the invention. Thus, those skilled in the art can provide numerous systems and methods that, although not explicitly shown or described herein, embody the principles of the invention and thus fall within its spirit and scope.

Claims (43)

1. A method for generating a bit stream of encoded video data using at least one processor, including: making a first determination as to whether the current layer of the current image is an independent layer; making a second determination as to whether resampling of the reference picture is enabled for the current layer; based on the first definition and the second definition, disable cyclic compensation for the current level and current level coding without cyclic compensation, wherein cyclic compensation is disabled based on the first determination indicating that the current layer is not an independent layer and/or the second determination indicating that reference picture resampling is enabled for the current layer. 2. The method of claim 1, wherein the first determination is made based on the first flag signaled in the first syntax structure, and the second determination is made based on the second flag signaled in the second syntax structure below the first syntax structure. 3. The method of claim 1, wherein the first flag is signaled in the video parameter set, and the second flag is signaled in the sequence parameter set. 4. The method of claim 3, wherein cyclic compensation is disabled based on the absence of the second flag in the sequence parameter set. 5. The method according to p. 1, also including: based on a first determination indicating that the current layer is not an independent layer and a second determination indicating that reference picture resampling is enabled for the current layer, making a third determination as to whether the width of the current picture is different from the width of the current reference Images, wherein the circular compensation is turned off based on the third determination indicating that the width of the current image is different from the width of the current reference image. 6. The method of claim 5, wherein the third determination is performed during the motion compensation interpolation process. 7. A device for generating a bit stream of encoded video data, comprising: at least one memory configured to store program code, and at least one processor configured to read the program code and operate in accordance with the instructions of the program code, wherein the program code includes: a first determination code configured to cause the at least one processor to perform a first determination as to whether the current layer of the current image is an independent layer; a second determination code configured to cause the at least one processor to perform a second determination as to whether reference picture resampling is enabled for the current layer; a disable code configured to cause at least one processor, based on the first determination and the second determination, to disable cyclic compensation for the current level, and an encoding code configured to allow at least one processor to encode the current level without cyclic compensation, wherein circular compensation is disabled based on the first determination indicating that the current layer is not an independent layer and/or the second determination indicating that reference picture resampling is enabled for the current layer. 8. The apparatus of claim 7, wherein the first determination is made based on the first flag signaled in the first syntax structure, and the second determination is made based on the second flag signaled in the second syntax structure below the first syntax structure. 9. The apparatus of claim 7, wherein the first flag is signaled in the video parameter set, and the second flag is signaled in the sequence parameter set. 10. The apparatus of claim 9, wherein cyclic compensation is disabled based on the absence of the second flag in the sequence parameter set. 11. The apparatus of claim 7, wherein the program code also includes a third determination code configured to provide at least one processor based on a first determination indicating that the current layer is not an independent layer and a second determination indicating that reference picture resampling is enabled for the current layer, making a third determination as to whether the width of the current picture is different from the width of the current reference picture, wherein the circular compensation is turned off based on the third determination indicating that the width of the current image is different from the width of the current reference image. 12. The apparatus of claim 11, wherein the third determination is made during the interpolation process for motion compensation. 13. A computer-readable medium that stores instructions, including: one or more instructions that, when executed by one or more processors of the device for generating an encoded video data bitstream, are configured to provide one or more processors with: making a first determination as to whether the current layer of the current image is an independent layer; making a second determination as to whether resampling of the reference picture is enabled for the current layer; based on the first definition and the second definition, disable cyclic compensation for the current level, and encoding the current level without cyclic compensation, wherein circular compensation is disabled based on the first determination indicating that the current layer is not an independent layer and/or the second determination indicating that reference picture resampling is enabled for the current layer. 14. The computer-readable medium of claim 13, wherein the first flag is signaled in the video parameter set, and the second flag is signaled in the sequence parameter set. 15. The computer-readable medium of claim 14, wherein cyclic compensation is disabled based on the absence of the second flag in the sequence parameter set. 16. The computer-readable medium of claim 13, wherein the one or more instructions are also executable, by one or more processors, based on a first definition indicating that the current layer is not an independent layer and a second definition indicating that reference picture resampling is enabled for the current level, a third determination as to whether the width of the current picture is different from the width of the current reference picture, wherein the circular compensation is turned off based on the third determination indicating that the width of the current image is different from the width of the current reference image. 17. The computer-readable medium of claim 16, wherein the third determination is made during the motion compensation interpolation process.

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