Interlayer prediction signaling in video bitstreams

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 on September 20, 2019, and U.S. Patent Application No. 17 / 019,713, filed on September 14, 2020, the entire contents of which are incorporated herein by reference.

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

Background Art

[0003] Video coding and decoding using inter-picture prediction with motion compensation has been known for decades. Uncompressed digital video can be composed of a series of pictures, each picture having, for example, spatial dimensions of 1920×1080 luminance samples and associated chrominance samples. A series of pictures can have, for example, a fixed or variable (also known informally as the frame rate) picture rate of 60 pictures per second or 60 Hz. Uncompressed video has significant bitrate requirements. For example, 1080p60 4:2:0 video (1920×1080 luminance sample resolution at 60 Hz frame rate) at 8 bits per sample requires a bandwidth close to 1.5 Gbit / s. One hour of such video requires storage space exceeding 600 GB.

[0004] One purpose of video coding and decoding may be to reduce the redundancy of the 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 a technique that allows an exact copy of the original signal to be restored from the compressed original signal. With lossy compression, the restored signal may not be identical to the original signal, but the distortion between the original and restored signals is small enough to make the restored signal useful for its intended purpose. For video, lossy compression is widely adopted. The amount of distortion that can be tolerated depends on the application; for example, users of a particular consumer streaming application may tolerate higher distortion than users of a television-contributing application. The feasible compression ratio can be shown to be higher as the tolerance / tolerance of distortion increases.

[0005] Video encoders and video decoders can utilize techniques from several broad categories, including motion compensation, transformation, quantization, and entropy coding, some of which are described below.

[0006] Historically, video encoders and decoders have almost always tended to operate with a given picture size defined and remaining constant for coded video sequences (CVS), picture groups (GOP), or similar multi-picture timeframes. For example, in MPEG-2, the system design is known to change the horizontal resolution (and thus the picture size) depending on factors such as scene activity, but only in the picture, and therefore usually for GOPs. Resampling of the reference picture 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 individual macroblocks up or down by a factor of 2 (in each dimension). Here again, the picture size remains the same. Since the size of macroblocks is fixed in H.263, they do not need to be signaled.

[0007] Changing the picture size of a predictive picture has become more prevalent in modern video coding. For example, VP9 allows for reference picture resampling (RPR) and changing the resolution of the entire picture. Similarly, several 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 in its entirety herein) allow for the resampling of the entire reference picture to different, higher or lower resolutions. That document proposes various candidate resolutions, coded within a sequence parameter set and referenced by per-picture syntactic elements within a picture parameter set. [Overview of the project] [Means for solving the problem]

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

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

[0010] The invention includes a method and apparatus comprising 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 comprises parsing code configured to cause at least one processor to parse at least one video parameter set (VPS) which 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; determination code configured to cause at least one processor to determine the number of dependent layers of the scalable bitstream, including its dependent layers, based on a plurality of flags contained in the VPS; first decoding code configured to cause at least one processor to decode pictures in dependent layers by parsing and interpreting an interlayer reference picture (ILRP) list; and second decoding code configured to cause at least one processor to decode pictures in independent layers without parsing and interpreting an ILRP list.

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

[0012] According to one embodiment, the interlayer reference picture list includes decoded pictures of other layers.

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

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

[0015] According to the embodiment, the parsing code is further configured to cause at least one VPS to be parsed by at least one processor by specifying the index of other layers and the index of at least one layer, thereby determining whether a flag indicates other layers as reference layers for at least one layer, and the parsing code is further configured to cause at least one VPS to be parsed by at least one processor by determining whether the VPS contains other syntactic elements that indicate a value less than the number of dependent layers determined.

[0016] According to the embodiment, the parsing code is further configured to cause at least one VPS to be parsed by at least one processor by specifying the index of other layers and the index of at least one layer, thereby determining whether a flag indicates that the other layers are not reference layers for at least one layer, and the parsing code is further configured to cause at least one VPS to be parsed by at least one processor by determining whether the VPS contains other syntactic elements that indicate a value less than the number of dependent layers determined.

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

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

[0019] According to one embodiment, the parsing code is further configured to cause at least one VPS to be parsed by at least one processor, further including determining whether the VPS includes a flag indicating whether multiple layers, including at least one layer, should decode the ILRP list by interpreting it.

[0020] Further features, properties, and various advantages of the disclosed subject matter are more evident from the embodiments for carrying out the invention described below and the accompanying drawings. [Brief explanation of the drawing]

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

[0022] [Figure 5D] Schematic diagram of options for signaling ARC / RPR parameters according to the related art. [Figure 5E] Schematic diagram of options for signaling ARC / RPR parameters according to the related art. [Figure 6] Schematic diagram of signaling picture resolution according to an embodiment. [Figure 7] Schematic diagram of signaling picture size and adaptive window within SPS according to an embodiment. [Figure 8] Schematic diagram of signaling the existence of inter-layer prediction within SPS according to an embodiment. [Figure 9] Schematic diagram of signaling an inter-layer prediction index within a slice header according to an embodiment. [Figure 10] Schematic diagram of a computer system according to an embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

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

[0024] Figure 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 its local location for transmission to another terminal (120) via the network (150). A second terminal (120) can receive the encoded video data from the other terminal via the network (150), decode the encoded data, and display the restored video data. Unidirectional data transmission may be common in media serving applications, etc.

[0025] Figure 1 shows a second pair of terminals (130, 140) provided to support the bidirectional transmission of coded video that may occur, for example, during a video conference. For bidirectional data transmission, each terminal (130, 140) can encode video data captured at its local location for transmission to other terminals over the network (150). Each terminal (130, 140) can also receive coded video data transmitted by other terminals, decode the coded data, and display the restored video data on a local display device.

[0026] In the example in Figure 1, the terminals (110, 120, 130, 140) may be represented as servers, personal computers, and smartphones, but the principles of this disclosure are not limited thereto. Embodiments of this disclosure find applications using laptop computers, tablet computers, media players, and / or dedicated video conferencing equipment. Network (150) represents any number of networks that transmit coded video data between terminals (110, 120, 130, 140), including, for example, wired and / or wireless communication networks. Communication networks (150) can exchange data over circuit-switched channels and / or packet-switched channels. Typical networks include telecommunications networks, local area networks, wide area networks, and / or the Internet. For the purposes of this description, the architecture and topology of network (150) may not be important to the operation of this disclosure unless described below herein.

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

[0028] The streaming system may include a capture subsystem (213) which may include a video source (201), such as a digital camera, that creates an uncompressed video sample stream (202). The sample stream (202), depicted as a thick line to highlight a higher data volume 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, as described in more detail below. The encoded video bitstream (204), depicted as a thin line to highlight a lower data volume compared to the sample stream, can be stored in a streaming server (205) for future use. One or more streaming clients (206, 208) can access the streaming server (205) to retrieve a copy (207, 209) of the encoded video bitstream (204). A client (206) may include a video decoder (210) that decodes an input copy of an encoded video bitstream (207) and creates an output video sample stream (211) that can be rendered to a display (212) or other rendering device (without rendering). In some streaming systems, the video bitstream (204, 207, 209) can be encoded according to a specific video coding / compression standard. An example of such a standard is ITU-T Recommendation H.265. A video coding standard informally known as Multipurpose Video Coding or VVC is under development. The disclosed subject matter may be used in connection with VVC.

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

[0030] The receiver (310) can receive one or more codec video sequences to be decoded by the decoder (210), in the same or different embodiments, one coded video sequence at a time, and the decoding of each coded video sequence is independent of other coded video sequences. Coded video sequences may be received from a channel (312), which may be a hardware / software link to a storage device that stores coded video data. The receiver (310) can receive coded video data together with other data that may be transferred to their respective usage entities (not described), such as coded audio data and / or auxiliary data streams. The receiver (310) can isolate coded video sequences from other data. To counteract network jitter, a buffer memory (315) may be coupled between the receiver (310) and the entropy decoder / parser (320) (hereinafter, "Parser"). When the receiver (310) is receiving data from a store / forward device with sufficient bandwidth and controllability, or from an isosynchronous network, the buffer (315) may not be needed or may be small. For use in best-effort packet networks such as the Internet, the buffer (315) may be needed, may be relatively large, and may be adaptively sized to its advantage.

[0031] The video decoder (210) may include a parser (320) to recover symbols (321) from an entropy-encoded video sequence. Categories of these symbols may include information used to manage the operation of the decoder (210), and potentially information for controlling rendering devices such as a display (212), which are not integral parts of the decoder but can be coupled to the decoder as shown in Figure 2. Control information for rendering devices may be in the form of supplemental extension information (SEI messages) or parameter set fragments (not depicted) of video usability information (VUI). The parser (320) can parse / entropy-decode the received coded video sequence. The coding of the coded video sequence may follow video coding techniques or standards, and may follow principles well known to those skilled in the art, including variable-length coding, Huffman coding, arithmetic coding, etc., with or without context sensitivity. The parser (320) may extract from the coded 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 a group. Subgroups can include picture groups (GOP), pictures, tiles, slices, macroblocks, coding units (CU), blocks, transform units (TU), and predictive units (PU). Entropy decoders / parsers can also extract information from coded video sequences, such as transform coefficients, quantizer parameter values, and motion vectors.

[0032] The parser (320) can perform an entropy decoding / parsing operation on the video sequence received from the buffer (315) in order to create a symbol (321).

[0033] The reconstruction of symbol (321) may involve multiple different units, depending on the type of coded video picture or part thereof (such as interpicture and intrapicture, interblock and intrablock), 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 multiple units described below is not depicted for clarity.

[0034] In addition to the functional blocks already described, the decoder 210 can be conceptually subdivided into several functional units, as described below. In actual implementations operating under commercial constraints, many of these units can interact closely with each other and, at least partially, integrate with one another. However, for the purpose of describing the disclosed subject matter, the conceptual subdivision into functional units described below is appropriate.

[0035] The first unit is the scaler / inverse unit (351). The scaler / inverse unit (351) receives control information from the parser (320) as symbols (321), including the quantization conversion coefficients, which conversion to use, block size, quantization coefficients, and quantization scaling matrix. It can output a block 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 predictive information from previously restored pictures but can use predictive information from previously restored portions of the current picture. Such predictive information can be provided by the intra-picture predictive unit (352). In some cases, the intra-picture predictive unit (352) generates blocks of the same size and shape as the block being restored, using already restored surrounding information fetched from the current (partially restored) picture (356). The aggregator (355) may, on a sample-by-sample basis, add the predictive information generated by the intra-predictive unit (352) to the output sample information provided by the scaler / inverse transform unit (351).

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

[0038] The output samples of the aggregator (355) can undergo various loop filtering techniques in the loop filter unit (356). The video compression technique may include in-loop filtering techniques controlled by parameters contained in the coded video bitstream, which are made available to the loop filter unit (356) as symbols (321) from the parser (320), but can also respond to previously restored and loop-filtered sample values, as well as metadata obtained during decoding of earlier portions (in decoding order) of the 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) and also stored in reference picture memory (356) for use in future interpicture prediction.

[0040] A particular coded picture, once fully restored, can be used as a reference picture for future predictions. Once a coded picture is fully restored and identified as a reference picture (for example, 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 starting the restoration of the next coded picture.

[0041] The video decoder 320 can perform decoding operations according to a predetermined video compression technique that may be documented in standards such as ITU-T Rec.H.265. The coded video sequence can conform to the syntax specified by the video compression technique or standard being used, in the sense that the coded video sequence adheres to the syntax of the video compression technique or standard specified in the video compression technique documentation or standard, specifically in the profile document within it. Furthermore, compliance requires that the complexity of the coded video sequence be within the range defined by the level of the video compression technique or standard. In some cases, the level may limit the maximum picture size, maximum frame rate, maximum recovery sample rate (measured, for example, in megasamples per second), maximum reference picture size, etc. The limitations set by the level may, in some cases, be further limited by the virtual reference decoder (HRD) specification and metadata for HRD buffer management signaled within the coded video sequence.

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

[0043] Figure 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) which is not part of the encoder and can capture video images that are encoded by the encoder (203).

[0045] The video source (201) can provide a source video sequence encoded 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) may be a storage device that stores previously prepared video. In a video conferencing system, the video source (203) may be a camera that captures local image information as a video sequence. The video data may be provided as a number of separate pictures that convey motion when viewed in sequence. The pictures themselves may be organized as a spatial array of pixels, each pixel may contain one or more samples, depending on the sampling structure, color space, etc., in use. Those skilled in the art will readily understand the relationship between pixels and samples. The following description will focus on samples.

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

[0047] Some video encoders operate in what is readily recognizable to those skilled in the art as a “coding loop.” In an overly simplified explanation, the coding loop may consist of an encoding portion of an encoder (430) (hereinafter “source encoder”) (involved in creating symbols based on the input and reference pictures to be coded), and a (local) decoder (433) incorporated into the encoder (203) that decodes the symbols to create sample data, which is also created by the (remote) decoder (since any compression between the symbols and the coded video bitstream is reversible in the video compression techniques considered in the disclosed subject). The decoded sample stream is input to the reference picture memory (434). Since decoding the symbol stream leads to bit-accurate results regardless of the decoder’s location (local or remote), the contents of the reference picture buffer are also bit-accurate between the local and remote encoders. In other words, the predictive portion of the encoder “sees” the exact same sample values ​​as the reference picture samples that the decoder “sees” when using predictions during decoding. This fundamental principle of the synchronization of reference pictures (and the resulting drift when, for example, synchronization cannot be maintained 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 that of the “remote” decoder (210), which has already been described in detail above in conjunction with Figure 3. However, referring again briefly to Figure 3, since symbols are available and the encoding / decoding of symbols to the coded video sequence by the entropy coder (445) and parser (320) may be reversible, 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 techniques other than parsing / entropy decoding present in the decoder must necessarily exist in substantially the same functional form within the corresponding encoder. Therefore, the subject matter disclosed will focus on the operation of the decoder. A description of the encoder techniques can be omitted, as it is the inverse of the comprehensively described decoder techniques. More detailed explanations are necessary only in specific areas and are provided below.

[0050] As part of this operation, the source coder (430) can perform motion-compensated predictive coding, predictively coding the input frame by referencing one or more previously coded frames from a video sequence designated as “reference frames”. In this way, the coding engine (432) codes the difference between the pixel blocks of the input frame and the pixel blocks of the reference frame which may be selected as the prediction criterion for the input frame.

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

[0052] The predictor (435) can perform predictive searches 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., which can serve as appropriate predictive criteria for the new picture. The predictor (435) can operate on a sample block vs. pixel block basis to find appropriate predictive criteria. In some cases, the input picture may have predictive criteria drawn from multiple reference pictures stored in the reference picture memory (434), as determined by the search results obtained by the predictor (435).

[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 video data.

[0054] The outputs of all the aforementioned functional units can undergo entropy coding in the entropy coder (445). The entropy coder converts the symbols generated by the various functional units into coded video sequences by lossless compression of 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 the communication channel (460), which may be a hardware / software link to a storage device for storing 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 specific coded picture type to each coded picture, which may affect the coding technique that can be applied to each picture. For example, a picture may often be assigned as one of the following frame types:

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

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

[0059] A bidirectional predictive picture (B-picture) can be a picture that can be coded and decoded using intra-prediction or inter-prediction, which uses at most two motion vectors and reference indices to predict the sample values ​​of each block. Similarly, a multiple predictive picture can use three or more reference pictures and associated metadata to reconstruct 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 each block can be coded. Blocks can be coded predictively by referencing other (already coded) blocks, as determined by the coding assignment applied to each picture in the block. For example, blocks in picture I can be coded unpredictably, or they can be coded predictively by referencing already coded blocks in the same picture (spatial prediction or intra-prediction). Pixel blocks in picture P can be coded unpredictably via spatial prediction or temporal prediction by referencing one previously coded reference picture. Blocks in picture B can be coded unpredictably via spatial prediction or temporal prediction by referencing one or two previously coded reference pictures.

[0061] The video encoder (203) can perform coding operations in accordance with a given video coding technique or standard, such as ITU-T Rec.H.265. In this operation, the video encoder (203) can perform various compression operations, including predictive coding operations that utilize temporal and spatial redundancy in the input video sequence. Thus, the coded video data can conform to the syntax specified by the video coding technique or standard being used.

[0062] In one embodiment, the transmitter (440) may transmit additional data along with the encoded video. The video coder (430) may include such data as part of the encoded video sequence. The additional data may include time / space / SNR extension layers, other forms of redundant data such as redundant pictures and slices, Auxiliary Enhancement Information (SEI) messages, Visual Usability Information (VUI) parameter set fragments, and the like.

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

[0064] Hereafter, a subpicture refers to a rectangular arrangement of samples, blocks, macroblocks, coding units, or similar entities that, depending on the context, may be semantically grouped and independently coded at a modified resolution. One or more subpictures may form a single picture. One or more coded subpictures may form a single coded picture. One or more subpictures may be assembled into a picture, and one or more subpictures may be extracted from a picture. In certain environments, one or more coded subpictures may be assembled within a compressed region without transcoding to a coded picture at the sample level, and in the same or certain other cases, one or more coded subpictures may be extracted from a coded picture within a compressed region.

[0065] Hereafter, "reference picture resampling (RPR)" or "adaptive resolution change (ARC)" refers to a mechanism that enables changes in the resolution of a picture or sub-picture within a coded video sequence, for example, by reference picture resampling. Hereafter, "RPR / ARC parameters" refers to the control information necessary to perform adaptive resolution change, which may include, for example, filter parameters, scaling factors, output and / or reference picture resolutions, and various control flags.

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

[0067] Referring to Figure 5, several novel options for signaling RPR / ARC parameters are shown. As described for each option, they have specific 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 prior art, to signal RPR / ARC parameters. The options do not have to be mutually exclusive and may be interchangeable based on application needs, relevant standard technologies, or encoder selection.

[0068] The classes of RPR / ARC parameters may include the following: - Upsampling / downsampling coefficients separated or combined in the X and Y dimensions, - Upsampling / downsampling coefficients with added time dimension, showing constant speed zoom in / zoom out for a given number of pictures. - Either of the above two may include coding of one or more possibly short syntactic elements that can refer to a table containing coefficients. - X-dimensional or Y-dimensional resolution of combined or separated input pictures, output pictures, reference pictures, coded pictures, samples, blocks, macroblocks, CUs, or any other appropriate unit of granularity (if there are two or more resolutions (e.g., a resolution for the input picture, a resolution for the reference picture, etc.), in some cases one set of values ​​may be inferred from another set of values. This can be gated, for example, by using flags. See below for more detailed examples.) -Similarly, "warping" coordinates with the appropriate granularity described above, similar to those used in H.263 Annex P (H.263 Annex P defines one efficient method for coding such warping coordinates, but other potentially more efficient methods may also be devised. For example, according to embodiments, the variable-length reversible "Huffman" style coding of warping coordinates in Annex P can be replaced by a binary coding of appropriate length, the length of which can be derived, for example, from the maximum picture size, possibly multiplied by a specific coefficient and offset by a specific value to allow "warping" outside the boundary of the maximum picture size), as well as / or - Upsampling or downsampling filter parameters (In the simplest case, only a single filter for upsampling and / or downsampling may exist. However, in some cases, it may be advantageous to allow more flexibility in 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 appropriate entropy coding techniques), or the filter may be implicitly selected via an upsampling / downsampling ratio signaled according to one of the mechanisms described above).

[0069] The following explanation assumes coding of a finite set of upsampling / downsampling coefficients (the same coefficients used in both the X and Y dimensions) represented by a codeword. This codeword can, conveniently, be coded to a variable length using Ext-Golomb code, which is common to certain syntactic elements in video coding specifications such as H.264 and H.265. One appropriate mapping of values ​​to upsampling / downsampling coefficients can follow, for example, Table 1 below.

[0070] [Table 1]

[0071] Many similar mappings can be devised depending on the application needs 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 code, for example, using binary coding. This can have certain advantages when the resampling factor is an external object of the video processing engine (encoder and decoder in the first place), as in MANE. Note that in the (perhaps) most common case where resolution change is not required, a short Ext-Golomb code of only 1 bit in the table above may be chosen. It can have coding efficiency advantages over using binary code in the most common cases.

[0072] The number of items in a table, as well as their semantics, may be fully or partially configurable. For example, the basic outline of a table may be communicated 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 technique or standard, and may be selected, for example, via a decoder parameter set or a sequence parameter set.

[0073] The following describes how the coded upsampling / downsampling coefficients (ARC information), as described above, may be incorporated into the syntax of video coding techniques or conventions. Similar considerations may apply to one or more codewords that control upsampling / downsampling filters. For explanations regarding situations where filters or other data structures require relatively large amounts of data, see below.

[0074] As shown in the example in Figure 5A, 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 sensible design choice when a) an available picture header exists and b) frequent changes to the ARC information are expected. However, the overhead when using H.263-style signaling can be very high, and since the picture header can be transient, the scaling factor may not be relevant between picture boundaries. Furthermore, as shown in the example in Figure 5B, 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 exemplary embodiments, Figure 5C shows an example (500C) in which tile group header information (508) and ARC information (509) are shown, Figure 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 Figure 5E shows an example (500E) in which adaptive parameter set (APS) information (511) and ARC information (512) are shown.

[0076] Figure 6 shows an example of a table (600) in which adaptive resolution is in use, in which the output resolution is coded in samples (613). The digit 613 refers to both output_pic_width_in_luma_samples and output_pic_height_in_luma_samples, which together define the resolution of the output picture. Elsewhere in the video coding technique or standard, specific limitations may be defined on either value. For example, a level definition may limit the total number of output samples, which may be the product of the values ​​of those two syntactic elements. Also, a specific video coding technique or standard, or an external technique or standard such as a system standard, may limit the numbering range (for example, one or both dimensions must be divisible by a power of 2) or the aspect ratio (for example, the width and height must be in a relationship such as 4:3 or 16:9). Such limitations 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] For certain applications, it may be desirable for the encoder to instruct the decoder to use a specific reference picture size rather than implicitly assuming that the size is the output picture size. In this example, the syntax element reference_pic_size_present_flag(614) gates the conditional existence of the reference picture dimensions(615) (similarly, the numbers refer to both width and height).

[0078] Certain video coding techniques or standards, such as VP9, ​​support spatial scalability by implementing a specific form of reference picture resampling (signaled entirely differently from the disclosed subject) along with temporal scalability to enable spatial scalability. In particular, certain reference pictures can be upsampled to a higher resolution using ARC-style techniques to form the base of a spatially extended layer. These upsampled pictures can then be enhanced at higher resolutions using conventional predictive mechanisms to add detail.

[0079] The disclosed subject matter can be used in such environments according to the embodiments. In some cases, in the same or different embodiments, a value in the NAL unit header, for example, the time ID field, can be used to indicate not only the time layer but also the spatial layer. Doing so has particular advantages in the case of a particular system design. For example, an existing selective transfer unit (SFU) created and optimized for time layer selective transfer based on the value of the NAL unit header time ID can be used without modification for a scalable environment. To enable this, there may be a requirement for mapping between coded picture size and time layer, which is indicated by the time ID field in the NAL unit header.

[0080] In the embodiment, information regarding interlayer dependencies may be signaled within a VPS (or DPS, SPS, or SEI message). Interlayer dependency information may be used to identify which layer can be used as a reference layer to decode 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 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 interlayer reference picture (ILRP) list may be explicitly signaled along with the interpredictive 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 reverse predictive reference picture lists.

[0082] In the same or other embodiments, syntactic elements within VPS (or other parameter sets) can indicate whether each layer is dependent or independent. Referring to example (700) in Figure 7, the syntactic element vps_max_layers_minus1(703) plus 1 can specify one or more maximum numbers of layers potentially allowed in all CVS, referring to VPS(701). vps_all_independent_layers_flag(704) equal to 1 can specify that all layers in CVS are coded independently, i.e., without using interlayer prediction. vps_all_independent_layers_flag(704) equal to 0 can specify that one or more layers in CVS can use interlayer 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, then the value of vps_independent_layer_flag[0] is presumed to be equal to 1.

[0083] Referring to Figure 7, a vps_independent_layer_flag[i](706) equal to 1 can specify that the layer with index i does not use interlayer prediction. A vps_independent_layer_flag[i] equal to 0 can specify that the layer with index i can use interlayer prediction and that vps_layer_dependency_flag[i] exists within the VPS. A vps_direct_dependency_flag[i][j](707) equal to 0 can specify that the layer with index j is not a direct reference layer for the layer with index i. A vps_direct_dependency_flag[i][j] equal to 1 can specify that the layer with index j is a direct reference layer for the layer with index i. When no vps_direct_dependency_flag[i][j] exists for i and j in the range of 0 to vps_max_layers_minus1, it can be inferred that it is equal to 0.

[0084] The variables DirectDependentLayerIdx[i][j], which specifies the j-th direct dependent layer of the i-th layer, and NumDependentLayers[i], which specifies 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 Figure 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. A value of 0 for vps_output_layers_mode (708) specifies that only the top layer should be output. A vps_output_layer_mode equal to 1 specifies that all layers can be output. A vps_output_layer_mode equal to 2 can specify that the output layer is the layer whose vps_output_layer_flag[i](709) is equal to 1. The value of vps_output_layers_mode is in the range of 0 to 2. A value of 3 for vps_output_layer_mode may be reserved for future use. If it does not exist, the value of vps_output_layers_mode may be assumed to be equal to 1. A vps_output_layer_flag[i] equal to 1 can specify that the i-th layer is output. A vps_output_layer_flag[i] equal to 0 can specify that the i-th layer is not output. The list OutputLayerFlag[i], which can specify that the i-th layer is output with a value of 1 and that the i-th layer is not output with a value of 0, 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. -Instead, if PictureOutputFlag is equal to 0, the current picture is not output but is stored in the DPB as specified in the section. -If not (PictureOutputFlag is equal to 1 and DpbOutputTime[n] is greater than CpbRemovalTime[n]), the current picture is output later, stored in D PB (as specified in the section), and output at time DpbOutputTime[n] unless it is indicated that it will not be output by decoding or inferring no_output_of_prior_pics_flag equal to 1 at a time preceding DpbOutputTime[n]. When output, the picture is cropped using the suitability cropping window specified within the PPS file for the picture.

[0087] In the same or a different embodiment, PictureOutputFlag may be set as follows: -If any of the following conditions are true, PictureOutputFlag is set to equal to 0. -The current picture is a RASL picture, and the NoIncorrectP icOutputFlag of the associated IRAP picture is equal to 1. -gdr_enabled_flag is equal to 1, and the current picture is a GDR picture where NoIncorrectPicOutputFlag is equal to 1. -gdr_enabled_flag is equal to 1, the current picture is associated with a GDR picture where 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 or 2, and OutputLayerFlag[GeneralLayerIdx[n uh_layer_id]] is equal to 0. - Otherwise, PictureOutputFlag will be set to equal to pic_output_flag.

[0088] Alternatively, in the same or other embodiments, PictureOutputFlag may be set as follows: -If any of the following conditions are true, PictureOutputFlag is set to equal to 0. -The current picture is a RASL picture, and the NoIncorrectP icOutputFlag of the associated IRAP picture is equal to 1. -gdr_enabled_flag is equal to 1, and the current picture is a GDR picture where NoIncorrectPicOutputFlag is equal to 1. -gdr_enabled_flag is equal to 1, the current picture is associated with a GDR picture where 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, the current access unit has a Picture OutputFlag equal to 1, a nuh_layer_id nuhLid greater than the current picture, and contains a picture that belongs to the output layer (i.e., OutputLayerFlag[GeneralLayerIdx[nuhLid]] is equal to 1). -vps_output_layer_mode is equal to 2 and OutputLayerFlag[GeneralLayerIdx[nuh_laye r_id]] is equal to 0. - Otherwise, PictureOutputFlag will be set to equal to pic_output_flag.

[0089] In the same or other embodiments, a flag in the VPS (or another set of parameters) may indicate whether an ILRP list is currently signaling for a slice (or picture). For example, referring to example (800) in Figure 8, an inter_layer_ref_pics_present_flag equal to 0 may specify that ILRP is not used for inter-prediction of any coded picture in the CVS. An 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 k-th layer is a dependent layer, the interlayer reference picture (ILRP) list for pictures in the k-th layer may or may not be signaled. However, when the k-th layer is an independent layer, the ILRP list for pictures in the k-th layer is not signaled, and no ILRPs are included in the reference picture list.

[0091] The value of inter_layer_ref_pics_present_flag may be set 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 example (900) in Figure 9, a set of syntactic elements explicitly indicating the ILRP list may be signaled within the SPS, PPS, APS, or slice header. The ILRP list may be used to construct the 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 the decryption picture buffer (DPB). Active reference pictures may be used as reference pictures for decoding the current picture, while inactive reference pictures may not be used for decoding the current picture but may be used for decoding subsequent pictures in the decoding order.

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

[0095] In the same or a different embodiment, the syntax element ilrp_idc[listIdx][rplsIdx][i] may be signaled within a VPS, SPS, PPS, APS, or slice header. The syntax element ilrp_idc[listIdx][rplsIdx][i] specifies the index of the i-th item of the ILRP in the ref_pic_list_struct(listIdx,rplsIdx) syntax structure to the list of directly dependent layers. The value of ilrp_idc[listIdx][rplsIdx][i] is between 0 and GeneralLayerIdx[nuh_layer_id]-1.

[0096] In the same embodiment, the syntactic 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] which is signaled within the VPS. In this case, the value of ilrp_idc[listIdx][rplsIdx][i] shall be in the range of 0 or greater and NumDependentLayers[GeneralLayerIdx[nuh_layer_id]]-1 or less.

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

[0098] In the same or another embodiment, referring further to Figure 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 (a 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 (a reference picA with the same nuh_layer_id as the current picture exists in the DPB, PicOrderCntVal&(MaxPicOrderCntLsb-1) is equal to PocLsbLt[i][k]) RefPicList[ i ][ j ] = picA else RefPicList[ i ][ j ]=“no reference picture” RefPicLtPocList[ i ][ j ]=PocLsbLt[ i ][ k ] else { if (a 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 (nuh_layer_id is equal to refPicLayerId) a referenced picture picA exists in the DPB, (The same PicOrderCntVal exists as in the current picture.) RefPicList[ i ][ j ] = picA else RefPicList[ i ][ j ]=“no reference picture” } } }

[0099] The techniques for signaling the adaptive resolution parameters described above can be implemented as computer software using computer-readable instructions and can be physically stored in one or more computer-readable media. For example, Figure 10 shows 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 undergo assembly, compilation, linking, or similar mechanisms to create code that contains instructions that can be executed directly or via interpretation, microcode execution, etc., by a computer central processing unit (CPU), graphics processing unit (GPU), etc.

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

[0102] The components shown in Figure 10 for the computer system (1000) are essentially illustrative and do not imply any limitations on the scope or functionality of computer software implementing embodiments of this disclosure. The configuration of the components should not be construed as having any dependence or requirement on any one or combination of components shown in the exemplary embodiments of the computer system (1000).

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

[0104] Input human interface devices may include one or more of the following: keyboard (1001), mouse (1002), trackpad (1003), touchscreen (1010), joystick (1005), microphone (1006), scanner (1007), and 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 the senses of one or more human users, for example, through tactile output, sound, light, and smell / taste. Such human interface output devices may include tactile output devices (e.g., touchscreens (1010), or tactile feedback via joysticks (1005), although there may also be tactile feedback devices that do not function as input devices), audio output devices (such as speakers (1009), 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, each with or without tactile feedback capabilities, some of which may be capable of outputting two-dimensional visual output or three-dimensional or more 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 associated media such as optical media including CD / DVD ROM / RW (1020) having CD / DVD or similar media (1021), thumb drives (1022), removable hard drives or solid-state drives (1023), legacy magnetic media such as tapes and floppy disks (not described), and special ROM / ASIC / PLD-based devices such as security dongles (not described).

[0107] Those skilled in the art should also understand that the term “computer-readable medium” as used in connection with the subject matter currently disclosed does not include a transmission medium, carrier wave, or other transient signal.

[0108] The computer system (1000) may also include interfaces to one or more communication networks. These networks may be, for example, wireless, wired, or optical. Networks may further be local, wide-area, metropolitan, vehicle and industrial, real-time, or latency-tolerant. Examples of networks include local area networks such as Ethernet and wireless LANs; cellular networks such as GSM, 3G, 4G, 5G, and LTE; wired or wireless wide-area digital networks for television, including cable TV, satellite TV, and terrestrial broadcast TV; and vehicle and industrial networks such as CANBus. Certain networks typically require external network interface adapters attached to specific general-purpose data ports or peripheral buses (1049) (e.g., USB ports on the computer system (1000)), while other networks are typically integrated into the core of the computer system (1000) by being attached to system buses as described below (e.g., an Ethernet interface to a PC computer system or a cellular network interface to a smartphone computer system). Using any of these networks, the computer system (1000) can communicate with other entities. Such communications can be unidirectional (e.g., broadcast TV), unidirectional (e.g., CANbus to a specific CANbus device), or bidirectional (e.g., with other computer systems using local or wide-area digital networks). Specific protocols and protocol stacks can be used with each of those networks and network interfaces described above.

[0109] The aforementioned human interface device, human-accessible storage device, and network interface can 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), special programmable processing units in the form of field-programmable gate areas (FPGAs) (1043), hardware accelerators for specific tasks (1044), etc. These devices may be connected via a system bus (1048) along with read-only memory (ROM) (1045), random access memory (1046), internal mass storage such as hard drives and SSDs that are not accessible to the internal user (1047). 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 connected 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 certain instructions that, when combined, can constitute the aforementioned computer code. This computer code can be stored in ROM (1045) or RAM (1046). Transition data can also be stored in RAM (1046), while persistent data can be stored, for example, in internal mass storage (1047). High-speed storage and retrieval of any of the memory devices can be enabled using cache memory that can be closely associated with one or more CPUs (1041), GPUs (1042), mass storage (1047), ROM (1045), RAM (1046), etc.

[0112] Computer-readable media may contain computer code for performing various computer implementation operations. The media and computer code may be specifically designed and constructed for the purposes of this disclosure, or they may be of a type that is well known and available to persons skilled in computer software technology.

[0113] As an example, and not as an limitation, a computer system (1000) having an architecture, 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 may be user-accessible mass storage as described above, as well as media associated with specific storage of the core (1040) of a non-transient nature, such as core 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 may include one or more memory devices or chips, depending on the specific needs. The software can cause the core (1040), and specifically the processor (including a CPU, GPU, FPGA, etc.) therein, to execute specific processes or specific parts of specific processes described herein, including defining data structures stored in RAM (1046) and modifying such data structures according to processes defined by the software. As an addition or alternative, a computer system may provide functionality as a result of logic wired or otherwise embodied in circuitry (e.g., accelerators (1044)) that can operate in place of or in conjunction with software, in order to perform a particular process or a particular part of a particular process described herein. Where necessary, references to software may encompass logic, and vice versa. Where necessary, references to computer-readable media may encompass circuitry (such as integrated circuits (ICs)) that stores software for execution, circuitry that embodies logic for execution, or both. This disclosure encompasses any suitable combination of hardware and software.

[0114] While this disclosure describes several exemplary embodiments, there are many variations, substitutions, and alternative equivalents that fall within the scope of this disclosure. Those skilled in the art will therefore understand that numerous systems and methods embodying the principles of this disclosure, and thus falling within its spirit and scope, can be devised, although these are not expressly illustrated or described herein. [Explanation of Symbols]

[0115] 100 Communication Systems 110 terminals 120 devices 130 devices 140 devices 150 Networks 201 Video Sources 202 Uncompressed Video Sample Streams 203 Video Encoders 204 Encoded video bitstream 205 Streaming Servers 206 Streaming Clients 207 Copy of encoded video bitstream 208 Streaming Clients 209 Coding video bitstream copy 210 Video Decoders 211 Output video sample stream 212 displays 213 Capture Subsystem 310 Receiver 312 channels 315 buffer memory 320 Entropy Decoder / Parser 321 Symbols 351 Scaler / Inverse Unit 352 IntraPicture Prediction Units 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 sequences 445 Entropy Coder 450 Controllers 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 Example of a 600 table 615 Reference Picture Dimensions 700 cases 701 VPS 800 cases 900 cases 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 Accelerators 1045 Read-only memory (ROM) 1046 Random Access Memory (RAM) 1047 Internal large-capacity storage 1048 System Bus 1049 Local buses 1050 Graphics Adapter 1054 Network Interface

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...

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