Signaling of inter layer prediction in video bitstream

Abstract

To provide a method and an apparatus for signaling of inter layer prediction in a video bitstream.SOLUTION: A method according to the present invention causes one or more processors to perform: parsing at least one video parameter set (VPS) including at least one syntax element indicating whether at least one layer in a scalable bitstream is one of a dependent layer of the scalable bitstream and an independent layer of the scalable bitstream; determining the number of dependent layers including the dependent layer, of the scalable bitstream, on the basis of multiple flags included in the VPS; decoding a picture in the dependent layer by parsing and interpreting an inter-layer reference picture list; and decoding a picture in an independent layer without parsing and interpreting the inter-layer reference picture list.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 903,652, filed September 20, 2019, and U.S. Patent Application No. 17 / 019,713, filed September 14, 2020, which are incorporated herein in their entireties.

[0002] The disclosed subject matter relates to video coding and decoding, and more particularly to signaling inter-layer prediction in a video bitstream. [Background technology]

[0003] Coding and decoding of video using inter-picture prediction with motion compensation has been known for decades. Uncompressed digital video may consist of a series of pictures, each having spatial dimensions of, for example, 1920 x 1080 luma samples and associated chroma samples. The series of pictures may have a fixed or variable picture rate (informally known as frame rate), for example, 60 pictures per second or 60 Hz. Uncompressed video has significant bitrate requirements. For example, 1080p60 4:2:0 video (1920 x 1080 luma sample resolution at a 60 Hz frame rate) at 8 bits per sample requires a bandwidth approaching 1.5 Gbit / s. One hour of such video requires more than 600 Gbytes of storage space.

[0004] One goal of video coding and decoding can be to reduce redundancy in an input video signal through compression. Compression can help reduce the aforementioned bandwidth or storage space requirements, sometimes by more than two orders of magnitude. Both lossless and lossy compression, as well as combinations thereof, can be employed. Lossless compression refers to techniques that can restore an exact copy of the original signal from a compressed version. With lossy compression, the restored signal may not be identical to the original, but the distortion between the original and restored signal is small enough to make the restored signal useful for the intended application. For video, lossy compression is widely adopted. The amount of acceptable distortion depends on the application; for example, users of certain consumer streaming applications can tolerate higher distortion than users of television contribution applications. Achievable compression ratios can indicate that the greater the acceptable / tolerable distortion, the higher the compression ratio.

[0005] Video encoders and decoders may utilize techniques from several broad categories, including, for example, motion compensation, transform, quantization, and entropy coding, some of which are introduced below.

[0006] Historically, video encoders and decoders have tended to operate with a given picture size that was defined and remained constant for a coded video sequence (CVS), group of pictures (GOP), or similar multi-picture time frame. For example, in MPEG-2, system designs have been known to change horizontal resolution (and, therefore, picture size) depending on factors such as scene activity, but only in I-pictures and therefore typically for GOPs. Resampling of reference pictures to use different resolutions within a CVS is known, for example, from ITU-T Rec. H.263 Annex P. However, here the picture size does not change; only the reference picture is resampled, potentially resulting in only a portion of the picture canvas being used (in the case of downsampling) or only a portion of the scene being captured (in the case of upsampling). Furthermore, H.263 Annex Q allows for resampling of individual macroblocks upward or downward by a factor of two (in each dimension). Again, the picture size remains the same. The size of a macroblock is fixed in H.263 and does not need to be signaled.

[0007] Changing the picture size of predicted pictures has become more mainstream in modern video coding. For example, VP9 allows for reference picture resampling (RPR) and changing the resolution of the entire picture. Similarly, some proposals made for 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 that document, various candidate resolutions are proposed that are coded in the sequence parameter set and referenced by per-picture syntax elements in the picture parameter set. Summary of the Invention [Means for solving the problem]

[0008] To address one or more different technical problems, this disclosure describes a new syntax and its use designed for signaling scaling in video bitstreams, thus enabling improved coding (decoding) efficiency.

[0009] According to embodiments herein, further support for scalability may be achieved by modifying the high-level syntax (HLS) using reference picture resampling (RPR) or adaptive resolution scaling (ARC). In technical terms, inter-layer prediction is employed in scalable systems to improve the coding efficiency of enhancement layers. In addition to the spatial and temporal motion compensation prediction available in single-layer codecs, inter-layer prediction predicts the current enhancement layer using resampled video data of a reconstructed reference picture from a reference layer. Then, by modifying the existing interpolation process for motion compensation, the resampling process for inter-layer prediction is performed at the block level, which means that no additional resampling process is required to support scalability. This disclosure discloses high-level syntax elements that support spatial / quality scalability using RPR.

[0010] The present invention provides a method and apparatus that includes a memory configured to store computer program code and one or more processors configured to access the computer program code and operate as instructed by the computer program code, the computer program code including: parsing code configured to cause at least one processor to parse at least one video parameter set (VPS) including at least one syntax element indicating whether at least one layer in a scalable bitstream is one of a dependent layer of the scalable bitstream and an independent layer of the scalable bitstream; decision code configured to cause the at least one processor to determine, based on a plurality of flags included in the VPS, the number of dependent layers of the scalable bitstream, including the dependent layer; first decoding code configured to cause the at least one processor to decode pictures in the dependent layers by parsing and interpreting an inter-layer reference picture (ILRP) list; and second decoding code configured to cause the at least one processor to decode pictures in the independent layers without parsing and interpreting the ILRP list.

[0011] According to an embodiment, the second decoding code is further configured to cause the at least one processor to decode pictures in the independent layer by parsing and interpreting a reference picture list that does not include any decoded pictures of other layers.

[0012] According to an embodiment, the inter-layer reference picture list contains decoded pictures of other layers.

[0013] According to an embodiment, the parsing code is further configured to cause the at least one processor to parse the at least one VPS by determining whether other syntax elements indicate a maximum number of layers.

[0014] According to an embodiment, the parsing code is further configured to cause the at least one processor to parse the at least one VPS by determining whether the VPS includes a flag indicating whether another layer in the scalable bitstream is a reference layer for the at least one layer.

[0015] According to an embodiment, the parsing code is further configured to cause the at least one processor to parse the at least one VPS by specifying an index of the other layer and an index of the at least one layer to determine whether a flag indicates the other layer as a reference layer for the at least one layer, and the parsing code is further configured to cause the at least one processor to parse the at least one VPS by determining whether the VPS includes other syntax elements indicating a value less than the determined number of dependent layers.

[0016] According to an embodiment, the parsing code is further configured to cause the at least one processor to parse the at least one VPS by specifying an index of the other layer and an index of the at least one layer to determine whether a flag indicates the other layer as not being a reference layer for the at least one layer, and the parsing code is further configured to cause the at least one processor to parse the at least one VPS by determining whether the VPS includes other syntax elements indicating a value less than the determined number of dependent layers.

[0017] According to an embodiment, the parsing code is further configured to cause the at least one processor to parse the at least one VPS by determining whether the VPS includes a flag indicating whether a plurality of layers including the at least one layer should be decoded by interpreting an I LRP list.

[0018] According to an embodiment, the parsing code is further configured to cause the at least one processor to parse the at least one VPS by determining whether the VPS includes a flag indicating whether a plurality of layers including the at least one layer should be decoded without interpreting an ILRP list.

[0019] According to an embodiment, the parsing code is further configured to cause the at least one processor to parse the at least one VPS, further comprising determining whether the VPS includes a flag indicating whether a plurality of layers including the at least one layer should be decoded by interpreting the ILRP list.

[0020] Further features, nature and various advantages of the disclosed subject matter will be more apparent from the following detailed description and accompanying drawings. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic diagram of a simplified block diagram of a communication system, according to one embodiment. [Figure 2] FIG. 1 is a schematic diagram of a simplified block diagram of a communication system, according to one embodiment. [Figure 3] FIG. 2 is a schematic diagram of a simplified block diagram of a decoder according to one embodiment. [Figure 4] FIG. 2 is a schematic diagram of a simplified block diagram of an encoder according to one embodiment. [Figure 5A] 1 is a schematic diagram of options for signaling ARC / RPR parameters according to the related art; [Figure 5B] 1 is a schematic diagram of options for signaling ARC / RPR parameters according to the related art; [Figure 5C] 1 is a schematic diagram of options for signaling ARC / RPR parameters according to the related art;

[0022] [Figure 5D] 1 is a schematic diagram of options for signaling ARC / RPR parameters according to the related art; [Figure 5E] 1 is a schematic diagram of options for signaling ARC / RPR parameters according to the related art; [Figure 6] FIG. 1 is a schematic diagram of signaling picture resolution according to an embodiment; [Figure 7] FIG. 1 is a schematic diagram of signaling picture size and adaptation window within an SPS according to an embodiment; [Figure 8] FIG. 1 is a schematic diagram of signaling the presence of inter-layer prediction within an SPS according to an embodiment. [Figure 9] FIG. 1 is a schematic diagram of signaling inter-layer prediction indexes in a slice header according to an embodiment; [Figure 10] FIG. 1 is a schematic diagram of a computer system, according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] The proposed functions described below may be used separately or combined in any order. Furthermore, the embodiments may be implemented by processing circuitry (e.g., one or more processors or one or more integrated circuits). In one example, the one or more processors execute a program stored on a non-transitory computer-readable medium.

[0024] 1 shows a simplified block diagram of a communication system (100) according to one embodiment of the present disclosure. The communication system (100) may include at least two terminals (110 and 120) interconnected via a network (150). For unidirectional data transmission, a first terminal (110) can encode video data at a local location for transmission to another terminal (120) via the network (150). The second terminal (120) can receive the other terminal's coded video data from the network (150), decode the coded data, and display the recovered video data. Unidirectional data transmission may be common in media serving applications, for example.

[0025] 1 illustrates a second pair of terminals (130, 140) provided to support two-way transmission of coded video, such as might occur during a video conference. For the two-way transmission of data, each terminal (130, 140) can code video data captured at a local location for transmission to the other terminal over a network (150). Each terminal (130, 140) can also receive coded video data transmitted by the other terminal, decode the coded data, and display the recovered video data on a local display device.

[0026] In the example of FIG. 1 , the terminals (110, 120, 130, 140) may be depicted as servers, personal computers, and smartphones, although the principles of the present disclosure need not be so limited. Embodiments of the present disclosure find application with laptop computers, tablet computers, media players, and / or dedicated videoconferencing equipment. The network (150) represents any number of networks that convey coded video data between the terminals (110, 120, 130, 140), including, for example, wired and / or wireless communication networks. The communication network (150) may exchange data over circuit-switched and / or packet-switched channels. Exemplary networks include telecommunications networks, local area networks, wide area networks, and / or the Internet. For purposes of this description, the architecture and topology of the network (150) may not be important to the operation of the present disclosure, unless otherwise described herein below.

[0027] 2 shows an arrangement of a video encoder and a video decoder in a streaming environment as an example for application of the disclosed subject matter. The disclosed subject matter may be equally applicable to other video-enabled applications including, for example, video conferencing, digital television, storage of compressed video on digital media including CDs, DVDs, memory sticks, etc.

[0028] The streaming system may include a video source (201), e.g., a capture subsystem (213), which may include a digital camera, that creates an uncompressed video sample stream (202). The sample stream (202), depicted as a bold line to emphasize its high data content compared to the encoded video bitstream, can be processed by an encoder (203) coupled to the camera (201). The encoder (203) may include hardware, software, or a combination thereof to enable or implement aspects of the disclosed subject matter, as described in more detail below. The encoded video bitstream (204), depicted as a thin line to emphasize its low data content compared to the sample stream, can be stored on a streaming server (205) for future use. One or more streaming clients (206, 208) can access the streaming server (205) to retrieve copies (207, 209) of the encoded video bitstream (204). The client (206) may include a video decoder (210) that decodes an input copy of the encoded video bitstream (207) and creates an output video sample stream (211) that can be rendered to a display (212) or other rendering device (not shown). In some streaming systems, the video bitstreams (204, 207, 209) may be encoded according to a particular video coding / compression standard. Examples of such standards include ITU-T Recommendation H.265. A video coding standard informally known as Versatile Video Coding, or VVC, is under development. The disclosed subject matter may be used in connection with VVC.

[0029] FIG. 3 may be a functional block diagram of a video decoder (210) according to one embodiment of the disclosure.

[0030] The receiver (310) can receive one or more codec video sequences decoded by the decoder (210), one coded video sequence at a time, in the same or another embodiment, with the decoding of each coded video sequence being independent of the other coded video sequences. The coded video sequences can be received from a channel (312), which can be a hardware / software link to a storage device that stores the coded video data. The receiver (310) can receive the coded video data along with other data, such as coded audio data and / or auxiliary data streams, that can be forwarded to their respective using entities (not depicted). The receiver (310) can separate the coded video sequences from other data. To combat network jitter, a buffer memory (315) can be coupled between the receiver (310) and the entropy decoder / parser (320) (hereinafter, "parser"). When the receiver (310) is receiving data from a store-and-forward device of sufficient bandwidth and controllability, or from an isosynchronous network, the buffer (315) may not be needed or may be small. For use with best-effort packet networks such as the Internet, the buffer (315) may be needed, may be relatively large, and may advantageously be of adaptive size.

[0031] The video decoder (210) may include a parser (320) to recover symbols (321) from the entropy-coded video sequence. These symbol categories include information used to manage the operation of the decoder (210) and, potentially, information for controlling a rendering device, such as a display (212), that is not an integral part of the decoder but may be coupled to the decoder as shown in FIG. 2. The control information for the rendering device may be in the form of a supplemental enhancement information (SEI) message or a video usability information (VUI) parameter set fragment (not depicted). The parser (320) can parse / entropy decode the received coded video sequence. The coding of the coded video sequence may follow a video coding technique or standard and may follow principles well known to those skilled in the art, including variable length coding, Huffman coding, arithmetic coding, with or without context sensitivity, etc. The parser (320) can extract a set of subgroup parameters for at least one of the subgroups of pixels in the video decoder from the coded video sequence based on at least one parameter corresponding to the group. The subgroups may include groups of pictures (GOPs), pictures, tiles, slices, macroblocks, coding units (CUs), blocks, transform units (TUs), prediction units (PUs), etc. The entropy decoder / parser may also extract information from the coded video sequence, such as transform coefficients, quantizer parameter values, motion vectors, etc.

[0032] The parser (320) can perform entropy decoding / parsing operations on the video sequence received from the buffer (315) to create symbols (321).

[0033] The reconstruction of the symbols (321) can involve several different units, depending on the type of coded video picture or portion thereof (e.g., inter-picture and intra-picture, inter-block and intra-block, etc.), as well as other factors. Which units are involved and how can be controlled by subgroup control information parsed from the coded video sequence by the parser (320). The flow of such subgroup control information between the parser (320) and the following units is not depicted for clarity.

[0034] In addition to the functional blocks already mentioned, decoder 210 can be conceptually subdivided into several functional units, as described below. In an actual implementation operating under commercial constraints, many of these units will interact closely with each other and may be at least partially integrated with each other. However, for purposes of describing the disclosed subject matter, the following conceptual subdivision into functional units is appropriate.

[0035] The first unit is the scalar / inverse transform unit (351). The scalar / inverse transform unit (351) receives quantized transform coefficients as well as control information from the parser (320) as symbols (321), including which transform to use, block size, quantization coefficients, quantization scaling matrices, etc. It can output blocks containing sample values that can be input to the aggregator (355).

[0036] In some cases, the output samples of the scaler / inverse transform (351) may relate to intra-coded blocks, i.e., blocks that do not use prediction information from a previously reconstructed picture but can use prediction information from a previously reconstructed portion of the current picture. Such prediction information may be provided by an intra-picture prediction unit (352). In some cases, the intra-picture prediction unit (352) uses surrounding already reconstructed information fetched from the current (partially reconstructed) picture (356) to generate blocks of the same size and shape as the block being reconstructed. The aggregator (355) optionally adds, on a sample-by-sample basis, the prediction information generated by the intra-prediction unit (352) to the output sample information provided by the scaler / inverse transform unit (351).

[0037] In other cases, the output samples of the scalar / inverse transform unit (351) may relate to an inter-coded, potentially motion-compensated block. In such cases, the motion-compensated prediction unit (353) may access a reference picture memory (357) to fetch samples used for prediction. After motion-compensating the fetched samples according to the symbols (321) associated with the block, these samples may be added by an aggregator (355) to the output of the scalar / inverse transform unit to generate output sample information (in this case, referred to as residual samples or residual signals). The addresses in the reference picture memory from which the motion-compensated prediction unit fetches prediction samples may be controlled by motion vectors available to the motion-compensated prediction unit, for example, in the form of symbols (321) that may have X, Y, and reference picture components. Motion compensation may also include interpolation of sample values fetched from the reference picture memory when sub-sample accurate motion vectors are used, motion vector prediction mechanisms, etc.

[0038] The output samples of the aggregator (355) can be subjected to various loop filtering techniques in a loop filter unit (356). Video compression techniques can include in-loop filter techniques controlled by parameters contained in the coded video bitstream and made available to the loop filter unit (356) as symbols (321) from the parser (320), but can also respond to previously reconstructed and loop-filtered sample values as well as to meta-information obtained during decoding of previous portions (in decoding order) of a coded picture or coded video sequence.

[0039] The output of the loop filter unit (356) may be a sample stream that can be output to the rendering device (212) as well as stored in the reference picture memory (356) for use in future inter-picture prediction.

[0040] Once a particular coded picture is fully reconstructed, it can be used as a reference picture for future prediction. Once a coded picture is fully reconstructed and the coded picture is identified as a reference picture (e.g., by the parser (320)), the current reference picture (356) can become part of the reference picture buffer (357), and any unused current picture memory can be reallocated before beginning reconstruction of the next coded picture.

[0041] Video decoder 320 can perform decoding operations according to a predetermined video compression technology, which may be documented in a standard such as ITU-T Rec. H.265. A coded video sequence can conform to the syntax specified by the video compression technology or standard being used in the sense that the coded video sequence adheres to the syntax of the video compression technology or standard specified in the video compression technology's document or standard, specifically in a profile document therein. Compliance also requires that the complexity of the coded video sequence be within a range defined by the level of the video compression technology or standard. In some cases, the level limits the maximum picture size, maximum frame rate, maximum reconstructed sample rate (e.g., measured in megasamples per second), maximum reference picture size, etc. The limits set by the level may, in some cases, be further limited by the specification of a hypothetical reference decoder (HRD) and metadata for HRD buffer management signaled within the coded video sequence.

[0042] In one embodiment, the receiver (310) can receive additional (redundant) data along with the encoded video. The additional data may be included as part of the coded video sequence. The additional data may be used by the video decoder (320) to properly decode the data and / or to more accurately recover the original video data. The additional data may be in the form of, for example, temporal, spatial, or SNR enhancement layers, redundant slices, redundant pictures, forward error correction codes, etc.

[0043] FIG. 4 may be a functional block diagram of a video encoder (203) according to one embodiment of the present disclosure.

[0044] The encoder (203) can receive video samples from a video source (201) (not part of the encoder) that can capture video images that are coded by the encoder (203).

[0045] The video source (201) can provide a source video sequence to be coded by the encoder (203) in the form of a digital video sample stream, which can be of any suitable bit depth (e.g., 8-bit, 10-bit, 12-bit, ...), any color space (e.g., BT.601 Y CrCB, RGB, ...), and any suitable sampling structure (e.g., Y CrCb 4:2:0, Y CrCb 4:4:4). In a media serving system, the video source (201) can be a storage device that stores previously prepared video. In a video conferencing system, the video source (203) can be a camera that captures local image information as a video sequence. The video data can be provided as multiple individual pictures that convey motion when viewed in sequence. The pictures themselves can be organized as a spatial array of pixels, each of which can contain one or more samples, depending on the sampling structure, color space, etc., in use. Those skilled in the art can readily understand the relationship between pixels and samples. The following description focuses on samples.

[0046] According to one embodiment, the encoder (203) can code and compress pictures of a source video sequence into a coded video sequence (443) in real time or under any other time constraint required by the application. Enforcing an appropriate coding rate is one function of the controller (450). The controller controls and is operatively coupled to other functional units described below. For clarity, coupling is not depicted. Parameters set by the controller may include rate control-related parameters (picture skip, quantizer, lambda value for rate-distortion optimization techniques, ...), picture size, group of pictures (GOP) layout, maximum motion vector search range, etc. Those skilled in the art can readily identify other functions of the controller (450) as being relevant to a video encoder (203) optimized for a given system design.

[0047] Some video encoders operate in what those skilled in the art readily recognize as a "coding loop." As an overly simplified explanation, the coding loop can consist of an encoding portion of an encoder (430) (hereinafter "source encoder") (responsible for creating symbols based on the input picture to be coded and reference pictures), as well as a (local) decoder (433) embedded in the encoder (203) that reconstructs the symbols to create sample data that a (remote) decoder also creates (since, in the video compression techniques considered in the disclosed subject matter, any compression between the symbols and the coded video bitstream is lossless). The reconstructed sample stream is input to a reference picture memory (434). Because decoding of the symbol stream leads to bit-exact results regardless of the decoder's location (local or remote), the contents of the reference picture buffer are also bit-exact between the local and remote encoders. In other words, the predictive portion of the encoder "sees" the exact same sample values as the decoder "sees" when using prediction during decoding. This basic principle of reference picture synchronism (and the resulting drift when synchronism cannot be maintained, for example, due to channel errors) is well known to those skilled in the art.

[0048] The operation of the "local" decoder (433) may be the same as the operation of the "remote" decoder (210), already described in detail above in conjunction with Figure 3. However, and with brief reference again to Figure 3, because symbols are available and the encoding / decoding of symbols into a coded video sequence by the entropy coder (445) and parser (320) may be lossless, the entropy decoding portion of the decoder (210), including the channel (312), receiver (310), buffer (315), and parser (320), may not be fully implemented in the local decoder (433).

[0049] An observation that can be made at this point is that any decoder technology other than parsing / entropy decoding that is present in a decoder must necessarily be present in substantially identical functional form in the corresponding encoder. For this reason, the disclosed subject matter focuses on the operation of the decoder. A description of the encoder technology can be omitted, as it is the reverse of the decoder technology that has been described generically. Only in certain areas is a more detailed description necessary, which is provided below.

[0050] As part of its operation, the source coder (430) may perform motion-compensated predictive coding, which predictively codes an input frame with reference to one or more previously coded frames from the video sequence designated as “reference frames.” In this manner, the coding engine (432) codes differences between pixel blocks of the input frame and pixel blocks of reference frames that may be selected as prediction references for the input frame.

[0051] The local video decoder (433) can decode coded video data of frames that may be designated as reference frames based on symbols created by the source coder (430). The operation of the coding engine (432) can advantageously be a lossy process. When the coded video data is decoded by a video decoder (not shown in FIG. 4), the reconstructed video sequence may be a replica of the source video sequence, typically with some errors. The local video decoder (433) can replicate the decoding process that may be performed by the video decoder on the reference frames, causing the reconstructed reference frames to be stored in a reference picture cache (434). In this way, the encoder (203) can locally store copies of reconstructed reference frames that have common content as reconstructed reference frames obtained by a far-end video decoder (without transmission errors).

[0052] The predictor (435) can perform a prediction search for the coding engine (432). That is, for a new frame to be coded, the predictor (435) can search the reference picture memory (434) for sample data (as candidate reference pixel blocks) or specific metadata, such as reference picture motion vectors, block shapes, etc., that can serve as appropriate prediction references for the new picture. The predictor (435) can operate on a sample block-by-pixel block basis to find an appropriate prediction reference. In some cases, as determined by the search results obtained by the predictor (435), the input picture can have prediction references drawn from multiple reference pictures stored in the reference picture memory (434).

[0053] The controller (450) can manage the coding operations of the video coder (430), including, for example, setting parameters and subgroup parameters used to encode the video data.

[0054] The outputs of all the aforementioned functional units may undergo entropy coding in an entropy coder (445), which converts the symbols produced by the various functional units into a coded video sequence by losslessly compressing the symbols according to techniques known to those skilled in the art, such as Huffman coding, variable length coding, arithmetic coding, etc.

[0055] The transmitter (440) can buffer the coded video sequence created by the entropy coder (445) and prepare it for transmission over a communication channel (460), which may be a hardware / software link to a storage device that stores the coded video data. The transmitter (440) can merge the coded video data from the video coder (430) with other data to be transmitted, such as coded audio data and / or auxiliary data streams (sources not shown).

[0056] The controller (450) can manage the operation of the video encoder (203). During coding, the controller (450) can assign a particular coded picture type to each coded picture, which may affect the coding technique that can be applied to the respective picture. For example, pictures may often be assigned as one of the following frame types:

[0057] An intra-picture (I-picture) may be a picture that can be coded and decoded without using any other frame in a sequence as a source of prediction. Some video codecs allow various types of intra-pictures, including, for example, independent decoder refresh pictures. Those skilled in the art are aware of these variations of I-pictures, as well as their respective uses and characteristics.

[0058] A predictive picture (P picture) may be a picture that can be coded and decoded using intra- or inter-prediction, which uses at most one motion vector and reference index to predict the sample values of each block.

[0059] A bidirectionally predicted picture (B picture) may be a picture that can be coded and decoded using intra- or inter-prediction, which uses at most two motion vectors and reference indices to predict the sample values of each block. Similarly, a multi-predicted picture may use more than two reference pictures and associated metadata for the reconstruction of a single block.

[0060] A source picture is typically spatially subdivided into multiple sample blocks (e.g., blocks of 4x4, 8x8, 4x8, or 16x16 samples each) and may be coded block by block. Blocks may be predictively coded with reference to other (already coded) blocks, as determined by the coding assignment applied to the block's respective picture. For example, blocks of an I-picture may be nonpredictively coded, or they may be predictively coded with reference to already coded blocks of the same picture (spatial prediction or intra-prediction). Pixel blocks of a P-picture may be nonpredictively coded via spatial prediction or via temporal prediction with reference to one previously coded reference picture. Blocks of a B-picture may be nonpredictively coded via spatial prediction or via temporal prediction with reference to one or two previously coded reference pictures.

[0061] The video encoder (203) may perform coding operations in accordance with a predetermined video coding technique or standard, such as ITU-T Rec. H.265. In doing so, the video coder (203) may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancies in the input video sequence. Thus, the coded video data may conform to a syntax specified by the video coding technique or standard being used.

[0062] In one embodiment, the transmitter (440) can transmit additional data along with the coded video. The video coder (430) may include such data as part of the coded video sequence. The additional data may include temporal / spatial / SNR enhancement layers, other forms of redundant data such as redundant pictures and slices, Supplemental Enhancement Information (SEI) messages, Visual Usability Information (VUI) parameter set fragments, etc.

[0063] Before describing some aspects of the disclosed subject matter in more detail, some terms that will be referenced in the remainder of this description need to be introduced.

[0064] Hereinafter, a subpicture refers to a rectangular arrangement of samples, blocks, macroblocks, coding units, or similar entities that may be semantically grouped and coded independently at varying resolutions. One or more subpictures may form a picture. One or more coded subpictures may form a coded picture. One or more subpictures may be assembled into a picture, or one or more subpictures may be extracted from a picture. In certain circumstances, one or more coded subpictures may be assembled in the compressed domain without transcoding the coded picture to the sample level, and in the same or certain other cases, one or more coded subpictures may be extracted from the coded picture in the compressed domain.

[0065] Hereinafter, reference picture resampling (RPR) or adaptive resolution change (ARC) refers to a mechanism that enables changing the resolution of a picture or sub-picture in a coded video sequence, e.g., by reference picture resampling. Hereinafter, RPR / ARC parameters refer to the control information needed to perform adaptive resolution change, which may include, e.g., filter parameters, scaling factors, output and / or reference picture resolutions, various control flags, etc.

[0066] The above description focuses on the coding and decoding of a single, semantically independent coded video picture. Before describing the implications of coding / decoding multiple sub-pictures with independent RPR / ARC parameters and the additional complexity that they imply, options for signaling the RPR / ARC parameters are described.

[0067] Referring to Figure 5, several novel options for signaling RPR / ARC parameters are shown. As noted for each option, they have certain advantages and disadvantages in terms of coding efficiency, complexity, and architecture. A video coding standard or technology may select one or more of these options, or options known from the prior art, for signaling RPR / ARC parameters. The options may not be mutually exclusive and may possibly be interchanged based on application needs, related standard technology, or encoder preference.

[0068] The classes of RPR / ARC parameters may include: - separate or combined upsample / downsample coefficients in the X and Y dimensions, - upsample / downsample factors with an additional time dimension, indicating a constant speed of zooming in / out for a given number of pictures; - Either of the above two may involve the coding of one or more possibly short syntax elements that can point to a table containing coefficients, -Resolution in the X or Y dimension of the input picture, output picture, reference picture, coded picture sample, block, macroblock, CU, or any other suitable unit of granularity, combined or separated (if there are two or more resolutions (e.g., one for the input picture, one for the reference picture, etc.), in some cases one set of values may be inferred from another set of values, which may be gated, for example, by using a flag; see below for more detailed examples); "Warping" coordinates similar to those used in H.263 Annex P, also with the appropriate granularity described above (H.263 Annex P defines one efficient way of encoding such warping coordinates, although other, potentially more efficient ways are likely to be devised. For example, according to an embodiment, the variable-length reversible "Huffman"-style coding of Annex P warping coordinates is replaced by appropriate-length binary coding, where the length of the binary codewords may, for example, be derived from the maximum picture size, possibly multiplied by a particular factor, and offset by a particular value to allow "warping" outside the boundaries of the maximum picture size); and / or - Upsample or downsample filter parameters (in the simplest case, there may be only a single filter for upsampling and / or downsampling. However, in some cases it may be advantageous to allow more flexibility in the filter design, which may require signaling of filter parameters. Such parameters may be selected via an index in a list of possible filter designs, the filter may be fully specified (e.g., via a list of filter coefficients using an appropriate entropy coding technique), or the filter may be selected implicitly via the upsample / downsample ratio signaled according to any of the mechanisms described above).

[0069] Hereinafter, the description assumes coding of a finite set of upsample / downsample coefficients (the same coefficients used in both the X and Y dimensions) indicated via codewords, which can advantageously be variable-length coded using, for example, Ext-Golomb codes common to certain syntax elements in video coding specifications such as H.264 and H.265. One suitable mapping of values to upsample / downsample coefficients can, for example, follow Table 1 below.

[0070] [Table 1]

[0071] Many similar mappings can be devised 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 can be extended to more values. The values may also be represented by entropy coding mechanisms other than Ext-Golomb codes, for example, using binary coding. This can have particular advantages when the resampling factor is a subject external to the video processing engine (initial encoder and decoder) itself, for example, with MANE. Note that in the (probably) most common case where no resolution change is required, a short Ext-Golomb code, only 1 bit in the table above, can be chosen, which can have coding efficiency advantages over using binary codes in the most common case.

[0072] The number of items in the table, as well as their semantics, may be fully or partially configurable. For example, a basic outline of the table may be conveyed in a "high" parameter set, such as a sequence parameter set or a decoder parameter set. Alternatively or additionally, one or more such tables may be defined in a video coding technology or standard and may be selected, for example, via a decoder parameter set or a sequence parameter set.

[0073] Below, we describe how the upsample / downsample coefficients (ARC information) coded as described above can be included in the syntax of a video coding technique or convention. Similar considerations may apply to one or several codewords that control an upsample / downsample filter. See below for an explanation of when a relatively large amount of data is required for a filter or other data structure.

[0074] As shown in the example of Figure 5A, the example (500A) shows that H.263 Annex P includes ARC information (502) in the form of four warping coordinates in the picture header (501), specifically in the H.263 PLUSPTYPE (503) header extension. This may be a wise design choice when a) there is a picture header available and b) frequent changes to the ARC information are expected. However, the overhead when using H.263-style signaling can be very high, and because picture headers can be temporal in nature, scaling factors may not be relevant across picture boundaries. Furthermore, as shown in the example of Figure 5B, the example (500B) shows that JVET-M0135 includes PPS information (504), ARC reference information (505), SPS information (507), and target resolution table information (506).

[0075] According to an exemplary embodiment, FIG. 5C shows an example (500C) in which tile group header information (508) and ARC information (509) are shown, FIG. 5D shows an example (500D) in which tile group header information (514), ARC reference information (513), SPS information (516), and ARC information (515) are shown, and FIG. 5E shows an example (500E) in which adaptation parameter set (APS) information (511) and ARC information (512) are shown.

[0076] FIG. 6 shows an example table (600) in which adaptive resolution is in use; in this example, the output resolution is coded in samples (613). The number 613 refers to both output_pic_width_in_luma_samples and output_pic_height_in_luma_samples, which together can define the resolution of the output picture. Elsewhere in a video coding technology or standard, specific restrictions on either value may be defined. For example, a level definition may limit the number of total output samples that can be the product of the values of those two syntax elements. Also, a particular video coding technology or standard, or an external technology or standard, such as a system standard, may limit the numbering range (e.g., one or both dimensions must be divisible by a power of two) or the aspect ratio (e.g., 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, as will be understood by those skilled in the art in light of this disclosure.

[0077] In certain applications, it may be desirable for an encoder to instruct a decoder to use a particular reference picture size rather than implicitly assuming that size is the output picture size. In this example, the syntax element reference_pic_size_present_flag (614) gates the conditional presence of the reference picture dimensions (615) (similarly, the numbers refer to both width and height).

[0078] Certain video coding techniques or standards, e.g., VP9, support spatial scalability by implementing a particular form of reference picture resampling (signaled quite differently than the disclosed subject matter) along with temporal scalability to enable spatial scalability. In particular, certain reference pictures can be upsampled to higher resolutions using ARC-style techniques to form the base of spatial enhancement layers. Those upsampled pictures can then be refined using normal prediction mechanisms at higher resolutions to add detail.

[0079] The disclosed subject matter can be and is used in such environments according to embodiments. In some cases, in the same or another embodiment, a value in a NAL unit header, e.g., a Time ID field, can be used to indicate not only a temporal layer but also a spatial layer. Doing so has certain advantages for certain system designs. For example, existing selective forwarding units (SFUs) created and optimized for temporal layer selective forwarding based on the value of the NAL unit header Time ID can be used without modification for scalable environments. To enable this, there may be a requirement for a mapping between coded picture sizes and temporal layers, which is indicated by the Time ID field in the NAL unit header.

[0080] In an embodiment, information about inter-layer dependency may be signaled in a VPS (or a DPS, SPS, or SEI message). The inter-layer dependency information may be used to identify which layers can be used as reference layers for decoding the current layer. A decoded picture picA in a directly dependent layer with nuh_layer_id equal to m may be used as a reference picture for a picture picB with nuh_layer_id equal to n when n is greater than m and the two pictures picA and picB belong to the same access unit.

[0081] In the same or other embodiments, the inter-layer reference picture (ILRP) list may be explicitly signaled along with the inter-prediction reference picture (IPRP) list in the slice header (or parameter set). Both the ILRP list and the IPRP list may be used to construct the forward and backward prediction reference picture lists.

[0082] In the same or other embodiments, a syntax element in the VPS (or other parameter set) can indicate whether each layer is dependent or independent. Referring to the example (700) of FIG. 7 , the syntax element vps_max_layers_minus1 (703) plus 1 can specify the maximum number of layers allowed in one or more, potentially all, CVSs that reference the VPS (701). A vps_all_independent_layers_flag (704) equal to 1 can specify that all layers in the CVS are coded independently, i.e., without using inter-layer prediction. A vps_all_independent_layers_flag (704) equal to 0 can specify that one or more of the layers in the CVS can use inter-layer prediction. When not present, the value of vps_all_independent_layers_flag may be inferred to be equal to 1. When vps_all_independent_layers_flag is equal to 1, the value of vps_independent_layer_flag[i] (706) may be inferred to be equal to 1. If vps_all_independent_layers_flag is equal to 0, the value of vps_independent_layer_flag[0] is inferred to be equal to 1.

[0083] Referring to Figure 7, vps_independent_layer_flag[i] (706) equal to 1 may specify that the layer with index i does not use inter-layer prediction. vps_independent_layer_flag[i] equal to 0 may specify that the layer with index i can use inter-layer prediction and vps_layer_dependency_flag[i] is present in the VPS. vps_direct_dependency_flag[i][j] (707) equal to 0 may specify that the layer with index j is not a direct reference layer for the layer with index i. vps_direct_dependency_flag[i][j] equal to 1 may specify that the layer with index j is a direct reference layer for the layer with index i. When vps_direct_dependency_flag[i][j] is not present for i and j in the range from 0 to vps_max_layers_minus1, it may be inferred to be equal to 0.

[0084] The variable DirectDependentLayerIdx[i][j] specifying the jth directly dependent layer of the i-th layer, and the variable NumDependentLayers[i] specifying the number of dependent layers of the i-th layer are derived as follows: for(i=1;i < vps_max_layers_minus1;i--) if(!vps_independent_layer_flag[ i ]){ for(j=i,k=0;j >=0;j--) if(vps_direct_dependency_flag[ i ][ j ]) DirectDependentLayerIdx[ i ][ k++]=j NumDependentLayers[ i ]=k }

[0085] In the same or another embodiment, referring to FIG. 7, when vps_max_layers_minus1 is greater than 0 and the value of vps_all_independent_layers_flag is equal to 0, vps_output_layers_mode and vps_output_layer_flags[i] may be signaled. vps_output_layers_mode (708) equal to 0 can specify that only the top layer is output. vps_output_layer_mode equal to 1 specifies that all layers can be output. vps_output_layer_mode equal to 2 may specify that the layers to be output are those for which vps_output_layer_flag[i] (709) is equal to 1. The value of vps_output_layers_mode shall be in the range 0 to 2, inclusive. A value of 3 for vps_output_layer_mode may be reserved for future use. When not present, a value of 1 for vps_output_layers_mode may be inferred. vps_output_layer_flag[i] equal to 1 may specify that the i-th layer is to be output. vps_output_layer_flag[i] equal to 0 may specify that the i-th layer is not to be output. The list OutputLayerFlag[i], where a value of 1 specifies that the i-th layer is to be output and a value of 0 specifies that the i-th layer is not to be output, is derived as follows: OutputLayerFlag[ vps_max_layers_minus1 ]=1 for(i=0;i < vps_max_layers_minus1;i++) if(vps_output_layer_mode==0) OutputLayerFlag[ i ]=0 else if(vps_output_layer_mode==1) OutputLayerFlag[ i ]=1 else if(vps_output_layer_mode==2) OutputLayerFlag[ i ]=vps_output_layer_flag[ i ]

[0086] In the same or another embodiment, the output of the current picture may be specified as follows: - If PictureOutputFlag is equal to 1 and DpbOutputTime[n] is equal to CpbRemovalTime[n], the current picture is output. - Otherwise, if PictureOutputFlag is equal to 0, the current picture is not output but is stored in the DPB as specified in the clause. - Otherwise (PictureOutputFlag is equal to 1 and DpbOutputTime[n] is greater than CpbRemovalTime[n]), the current picture will be output later, stored in the DPB (as specified in Section ) and output at time DpbOutputTime[n], unless it is indicated not to be output by decoding or inferring no_output_of_prior_pics_flag equal to 1 at the time preceding DpbOutputTime[n]. When output, the picture is cropped using the adaptive cropping window specified in the PPS for the picture.

[0087] In the same or another embodiment, PictureOutputFlag may be set as follows: - PictureOutputFlag is set equal to 0 if one of the following conditions is true: - The current picture is an RASL picture and the associated IRAP picture's NoIncorrectPicOutputFlag is equal to 1. -gdr_enabled_flag is equal to 1 and the current picture is a GDR picture with NoIncorrectPicOutputFlag equal to 1. -gdr_enabled_flag is equal to 1, the current picture is associated with a GDR picture whose NoIncorrectPicOutputFlag is equal to 1, and the current picture's PicOrderCntVal is less than the associated GDR picture's RpPicOrderCntVal. -vps_output_layer_mode equals 0 or 2 and OutputLayerFlag[GeneralLayerIdx[n uh_layer_id]] equals 0. Otherwise, PictureOutputFlag is set equal to pic_output_flag.

[0088] Alternatively, in the same or other embodiments, PictureOutputFlag may be set as follows: - PictureOutputFlag is set equal to 0 if one of the following conditions is true: - The current picture is an RASL picture and the associated IRAP picture's NoIncorrectPicOutputFlag is equal to 1. -gdr_enabled_flag is equal to 1 and the current picture is a GDR picture with NoIncorrectPicOutputFlag equal to 1. -gdr_enabled_flag is equal to 1, the current picture is associated with a GDR picture whose NoIncorrectPicOutputFlag is equal to 1, and the current picture's PicOrderCntVal is less than the associated GDR picture's RpPicOrderCntVal. -vps_output_layer_mode is equal to 0 and the current access unit contains a picture that has Picture OutputFlag equal to 1, has a nuh_layer_id nuhLid greater than the current picture, and belongs to an output layer (i.e., OutputLayerFlag[GeneralLayerIdx[nuhLid]] is equal to 1). -vps_output_layer_mode equals 2 and OutputLayerFlag[GeneralLayerIdx[nuh_laye r_id]] equals 0. Otherwise, PictureOutputFlag is set equal to pic_output_flag.

[0089] In the same or other embodiments, a flag in the VPS (or another parameter set) may indicate whether an ILRP list is signaled for the current slice (or picture). For example, referring to the example (800) of Figure 8, inter_layer_ref_pics_present_flag equal to 0 may specify that ILRP is not used for inter prediction of any coded pictures in the CVS. inter_layer_ref_pics_flag equal to 1 may specify that ILRP may be used for inter prediction of one or more coded pictures in the CVS.

[0090] In the same or other embodiments, when the kth layer is a dependent layer, the inter-layer reference picture (ILRP) list for pictures in the kth layer may or may not be signaled. However, when the kth layer is an independent layer, the ILRP list for pictures in the kth layer shall not be signaled and no ILRP shall be included in the reference picture list.

[0091] The value of inter_layer_ref_pics_present_flag may be set equal to 0 when sps_video_parameter_set_id is equal to 0, when nuh_layer_id is equal to 0, or when vps_independent_layer_flag[GeneralLaye rIdx[nuh_layer_id]] is equal to 1.

[0092] In the same or other embodiments, referring to the example (900) of Figure 9, a set of syntax elements that explicitly indicate the ILRP list may be signaled in an SPS, PPS, APS, or slice header. The ILRP list may be used to construct a reference picture list for the current picture.

[0093] In the same or other embodiments, the ILRP list may be used to identify active or inactive reference pictures in a decoded picture buffer (DPB). An active reference picture may be used as a reference picture for decoding the current picture, and an inactive reference picture may not be used to decode the current picture but may be used to decode a subsequent picture in decoding order.

[0094] In the same or another embodiment, the ILRP list may be used to identify which reference pictures may be stored in the DPB or output and removed from the DPB, which information may be used to operate a decoder based on a hypothetical reference decoder (HRD) model and parameters.

[0095] In the same or another embodiment, the syntax element ilrp_idc[listIdx][rplsIdx][i] may be signaled in a VPS, SPS, PPS, APS, or slice header. The syntax element ilrp_idc[listIdx][rplsIdx][i] specifies the index into the list of directly dependent layers of the ILRP of the ith item in the ref_pic_list_struct(listIdx,rplsIdx) syntax structure. The value of ilrp_idc[listIdx][rplsIdx][i] shall be in the range from 0 to GeneralLayerIdx[nuh_layer_id]-1, inclusive.

[0096] In the same embodiment, the syntax element ilrp_idc[listIdx][rplsIdx][i] may be an index indicating an ILRP picture in a directly dependent layer identified by vps_direct_dependency_flag[i][j] signaled in the VPS, where the value of ilrp_idc[listIdx][rplsIdx][i] shall be in the range 0 to NumDependentLayers[GeneralLayerIdx[nuh_layer_id]]-1, inclusive.

[0097] In the same embodiment, if the nuh_layer_id of the current layer is equal to k, it may be bit-efficient to signal an index indicating an ILRP in a directly subordinate layer compared to signaling an index indicating an ILRP in all layers whose nuh_layer_id is less than k.

[0098] In the same or another embodiment, and still referring to FIG. 9, the reference picture lists RefPicList[0] and RefPicList[1] may be constructed as follows: for(i=0;i < 2;i++){ for(j=0,k=0,pocBase=PicOrderCntVal;j < num_ref_entries[ i ][RplsIdx[ i ] ];j++){ if(!(inter_layer_ref_pic_flag[ i ][ RplsIdx[ i ] ][ j ]&&GeneralLayerIdx[ nuh_layer_id ])) { if(st_ref_pic_flag[ i ][ RplsIdx[ i ] ][ j ]){ RefPicPocList[ i ][ j ]=pocBase-DeltaPocValSt[ i ][RplsIdx[ i ] ][ j ] if(reference picture picA with the same nuh_layer_id as the current picture exists in the DPB, and PicOrderCntVal is equal to RefPicPocList[i][j]) RefPicList[ i ][ j ]=picA else RefPicList[ i ][ j ]=“no reference picture” (-) pocBase=RefPicPocList[ i ][ j ] } else { if(!delta_poc_msb_cycle_lt[ i ][ k ]){ if(reference picA with the same nuh_layer_id as the current picture exists in the DPB, PicOrderCntVal&(MaxPicOrderCntLsb-1) equals PocLsbLt[i][k]) RefPicList[ i ][ j ]=picA else RefPicList[ i ][ j ]=“no reference picture” RefPicLtPocList[ i ][ j ]=PocLsbLt[ i ][ k ] } else { if(reference picA with the same nuh_layer_id as the current picture exists in the DPB, PicOrderCntVal is equal to FullPocLt[i][k]) RefPicList[ i ][ j ]=picA else RefPicList[ i ][ j ]=“no reference picture” RefPicLtPocList[ i ][ j ]=FullPocLt[ i ][ k ] } k++ } } else { layerIdx=DirectDependentLayerIdx[ GeneralLayerIdx[ nuh_layer_id] ][ ilrp_idc[ i ][ RplsIdx[ i ] ][ j ] ] refPicLayerId=vps_layer_id[ layerIdx ] if(reference picture picA with nuh_layer_id equal to refPicLayerId exists in DPB, (The same PicOrderCntVal as the current picture exists) RefPicList[ i ][ j ]=picA else RefPicList[ i ][ j ]=“no reference picture” } } }

[0099] The techniques for signaling adaptive resolution parameters described above can be implemented as computer software using computer-readable instructions and physically stored on one or more computer-readable media. For example, Figure 10 illustrates a computer system (1000) suitable for implementing some embodiments of the disclosed subject matter.

[0100] Computer software can be coded using any suitable machine code or computer language that can be assembled, compiled, linked, or similar mechanisms to create code containing instructions that can be executed by a computer central processing unit (CPU), graphics processing unit (GPU), etc., directly, or via interpretation, microcode execution, etc.

[0101] The instructions may be executed on various types of computers or components thereof, including, for example, personal computers, tablet computers, servers, smartphones, gaming devices, Internet of Things devices, and the like.

[0102] 10 for computer system (1000) are exemplary in nature and are not intended to suggest any limitation on the scope of use or functionality of the computer software implementing the embodiments of the present disclosure. The arrangement of components should not be interpreted as having any dependency or requirement regarding any one or combination of components illustrated in the exemplary embodiment of computer system (1000).

[0103] The computer system (1000) may include certain human interface input devices. Such human interface input devices may respond to input by one or more human users, for example, via tactile input (such as keystrokes, swipes, or data glove movements), audio input (such as voice or claps), visual input (such as gestures), or olfactory input (not depicted). Human interface devices may also be used to capture certain media not necessarily directly associated with conscious human input, such as audio (such as voice, music, or ambient sounds), images (such as scanned images or photographic images obtained from a still camera), or video (such as two-dimensional video, three-dimensional video, including stereoscopic video).

[0104] The input human interface devices may include one or more of a keyboard (1001), a mouse (1002), a trackpad (1003), a touchscreen (1010), a joystick (1005), a microphone (1006), a scanner (1007), and a camera (1008) (only one of each is depicted).

[0105] The computer system (1000) may also include certain human interface output devices. Such human interface output devices may stimulate one or more of the human user's senses, for example, through tactile output, sound, light, and smell / taste. Such human interface output devices may include haptic output devices (e.g., haptic feedback via a touchscreen (1010) or a joystick (1005), although haptic feedback devices that do not function as input devices may also be present), audio output devices (such as speakers (1009) or headphones (not depicted)), visual output devices (such as screens (1010), including CRT screens, LCD screens, plasma screens, and OLED screens, each with or without touchscreen input capabilities and each with or without haptic feedback capabilities, some of which may be capable of outputting two-dimensional visual output or three-dimensional or higher-dimensional output via means such as stereographic output, virtual reality glasses (not depicted), holographic displays, and smoke tanks (not depicted)), and printers (not depicted).

[0106] The computer system (1000) may also include human-accessible storage devices and their associated media, such as optical media including CD / DVD ROM / RW (1020) with CD / DVD or similar media (1021), thumb drives (1022), removable hard drives or solid state drives (1023), legacy magnetic media (not depicted) such as tape and floppy disks, and specialized ROM / ASIC / PLD-based devices (not depicted) such as security dongles.

[0107] Those skilled in the art should also understand that the term "computer-readable medium" as used in connection with the presently disclosed subject matter does not encompass transmission media, carrier waves, or other transitory signals.

[0108] The computer system (1000) may also include interfaces to one or more communication networks. Networks may be, for example, wireless, wired, or optical. Networks may further be local, wide-area, metropolitan, vehicular, and industrial, real-time, delay-tolerant, and the like. Examples of networks include local area networks such as Ethernet and wireless LAN; cellular networks including GSM, 3G, 4G, 5G, LTE, and the like; wired or wireless wide-area digital TV networks including cable TV, satellite TV, and terrestrial broadcast TV; and vehicular and industrial networks including CAN Bus. Certain networks typically require an external network interface adapter attached to a specific general-purpose data port (e.g., a USB port on the computer system (1000)) or peripheral bus (1049), while other networks are typically integrated into the core of the computer system (1000) by attaching to a system bus (e.g., an Ethernet interface to a PC computer system or a cellular network interface to a smartphone computer system), as described below. Using any of these networks, the computer system (1000) can communicate with other entities. Such communications may be one-way receive only (e.g., broadcast TV), one-way transmit only (e.g., CANbus to a specific CANbus device), or two-way with other computer systems, for example, using local or wide-area digital networks. Specific protocols and protocol stacks may be used with each of the networks and network interfaces described above.

[0109] The aforementioned human interface devices, human-accessible storage devices, and network interfaces may be attached to the core (1040) of the computer system (1000).

[0110] The core (1040) may include one or more central processing units (CPUs) (1041), graphics processing units (GPUs) (1042), specialized programmable processing units in the form of field programmable gate arrays (FPGAs) (1043), task-specific hardware accelerators (1044), etc. These devices, along with read-only memory (ROM) (1045), random access memory (1046), and internal mass storage (1047) such as an internal non-user-accessible hard drive or SSD, may be connected via a system bus (1048). In some computer systems, the system bus (1048) may be accessible in the form of one or more physical plugs to allow expansion with additional CPUs, GPUs, etc. Peripheral devices may be attached directly to the core's system bus (1048) or via a peripheral bus (1049). Architectures for peripheral buses include PCI, USB, etc.

[0111] The CPU (1041), GPU (1042), FPGA (1043), and accelerator (1044) can execute specific instructions that, in combination, can constitute the aforementioned computer code. That computer code can be stored in ROM (1045) or RAM (1046). Persistent data can be stored, for example, in internal mass storage (1047), while transient data can also be stored in RAM (1046). Rapid storage and retrieval from any of the memory devices can be enabled using cache memory, which can be closely associated with one or more of the CPU (1041), GPU (1042), mass storage (1047), ROM (1045), RAM (1046), etc.

[0112] The computer-readable medium can have computer code thereon for performing various computer-implemented operations. The medium and computer code may be those specially designed and constructed for the purposes of the present disclosure, or they may be of the kind well known and available to those skilled in the computer software arts.

[0113] By way of example, and not limitation, a computer system (1000) having an architecture, and specifically a core (1040), can provide functionality as a result of a processor (including a CPU, GPU, FPGA, accelerator, etc.) executing software embodied in one or more tangible computer-readable media. Such computer-readable media can be the user-accessible mass storage introduced above, as well as media associated with specific storage of the core (1040) that is non-transitory in nature, such as the core's internal mass storage (1047) or ROM (1045). Software implementing various embodiments of the present disclosure can be stored in such devices and executed by the core (1040). The computer-readable media can include one or more memory devices or chips, depending on particular needs. The software can cause the core (1040), and specifically the processor (including a CPU, GPU, FPGA, etc.) therein, to perform particular processes or particular portions of particular processes described herein, including defining data structures stored in RAM (1046) and modifying such data structures according to software-defined processes. Additionally or alternatively, a computer system may provide functionality as a result of logic hardwired or otherwise embodied in circuitry (e.g., accelerator (1044)) that can operate in place of or together with software to perform particular processes or particular portions of particular processes described herein. Where appropriate, references to software may encompass logic, and vice versa. Where appropriate, references to computer-readable media may encompass circuitry (such as an integrated circuit (IC)) that stores software for execution, circuitry that embodies logic for execution, or both. The present disclosure encompasses any suitable combination of hardware and software.

[0114] While this disclosure describes several exemplary embodiments, there are alterations, substitutions, and various substitute equivalents that fall within the scope of this disclosure. It will thus be appreciated that those skilled in the art will be able to devise numerous systems and methods that, although not explicitly shown or described herein, embody the principles of the present disclosure and are therefore within its spirit and scope. [Explanation of symbols]

[0115] 100 Communication Systems 110 terminals 120 terminals 130 terminals 140 terminals 150 Network 201 Video Sources 202 uncompressed video sample streams 203 Video Encoder 204 coded video bitstream 205 Streaming Server 206 Streaming Client 207 Copying Encoded Video Bitstreams 208 Streaming Client 209 Copying a coded video bitstream 210 Video Decoder 211 output video sample stream 212 Display 213 Capture Subsystem 310 Receiver 312 channels 315 Buffer Memory 320 Entropy Decoder / Parser 321 Symbol 351 Scaler / Descaler Unit 352 Intra-picture prediction unit 353 Motion Compensation Prediction Unit 355 Aggregator 356 Current Picture / Loop Filter Unit 357 Reference Picture Memory 430 Source Coder 432 Coding Engine 433 (local) decoder 434 Reference Picture Memory 435 Predictor 440 Transmitter 443 coded video sequence 445 Entropy Coder 450 Controller 460 Communication Channels 500A example 500B Example 501 Picture Header 502 ARC information 503 H.263 PLUSPTYPE 504 PPS Information 505 ARC Reference Information 506 Target resolution table information 507 SPS Information 508 Tile Group Header Information 509 ARC information 511 Adaptive Parameter Set (APS) Information 512 ARC information 513 ARC Reference Information 514 Tile Group Header Information 515 ARC information 516 SPS Information 600 Table Examples 615 Reference Picture Dimensions 700 examples 701 VPS 800 examples 900 examples 1000 Computer Systems 1001 keyboard 1002 Mouse 1003 Trackpad 1005 Joystick 1006 Microphone 1007 Scanner 1008 Camera 1009 Speaker 1010 Touchscreen 1020 CD / DVD ROM / RW 1021 CD / DVD or similar media 1022 thumb drive 1023 removable hard drive or solid state drive 1040 cores 1041 Central Processing Unit (CPU) 1042 Graphics Processing Unit (GPU) 1043 Field Programmable Gate Area (FPGA) 1044 Hardware Accelerator 1045 Read-Only Memory (ROM) 1046 Random Access Memory (RAM) 1047 Internal Mass Storage 1048 System Bus 1049 Peripheral Bus 1050 graphics adapter 1054 network interfaces

Claims

1. A video encoding method performed by at least one processor, A step of signaling a plurality of flags within at least one video parameter set (VPS), wherein the VPS includes at least one syntactic element indicating whether at least one layer in a scalable bitstream is one of the dependent layers and independent layers of the scalable bitstream, and the plurality of flags include a first flag specifying that each of the at least one layer is the independent layer and a second flag specifying that each of the at least one layer is the directly dependent layer, and the VPS The steps include: the plurality of flags included are used to determine the number of dependent layers in the scalable bitstream, including the dependent layers, the first flag is determined to be positive or negative for each of the at least one layer, if the first flag is negative, the second flag is determined to be positive or negative, if the second flag is positive, the layer for which the second flag is positive is determined to be a direct dependent layer, and the number of direct dependent layers is determined to be the number of dependent layers; A step of signaling an interlayer reference picture (ILRP) list, wherein the ILRP list is used to decode pictures in the dependent layers by parsing and interpreting, the ILRP list includes an index of an ILRP, where the value of the ILRP index is in the range of 0 or greater and less than or equal to the number of dependent layers minus 1, and the first flag is used to specify whether a picture in the independent layer and another picture in the dependent layer are decoded, respectively, without parsing and interpreting the ILRP list. Methods that include...

2. The method according to claim 1, wherein the interlayer reference picture list includes decoded pictures of other layers.

3. The method according to claim 1 or 2, wherein the at least one VPS is otherwise represented by a syntactic element indicating the maximum number of layers.

4. The method according to any one of claims 1 to 3, wherein the second flag indicates whether any other layer in the scalable bitstream is a reference layer for at least one of the layers.

5. The at least one VPS indicates the other layer as the reference layer for the at least one layer by specifying the index of the other layer and the index of the at least one layer, The at least one VPS is used to determine whether the VPS contains other syntactic elements that have a value less than the number of dependent layers determined. The method according to claim 4.

6. The at least one VPS indicates that the second flag is not the reference layer for the at least one layer by specifying the index of the other layer and the index of the at least one layer, The at least one VPS is used to determine whether the VPS contains other syntactic elements that have a value less than the number of dependent layers determined. The method according to claim 4.

7. The method according to any one of claims 1 to 6, wherein the at least one VPS is used to determine whether the VPS includes the first flag indicating whether a plurality of layers, including the at least one layer, should be decoded by interpreting the ILRP list.

8. The method according to any one of claims 1 to 7, wherein the at least one VPS is used to determine whether the VPS includes the first flag indicating whether a plurality of layers, including the at least one layer, should be decrypted without interpreting the ILRP list.

9. An apparatus configured to perform the method described in any one of claims 1 to 8.

10. A program for causing a computer to perform the method described in any one of claims 1 to 8.

11. A method for video encoding in an encoder, wherein the method is: The steps include generating a coded scalable bitstream, The steps include storing the coded scalable bitstream in a computer-readable storage medium, The step of generating the coded scalable bitstream is: A step of signaling a plurality of flags within at least one video parameter set (VPS), wherein the VPS includes at least one syntactic element indicating whether at least one layer in the scalable bitstream is one of the dependent layers and independent layers of the scalable bitstream, the plurality of flags including a first flag specifying that each of the at least one layer is the independent layer and a second flag specifying that each of the at least one layer is the directly dependent layer, and the VPS The steps include: the plurality of flags included in the scalable bitstream are used to determine the number of dependent layers, including the dependent layers, the first flag is determined to be positive or negative for each of the at least one layer, if the first flag is negative, the second flag is determined to be positive or negative, if the second flag is positive, the layer for which the second flag is positive is determined to be a direct dependent layer, and the number of direct dependent layers is determined to be the number of dependent layers; A step of signaling an interlayer reference picture (ILRP) list, wherein the ILRP list is used to decode pictures in the dependent layers by parsing and interpreting, the ILRP list includes an index of ILRPs, where the value of the ILRP index is in the range of 0 or greater and less than or equal to the number of dependent layers minus 1, and the first flag is used to specify whether a picture in an independent layer and another picture in the dependent layer are decoded, respectively, without parsing and interpreting the ILRP list. Methods that include...

12. A method for video decoding of a scalable bitstream, performed by at least one processor, The steps include parsing at least one video parameter set (VPS) which includes at least one syntactic element indicating whether at least one layer in the scalable bitstream is one of the dependent layers and independent layers of the scalable bitstream, A step of determining the number of dependent layers of the scalable bitstream, including the dependent layers, based on a plurality of flags included in the VPS, wherein the plurality of flags include a first flag specifying that each of the at least one layers is the independent layer and a second flag specifying that each of the at least one layer is a direct dependent layer, the step of determining the number of dependent layers of the scalable bitstream, including the dependent layers, based on a plurality of flags included in the VPS, includes determining whether the first flag is positive or negative for each of the at least one layer, if the first flag is negative, determining whether the second flag is positive or negative, if the second flag is positive, determining that the layer for which the second flag is positive is a direct dependent layer, and determining that the number of direct dependent layers is the number of dependent layers, A step of decoding a picture in a dependent layer by parsing and interpreting an interlayer reference picture (ILRP) list, wherein the ILRP list includes an index of an ILRP, and if the index of an ILRP directly points to an ILRP picture in a dependent layer, the value of the index of the ILRP is in the range of 0 or greater and less than or equal to the number of dependent layers minus 1. The steps include decoding a picture in an independent layer and another picture in a dependent layer, respectively, without parsing and interpreting the ILRP list. Methods that include...

Images