Sub-picture signaling in high-level syntax for video codecs

Abstract

An example device includes a memory and one or more processors implemented in circuitry and communicatively coupled to the memory. The one or more processors are configured to determine a value of a first syntax element indicating a number of sub-pictures in a picture of video data. The one or more processors are configured to determine, for each sub-picture in the picture, a value of a corresponding second syntax element indicating an identity of the corresponding sub-picture. The one or more processors are further configured to encode or decode the corresponding sub-picture identified by the corresponding second syntax element.

Description

[0001] This application claims priority to U.S. Application No. 17 / 022,253, filed on September 16, 2020, which claims the benefit of U.S. Provisional Application No. 62 / 903,394, filed on September 20, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to video encoding and video decoding. Background Art

[0003] Digital video capabilities can be incorporated into a wide variety of devices, including digital televisions, digital live broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, digital cameras, digital recording devices, digital media players, video game devices, video game consoles, cellular or satellite wireless telephones, so-called "smart phones", video teleconferencing devices, video streaming devices, etc. Digital video devices implement video codec technologies, such as those described in the standards defined by MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264 / MPEG-4 Part 10, Advanced Video Codec (AVC), ITU-T H.265 / High Efficiency Video Codec (HEVC), and extensions of such standards. Video devices can more efficiently transmit, receive, encode, decode, and / or store digital video information by implementing such video codec technologies.

[0004] Video coding techniques include spatial (intra-picture) prediction and / or temporal (inter-picture) prediction to reduce or remove redundancy inherent in video sequences. For block-based video coding, a video slice (e.g., a video picture or a portion of a video picture) can be partitioned into video blocks, which can also be referred to as codec tree units (CTUs), codec units (CUs), and / or codec nodes. Video blocks in an intra-frame codec (I) slice of a picture are encoded using spatial prediction relative to reference samples in neighboring blocks in the same picture. Video blocks in an inter-frame codec (P or B) slice of a picture can use spatial prediction relative to reference samples in neighboring blocks in the same picture or temporal prediction relative to reference samples in other reference pictures. Pictures can be referred to as frames, and reference pictures can be referred to as reference frames. Summary of the Invention

[0005] In general, this disclosure describes techniques for signaling sub-pictures for video codecs. For example, some video decoders may have difficulty determining how many sub-pictures are present, or which sub-picture is associated with the video data to be decoded. The techniques of this disclosure address these issues.

[0006] In one example, a method for encoding and decoding video data includes: determining a value of a first syntax element indicating the number of sub-pictures in a picture of the video data; determining, for each sub-picture among the sub-pictures in the picture, a value of a corresponding second syntax element indicating an identification of the corresponding sub-picture; and encoding and decoding the corresponding sub-picture identified by the corresponding second syntax element.

[0007] In another example, a device for encoding and decoding video data includes: a memory configured to store the video data; and one or more processors implemented in a circuit and communicatively coupled to the memory, the one or more processors configured to: determine a value of a first syntax element indicating the number of sub-pictures in a picture of the video data; determine, for each sub-picture among the sub-pictures in the picture, a value of a corresponding second syntax element indicating an identification of the corresponding sub-picture; and encode and decode the corresponding sub-picture identified by the corresponding second syntax element.

[0008] In another example, an apparatus for encoding and decoding video data includes: a component for determining a value of a first syntax element indicating the number of sub-pictures in a picture of the video data; a component for determining, for each sub-picture among the sub-pictures in the picture, a value of a corresponding second syntax element indicating an identification of the corresponding sub-picture; and a component for encoding and decoding the corresponding sub-picture identified by the corresponding second syntax element.

[0009] In another example, a non-transitory computer-readable storage medium stores instructions that, when executed, cause one or more processors to: determine a value of a first syntax element indicating the number of sub-pictures in a picture of video data, determine, for each sub-picture among the sub-pictures in the picture, a value of a corresponding second syntax element indicating an identity of the corresponding sub-picture, and encode or decode the corresponding sub-picture identified by the corresponding second syntax element.

[0010] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a block diagram illustrating an example video encoding and decoding system that may perform the techniques of this disclosure.

[0012] Figure 2A and Figure 2B is a conceptual diagram illustrating an example quadtree binary tree (QTBT) structure and a corresponding codec tree unit (CTU).

[0013] Figure 3 is a block diagram illustrating an example video encoder that may perform the techniques of this disclosure.

[0014] Figure 4 is a block diagram illustrating an example video decoder that may perform the techniques of this disclosure.

[0015] Figure 5 is a flow chart illustrating an example of sub-picture signaling according to the techniques of this disclosure.

[0016] Figure 6 is a flowchart illustrating a method of encoding video data according to the techniques of this disclosure.

[0017] Figure 7 is a flowchart illustrating a method of decoding video data according to the techniques of this disclosure. DETAILED DESCRIPTION

[0018] Some video standards or drafts thereof may be designed to facilitate the extraction of sub-pictures from original pictures so that sub-pictures can be decoded without decoding the entire original picture, or can be decoded separately from other sub-pictures. For example, a viewer of video data may be interested in only a portion of a picture (e.g., a sub-picture). However, some video decoders may not be able to determine how to process sub-pictures. Some video decoders may not be able to determine how to extract sub-pictures from original pictures. Some video decoders may not be able to determine how to identify which sub-pictures to extract. If a video decoder cannot determine how to process sub-pictures, the video decoder may incorrectly decode video data associated with a picture or sub-picture, which may result in a poor user experience.

[0019] According to the techniques of this disclosure, a video encoder can signal syntax elements, and a video decoder can parse the syntax elements, enabling the video decoder to determine how to process sub-pictures. This disclosure describes several examples that can improve the signaling in sequence parameter sets (SPSs), picture parameter sets (PPSs), and slice headers related to sub-pictures. By parsing the signaled syntax elements according to the techniques of this disclosure, a video decoder can determine how to process sub-pictures and avoid erroneous decoding of video data associated with a picture or a sub-picture of a picture.

[0020] Figure 1 is a block diagram illustrating an example video encoding and decoding system 100 that can perform the techniques of the present disclosure. The techniques of the present disclosure are generally directed to encoding and decoding (encoding and / or decoding) video data. Generally speaking, video data includes any data used to process video. Thus, video data can include original unencoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata, such as signaling data.

[0021] like Figure 1As shown, in this example, a video encoding and decoding system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a destination device 116. Specifically, source device 102 provides the video data to destination device 116 via a computer-readable medium 110. Source device 102 and destination device 116 may include any of a variety of devices, including desktop computers, mobile devices (e.g., notebook (i.e., laptop) computers, tablet computers, telephone handsets (such as smartphones), cameras, etc.), set-top boxes, televisions, display devices, broadcast receiver devices, digital media players, video game consoles, video streaming devices, etc. In some cases, source device 102 and destination device 116 may be equipped for wireless communication and, therefore, may be referred to as wireless communication devices.

[0022] exist Figure 1 In the example of , source device 102 includes a video source 104, a memory 106, a video encoder 200, and an output interface 108. Destination device 116 includes an input interface 122, a video decoder 300, the memory 120, and a display device 118. According to the present disclosure, the video encoder 200 of source device 102 and the video decoder 300 of destination device 116 can be configured to apply the techniques described in the present disclosure to signaling notifications of sub-pictures. Source device 102 represents an example of a video encoding device, while destination device 116 represents an example of a video decoding device. In other examples, the source device and destination device can include other components or arrangements. For example, source device 102 can receive video data from an external video source (such as an external camera). Similarly, destination device 116 can be connected to an external display device instead of including an integrated display device.

[0023] like Figure 1The illustrated video encoding and decoding system 100 is merely an example. Generally speaking, any digital video encoding and / or decoding device can implement the techniques for signaling sub-pictures. Source device 102 and destination device 116 are merely examples of such codec devices, in which source device 102 generates encoded and decoded video data for transmission to destination device 116. This disclosure refers to a "codec" device as a device that performs encoding and / or decoding (encoding and / or decoding) of data. Thus, video encoder 200 and video decoder 300 represent examples of codec devices, and more specifically, examples of video encoders and video decoders, respectively. In some examples, source device 102 and destination device 116 can operate in a substantially symmetrical manner, such that each of source device 102 and destination device 116 includes video encoding and decoding components. Thus, video encoding and decoding system 100 can support one-way or two-way video transmission between source device 102 and destination device 116, for example, for video streaming, video playback, video broadcasting, or video telephony.

[0024] In general, video source 104 represents a source of video data (i.e., original, unencoded video data) and provides a continuous series of pictures (also referred to as "frames") of video data to video encoder 200, which encodes the picture data. Video source 104 of source device 102 may include a video capture device, such as a camera, a video archive containing previously captured raw video, and / or a video feed interface that receives video from a video content provider. As a further alternative, video source 104 may generate computer graphics-based data as the source video, or a combination of live video, archived video, and computer-generated video. In each case, video encoder 200 encodes captured, pre-captured, or computer-generated video data. Video encoder 200 may rearrange the pictures from the order in which they were received (sometimes referred to as "display order") into a codec order for encoding and decoding. Video encoder 200 may generate a bitstream comprising the encoded video data. Source device 102 may then output the encoded video data onto computer-readable medium 110 via output interface 108 for receipt and / or retrieval by, for example, input interface 122 of destination device 116 .

[0025] Memory 106 of source device 102 and memory 120 of destination device 116 represent general purpose memory. In some examples, memory 106 and memory 120 can store raw video data, e.g., raw video from video source 104 and raw decoded video data from video decoder 300. Additionally or alternatively, memory 106 and memory 120 can store executable software instructions (e.g., executable by video encoder 200 and video decoder 300, respectively). Although in this example, memory 106 and memory 120 are shown as separate from video encoder 200 and video decoder 300, it should be understood that video encoder 200 and video decoder 300 can also include internal memory for functionally similar or equivalent purposes. Furthermore, memory 106 and memory 120 can store encoded video data, e.g., encoded video data output from video encoder 200 and input to video decoder 300. In some examples, portions of memory 106 and memory 120 may be allocated as one or more video buffers, eg, for storing raw, decoded, and / or encoded video data.

[0026] The computer-readable medium 110 can represent any type of medium or device capable of transmitting encoded video data from the source device 102 to the destination device 116. In one example, the computer-readable medium 110 represents a communication medium that enables the source device 102 to transmit the encoded video data directly to the destination device 116 in real time (e.g., via a radio frequency network or a computer-based network). According to a communication standard such as a wireless communication protocol, the output interface 108 can modulate a transmission signal including the encoded video data, and the input interface 122 can demodulate the received transmission signal. The communication medium can include any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium can form part of a packet-based network such as a local area network, a wide area network, or a global network such as the Internet. The communication medium can include routers, switches, base stations, or any other device that can be used to facilitate communication from the source device 102 to the destination device 116.

[0027] In some examples, source device 102 may output the encoded data from output interface 108 to storage device 112. Similarly, destination device 116 may access the encoded data from storage device 112 via input interface 122. Storage device 112 may include any of a variety of distributed or locally accessed data storage media, such as a hard drive, Blu-ray disc, DVD, CD-ROM, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data.

[0028] In some examples, source device 102 may output the encoded video data to file server 114 or another intermediate storage device that may store the encoded video generated by source device 102. Destination device 116 may access the stored video data from file server 114 via streaming or downloading. File server 114 may be any type of server device capable of storing and transmitting the encoded video data to destination device 116. File server 114 may represent a network server (e.g., for a website), a file transfer protocol (FTP) server, a content delivery network device, or a network attached storage (NAS) device. Destination device 116 may access the encoded video data from file server 114 via any standard data connection, including an internet connection. This may include a wireless channel (e.g., a Wi-Fi connection), a wired connection (e.g., a digital subscriber line (DSL), a cable modem, etc.), or a combination of both, suitable for accessing the encoded video data stored on file server 114. File server 114 and input interface 122 may be configured to operate according to a streaming protocol, a download transfer protocol, or a combination thereof.

[0029] The output interface 108 and the input interface 122 may represent wireless transmitters / receivers, modems, wired network components (e.g., Ethernet cards), wireless communication components operating according to any of the various IEEE 802.11 standards, or other physical components. In examples where the output interface 108 and the input interface 122 include wireless components, the output interface 108 and the input interface 122 may be configured to transmit data (such as encoded video data) according to a cellular communication standard (such as 4G, 4G-LTE (Long Term Evolution), LTE-Advanced, 5G, etc.). In some examples where the output interface 108 includes a wireless transmitter, the output interface 108 and the input interface 122 may be configured to transmit data (such as encoded video data) according to other wireless standards (such as IEEE 802.11 specifications, IEEE 802.15 specifications (e.g., ZigBee TM ), Bluetooth TM Standards, etc.) for transmitting data (such as encoded video data). In some examples, source device 102 and / or destination device 116 may include corresponding system-on-chip (SoC) devices. For example, source device 102 may include a SoC device to perform the functions attributed to video encoder 200 and / or output interface 108, and destination device 116 may include a SoC device to perform the functions attributed to video decoder 300 and / or input interface 122.

[0030] The technology of the present disclosure can be applied to video encoding and decoding to support any of a variety of multimedia applications, such as over-the-air television broadcasting, cable television transmission, satellite television transmission, Internet streaming video transmission (e.g., Dynamic Adaptive Streaming over HTTP (DASH)), digital video encoded onto a data storage medium, decoding of digital video stored on a data storage medium, or other applications.

[0031] The input interface 122 of the destination device 116 receives the encoded video bitstream from the computer-readable medium 110 (e.g., a communication medium, a storage device 112, a file server 114, etc.). The encoded video bitstream may include signaling information defined by the video encoder 200 and used by the video decoder 300, such as syntax elements with values describing characteristics and / or processing of video blocks or other codec units (e.g., slices, pictures, groups of pictures, sequences, etc.). The display device 118 displays decoded pictures of the decoded video data to a user. The display device 118 may represent any of a variety of display devices, such as a cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or other types of display devices.

[0032] although Figure 1 2. Although not shown, in some examples, the video encoder 200 and the video decoder 300 can each be integrated with an audio encoder and / or an audio decoder and can include appropriate multiplexing-demultiplexing (MUX-DEMUX) units or other hardware and / or software to process a multiplexed stream including both audio and video in a common data stream. If applicable, the MUX-DEMUX units can conform to the ITU H.223 multiplexer protocol, or other protocols such as the User Datagram Protocol (UDP).

[0033] The video encoder 200 and the video decoder 300 can each be implemented as any of a variety of suitable encoder and / or decoder circuits, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic, software, hardware, firmware, or any combination thereof. When these techniques are partially implemented in software, the device can store the instructions of the software in a suitable non-transitory computer-readable medium and execute these instructions in hardware using one or more processors to perform the techniques of the present disclosure. Each of the video encoder 200 and the video decoder 300 can be included in one or more encoders or decoders, any of which can be integrated as part of a combined encoder / decoder (codec (CODEC)) in the corresponding device. A device including the video encoder 200 and / or the video decoder 300 can include an integrated circuit, a microprocessor, and / or a wireless communication device, such as a cellular phone.

[0034] The video encoder 200 and the video decoder 300 can operate according to a video codec standard, such as ITU-T H.265, also known as High Efficiency Video Coding (HEVC), or an extension thereof, such as a multi-view and / or scalable video codec extension. Alternatively, the video encoder 200 and the video decoder 300 can operate according to other proprietary or industry standards, such as ITU-T H.266, also known as Versatile Video Coding (VVC). "Versatile Video Coding (Draft 6)" by Bross et al. (Joint Video Experts Group (JVET) of ITU-T SG 16WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11, 15th Meeting: Gothenburg, SE, July 3-12, 2019, JVET-O2001-vE) (hereinafter referred to as "VVC Draft 6") is the latest draft of the VVC standard. However, the technology of the present disclosure is not limited to any particular codec standard.

[0035] In general, the video encoder 200 and the video decoder 300 can perform block-based encoding and decoding of pictures. The term "block" generally refers to a structure that includes data to be processed (e.g., data that is encoded, decoded, or otherwise used in the encoding and / or decoding process). For example, a block can include a two-dimensional matrix of samples of luma data and / or chroma data. In general, the video encoder 200 and the video decoder 300 can encode and decode video data represented in a YUV (e.g., Y, Cb, Cr) format. That is, instead of encoding and decoding red, green, and blue (RGB) data of samples of a picture, the video encoder 200 and the video decoder 300 can encode and decode luma components and chroma components, where the chroma components can include both red and blue hues. In some examples, the video encoder 200 converts received RGB formatted data into a YUV representation before encoding, and the video decoder 300 converts the YUV representation into an RGB format. Alternatively, a pre-processing unit and a post-processing unit (not shown) can perform these conversions.

[0036] The present disclosure may generally relate to the encoding and decoding of pictures (e.g., encoding and decoding), including the process of encoding or decoding the data of a picture. Similarly, the present disclosure may relate to the encoding and decoding of blocks of a picture, including the process of encoding or decoding the data of the block, for example, predictive encoding and / or residual encoding and decoding. The encoded video bitstream generally includes a series of syntax element values that represent the encoding and decoding decisions (e.g., the encoding and decoding mode) and the partitioning of the picture into blocks. Therefore, references to encoding and decoding a picture or block should generally be understood as encoding and decoding the values of the syntax elements that form the picture or block.

[0037] HEVC defines various blocks, including codec units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video codec (such as the video encoder 200) partitions a codec tree unit (CTU) into CUs according to a quadtree structure. That is, the video codec partitions the CTU and CU into four equal, non-overlapping squares, and each node of the quadtree has zero or four child nodes. A node without child nodes may be referred to as a "leaf node," and the CU of such a leaf node may include one or more PUs and / or one or more TUs. The video codec may further partition the PUs and TUs. For example, in HEVC, the residual quadtree (RQT) represents the partitioning of the TU. In HEVC, PU represents inter-frame prediction data, and TU represents residual data. An intra-predicted CU includes intra-frame prediction information, such as an intra-frame mode indication.

[0038] As another example, the video codec 200 and the video decoder 300 can be configured to operate according to VVC. According to VVC, a video codec (such as the video encoder 200) partitions a picture into multiple codec tree units (CTUs). The video encoder 200 can partition the CTU according to a tree structure (such as a quadtree-binary tree (QTBT) structure or a multi-type tree (MTT) structure). The QTBT structure removes the concept of multiple partition types, such as the separation between CU, PU and TU in HEVC. The QTBT structure includes two layers: a first layer that is partitioned according to quadtree partitioning, and a second layer that is partitioned according to binary tree partitioning. The root node of the QTBT structure corresponds to the CTU. The leaf nodes of the binary tree correspond to the codec units (CUs).

[0039] In the MTT partitioning structure, blocks can be partitioned using quadtree (QT) partitioning, binary tree (BT) partitioning, and one or more types of ternary tree (TT) (also known as triple tree (TT)) partitioning. Triple or triple tree partitioning is a partitioning that divides a block into three sub-blocks. In some examples, the ternary tree or triple tree partitioning divides the block into three sub-blocks without dividing the original block through the center. The partitioning types in MTT (e.g., QT, BT, and TT) can be symmetric or asymmetric.

[0040] In some examples, the video encoder 200 and the video decoder 300 may use a single QTBT or MTT structure to represent each of the luma and chroma components, while in other examples, the video encoder 200 and the video decoder 300 may use two or more QTBT or MTT structures, such as one QTBT / MTT structure for the luma component and another QTBT / MTT structure for the two chroma components (or two QTBT / MTT structures for the corresponding chroma components).

[0041] The video encoder 200 and the video decoder 300 can be configured to use quadtree segmentation, QTBT segmentation, MTT segmentation, or other segmentation structures in accordance with HEVC. For purposes of explanation, the description of the techniques of the present disclosure is presented with respect to QTBT segmentation. However, it should be understood that the techniques of the present disclosure can also be applied to video codecs configured to use quadtree segmentation or other types of segmentation.

[0042] Blocks (e.g., CTUs or CUs) can be grouped in a picture in various ways. As an example, a block can refer to a rectangular area of a CTU row within a particular slice in a picture. A tile can be a rectangular area of a CTU within a particular slice column and a particular slice row in a picture. A slice column refers to a rectangular area of a CTU whose height is equal to the height of the picture and whose width is specified by a syntax element (e.g., such as in a picture parameter set). A slice row refers to a rectangular area of a CTU whose height is specified by a syntax element (e.g., such as in a picture parameter set) and whose width is equal to the width of the picture.

[0043] In some examples, a slice may be partitioned into multiple tiles, each of which may include one or more CTU rows within the slice. A slice that is not partitioned into multiple tiles may also be referred to as a tile. However, a tile that is a true subset of a slice may not be referred to as a slice.

[0044] Tiles in a picture can also be arranged into slices. A slice can be an integer number of tiles of a picture that can be exclusively contained in a single Network Abstraction Layer (NAL) unit. In some examples, a slice includes a contiguous sequence of complete tiles of multiple complete slices or just one slice.

[0045] This disclosure may use "N×N" and "N by N" interchangeably to refer to the sample size of a block (such as a CU or other video block) in terms of vertical and horizontal dimensions, for example, 16×16 samples or 16 by 16 samples. In general, a 16×16 CU has 16 samples in the vertical direction (y=16) and 16 samples in the horizontal direction (x=16). Similarly, an N×NCU typically has N samples in the vertical direction and N samples in the horizontal direction, where N represents a non-negative integer value. The samples in a CU can be arranged in rows and columns. In addition, a CU does not need to have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU may include N×M samples, where M is not necessarily equal to N.

[0046] The video encoder 200 encodes the video data of the CU representing prediction information and / or residual information and other information. The prediction information indicates how the CU will be predicted to form the prediction block of the CU. The residual information generally represents the sample-by-sample difference between the samples of the CU before encoding and the prediction block.

[0047] To predict a CU, the video encoder 200 may typically form a prediction block for the CU through inter-frame prediction or intra-frame prediction. Inter-frame prediction typically refers to predicting a CU based on data of a previously coded picture, while intra-frame prediction typically refers to predicting a CU based on previously coded data of the same picture. To perform inter-frame prediction, the video encoder 200 may use one or more motion vectors to generate a prediction block. The video encoder 200 may typically perform a motion search to identify a reference block that closely matches the CU, for example, in terms of the difference between the CU and the reference block. The video encoder 200 may calculate a difference metric using the sum of absolute differences (SAD), the sum of squared differences (SSD), the mean absolute difference (MAD), the mean squared difference (MSD), or other such difference calculations to determine whether the reference block closely matches the current CU. In some examples, the video encoder 200 may use unidirectional prediction or bidirectional prediction to predict the current CU.

[0048] Some examples of VVC also provide an affine motion compensation mode, which can be considered an inter-prediction mode. In affine motion compensation mode, the video encoder 200 can determine two or more motion vectors representing non-translational motion, such as zooming in or out, rotation, perspective motion, or other irregular motion types.

[0049] To perform intra prediction, the video encoder 200 can select an intra prediction mode to generate a prediction block. Some examples of VVC provide 67 intra prediction modes, including various directional modes as well as planar and DC modes. In general, the video encoder 200 selects an intra prediction mode that describes the neighboring samples of the current block (e.g., the block of the CU) and predicts the samples of the current block based on the mode. Assuming that the video encoder 200 encodes and decodes the CTU and CU in raster scan order (from left to right, from top to bottom), such samples can typically be above, to the upper left, or to the left of the current block in the same picture as the current block.

[0050] The video encoder 200 encodes data indicating a prediction mode for the current block. For example, for inter-frame prediction mode, the video encoder 200 may encode data indicating which of various available inter-frame prediction modes to use, as well as motion information for the corresponding mode. For example, for unidirectional or bidirectional inter-frame prediction, the video encoder 200 may encode motion vectors using advanced motion vector prediction (AMVP) or merge mode. The video encoder 200 may use a similar mode to encode motion vectors for affine motion compensation mode.

[0051] After a prediction (such as intra-frame prediction or inter-frame prediction of a block), the video encoder 200 can calculate residual data for the block. The residual data (such as a residual block) represents the sample-by-sample difference between the block and a predicted block of the block formed using the corresponding prediction mode. The video encoder 200 can apply one or more transforms to the residual block to generate transform data in a transform domain rather than a sample domain. For example, the video encoder 200 can apply a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to the residual video data. In addition, the video encoder 200 can apply a secondary transform after the first transform, such as a mode-dependent non-separable secondary transform (MDNSST), a signal-dependent transform, a Karhunen-Loeve transform (KLT), etc. The video encoder 200 generates transform coefficients after applying one or more transforms.

[0052] As described above, after any transform that produces transform coefficients, the video encoder 200 can perform quantization of the transform coefficients. Quantization generally refers to a process in which transform coefficients are quantized to minimize the amount of data used to represent the transform coefficients, thereby providing further compression. By performing the quantization process, the video encoder 200 can reduce the bit depth associated with some or all transform coefficients. For example, the video encoder 200 can round down an n-bit value to an m-bit value during quantization, where n is greater than m. In some examples, to perform quantization, the video encoder 200 can perform a bit-by-bit right shift of the value to be quantized.

[0053] After quantization, the video encoder 200 can scan the transform coefficients to produce a one-dimensional vector based on the two-dimensional matrix including the quantized transform coefficients. The scan can be designed to place transform coefficients with higher energy (and therefore lower frequency) at the front of the vector and transform coefficients with lower energy (and therefore higher frequency) at the back of the vector. In some examples, the video encoder 200 can scan the quantized transform coefficients using a predefined scan order to produce a serialized vector and then entropy encode the quantized transform coefficients of the vector. In other examples, the video encoder 200 can perform adaptive scanning. After scanning the quantized transform coefficients to form a one-dimensional vector, the video encoder 200 can entropy encode the one-dimensional vector (e.g., according to context-adaptive binary arithmetic coding (CABAC)). The video encoder 200 can also entropy encode the values of syntax elements that describe metadata associated with the encoded video data for use by the video decoder 300 when decoding the video data.

[0054] To perform CABAC, the video encoder 200 may assign context within a context model to a symbol to be transmitted. The context may relate to, for example, whether the neighboring values of the symbol are zero values. The probability determination may be based on the context assigned to the symbol.

[0055] The video encoder 200 may also generate syntax data (such as block-based syntax data, picture-based syntax data, and sequence-based syntax data) to the video decoder 300 (e.g., in a picture header, block header, slice header, or other syntax data such as a sequence parameter set (SPS), a picture parameter set (PPS), or a video parameter set (VPS)). The video decoder 300 may also decode such syntax data to determine how to decode the corresponding video data.

[0056] In this way, the video encoder 200 can generate a bitstream including the encoded video data, for example, syntax elements describing the partitioning of a picture into blocks (e.g., CUs) or sub-pictures, and prediction information and / or residual information of the blocks or sub-pictures. Ultimately, the video decoder 300 can receive the bitstream and decode the encoded video data.

[0057] In general, the video decoder 300 performs a process that is inverse to the process performed by the video encoder 200 to decode the encoded video data of the bitstream. For example, the video decoder 300 can use CABAC to decode the values of the syntax elements of the bitstream in a manner substantially similar to (although inverse to) the CABAC encoding process of the video encoder 200. The syntax elements can define partitioning information for partitioning a picture into CTUs and partitioning each CTU according to a corresponding partitioning structure (such as a QTBT structure) to define CUs of the CTU. The syntax elements can also define prediction information and residual information for a block of video data (e.g., a CU).

[0058] The residual information may be represented by, for example, quantized transform coefficients. The video decoder 300 may inverse quantize and inverse transform the quantized transform coefficients of the block to reproduce a residual block for the block. The video decoder 300 uses the signaled prediction mode (intra-frame prediction or inter-frame prediction) and related prediction information (e.g., motion information for inter-frame prediction) to form a prediction block for the block. The video decoder 300 may then combine the prediction block and the residual block (on a sample-by-sample basis) to reproduce the original block. The video decoder 300 may perform additional processing, such as performing a deblocking process to reduce visual artifacts along block boundaries.

[0059] As described above, a video decoder (such as video decoder 300) may not be able to determine how to handle sub-pictures within a picture. The techniques of the present disclosure provide a method by which a video encoder (such as video encoder 200) can signal syntax elements and a video decoder (such as video decoder 300) can parse the syntax elements, thereby enabling the video decoder to determine how to handle sub-pictures within a picture.

[0060] According to the technology of the present disclosure, a method for encoding and decoding video data includes: determining the value of a first syntax element indicating the number of sub-pictures in a picture of the video data; determining, for each sub-picture among the sub-pictures in the picture, the value of a corresponding second syntax element indicating the identification of the corresponding sub-picture; and encoding and decoding the corresponding sub-picture identified by the corresponding second syntax element.

[0061] According to the technology of the present disclosure, a device includes: a memory (e.g., Figure 1 ), configured to store video data; one or more processors implemented in circuitry and communicatively coupled to the memory, the one or more processors being configured to: determine a value of a first syntax element indicating the number of sub-pictures in a picture of the video data; determine, for each sub-picture among the sub-pictures in the picture, a value of a corresponding second syntax element indicating an identification of the corresponding sub-picture; and encode and decode the corresponding sub-picture identified by the corresponding second syntax element.

[0062] According to the technology of the present disclosure, a device includes: a component for determining a value of a first syntax element indicating the number of sub-pictures in a picture of video data; a component for determining, for each sub-picture among the sub-pictures in the picture, a value of a corresponding second syntax element indicating an identification of the corresponding sub-picture; and a component for encoding and decoding the corresponding sub-picture identified by the corresponding second syntax element.

[0063] According to the technology of the present disclosure, a computer-readable storage medium is encoded with instructions that, when executed, cause one or more processors to: determine a value of a first syntax element indicating the number of sub-pictures in a picture of video data, determine, for each sub-picture among the sub-pictures in the picture, a value of a corresponding second syntax element indicating an identification of the corresponding sub-picture, and encode or decode the corresponding sub-picture identified by the corresponding second syntax element.

[0064] This disclosure may generally refer to "signaling" certain information, such as syntax elements. The term "signaling" may generally refer to the communication of syntax element values and / or other data used to decode encoded video data. That is, video encoder 200 may signal the values of syntax elements in a bitstream. Generally speaking, signaling refers to generating values in a bitstream. As described above, source device 102 may transmit the bitstream to destination device 116 in substantially real time or in non-real time (such as may occur when storing syntax elements to storage device 112 for later retrieval by destination device 116).

[0065] Figure 2A and Figure 2Bis a conceptual diagram showing an example quadtree binary tree (QTBT) structure 130 and a corresponding codec tree unit (CTU) 132. Solid lines represent quadtree partitions, while dashed lines represent binary tree partitions. In each partition (i.e., non-leaf) node of the binary tree, a flag is signaled to indicate which partition type (i.e., horizontal or vertical) is used, where in this example, 0 indicates horizontal partitioning and 1 indicates vertical partitioning. For quadtree partitioning, there is no need to indicate the partition type because the quadtree node divides the block horizontally and vertically into 4 equally sized sub-blocks. Accordingly, the video encoder 200 can encode and the video decoder 300 can decode syntax elements (such as partition information) of the region tree level (i.e., solid lines) of the QTBT structure 130 and syntax elements (such as partition information) of the prediction tree level (i.e., dashed lines) of the QTBT structure 130. The video encoder 200 may encode and the video decoder 300 may decode video data, such as prediction data and transform data, of the CU represented by the terminal leaf node of the QTBT structure 130 .

[0066] Generally speaking, Figure 2B The CTU 132 may be associated with parameters defining block sizes corresponding to nodes at the first and second levels of the QTBT structure 130. These parameters may include a CTU size (indicating the size of the CTU 132 in a sample), a minimum quadtree size (MinQTSize, indicating the minimum allowed quadtree leaf node size), a maximum binary tree size (MaxBTSize, indicating the maximum allowed binary tree root node size), a maximum binary tree depth (MaxBTDepth, indicating the maximum allowed binary tree depth), and a minimum binary tree size (MinBTSize, indicating the minimum allowed binary tree leaf node size).

[0067] The root node of the QTBT structure corresponding to the CTU can have four child nodes at the first level of the QTBT structure, and each child node can be split according to the quadtree partitioning. That is, the nodes of the first level are either leaf nodes (no child nodes) or have four child nodes. The example of the QTBT structure 130 represents such a node as including a parent node and a child node with a solid line branch. If the node of the first level is not larger than the maximum allowed binary tree root node size (MaxBTSize), the node can be further partitioned by the corresponding binary tree. The binary tree partitioning of a node can be iterated until the node generated by the partition reaches the minimum allowed binary tree leaf node size (MinBTSize) or the maximum allowed binary tree depth (MaxBTDepth). The example of the QTBT structure 130 represents such a node as having a dotted line branch. The binary tree leaf node is called a coding unit (CU), which is used for prediction (e.g., intra-picture prediction or inter-picture prediction) and transformation without any further partitioning. As described above, a CU can also be referred to as a "video block" or "block".

[0068] In one example of a QTBT partitioning structure, the CTU size is set to 128×128 (a luma sample and two corresponding 64×64 chroma samples), MinQTSize is set to 16×16, MaxBTSize is set to 64×64, MinBTSize (for width and height) is set to 4, and MaxBTDepth is set to 4. Quadtree partitioning is first applied to the CTU to generate quadtree leaf nodes. The size of the quadtree leaf node can be from 16×16 (i.e., MinQTSize) to 128×128 (i.e., the CTU size). If the leaf quadtree node is 128×128, the leaf quadtree node will not be further partitioned by the binary tree because the size exceeds MaxBTSize (i.e., 64×64 in this example). Otherwise, the leaf quadtree node will be further partitioned by the binary tree. Therefore, the quadtree leaf node is also the root node of the binary tree, and its binary tree depth is 0. When the binary tree depth reaches MaxBTDepth (4 in this example), no further splitting is allowed. When the width of a binary tree node is equal to MinBTSize (4 in this example), this means that no further vertical splitting is allowed. Similarly, a binary tree node with a height equal to MinBTSize means that no further horizontal splitting is allowed for the binary tree node. As described above, the leaf nodes of the binary tree are called CUs and are further processed according to prediction and transformation without further splitting.

[0069] Figure 3 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure. Figure 3This is provided for purposes of explanation and should not be considered limiting of the techniques broadly exemplified and described in this disclosure. For purposes of explanation, this disclosure describes video encoder 200 in the context of video codec standards, such as the HEVC video codec standard and the developing H.266 video codec standard. However, the techniques of this disclosure are not limited to these video codec standards and are generally applicable to video encoding and decoding.

[0070] exist Figure 3 In the example of FIG, the video encoder 200 includes a video data memory 230, a mode selection unit 202, a residual generation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a filter unit 216, a decoded picture buffer (DPB) 218, and an entropy coding unit 220. Any or all of the video data memory 230, the mode selection unit 202, the residual generation unit 204, the transform processing unit 206, the quantization unit 208, the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the filter unit 216, the DPB 218, and the entropy coding unit 220 may be implemented in one or more processors or in processing circuitry. Furthermore, the video encoder 200 may include additional or alternative processors or processing circuitry to perform these and other functions.

[0071] The video data memory 230 may store video data encoded by the components of the video encoder 200. The video encoder 200 may receive video data from, for example, the video source 104 ( Figure 1 ) receives video data stored in the video data memory 230. The DPB 218 can act as a reference picture memory that stores reference video data for use by the video encoder 200 when predicting subsequent video data. The video data memory 230 and the DPB 218 can be formed by any of a variety of memory devices, such as dynamic random access memory (DRAM) (including synchronous DRAM (SDRAM)), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. The video data memory 230 and the DPB 218 can be provided by the same memory device or separate memory devices. In various examples, the video data memory 230 can be located on the chip with the other components of the video encoder 200, as shown, or off-chip relative to those components.

[0072] In this disclosure, references to the video data memory 230 should not be construed as limited to memory internal to the video encoder 200, unless specifically described as such, or to memory external to the video encoder 200, unless specifically described as such. Rather, references to the video data memory 230 should be understood as reference memory that stores video data received by the video encoder 200 for encoding (e.g., video data of a current block to be encoded). Figure 1 The memory 106 may also provide temporary storage for outputs from the various units of the video encoder 200 .

[0073] Shown Figure 3 The various units of the video encoder 200 are described to help understand the operations performed by the video encoder 200. These units can be implemented as fixed-function circuits, programmable circuits, or a combination thereof. Fixed-function circuits refer to circuits that provide a specific function and have preset operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functions in the operations that can be performed. For example, a programmable circuit can execute software or firmware that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. Fixed-function circuits can execute software instructions (for example, to receive parameters or output parameters), but the type of operations performed by the fixed-function circuits are generally immutable. In some examples, one or more units can be different circuit blocks (fixed-function or programmable), and in some examples, one or more units can be integrated circuits.

[0074] The video encoder 200 may include an arithmetic logic unit (ALU), an elementary function unit (EFU), a digital circuit, an analog circuit, and / or a programmable core formed by a programmable circuit. In an example where the operation of the video encoder 200 is performed using software executed by a programmable circuit, the memory 106 ( Figure 1 ) may store instructions (eg, object code) for software received and executed by the video encoder 200, or another memory (not shown) within the video encoder 200 may store such instructions.

[0075] The video data memory 230 is configured to store received video data. The video encoder 200 can retrieve a picture of the video data from the video data memory 230 and provide the video data to the residual generation unit 204 and the mode selection unit 202. The video data in the video data memory 230 can be the original video data to be encoded.

[0076] The mode selection unit 202 includes a motion estimation unit 222, a motion compensation unit 224, and an intra prediction unit 226. The mode selection unit 202 may include additional functional units to perform video prediction according to other prediction modes. For example, the mode selection unit 202 may include a palette unit, an intra block copy unit (which may be part of the motion estimation unit 222 and / or the motion compensation unit 224), an affine unit, a linear model (LM) unit, etc.

[0077] The mode selection unit 202 typically coordinates multiple encoding passes to test combinations of encoding parameters and the resulting rate-distortion values of these combinations. The encoding parameters may include partitioning information for partitioning a CTU into CUs, a prediction mode for a CU, a transform type for residual data of a CU, a quantization parameter for residual data of a CU, etc. The mode selection unit 202 may ultimately select a combination of encoding parameters that has a better rate-distortion value than other tested combinations.

[0078] The video encoder 200 may partition a picture retrieved from the video data memory 230 into a series of CTUs and encapsulate one or more CTUs into a slice. The mode selection unit 202 may partition the CTUs of the picture according to a tree structure (such as the QTBT structure described above or the quadtree structure of HEVC). As described above, the video encoder 200 may form one or more CUs by partitioning the CTUs according to the tree structure. Such CUs may also be generally referred to as "video blocks" or "blocks."

[0079] In general, the mode select unit 202 also controls its components (e.g., the motion estimation unit 222, the motion compensation unit 224, and the intra prediction unit 226) to generate a prediction block for the current block (e.g., the current CU, or, in HEVC, the overlapping portions of the PU and TU). For inter prediction of the current block, the motion estimation unit 222 may perform a motion search to identify one or more closely matching reference blocks in one or more reference pictures (e.g., one or more previously coded pictures stored in the DPB 218). Specifically, the motion estimation unit 222 may calculate a value representing how similar the potential reference blocks are to the current block (e.g., based on the sum of absolute differences (SAD), sum of squared differences (SSD), mean absolute difference (MAD), mean squared difference (MSD), etc.). The motion estimation unit 222 may typically perform these calculations using the sample-by-sample differences between the current block and the reference block being considered. The motion estimation unit 222 may identify the reference block with the lowest value resulting from these calculations, thereby indicating the reference block that most closely matches the current block.

[0080] Motion estimation unit 222 may form one or more motion vectors (MVs) that define the position of a reference block in a reference picture relative to the position of a current block in a current picture. Motion estimation unit 222 may then provide the motion vectors to motion compensation unit 224. For example, for unidirectional inter prediction, motion estimation unit 222 may provide a single motion vector, while for bidirectional inter prediction, motion estimation unit 222 may provide two motion vectors. Motion compensation unit 224 may then use the motion vectors to generate a prediction block. For example, motion compensation unit 224 may use the motion vectors to retrieve data for the reference block. As another example, if the motion vectors have fractional sample precision, motion compensation unit 224 may interpolate the values of the prediction block based on one or more interpolation filters. Furthermore, for bidirectional inter prediction, motion compensation unit 224 may retrieve data for two reference blocks identified by the corresponding motion vectors and combine the retrieved data (e.g., by sample-by-sample averaging or weighted averaging).

[0081] As another example, for intra prediction or intra prediction codecs, the intra prediction unit 226 can generate a prediction block based on samples adjacent to the current block. For example, for directional mode, the intra prediction unit 226 can generally mathematically combine the values of the adjacent samples and pad these calculated values in a defined direction on the current block to produce a prediction block. As another example, for DC mode, the intra prediction unit 226 can calculate the average of the adjacent samples of the current block and generate a prediction block including this average for each sample of the prediction block.

[0082] Mode selection unit 202 provides the prediction block to residual generation unit 204. Residual generation unit 204 receives the original, unencoded version of the current block from video data memory 230 and the prediction block from mode selection unit 202. Residual generation unit 204 calculates the sample-by-sample difference between the current block and the prediction block. The resulting sample-by-sample difference defines a residual block for the current block. In some examples, residual generation unit 204 may also determine the difference between the sample values in the residual block to generate the residual block using residual differential pulse code modulation (RDPCM). In some examples, residual generation unit 204 may be implemented using one or more subtractor circuits that perform binary subtraction.

[0083] In some examples, mode selection unit 202 may determine a first syntax element indicating the number of sub-pictures in the picture. For at least one corresponding sub-picture in the sub-pictures in the picture, mode selection unit 202 may also determine a corresponding second syntax element indicating an identity of the at least one corresponding sub-picture.

[0084] In the example where the mode selection unit 202 partitions the CU into PUs, each PU may be associated with a luma prediction unit and a corresponding chroma prediction unit. The video encoder 200 and the video decoder 300 may support PUs of various sizes. As described above, the size of the CU may refer to the size of the luma codec block of the CU, and the size of the PU may refer to the size of the luma prediction unit of the PU. Assuming that the size of a particular CU is 2N×2N, the video encoder 200 may support PU sizes of 2N×2N or N×N for intra prediction, and symmetric PU sizes of 2N×2N, 2N×N, N×2N, N×N, or similar for inter prediction. The video encoder 200 and the video decoder 300 may also support asymmetric partitioning of PU sizes of 2N×nU, 2N×nD, nL×2N, and nR×2N for inter prediction.

[0085] In an example where the mode selection unit 202 does not further partition the CU into PUs, each CU may be associated with a luma codec block and a corresponding chroma codec block. As described above, the size of a CU may refer to the size of the luma codec block of the CU. The video encoder 200 and the video decoder 300 may support CU sizes of 2N×2N, 2N×N, or N×2N.

[0086] For other video codecs, such as intra block copy mode codec, affine mode codec, and linear model (LM) mode codec, as a few examples, the mode selection unit 202 generates a prediction block for the current block being encoded via the corresponding unit associated with the codec. In some examples, such as palette mode codec, the mode selection unit 202 may not generate a prediction block, but instead generate syntax elements indicating how to reconstruct the block based on the selected palette. In such a mode, the mode selection unit 202 may provide these syntax elements to the entropy coding unit 220 for encoding.

[0087] As described above, the residual generation unit 204 receives video data of a current block and a corresponding prediction block. The residual generation unit 204 then generates a residual block for the current block. To generate the residual block, the residual generation unit 204 calculates the sample-by-sample difference between the prediction block and the current block.

[0088] The transform processing unit 206 applies one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a "transform coefficient block"). The transform processing unit 206 may apply various transforms to the residual block to form the transform coefficient block. For example, the transform processing unit 206 may apply a discrete cosine transform (DCT), a directional transform, a Karhunen-Loeve transform (KLT), or a conceptually similar transform to the residual block. In some examples, the transform processing unit 206 may perform multiple transforms on the residual block, for example, a primary transform and a secondary transform, such as a rotation transform. In some examples, the transform processing unit 206 does not apply a transform to the residual block.

[0089] The quantization unit 208 may quantize the transform coefficients in the transform coefficient block to produce a quantized transform coefficient block. The quantization unit 208 may quantize the transform coefficients of the transform coefficient block according to a quantization parameter (QP) value associated with the current block. The video encoder 200 (e.g., via the mode selection unit 202) may adjust the degree of quantization applied to the transform coefficient block associated with the current block by adjusting the QP value associated with the CU. Quantization may introduce a loss of information, and therefore, the quantized transform coefficients may have a lower precision than the original transform coefficients produced by the transform processing unit 206.

[0090] The inverse quantization unit 210 and the inverse transform processing unit 212 may apply inverse quantization and inverse transform, respectively, to the quantized transform coefficient block to reconstruct a residual block based on the transform coefficient block. The reconstruction unit 214 may generate a reconstructed block corresponding to the current block (albeit potentially with some degree of distortion) based on the reconstructed residual block and the prediction block generated by the mode selection unit 202. For example, the reconstruction unit 214 may add samples of the reconstructed residual block to corresponding samples from the prediction block generated by the mode selection unit 202 to generate the reconstructed block.

[0091] Filter unit 216 may perform one or more filtering operations on the reconstructed block. For example, filter unit 216 may perform a deblocking operation to reduce blocking artifacts along the edges of the CU. In some examples, the operations of filter unit 216 may be skipped.

[0092] The video encoder 200 stores the reconstructed block in the DPB 218. For example, in examples where the operation of the filter unit 216 is not required, the reconstruction unit 214 can store the reconstructed block in the DPB 218. In examples where the operation of the filter unit 216 is required, the filter unit 216 can store the filtered reconstructed block in the DPB 218. The motion estimation unit 222 and the motion compensation unit 224 can retrieve a reference picture formed by the reconstructed (and potentially filtered) block from the DPB 218 to perform inter-frame prediction on blocks of subsequently encoded pictures. In addition, the intra-frame prediction unit 226 can use the reconstructed block in the DPB 218 of the current picture to perform intra-frame prediction on other blocks in the current picture.

[0093] In general, entropy coding unit 220 may entropy encode syntax elements received from other functional components of video encoder 200. For example, entropy coding unit 220 may entropy encode quantized transform coefficient blocks from quantization unit 208. As another example, entropy coding unit 220 may entropy encode prediction syntax elements (e.g., motion information for inter-frame prediction or intra-frame mode information for intra-frame prediction) from mode selection unit 202. Entropy coding unit 220 may perform one or more entropy coding operations on syntax elements, another example of video data, to generate entropy-encoded data. For example, entropy coding unit 220 may perform a context-adaptive variable length coding (CAVLC) operation, a CABAC operation, a variable-to-variable (V2V) length coding operation, a syntax-based context-adaptive binary arithmetic coding (SBAC) operation, a probability interval partitioning entropy (PIPE) coding operation, an exponential-Golomb coding operation, or another type of entropy coding operation on the data. In some examples, entropy coding unit 220 may operate in a bypass mode in which no entropy coding is performed on the syntax elements.

[0094] The video encoder 200 may output a bitstream including entropy-encoded syntax elements required to reconstruct a block of a slice or picture. Specifically, the entropy encoding unit 220 may output a bitstream.

[0095] The operations described above are described with respect to blocks. This description should be understood as operations on luma codec blocks and / or chroma codec blocks. As described above, in some examples, the luma codec blocks and chroma codec blocks are the luma components and chroma components of a CU. In some examples, the luma codec blocks and chroma codec blocks are the luma components and chroma components of a PU.

[0096] In some examples, the operations performed for luma codec blocks do not need to be repeated for chroma codec blocks. As an example, the operations for identifying the motion vector (MV) and reference picture for the luma codec block do not need to be repeated for identifying the MV and reference picture for the chroma blocks. Instead, the MV of the luma codec block can be scaled to determine the MV of the chroma blocks, and the reference picture can be the same. As another example, the intra prediction process can be the same for luma codec blocks and chroma codec blocks.

[0097] Video encoder 200 represents an example of a device configured to encode video data, the device comprising: a memory configured to store the video data; and one or more processors implemented in circuitry and communicatively coupled to the memory, the one or more processors configured to: determine a value of a first syntax element indicating a number of sub-pictures in a picture of the video data, determine, for each sub-picture among the sub-pictures in the picture, a value of a corresponding second syntax element indicating an identity of the corresponding sub-picture, and encode the corresponding sub-picture identified by the corresponding second syntax element.

[0098] Figure 4 is a block diagram illustrating an example video decoder 300 that may perform the techniques of this disclosure. Figure 4 This is provided for the purpose of explanation and does not limit the techniques broadly exemplified and described in this disclosure. For the purpose of explanation, this disclosure describes a video decoder 300 based on techniques of VVC and HEVC. However, the techniques of this disclosure can be performed by video codec devices configured to comply with other video codec standards.

[0099] exist Figure 4 In the example of FIG, the video decoder 300 includes a codec picture buffer (CPB) memory 320, an entropy decoding unit 302, a prediction processing unit 304, an inverse quantization unit 306, an inverse transform processing unit 308, a reconstruction unit 310, a filter unit 312, and a decoded picture buffer (DPB) 314. Any or all of the CPB memory 320, the entropy decoding unit 302, the prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, the filter unit 312, and the DPB 314 may be implemented in one or more processors or in processing circuitry. Furthermore, the video decoder 300 may include additional or alternative processors or processing circuitry to perform these and other functions.

[0100] The prediction processing unit 304 includes a motion compensation unit 316 and an intra prediction unit 318. The prediction processing unit 304 may include additional units to perform prediction according to other prediction modes. As an example, the prediction processing unit 304 may include a palette unit, an intra block copy unit (which may form part of the motion compensation unit 316), an affine unit, a linear model (LM) unit, etc. In other examples, the video decoder 300 may include more, fewer, or different functional components.

[0101] The CPB memory 320 may store video data, such as an encoded video bitstream, to be decoded by components of the video decoder 300. The video data stored in the CPB memory 320 may be obtained from, for example, the computer readable medium 110 ( Figure 1 ). The CPB memory 320 may include a CPB that stores coded video data (e.g., syntax elements) from the coded video bitstream. In addition, the CPB memory 320 may store video data other than syntax elements for codecd pictures, such as temporary data representing outputs from various units of the video decoder 300. The DPB 314 typically stores decoded pictures, which the video decoder 300 may output and / or use as reference video data when decoding subsequent data or pictures of the coded video bitstream. The CPB memory 320 and the DPB 314 may be formed from any of a variety of memory devices, such as DRAM (including SDRAM), MRAM, RRAM, or other types of memory devices. The CPB memory 320 and the DPB 314 may be provided by the same memory device or by separate memory devices. In various examples, the CPB memory 320 may be located on-chip with other components of the video decoder 300, or off-chip relative to those components.

[0102] Additionally or alternatively, in some examples, video decoder 300 may retrieve the video from memory 120 ( Figure 1 ) to retrieve the encoded and decoded video data from the CPB memory 320. That is, the memory 120 may store data as discussed above with respect to the CPB memory 320. Similarly, when some or all of the functionality of the video decoder 300 is implemented in software executed by the processing circuitry of the video decoder 300, the memory 120 may store instructions executed by the video decoder 300.

[0103] Shown Figure 4 The various units are shown in the figure to help understand the operations performed by the video decoder 300. These units can be implemented as fixed function circuits, programmable circuits, or a combination thereof. Figure 3Similarly, a fixed-function circuit is a circuit that provides a specific function and has preset operations that can be performed. A programmable circuit is a circuit that can be programmed to perform a variety of tasks and provides flexible functionality in the operations that can be performed. For example, a programmable circuit can execute software or firmware that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. A fixed-function circuit can execute software instructions (for example, to receive parameters or output parameters), but the type of operation performed by the fixed-function circuit is generally immutable. In some examples, one or more units can be different circuit blocks (fixed-function or programmable), and in some examples, one or more units can be integrated circuits.

[0104] The video decoder 300 may include an ALU, an EFU, digital circuits, analog circuits, and / or a programmable core formed by programmable circuits. In examples where the operation of the video decoder 300 is performed by software executed on the programmable circuits, on-chip or off-chip memory may store instructions (e.g., object code) of the software received and executed by the video decoder 300.

[0105] The entropy decoding unit 302 may receive the encoded video data from the CPB and perform entropy decoding on the video data to reproduce syntax elements. The prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, and the filter unit 312 may generate decoded video data based on the syntax elements extracted from the bitstream.

[0106] Generally speaking, the video decoder 300 reconstructs a picture on a block-by-block basis. The video decoder 300 may perform a reconstruction operation on each block individually (where the block currently being reconstructed (ie, decoded) may be referred to as the "current block").

[0107] The entropy decoding unit 302 may entropy decode syntax elements defining the quantized transform coefficients of the quantized transform coefficient block and transform information, such as a quantization parameter (QP) and / or transform mode indication(s). The inverse quantization unit 306 may use the QP associated with the quantized transform coefficient block to determine a degree of quantization and, similarly, a degree of inverse quantization to be applied by the inverse quantization unit 306. The inverse quantization unit 306 may, for example, perform a bitwise left shift operation to inverse quantize the quantized transform coefficients. The inverse quantization unit 306 may thereby form a transform coefficient block comprising the transform coefficients.

[0108] After the inverse quantization unit 306 forms the transform coefficient block, the inverse transform processing unit 308 may apply one or more inverse transforms to the transform coefficient block to generate a residual block associated with the current block. For example, the inverse transform processing unit 308 may apply an inverse DCT, an inverse integer transform, an inverse Karhunen-Loeve transform (KLT), an inverse rotational transform, an inverse directional transform, or another inverse transform to the transform coefficient block.

[0109] In addition, prediction processing unit 304 generates a prediction block based on the prediction information syntax element entropy decoded by entropy decoding unit 302. For example, if the prediction information syntax element indicates that the current block is inter-predicted, motion compensation unit 316 may generate a prediction block. In this case, the prediction information syntax element may indicate a reference picture in DPB 314 from which to retrieve the reference block, and a motion vector that identifies the position of the reference block in the reference picture relative to the position of the current block in the current picture. Motion compensation unit 316 may generally generate a prediction block in a manner substantially similar to that described with respect to motion compensation unit 224 ( Figure 3 ) to perform the inter-frame prediction process in the manner described.

[0110] As another example, if the prediction information syntax element indicates that the current block is intra-predicted, the intra-prediction unit 318 may generate a prediction block according to the intra-prediction mode indicated by the prediction information syntax element. Likewise, the intra-prediction unit 318 may generally generate a prediction block in a manner substantially similar to that described with respect to the intra-prediction unit 226 ( Figure 3 The intra prediction process is performed in the manner described in ). The intra prediction unit 318 can retrieve the data of the neighboring samples of the current block from the DPB 314.

[0111] In some examples, prediction processing unit 304 may determine a first syntax element indicating the number of sub-pictures in the picture. For at least one corresponding sub-picture in the sub-pictures in the picture, prediction processing unit 304 may also determine a corresponding second syntax element indicating an identity of the at least one corresponding sub-picture.

[0112] The reconstruction unit 310 may reconstruct the current block using the prediction block and the residual block. For example, the reconstruction unit 310 may add samples of the residual block to corresponding samples of the prediction block to reconstruct the current block.

[0113] The filter unit 312 may perform one or more filtering operations on the reconstructed block. For example, the filter unit 312 may perform a deblocking operation to reduce blocking artifacts along the edges of the reconstructed block. The operations of the filter unit 312 may not necessarily be performed in all examples.

[0114] The video decoder 300 may store the reconstructed block in the DPB 314. For example, in an example where the operation of the filter unit 312 is not performed, the reconstruction unit 310 may store the reconstructed block in the DPB 314. In an example where the operation of the filter unit 312 is performed, the filter unit 312 may store the filtered reconstructed block in the DPB 314. As described above, the DPB 314 may provide reference information to the prediction processing unit 304, such as samples of the current picture for intra-frame prediction and previously decoded pictures for subsequent motion compensation. In addition, the video decoder 300 may output a decoded picture (e.g., a decoded video) from the DPB 314 for subsequent display on a display device (such as a video processor). Figure 1 is presented on a display device 118).

[0115] In this manner, the video decoder 300 represents an example of a video decoding device comprising a memory configured to store video data, and one or more processors implemented in circuitry and communicatively coupled to the memory, the one or more processors configured to determine a value of a first syntax element indicating a number of sub-pictures in a picture of the video data, determine a value of a corresponding second syntax element indicating an identity of the corresponding sub-picture for each sub-picture among the sub-pictures in the picture, and decode the corresponding sub-picture identified by the corresponding second syntax element.

[0116] This disclosure describes signaling methods for sub-pictures. These techniques can be applied to the VVC standard and other future video codec standards.

[0117] Video codec standards include ITU-T H.261, ISO / IEC MPEG-1 Visual, ITU-T H.262 or ISO / IEC MPEG-2 Visual, ITU-T H.263, ISO / IEC MPEG-4 Visual, and ITU-T H.264 (also known as ISO / IEC MPEG-4 AVC), including its Scalable Video Codec (SVC) and Multi-view Video Codec (MVC) extensions. Furthermore, new video codec standards (i.e., HEVC or ITU-T H.265, including its Range and Screen Content Codec extensions, 3D Video Codec (3D-HEVC), Multi-view Extension (MV-HEVC), and Scalable Extension (SHVC)) have recently been developed by the Joint Collaborative Team on Video Codecs (JCT-VC) and the Joint Collaborative Team on 3D Video Codec Extension Development (JCT-3V) of the ITU-T Video Coding Experts Group (VCEG) and the ISO / IEC Moving Picture Experts Group (MPEG). In 2016, MPEG and ITU-TVCEG established the Joint Video Exploration Team (JVET) to explore and develop new video coding tools for the next generation video codec standard, called VVC. The reference software is called the VVC Test Model (VTM).

[0118] Table 1 lists example portions of VVC draft 6 that may be affected by the techniques of this disclosure as follows:

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125]

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132]

[0133]

[0134] Table 1

[0135] VVC draft 6 is intended to facilitate the extraction of sub-pictures from an original picture so that the sub-picture can be decoded without decoding the entire original picture, or can be decoded separately from other sub-pictures. For example, a sub-picture can be an independently decodable portion of a picture. However, there may be problems because a video decoder (e.g., video decoder 300) may not be able to determine how to process the sub-picture. For example, a video decoder may not be able to determine how to extract a sub-picture from an original picture. A video decoder may not be able to determine how to identify which sub-pictures to extract from a picture. If a video decoder cannot determine how to process a sub-picture, the video decoder may incorrectly decode video data associated with a picture or sub-picture, which may result in a poor user experience.

[0136] This document discloses several techniques to address the sub-picture extraction problem. This disclosure describes several examples that can improve signaling in sequence parameter sets (SPSs), picture parameter sets (PPSs), and slice headers. At least one of the techniques disclosed below, or a combination of at least two of the techniques disclosed below, can be applied to VVC Draft 6 and / or future video codec standards. Example techniques are described below.

[0137] As described above, in VVC draft 6, there may be a problem because a video decoder (e.g., video decoder 300) may not be able to determine which sub-pictures to extract from the original picture. To address this issue, the video encoder 200 may determine the value of a syntax element indicating the number of sub-pictures within a picture and signal this syntax element. Furthermore, the video encoder 200 may determine the value of a sub-picture ID associated with each sub-picture at the PPS level (e.g., within the PPS) and signal this sub-picture ID. The video decoder 300 may parse the syntax elements to determine the values of the syntax elements and determine which sub-pictures to extract from the original picture. For example, the video encoder 200 or video decoder 300 may determine the value of a first syntax element indicating the number of sub-pictures in the picture. For at least one corresponding sub-picture in the picture (or for each corresponding sub-picture in the picture), the video encoder 200 or video decoder 300 may determine the value of a second syntax element indicating the identity of the at least one corresponding sub-picture. The video encoder 200 or video decoder 300 may encode or decode the at least one corresponding sub-picture identified by the second syntax element. In some examples, the first syntax element and the second syntax element are within the PPS. In some examples, the value of the first syntax element is equal to the number of sub-pictures in the picture minus 1. In some examples, the second syntax element includes an identification of sub-picture[i], where the identification of sub-picture[i] specifies the sub-picture identification of the i-th sub-picture.

[0138] For this example, the syntax changes to VVC draft 6 are as follows in Table 2: <change> and< / change> Described between.

[0139]

[0140]

[0141] Table 2

[0142] In another example, an alternative technique for signaling sub-picture IDs in the above example is now disclosed. In this example, the video encoder 200 can signal the offset (delta) of two adjacent sub-picture IDs. For example, the video encoder 200 can signal the difference between one sub-picture ID and an adjacent sub-picture ID. The video decoder 300 can parse the offset of the two adjacent sub-picture IDs to determine which sub-picture to extract from the original picture. For this example, the syntax changes of VVC draft 6 are as shown in Table 3. <change> and< / change> Described between.

[0143]

[0144]

[0145] Table 3

[0146] In addition to or as an alternative to any of the above techniques, a video decoder (such as video decoder 300) may need to determine a sub-picture ID in a slice header to determine the location of the sub-picture in the picture. In this example, the video encoder 200 may signal the sub-picture ID in the slice header so that the video decoder 300 can parse the sub-picture ID to determine the location of the sub-picture in the picture. For example, the video encoder 200 or video decoder 300 may determine the value of a corresponding third syntax element indicating a sub-picture identifier for each sub-picture in the slice header based at least in part on the presence of the corresponding sub-picture. In some examples, the video encoder 200 or video decoder 300 may also determine the value of the third syntax element based on the number of sub-pictures being greater than one. In some examples, the video encoder 200 or video decoder 300 may determine whether at least one corresponding sub-picture exists by determining the value of a fourth syntax element indicating the presence of the corresponding sub-picture. In some examples, the value of the third syntax element specifies the sub-picture identifier associated with the slice associated with the slice header. In some examples, the length of the third syntax element is equal to the value of the fifth syntax element indicating the length plus one bit. In some examples, the value of the fifth syntax element indicates the length of the picture identifier. In some examples, the fifth syntax element is in the PPS.

[0147] According to the technology of this example, the syntax changes to VVC draft 6 are as shown in Table 4. <change> and< / change> Described between.

[0148]

[0149]

[0150] Table 4

[0151] In another example, a video codec (eg, video encoder 200) may signal slice_subpicture_id using a number of bits equal to the length of signaled_picture_id_length_minus1+1 bits, where signaled_picture_id_length_minus1 may be signaled in the PPS. In this example, the value of slice_subpicture_id may be between 0 and 2. (signalled_picture_id_length_minus1+1) -1, including 0 and 2 (signalled_picture_id_length_minus1+1) –1.

[0152] Figure 5is a flowchart illustrating an example of sub-picture signaling according to the techniques of this disclosure. The video encoder 200 or the video decoder 300 may determine a value of a first syntax element indicating the number of sub-pictures in a picture (330). For example, the video encoder 200 may determine a value of the first syntax element, which may be equal to the number of sub-pictures in the picture minus 1, and may signal the first syntax element in the bitstream. The video decoder 300 may parse the first syntax element to determine the value of the first syntax element. The video decoder 300 may determine the number of sub-pictures in the picture by taking the value of the first syntax element (which may be equal to the number of sub-pictures in the picture minus 1) and adding 1.

[0153] For each sub-picture among the sub-pictures in the picture, the video encoder 200 or the video decoder 300 may determine a value of a corresponding second syntax element indicating an identification of the corresponding sub-picture (332). For example, the video encoder 200 may determine a value of a corresponding second syntax element that identifies a particular sub-picture in the picture and signal the corresponding second syntax element in the bitstream. The video decoder 300 may parse the corresponding second syntax element to determine the value of the corresponding second syntax element and identify the particular sub-picture.

[0154] The video encoder 200 or the video decoder 300 may encode or decode the corresponding sub-picture identified by the corresponding second syntax element (334). For example, the video encoder 200 may encode the video data based on the determination of the first syntax element and the second syntax element, and the video decoder 300 may decode the video data based on the determination of the first syntax element and the second syntax element.

[0155] In some examples, the first syntax element and the second syntax element are in a PPS. In some examples, the value of the first syntax element is equal to the number of sub-pictures in the picture of the video data to which the first syntax element applies minus 1. In some examples, the second syntax element includes an identification of the i-th sub-picture in the picture.

[0156] In some examples, video encoder 200 or video decoder 300 determines a value for a third syntax element in a slice header indicating a sub-picture identification for each sub-picture based at least in part on the presence of the corresponding sub-picture, and determines the identification of the corresponding sub-picture based on the value of the third syntax element. In some examples, video encoder 200 or video decoder 300 may also determine the value of the third syntax element based on the number of sub-pictures being greater than one. In some examples, video encoder 200 or video decoder 300 may determine whether the corresponding sub-picture exists by determining the value of a fourth syntax element indicating the presence of the corresponding sub-picture. In some examples, the value of the third syntax element specifies the sub-picture identification associated with the slice associated with the slice header. In some examples, the length of the third syntax element is equal to the value of the fifth syntax element indicating the length plus one bit. In some examples, the value of the fifth syntax element indicates the length of the picture identification.

[0157] Figure 6 is a flowchart illustrating an example method for encoding a current block. The current block may include a current CU of a picture. Although for the video encoder 200 ( Figure 1 and Figure 3 ) is described, but it should be understood that other devices may be configured to perform similar Figure 6 method.

[0158] exist Figure 6 In an example, the video encoder 200 initially predicts a current block (350). For example, the video encoder 200 may form a prediction block for the current block. In some examples, while forming the prediction block, the video encoder 200 may determine a first syntax element indicating a number of sub-pictures in a picture, and may determine a corresponding second syntax element indicating an identity of at least one corresponding sub-picture of the sub-pictures in the picture. The video encoder 200 may then calculate a residual block for the current block (352). To calculate the residual block, the video encoder 200 may calculate a difference between the original uncoded block and the prediction block for the current block. The video encoder 200 may then transform and quantize transform coefficients of the residual block (354). Next, the video encoder 200 may scan the quantized transform coefficients of the residual block (356). During the scan, or after the scan, the video encoder 200 may entropy encode the transform coefficients (358). For example, the video encoder 200 may encode the transform coefficients using CAVLC or CABAC. The video encoder 200 may then output entropy encoded data for the block (360).

[0159] Figure 7 is a flow chart illustrating an example method for decoding a current block of video data. The current block may include a current CU of a picture. Although for video decoder 300 ( Figure 1 and Figure 4 ) is described, but it should be understood that other devices may be configured to perform similar Figure 7 method.

[0160] The video decoder 300 may receive entropy coded data for a current block, such as entropy coded prediction information and entropy coded data for transform coefficients of a residual block corresponding to the current block (370). The video decoder 300 may entropy decode the entropy coded data to determine prediction information for the current block and reproduce transform coefficients of the residual block (372). In some examples, the entropy coded data may include a first syntax element indicating the number of sub-pictures in a picture and, for at least one corresponding sub-picture of the sub-pictures of the picture, may include a corresponding second syntax element indicating an identity of the at least one corresponding sub-picture. In these examples, the video decoder 300 may determine the first syntax element indicating the number of sub-pictures in the picture and, for at least one corresponding sub-picture of the sub-pictures of the picture, determine the corresponding second syntax element indicating an identity of the at least one corresponding sub-picture. The video decoder 300 may predict the current block (374) (e.g., using an intra-frame or inter-frame prediction mode as indicated by the prediction information for the current block) to calculate a prediction block for the current block. The video decoder 300 may then inverse scan the reproduced transform coefficients (376) to create a block of quantized transform coefficients. The video decoder 300 may then inverse quantize and inverse transform the transform coefficients to generate a residual block (378). The video decoder 300 may ultimately decode the current block by combining the prediction block and the residual block (380).

[0161] According to the techniques of this disclosure, a video encoder can signal syntax elements, and a video decoder can parse the syntax elements, enabling the video decoder to determine how to process sub-pictures. This disclosure describes several examples that can improve signaling in sequence parameter sets (SPSs), picture parameter sets (PPSs), and slice headers related to sub-pictures.

[0162] This disclosure includes the following examples.

[0163] Example 1. A method for encoding and decoding video data, the method comprising: determining a first syntax element indicating the number of sub-pictures in a picture of the video data; determining a corresponding second syntax element indicating an identification of at least one corresponding sub-picture in the sub-pictures in the picture; and encoding and decoding the at least one corresponding sub-picture identified by the corresponding second syntax element.

[0164] Example 2. The method of Example 1, wherein the first syntax element and the second syntax element are in a picture parameter set (PPS).

[0165] Example 3. A method according to any of Examples 1 or 2, wherein the value of the first syntax element is equal to the number of sub-pictures in the picture of the video data to which the first syntax element is applicable minus 1.

[0166] Example 4. The method of Example 3, wherein the second syntax element comprises an identifier of sub-picture [i], and wherein the identifier of sub-picture [i] specifies the sub-picture identifier of the i-th sub-picture.

[0167] Example 5. The method of Example 4, wherein for (i=0; i<=first syntax element; i++), second syntax element [i].

[0168] Example 6. A method according to any combination of Examples 1-5, further comprising determining a third syntax element indicating a sub-picture identification of at least one corresponding sub-picture in a slice header based at least in part on the presence of the sub-picture, and determining the identification of the at least one corresponding sub-picture based on the third syntax element.

[0169] Example 7. The method of Example 6, wherein determining the third syntax element is further based on the number of sub-pictures being greater than one.

[0170] Example 8. The method of Example 6 or 7, further comprising determining whether the at least one corresponding sub-picture exists by determining a fourth syntax element indicating that the at least one corresponding sub-picture exists.

[0171] Example 9. The method of any combination of Examples 6-8, wherein the third syntax element specifies a sub-picture identification associated with a slice associated with the slice header.

[0172] Example 10. The method of any combination of Examples 6-9, wherein the length of the third syntax element is equal to the value of the fifth syntax element indicating the length plus 1 bit.

[0173] Example 11. The method of Example 10, wherein the fifth syntax element indicates a length of the picture identification.

[0174] Example 12. A method for encoding and decoding video data, the method comprising: determining a number of sub-pictures to be extracted from an original picture based on a first syntax element; determining which sub-pictures to extract based on at least one second syntax element; and encoding and decoding the video data based on the determination.

[0175] Example 13. The method of Example 12, wherein at least one second syntax element comprises a sub-picture identification (ID).

[0176] Example 14. The method of Example 12 or Example 13, wherein at least one second syntax element comprises an offset of two adjacent sub-picture IDs.

[0177] Example 15. The method of any combination of Examples 12-14, wherein the first syntax element and the at least one second syntax element are in a picture parameter set (PPS).

[0178] Example 16. The method of any combination of Examples 12-15, wherein the at least one second syntax element is in a slice header.

[0179] Example 17. The method of Example 16, wherein the at least one second syntax element comprises a slice_subpicture_id, wherein the length of the slice_subpicture_id is signalled_picture_id_length_minus1+1 bits.

[0180] Example 18. The method of Example 16, wherein signalled_picture_id_length_minus1 is in the PPS.

[0181] Example 19. The method of Example 17 or Example 18, wherein the value of slice_subpicture_id is between 0 and 2. (signalled_picture_id_length_minus1+1) -1, including 0 and 2 (signalled_picture_id_length_minus1+1) –1.

[0182] Example 20. A method for encoding video data, the method comprising: determining a number of sub-pictures to be extracted from an original picture; signaling the number of sub-pictures to be extracted from the original picture with a first syntax element; determining which sub-pictures to be extracted from the original picture; signaling which sub-pictures to be extracted from the original picture with at least one second syntax element; and encoding the video data based on the determination.

[0183] Example 21. The method of Example 20, wherein at least one second syntax element comprises a sub-picture identification (ID).

[0184] Example 22. The method of Example 20 or Example 21, wherein at least one second syntax element comprises an offset of two adjacent sub-picture IDs.

[0185] Example 23. The method of any combination of Examples 20-22, wherein the first syntax element and the at least one second syntax element are in a picture parameter set (PPS).

[0186] Example 24. The method of any combination of Examples 20-23, wherein the at least one second syntax element is in a slice header.

[0187] Example 25. The method of Example 24, wherein the at least one second syntax element comprises a slice_subpicture_id, wherein the length of the slice_subpicture_id is signalled_picture_id_length_minus1+1 bits.

[0188] Example 26. The method of Example 25, wherein signaled_picture_id_length_minus1 is signaled in a picture parameter set (PPS).

[0189] Example 27. The method of Example 25 or 26, wherein the value of slice_subpicture_id is between 0 and 2. (signalled_picture_id_length_minus1+1) -1, including 0 and 2 (signalled_picture_id_length_minus1+1) –1.

[0190] Example 28. An apparatus for encoding and decoding video data, the apparatus comprising one or more components for performing the method according to any of Examples 1-27.

[0191] Example 29. The apparatus of Example 28, wherein the one or more components include one or more processors implemented in circuitry.

[0192] Example 30. The apparatus of Example 28 or 29, further comprising a memory for storing video data.

[0193] Example 31. The apparatus of any of Examples 28-30, further comprising a display configured to display the decoded video data.

[0194] Example 32. A device according to any of Examples 28-31, wherein the device includes one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0195] Example 33. The apparatus of any of Examples 28-32, wherein the apparatus comprises a video decoder.

[0196] Example 34. The apparatus of any of Examples 28-33, wherein the apparatus comprises a video encoder.

[0197] Example 35. A computer-readable storage medium having stored thereon instructions that, when executed, cause one or more processors to perform the method of any one of Examples 1-27.

[0198] It should be appreciated that, depending on the example, certain actions or events of any of the techniques described herein may be performed in a different order, may be added, combined, or omitted entirely (e.g., not all described actions or events are necessary for practice of the techniques). Furthermore, in some examples, actions or events may be performed concurrently, for example, through multithreading, interrupt handling, or multiple processors, rather than sequentially.

[0199] In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored or transmitted on a computer-readable medium as one or more instructions or codes and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media corresponding to tangible media such as data storage media, or communication media including any medium that facilitates the delivery of a computer program from one place to another (e.g., according to a communication protocol). In this manner, computer-readable media may generally correspond to (1) a non-transitory, tangible computer-readable storage medium, or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures for implementing the techniques described in this disclosure. A computer program product may include computer-readable media.

[0200] As an example and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage devices, magnetic disk storage devices or other magnetic storage devices, flash memory, or any other medium that can be used to store the required program code in the form of instructions or data structures and can be accessed by a computer. In addition, any connection is properly referred to as a computer-readable medium. For example, if a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technology (such as infrared, radio and microwave) is used to transmit instructions from a website, server or other remote source, then the coaxial cable, fiber optic cable, twisted pair, DSL or wireless technology (such as infrared, radio and microwave) is included in the definition of the medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals or other temporary media, but rather point to non-temporary tangible storage media. The disks and optical disks used herein include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks and blue-ray discs, wherein disks usually reproduce data magnetically, while optical discs reproduce data optically with lasers. The above combinations should also be included in the scope of computer-readable media.

[0201] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Accordingly, the terms "processor" and "processing circuitry" as used herein may refer to any of the aforementioned structures or any other structure suitable for implementing the techniques described herein. Furthermore, in some aspects, the functionality described herein may be provided in dedicated hardware and / or software modules configured for encoding and decoding, or incorporated into a combined codec. Furthermore, these techniques may be implemented entirely in one or more circuits (including programmable circuits and / or fixed-function circuits) or logic elements.

[0202] The techniques of this disclosure can be implemented in a variety of devices or apparatuses, including wireless handsets, integrated circuits (ICs), or sets of ICs (e.g., chipsets). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily need to be implemented by different hardware units. Instead, as described above, in conjunction with appropriate software and / or firmware, the various units can be combined in a codec hardware unit or provided by a collection of interoperable hardware units, including one or more processors as described above.

Claims

1. A method for encoding and decoding video data, the method comprising: Encoding and decoding, within a picture parameter set (PPS), a first syntax element equal to a number of sub-pictures in a picture of the video data minus one; encoding and decoding, for each corresponding sub-picture among the plurality of sub-pictures in the picture, a corresponding second syntax element that specifies a corresponding sub-picture identification ID of the corresponding sub-picture within the PPS; encoding and decoding, within a slice header associated with a slice of a picture, a slice header sub-picture identification ID that specifies a sub-picture ID of a sub-picture comprising the slice, the sub-picture being among the plurality of sub-pictures in the picture; and encoding and decoding the plurality of sub-pictures in the picture, The length of the slice header sub-picture ID is equal to the value of the fourth syntax element indicating the length of the picture identification syntax element plus 1 bit.

2. The method according to claim 1, wherein The second syntax element includes an identifier of an i-th sub-picture among the multiple sub-pictures in the picture. 3 . The method according to claim 1 , further comprising encoding and decoding a value of a third syntax element indicating whether the corresponding sub-picture exists.

4. The method according to claim 1, wherein The fourth syntax element is in a parameter set. The method according to claim 1 , wherein the method of encoding and decoding video data comprises a method of encoding video data. The method according to claim 1 , wherein the method of encoding and decoding video data comprises a method of decoding video data.

7. A device for encoding and decoding video data, the device comprising: a memory configured to store video data; as well as one or more processors embodied in circuitry and communicatively coupled to the memory, the one or more processors configured to: Encoding and decoding, within a picture parameter set (PPS), a first syntax element equal to a number of sub-pictures in a picture of the video data minus one; encoding and decoding, for each corresponding sub-picture among the plurality of sub-pictures in the picture, a corresponding second syntax element that specifies a corresponding sub-picture identification ID of the corresponding sub-picture within the PPS; encoding and decoding, within a slice header associated with a slice of the picture, a slice header sub-picture identification ID that specifies a sub-picture ID of a sub-picture comprising the slice, the sub-picture being among the plurality of sub-pictures in the picture; and encoding and decoding the plurality of sub-pictures in the picture, The length of the slice header sub-picture ID is equal to the value of the fourth syntax element indicating the length of the picture identification syntax element plus 1 bit.

8. The apparatus according to claim 7, wherein The second syntax element includes an identifier of an i-th sub-picture among the multiple sub-pictures in the picture. 9 . The apparatus of claim 7 , wherein the one or more processors are further configured to encode or decode a value of a third syntax element indicating whether the corresponding sub-picture exists.

10. The apparatus according to claim 7, wherein The fourth syntax element is in a parameter set.

11. The apparatus according to claim 7, wherein The device comprises a wireless communication device.

12. The apparatus according to claim 7, wherein An apparatus for encoding and decoding video data includes a video encoder.

13. The apparatus according to claim 7, wherein An apparatus for encoding and decoding video data includes a video decoder.

14. A non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors to: Encoding and decoding, within a picture parameter set (PPS), a first syntax element equal to a number of sub-pictures in a picture of the video data minus one; encoding and decoding, for each corresponding sub-picture among the plurality of sub-pictures in the picture, a corresponding second syntax element specifying a corresponding sub-picture identification ID of the corresponding sub-picture within the PPS; encoding and decoding, within a slice header associated with a slice of the picture, a slice header sub-picture identification ID that specifies a sub-picture ID of a sub-picture comprising the slice, the sub-picture being among the plurality of sub-pictures in the picture; and encoding and decoding the plurality of sub-pictures in the picture, in, The length of the slice header sub-picture ID is equal to the value of the fourth syntax element indicating the length of the picture identification syntax element plus 1 bit. 15 . The non-transitory computer-readable storage medium of claim 14 , wherein the second syntax element comprises an identification of an i-th sub-picture among the plurality of sub-pictures in the picture.

16. The non-transitory computer-readable storage medium of claim 14, further storing instructions that, when executed, cause the one or more processors to encode or decode a value of a third syntax element, the value of the third syntax element indicating whether the corresponding sub-picture exists.

17. The non-transitory computer-readable storage medium of claim 14, wherein: The fourth syntax element is in a parameter set.

18. A device for encoding and decoding video data, the device comprising: means for encoding and decoding, within a picture parameter set (PPS), a first syntax element equal to a number of sub-pictures in a picture of the video data minus one; means for encoding and decoding, for each corresponding sub-picture among the plurality of sub-pictures in the picture, a corresponding second syntax element specifying a corresponding sub-picture identification ID of the corresponding sub-picture within the PPS; means for encoding and decoding, within a slice header associated with a slice of the picture, a slice header sub-picture identification ID specifying a sub-picture ID of a sub-picture comprising the slice, the sub-picture being among the plurality of sub-pictures in the picture; and means for encoding and decoding the plurality of sub-pictures in the picture, The length of the slice header sub-picture ID is equal to the value of the fourth syntax element indicating the length of the picture identification syntax element plus 1 bit.

19. The apparatus according to claim 18, wherein The second syntax element includes an identifier of an i-th sub-picture among the multiple sub-pictures in the picture.

20. The apparatus according to claim 18, further comprising means for encoding and decoding a value of a third syntax element, the value of the third syntax element indicating whether a corresponding sub-picture exists.

21. The apparatus of claim 18, wherein The fourth syntax element is in a parameter set.

22. A computer program product comprising computer instructions which, when executed by a processor, perform the method according to any one of claims 1 to 6.

Images