Method and decoder for decoding video data from bitstream, method and encoder for encoding video data in bitstream, computer program product and computer readable storage medium

Abstract

The present invention relates to a method and a decoder for decoding video data from a bitstream, a method and an encoder for encoding video data in a bitstream, a computer program product and a computer readable storage medium. A method of decoding video data from a bitstream including video data corresponding to one or more than one slice is provided. Each stripe may include one or more tiles. The bitstream includes a picture header including syntactic elements to be used in decoding one or more slices and a slice header including syntactic elements to be used. Decoding the slice includes parsing the syntactic elements. In a case where a slice contains a plurality of tiles, if a syntax element is parsed and instructs to signal a picture header in a slice header, parsing of the syntax element indicating an address of the slice is omitted. A bitstream is decoded using the syntactic elements.

Description

[0001] (This application is a divisional application of application No. 2021800225855, filed on March 17, 2021, entitled “Method, decoder, encoder, computer program product, and computer-readable storage medium for video encoding and decoding.”) Technical Field

[0002] The present invention relates to video encoding and decoding, and in particular to high-level syntax for use in bitstreams. Background Art

[0003] Recently, the Joint Video Experts Team (JVET) (a collaboration between MPEG and ITU-T Study Group 16, VCEG) began work on a new video coding standard called Versatile Video Coding (VVC). The goal of VVC is to provide significant improvements in compression performance over the existing HEVC standard (i.e., typically twice as fast as before) and to be completed in 2020. Key target applications and services include, but are not limited to, 360-degree and high dynamic range (HDR) video. In total, JVET evaluated feedback from 32 organizations using formal subjective tests conducted by independent test labs. Some proposals showed compression efficiency improvements of 40% or more, typically when compared to using HEVC. Particular improvements were shown on ultra-high-definition (UHD) video test material. Therefore, we can expect compression efficiency improvements far exceeding the targeted 50% for the final standard.

[0004] The JVET Exploration Model (JEM) uses all HEVC tools and has introduced several new tools. These changes require changes to the structure of the bitstream, especially the high-level syntax, which may have an impact on the overall bitrate of the bitstream. Summary of the Invention

[0005] The present invention involves improvements to high-level syntax structures, which result in reduced complexity without any degradation in coding performance.

[0006] According to a first aspect of the present invention, a method for decoding video data from a bitstream is provided, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, and the slice header including syntax elements to be used when decoding the slices, the method comprising: parsing the syntax elements, and if a slice (or picture) includes multiple tiles, if a syntax element indicating that a picture header is signaled in the slice header is parsed, omitting parsing a syntax element indicating an address of the slice; and decoding the bitstream using the syntax elements. According to another aspect of the present invention, a method for decoding video data from a bitstream is provided, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, and the slice header including syntax elements to be used when decoding the slice, the method comprising: parsing the syntax elements and, if a slice or picture includes multiple tiles, omitting parsing a syntax element indicating an address of a slice if a syntax element indicating that a picture header is signaled in the slice header is parsed; and decoding the bitstream using the syntax elements. According to another additional aspect of the present invention, a method for decoding video data from a bitstream is provided, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, the slice header including syntax elements to be used when decoding the slices, the bitstream being constrained such that, if the bitstream includes a syntax element having a value indicating that a slice or picture includes a plurality of tiles and the bitstream includes a syntax element indicating that a picture header is signaled in the slice header, the bitstream also includes a syntax element indicating that a syntax element indicating an address of a slice is not to be parsed, the method comprising decoding the bitstream using the syntax element.

[0007] Therefore, when the picture header is in the slice header, the slice address is not parsed, which reduces the bit rate, especially for low-latency and low-bit-rate applications. In addition, when the picture is signaled in the slice header, the parsing complexity can be reduced.

[0008] In an embodiment, the omission is performed (only) when the raster scan stripe mode is to be used to decode the stripe. This reduces the parsing complexity but still allows some bit rate reduction.

[0009] Omission may also include omitting parsing of a syntax element indicating the number of blocks in a slice. Thus, a further reduction in bit rate may be achieved.

[0010] In a second aspect, a method for decoding video data from a bitstream is provided, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, the slice header including syntax elements to be used when decoding the slice, and the decoding including: parsing the one or more syntax elements and, if a slice (or picture) contains multiple tiles, omitting parsing a syntax element indicating the number of tiles in the slice if a syntax element indicating that the picture header is signaled in the slice header is parsed; and decoding the bitstream using the syntax elements. In another aspect, a method of decoding video data from a bitstream is provided, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, the slice header including syntax elements to be used when decoding the slices, and the decoding including: parsing the one or more syntax elements and, if a slice or picture includes multiple tiles, omitting parsing a syntax element indicating the number of tiles in the slice if a syntax element indicating that the picture header is signaled in the slice header is parsed; and decoding the bitstream using the syntax elements. In another aspect of the present invention, a method for decoding video data from a bitstream is provided, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, the slice header including syntax elements to be used when decoding the slices, the bitstream being constrained such that, if the bitstream includes a syntax element having a value indicating that a slice or picture includes a plurality of tiles and the bitstream includes a syntax element indicating that the picture header is signaled in the slice header, the bitstream also includes a syntax element indicating that a syntax element indicating the plurality of tiles in the slice is not to be parsed, the method including decoding the bitstream using the syntax elements.

[0011] Therefore, the bit rate can be reduced, which is particularly beneficial for low-latency and low-bit-rate applications that do not need to send multiple blocks.

[0012] This can be omitted (only) when a raster scan stripe mode is to be used to decode the stripe. This reduces parsing complexity but still allows some bit rate reduction.

[0013] The method may further include parsing a syntax element indicating the number of blocks in the picture, and determining the number of blocks in the slice based on the number of blocks in the picture indicated by the parsed syntax element. This is advantageous because it allows the number of blocks in the slice to be easily predicted without further signaling in the picture header signaled in the slice header.

[0014] The omission may also include omitting parsing of a syntax element indicating an address of a slice. Thus, the bit rate may be further reduced.

[0015] In a third aspect of the present invention, a method is provided for decoding video data from a bitstream, the bitstream comprising video data corresponding to one or more slices, wherein each slice may comprise one or more tiles, wherein the bitstream comprises a picture header and a slice header, the picture header comprising syntax elements to be used when decoding the one or more slices, the slice header comprising syntax elements to be used when decoding the slices, and the decoding comprising: parsing the one or more syntax elements and, if a slice (or picture) comprises multiple tiles, omitting parsing a syntax element indicating a slice address if the number of tiles in the slice is equal to the number of tiles in the picture; and decoding the bitstream using the syntax elements. This utilizes the insight that if the number of tiles in the slice is equal to the number of tiles in the picture, then the current picture is guaranteed to contain only one slice. Thus, by omitting the slice address, bit rate can be improved and parsing and / or encoding complexity can be reduced.

[0016] This can be omitted (only) when the raster scan stripe mode is to be used to decode the stripe. Thus, the complexity can be reduced while still providing some bit rate reduction.

[0017] The decoding may further include parsing, in the slice, a syntax element indicating a number of blocks in the slice; and parsing, in the picture parameter set, a syntax element indicating a number of blocks in the picture, wherein omitting parsing the syntax element indicating the slice address is based on the parsed syntax element.

[0018] Decoding may also include parsing a syntax element in the slice that indicates a number of blocks in the slice prior to the one or more syntax elements used to signal the slice address.

[0019] The decoding may further include parsing, in the slice, a syntax element indicating whether the picture header is signaled in the slice header, and determining (inferring) that the number of blocks in the slice is equal to the number of blocks in the picture if the parsed syntax element indicates that the picture header is signaled in the slice header.

[0020] In a fourth aspect, a method is provided for decoding video data from a bitstream, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more blocks, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, the slice header including syntax elements to be used when decoding the slices, and the decoding comprising: parsing the one or more syntax elements and, if the syntax elements indicate that a raster scan decoding mode is enabled for the slice, decoding at least one of a slice address and a number of blocks in the slice from the one or more syntax elements, wherein if the raster scan decoding mode is enabled for the slice, at least one of the slice address and the number of blocks in the slice decoded from the one or more syntax elements does not depend on the number of blocks in the picture; and decoding the bitstream using the syntax elements. Thus, the parsing complexity of the slice header can be reduced.

[0021] According to a fifth aspect of the present invention, a method including the first and second aspects is provided.

[0022] In a sixth aspect according to the present invention, a method including the first aspect, the second aspect and the third aspect is provided.

[0023] According to a seventh aspect of the present invention, there is provided a method for encoding video data into a bitstream, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, the slice header including syntax elements to be used when encoding the slice, and the encoding including: determining one or more syntax elements for encoding the video data, and, in a case where a slice (or picture) includes multiple tiles, omitting encoding a syntax element indicating an address of the slice if the syntax element indicates that the picture header is signaled in the slice header; and encoding the video data using the syntax elements. According to an additional aspect of the present invention, there is provided a method of encoding video data into a bitstream, the bitstream comprising the video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream comprises a picture header and a slice header, the picture header comprising syntax elements to be used when decoding the one or more slices, the slice header comprising syntax elements to be used when encoding the slice, and the encoding comprising: determining one or more syntax elements for encoding the video data and, if a slice or picture includes multiple tiles, omitting encoding a syntax element indicating an address of a slice if the syntax element indicates that the picture header is signaled in the slice header; and encoding the video data using the syntax elements. According to an additional supplementary aspect of the present invention, a method of encoding video data into a bitstream is provided, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, and the slice header including syntax elements to be used when encoding the slices, the bitstream being constrained such that, in a case where the bitstream includes a syntax element having a value indicating that a slice or picture includes a plurality of tiles and the bitstream includes a syntax element indicating that a picture header is signaled in the slice header, the bitstream also includes a syntax element indicating that a syntax element indicating an address of a slice is not to be parsed; the method comprising encoding the video data using the syntax elements.

[0024] In one or more embodiments, the omission is performed (only) when a raster scan striping mode is used to encode the stripes.

[0025] Omitting may also include omitting encoding a syntax element indicating the number of blocks in a slice.

[0026] According to an eighth aspect of the present invention, there is provided a method for encoding video data into a bitstream, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, the slice header including syntax elements to be used when decoding the slice, and the encoding including: determining one or more syntax elements for encoding the video data, and, in a case where a slice includes multiple tiles, omitting encoding a syntax element indicating the number of tiles in the slice if a syntax element indicating that the picture header is signaled in the slice header is determined for encoding; and encoding the video data using the syntax elements. According to another additional aspect of the present invention, a method of encoding video data into a bitstream is provided, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, the slice header including syntax elements to be used when decoding the slices, and the encoding including: determining one or more syntax elements for encoding the video data, and, if a slice or picture includes multiple tiles, omitting encoding a syntax element indicating the number of tiles in the slice if a syntax element indicating signaling of a picture header in a slice header is determined for encoding; and encoding the video data using the syntax elements. According to another supplementary aspect of the present invention, a method for encoding video data into a bitstream is provided, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more blocks, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, the slice header including syntax elements to be used when decoding the slices, the bitstream being constrained such that, in a case where the bitstream includes a syntax element having a value indicating that a slice or picture includes a plurality of blocks and the bitstream includes a syntax element determined for encoding indicating that the picture header is signaled in the slice header, the bitstream also includes a syntax element indicating that a syntax element indicating the number of blocks in the slice is not to be parsed, the method comprising encoding the video data using the syntax element.

[0027] In an embodiment, the omission is performed (only) if a raster scan stripe mode is to be used to encode the stripe.

[0028] The encoding may also include encoding a syntax element indicating a number of blocks in the picture, wherein the number of blocks in the slice is based on the number of blocks in the picture indicated by the parsed syntax element.

[0029] Omitting may also include omitting encoding a syntax element indicating the address of the slice.

[0030] According to a ninth aspect of the present invention, there is provided a method for encoding video data into a bitstream, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more tiles, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, the slice header including syntax elements to be used when decoding the slice, and the encoding including: determining one or more syntax elements and, in a case where a slice (or picture) includes multiple tiles, omitting encoding a syntax element indicating a slice address if the number of tiles in the slice is equal to the number of tiles in the picture; and encoding the video data using the syntax elements.

[0031] In one or more embodiments, the omission is performed (only) when a raster scan stripe mode is to be used to decode the stripe.

[0032] The encoding may also include encoding a syntax element in the slice indicating the number of blocks in the slice; and encoding a syntax element in the picture parameter set indicating the number of blocks in the picture, wherein omitting or not omitting encoding the syntax element indicating the slice address is based on the value of the encoded syntax element.

[0033] The encoding may also include encoding in the slice a syntax element indicating a number of blocks in the slice prior to the one or more syntax elements for signaling the slice address.

[0034] The encoding may further include encoding a syntax element in the slice indicating whether the picture header is signaled in the slice header, and if the syntax element to be encoded indicates that the picture header is signaled in the slice header, determining that the number of blocks in the slice is equal to the number of blocks in the picture.

[0035] According to a tenth aspect of the present invention, there is provided a method for encoding video data into a bitstream, the bitstream including video data corresponding to one or more slices, wherein each slice may include one or more blocks, wherein the bitstream includes a picture header and a slice header, the picture header including syntax elements to be used when decoding the one or more slices, the slice header including syntax elements to be used when decoding the slices, and the encoding including: determining one or more syntax elements for encoding the video data, and if the syntax elements determined for encoding indicate that a raster scan decoding mode is enabled for the slice, encoding a syntax element indicating at least one of a slice address and the number of blocks in the slice, wherein if the raster scan decoding mode is enabled for the slice, decoding at least one of the slice address and the number of blocks in the slice from the one or more syntax elements does not depend on the number of blocks in the picture; and encoding the bitstream using the syntax elements.

[0036] In an eleventh aspect according to the present invention, a method including the seventh and eighth aspects is provided.

[0037] In a twelfth aspect according to the present invention, a method including the seventh aspect, the eighth aspect and the ninth aspect is provided.

[0038] According to a thirteenth aspect of the present invention, there is provided a decoder for decoding video data from a bit stream, the decoder being configured to perform the method of any one of the first to sixth aspects.

[0039] According to a fourteenth aspect of the present invention, there is provided an encoder for encoding video data into a bit stream, the encoder being configured to perform the method of any one of the seventh to twelfth aspects.

[0040] According to a fifteenth aspect of the present invention, there is provided a computer program which, when executed, causes the method of any one of aspects 1 to 12 to be performed. The program may be provided separately, or may be on, carried by, or carried in a carrier medium. The carrier medium may be non-transitory, such as a storage medium, in particular a computer-readable storage medium. The carrier medium may also be transient, such as a signal or other transmission medium. The signal may be transmitted via any suitable network, including the Internet.

[0041] Any features in one aspect of the invention may be applied to other aspects of the invention in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa.

[0042] Furthermore, features implemented in hardware may be implemented in software, and vice versa. Any references herein to software and hardware features should be interpreted accordingly.

[0043] Any apparatus features as described herein may also be provided as method features, and vice versa.As used herein, means-plus-function features may alternatively be expressed in terms of their corresponding structure (such as a suitably programmed processor and associated memory, etc.).

[0044] It will also be understood that specific combinations of the various features described and defined in any aspect of the present invention may be independently implemented, provided and / or used. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Reference will now be made by way of example to the accompanying drawings, in which:

[0046] Figure 1 is a diagram for explaining the coding structure used in HEVC and VVC;

[0047] Figure 2 is a block diagram schematically illustrating a data communication system in which one or more embodiments of the present invention may be implemented;

[0048] Figure 3 is a block diagram illustrating components of a processing device that may implement one or more embodiments of the present invention;

[0049] Figure 4 is a flow chart illustrating the steps of an encoding method according to an embodiment of the present invention;

[0050] Figure 5 is a flowchart illustrating the steps of a decoding method according to an embodiment of the present invention;

[0051] Figure 6 shows the structure of a bitstream in an exemplary coding system VVC;

[0052] Figure 7 Another structure of a bit stream in an exemplary coding system VVC is shown;

[0053] Figure 8 Shows Luma Modelling Chroma Scaling (LMCS);

[0054] Figure 9 Shows the sub-tools of LMCS;

[0055] Figure 10 This is a diagram of the raster scan strip mode and rectangular strip mode of the current VVC draft standard;

[0056] Figure 11A diagram showing a system including an encoder or decoder and a communication network according to an embodiment of the present invention;

[0057] Figure 12 is a schematic block diagram of a computing device for implementing one or more embodiments of the present invention;

[0058] Figure 13 is a diagram showing a network camera system; and

[0059] Figure 14 is a diagram showing a smartphone. DETAILED DESCRIPTION

[0060] Figure 1 The present invention relates to a coding structure used in the High Efficiency Video Coding (HEVC) video standard. A video sequence 1 consists of a series of digital images i. Each of these digital images is represented by one or more matrices. The matrix coefficients represent pixels.

[0061] The images 2 of the sequence may be partitioned into slices 3. In some cases, one slice may constitute the entire image. These slices are partitioned into non-overlapping Coding Tree Units (CTUs). The Coding Tree Unit (CTU) is the basic processing unit of the High Efficiency Video Coding (HEVC) video standard and conceptually corresponds in structure to the macroblock unit used in several previous video standards. A CTU is sometimes also called a Largest Coding Unit (LCU). A CTU has luminance and chrominance component parts, each of which is called a Coding Tree Block (CTB). These different color components are not Figure 1 Shown in.

[0062] A CTU is typically 64 pixels by 64 pixels in size. Each CTU can be iteratively partitioned into smaller, variable-sized coding units (CUs) using a quadtree decomposition.

[0063] The coding unit is the basic coding element and is composed of two subunits called prediction units (PUs) and transform units (TUs). The maximum size of a PU or TU is equal to the CU size. A prediction unit corresponds to a partition of a CU used for prediction of pixel values. Various different partitions of a CU into PUs are possible, as shown in Figure 6, including a partition into four square PUs and two different partitions into two rectangular PUs. A transform unit is the basic unit for spatial transformation using DCT. A CU can be partitioned into TUs based on a quadtree representation.

[0064] Each slice is embedded in a network abstraction layer (NAL) unit. In addition, the coding parameters of the video sequence are stored in a dedicated NAL unit called a parameter set. In HEVC and H.264 / AVC, two types of parameter set NAL units are used: first, the sequence parameter set (SPS) NAL unit, which collects all parameters that do not change during the entire video sequence. Typically, it handles the coding profile, the size of the video frame, and other parameters. Second, the picture parameter set (PPS) NAL unit, which includes parameters that can change from one image (or frame) of the sequence to other images (or frames). HEVC also includes a video parameter set (VPS) NAL unit, which contains parameters that describe the overall structure of the bitstream. VPS is a new type of parameter set defined in HEVC and applies to all layers of the bitstream. A layer can contain multiple temporal sublayers, and all version 1 bitstreams are limited to a single layer. HEVC has certain layered extensions for scalability and multi-view, and these extensions will allow multiple layers with a backward-compatible version 1 base layer.

[0065] In the current definition of Versatile Video Coding (VVC), there are three high-level possibilities for partitioning pictures: sub-pictures, slices, and tiles. Each has its own characteristics and usefulness. Partitioning into sub-pictures allows for spatial extraction and / or merging of regions of the video. Partitioning into slices is based on similar concepts to previous standards and corresponds to packetization for video transmission (even though it can be used for other applications). Partitioning into tiles is conceptually an encoder parallelization tool, as it splits the picture into independently coded regions of (almost) the same size. But this tool can also be used for other applications.

[0066] Since these three high-level possible ways of using picture partitioning together exist, there are several modes for its use. As defined in the current draft specification for VVC, two modes for defining slices are defined. For raster scan slice mode, a slice contains a complete sequence of tiles in a raster scan of the tiles of a picture. This mode in the current VVC specification is in Figure 10 As shown in (a), the picture contains 18 by 12 luma CTUs shown as partitioned into 12 stripes and 3 raster scan stripes.

[0067] For the second (rectangular strip mode), the strip contains several complete blocks from a common rectangular area of the picture. Figure 10 In this example, the picture has 18 by 12 luma TUs shown partitioned into 24 blocks and 9 rectangular strips.

[0068] Figure 2The data communication system in which one or more embodiments of the present invention may be implemented is illustrated. The data communication system includes a transmitting device (in this case, a server 201) operable to transmit data packets of a data stream to a receiving device (in this case, a client terminal 202) via a data communication network 200. The data communication network 200 may be a wide area network (WAN) or a local area network (LAN). Such a network may be, for example, a wireless network (Wifi / 802.11a, b, or g), an Ethernet network, an Internet network, or a hybrid network consisting of several different networks. In a specific embodiment of the present invention, the data communication system may be a digital television broadcast system in which the server 201 transmits the same data content to multiple clients.

[0069] The data stream 204 provided by the server 201 may be composed of multimedia data representing video and audio data. In some embodiments of the present invention, the audio and video data streams may be captured by the server 201 using a microphone and a camera, respectively. In some embodiments, the data streams may be stored on the server 201 or received by the server 201 from other data providers, or generated at the server 201. The server 201 is provided with an encoder for encoding the video and audio streams, in particular for providing a compressed bit stream for transmission, which is a more compact representation of the data presented as input to the encoder.

[0070] In order to obtain a better ratio of quality of transmitted data to the amount of transmitted data, the video data may be compressed, for example, according to the HEVC format or the H.264 / AVC format.

[0071] The client 202 receives the transmitted bitstream and decodes the reconstructed bitstream to reproduce a video image on a display device and reproduce audio data using a speaker.

[0072] Despite Figure 2 A streaming scenario is considered in the examples of FIG, but it will be appreciated that in some embodiments of the invention, data communication between the encoder and decoder may be performed using, for example, a media storage device such as an optical disc.

[0073] In one or more embodiments of the present invention, a video image is transmitted along with data representing a compensating offset to be applied to reconstructed pixels of the image to provide filtered pixels in the final image.

[0074] Figure 3 The processing device 300 configured to implement at least one embodiment of the present invention is schematically illustrated. The processing device 300 may be a device such as a microcomputer, a workstation, or a lightweight portable device.

[0075] The apparatus 300 comprises a communication bus 313 connected to:

[0076] - a central processing unit 311 denoted as CPU, such as a microprocessor;

[0077] - a read-only memory 306 denoted as ROM, for storing the computer program implementing the invention;

[0078] a random access memory 312, represented as a RAM, for storing executable codes of the method according to an embodiment of the present invention, and registers suitable for recording variables and parameters required for implementing the method for encoding a digital image sequence and / or the method for decoding a bit stream according to an embodiment of the present invention; and

[0079] A communication interface 302 connected to a communication network 303, via which digital data to be processed are transmitted or received.

[0080] Optionally, the device 300 may further include the following components:

[0081] - a data storage component 304, such as a hard disk, for storing a computer program for implementing the method of one or more embodiments of the present invention and data used or generated during the implementation of one or more embodiments of the present invention;

[0082] a disk drive 305 for a disk 306, which is suitable for reading data from the disk 306 or writing data to said disk;

[0083] - A screen 309 for displaying data and / or serving as a graphical interface for interaction with the user by means of a keyboard 310 or any other pointing means.

[0084] Device 300 may be connected to various peripheral devices such as digital camera 320 or microphone 308 , each of which is connected to an input / output card (not shown) to provide multimedia data to device 300 .

[0085] The communication bus provides communication and interoperability between the various elements included in or connected to device 300. The representation of a bus is not limiting, and in particular, the central processing unit is operable to communicate instructions to any element of device 300, either directly or via other elements of device 300.

[0086] The disk 306 may be replaced by any information medium, such as a rewritable or non-rewritable compact disk (CD-ROM), a ZIP disk or a memory card, and in general by an information storage element that can be read by a microcomputer or a microprocessor, the disk 306 being integrated into the device or not, possibly removable and suitable for storing one or more programs whose execution enables the implementation of the method for encoding a digital image sequence and / or the method for decoding a bit stream according to the invention.

[0087] The executable code may be stored in a read-only memory 306, on a hard disk 304 or on a removable digital medium such as, for example, the disk 306 as previously described. According to a variant, the executable code of the program may be received via the interface 302 by means of the communication network 303 to be stored in one of the storage means of the device 300 (such as the hard disk 304) before being executed.

[0088] The central processing unit 311 is adapted to control and direct the execution of instructions or portions of software code for executing one or more programs according to the present invention, instructions stored in one of the aforementioned storage means. Upon power-up, one or more programs stored in non-volatile memory (e.g., on the hard disk 304 or in the read-only memory 306) are transferred to the random access memory 312 (which then contains the executable code of the one or more programs) and registers for storing variables and parameters necessary for the implementation of the present invention.

[0089] In this embodiment, the device is a programmable device that implements the invention using software. Alternatively, however, the invention may be implemented in hardware (for example in the form of an application specific integrated circuit or ASIC).

[0090] Figure 4 A block diagram illustrating an encoder according to at least one embodiment of the present invention. The encoder is represented by connected modules, each module being adapted to implement at least one corresponding step of at least one embodiment of a method for encoding an image of a sequence of images according to one or more embodiments of the present invention, e.g., in the form of programming instructions executed by a CPU 311 of an apparatus 300.

[0091] The encoder 400 receives digital images i0 to i n The original sequence 401 of is taken as input. Each digital image is represented by a set of samples (called pixels).

[0092] After implementing the encoding process, the encoder 400 outputs a bitstream 410. The bitstream 410 includes a plurality of coding units or slices, each slice including a slice header for transmitting encoded values of encoding parameters used for slice encoding, and a slice body including encoded video data.

[0093] Module 402 inputs digital images i0 to i n 401 is divided into pixel blocks. A block corresponds to an image portion and can have a variable size (e.g., 4×4, 8×8, 16×16, 32×32, 64×64, 128×128 pixels, and several rectangular block sizes are also considered). A coding mode is selected for each input block. Two families of coding modes are provided: coding modes based on spatial prediction coding (intra-frame prediction) and coding modes based on temporal prediction (inter-frame coding, merge, skip). Possible coding modes are tested.

[0094] Module 403 implements an intra-frame prediction process in which a given block to be coded is predicted by a predictor calculated from its neighboring pixels. If intra-frame coding is selected, the selected intra-frame predictor and an indication of the difference between the given block and its predictor are encoded to provide a residual.

[0095] Temporal prediction is implemented by the motion estimation module 404 and the motion compensation module 405. First, a reference image is selected from the reference image set 416, and the motion estimation module 404 selects a portion of the reference image (also called a reference region or image portion) that is closest to the given block to be encoded. The motion compensation module 405 then uses the selected region to predict the block to be encoded. The motion compensation module 405 calculates the difference between the selected reference region and the given block (also called the residual block). The selected reference region is indicated by a motion vector.

[0096] Thus, in both cases (spatial and temporal prediction), the residual is calculated by subtracting the prediction from the original block.

[0097] In the intra-frame prediction implemented by module 403, the prediction direction is encoded. In the temporal prediction, at least one motion vector is encoded. In the inter-frame prediction implemented by modules 404, 405, 416, 418, 417, at least one motion vector or data for identifying such a motion vector is encoded for the temporal prediction.

[0098] If inter prediction is selected, information about the motion vector and the residual block is encoded. To further reduce the bit rate, the motion vector is encoded as a difference relative to the motion vector predictor, assuming that the motion is homogeneous. The motion vector predictor from the set of motion information predictors is obtained by the motion vector prediction and encoding module 417 from the motion vector field 418.

[0099] The encoder 400 further includes a selection module 406 for selecting a coding mode by applying a coding cost criterion, such as a rate-distortion criterion. To further reduce redundancy, a transform (such as DCT) is applied to the residual block by a transform module 407, and the resulting transformed data is then quantized by a quantization module 408 and entropy encoded by an entropy coding module 409. Finally, the encoded residual block of the current block being encoded is inserted into a bitstream 410.

[0100] The encoder 400 also decodes the encoded image to generate a reference image for motion estimation of subsequent images. This allows the encoder and decoder receiving the bitstream to have the same reference frame. The inverse quantization module 411 performs inverse quantization of the quantized data, followed by an inverse transform by the inverse transform module 412. The inverse intra prediction module 413 uses the prediction information to determine which predictor to use for a given block, and the inverse motion compensation module 414 actually adds the residual obtained by module 412 to the reference region obtained from the reference image set 416.

[0101] Post filtering is then applied by module 415 to filter the reconstructed pixel frame. In an embodiment of the present invention, a SAO loop filter is used, wherein a compensating offset is added to the pixel values of the reconstructed pixels of the reconstructed image.

[0102] Figure 5 A block diagram of a decoder 60 according to an embodiment of the present invention is shown, which can be used to receive data from an encoder. The decoder is represented by connected modules, each module being adapted to implement the corresponding steps of the method implemented by the decoder 60, for example in the form of programming instructions to be executed by the CPU 311 of the device 300.

[0103] The decoder 60 receives a bitstream 600 comprising coding units, each consisting of a header containing information about the coded parameters and a body containing the coded video data. Figure 6 The structure of the bitstream in VVC is described in more detail. Figure 4 As illustrated, for a given block, the coded video data is entropy coded on a predetermined number of bits and the index of the motion vector predictor is encoded. The received coded video data is entropy decoded by module 62. The residual data is then dequantized by module 63, after which an inverse transform is applied by module 64 to obtain pixel values.

[0104] Mode data indicating an encoding mode is also entropy-decoded, and based on the mode, an encoding block of image data is subjected to intra-type decoding or inter-type decoding.

[0105] In the case of intra mode, the intra inverse prediction module 65 determines the intra predictor based on the intra prediction mode specified in the bitstream.

[0106] If the mode is inter, motion prediction information is extracted from the bitstream to find the reference region used by the encoder. The motion prediction information consists of a reference frame index and a motion vector residual. The motion vector predictor is added to the motion vector residual to obtain the motion vector by the motion vector decoding module 70.

[0107] A motion vector decoding module 70 applies motion vector decoding to each current block coded by motion prediction. Once the index of the motion vector predictor for the current block has been obtained, the actual value of the motion vector associated with the current block can be decoded and used to apply inverse motion compensation by module 66. The portion of the reference image indicated by the decoded motion vector is extracted from the reference image 68 to apply inverse motion compensation 66. The decoded motion vector is used to update the motion vector field data 71 for use in inverse prediction of subsequently decoded motion vectors.

[0108] Finally, a decoded block is obtained. Post filtering is applied by a post filtering module 67. The decoder 60 finally provides a decoded video signal 69.

[0109] Figure 6 The organization of the bitstream in an exemplary coding system VVC as described in JVET_Q2001-vD is shown.

[0110] The bitstream 61 according to the VVC coding system consists of an ordered sequence of syntax elements and encoded data. The syntax elements and encoded data are placed into network abstraction layer (NAL) units 601-608. There are different NAL unit types. The network abstraction layer provides the ability to encapsulate the bitstream into different protocols (such as RTP / IP (Real Time Protocol / Internet Protocol), ISO base media file format, etc.). The network abstraction layer also provides a framework for packet loss resistance.

[0111] NAL units are divided into video coding layer (VCL) NAL units and non-VCL NAL units. VCL NAL units contain the actual coded video data. Non-VCL NAL units contain additional information. This additional information can be parameters required to decode the coded video data or supplementary data that can enhance the usability of the decoded video data. NAL units 606 correspond to slices and constitute the VCL NAL units of the bitstream.

[0112] Different NAL units 601-605 correspond to different parameter sets, which are non-VCL NAL units. The decoder parameter set (DPS) NAL unit 301 contains parameters that are constant for a given decoding process. The video parameter set (VPS) NAL unit 602 contains parameters defined for the entire video and therefore the entire bitstream. The DPS NAL unit can define parameters that are more static than those in the VPS. In other words, the parameters of the DPS change less frequently than those of the VPS.

[0113] The sequence parameter set (SPS) NAL unit 603 contains parameters defined for a video sequence. Specifically, the SPS NAL unit may define the sub-picture layout and associated parameters of the video sequence. Parameters associated with each sub-picture specify the coding constraints applied to the sub-picture. Specifically, a flag is included to indicate that temporal prediction between sub-pictures is restricted to data from the same sub-picture. Another flag may enable or disable loop filters across sub-picture boundaries.

[0114] Picture parameter set (PPS) NAL unit 604. The PPS contains parameters defined for a picture or group of pictures. Adaptation parameter set (APS) NAL unit 605 contains parameters for the loop filter, which is typically an adaptive loop filter (ALF) or a shaper model (or a luma map with chroma scaling (LMCS) model) or a scaling matrix used at the slice level.

[0115] The syntax of PPS as proposed in the current version of VVC includes syntax elements that specify the size of a picture in units of luma samples and the partitioning of each picture into blocks and slices.

[0116] The PPS contains syntax elements that allow the location of slices within a frame to be determined. Since a sub-picture forms a rectangular area within a frame, the set of slices, tile portions, or tiles belonging to a sub-picture can be determined from the parameter set NAL unit. Like the APS, the PPS has an ID mechanism to limit the number of transmissions of the same PPS.

[0117] The main difference between the PPS and the picture header is its transmission, which is usually sent for a group of pictures, compared to the PH which is systematically sent for each picture. Therefore, in contrast to the PH, the PPS contains parameters that can be constant for several pictures.

[0118] The bitstream may also contain Supplemental Enhancement Information (SEI) NAL units ( Figure 6(Not shown in the image). The periodicity of these parameter sets in the bitstream is variable. A VPS defined for the entire bitstream may appear only once in the bitstream. Conversely, an APS defined for a slice may appear once for each slice in each picture. In practice, different slices may rely on the same APS, and therefore there are typically fewer APSs than slices in each picture. Specifically, the APS is defined in the picture header. However, the ALF APS can be refined in the slice header.

[0119] The Access Unit Delimiter (AUD) NAL unit 607 separates two access units. An access unit is a collection of NAL units that may include one or more coded pictures with the same decoding timestamp. This optional NAL unit contains only one syntax element from the current VVC specification: pic_type, which indicates that the slice_type value is used for all slices of the coded pictures in the AU. If pic_type is set to 0, the AU contains only intra slices. If it is 1, it contains P and I slices. If it is 2, it contains B, P, or intra slices.

[0120] This NAL unit contains only one syntax element, pic-type.

[0121] Table 1 Syntax AUD

[0122]

[0123] In JVET-Q2001-vD, pic-type is defined as follows:

[0124] "pic_type indicates that the slice_type values of all slices of the coded pictures in the AU containing the AU delimiter NAL unit are members of the set listed in Table 2 for the given pic_type value. The value of pic_type shall be equal to 0, 1, or 2 in bitstreams conforming to this version of this specification. Other values of pic_type are reserved for future use by ITUT|ISO / IEC. Decoders conforming to this version of this specification shall ignore the reserved values of pic_type."

[0125] rbsp_trailing_bits() is a function that adds bits to align with the end of a byte. Therefore, after this function, the amount of the bit stream parsed is an integer number of bytes.

[0126] Table 2 Explanation of pic_type

[0127] pic_type Possible slice_type values in AU 0 I 1 P,I 2 B,P,I

[0128] The PH NAL unit 608 is a picture header NAL unit that groups common parameters for a set of slices of one coded picture.A picture may refer to one or more APSs to indicate the AFL parameters, shaper models, and scaling matrices used by the slices of the picture.

[0129] Each VCL NAL unit 606 contains a slice. A slice can correspond to an entire picture or a sub-picture, a single block, or multiple blocks or a fragment of a block. For example, Figure 6 A slice comprises a number of blocks 620 . A slice consists of a slice header 610 and a raw byte sequence payload RBSP 611 , which contains coded pixel data coded as coded blocks 640 .

[0130] The syntax of the PPS as proposed in the current version of VVC includes syntax elements that specify the size of a picture in units of luma samples and the partitioning of each picture in units of blocks and slices.

[0131] The PPS contains syntax elements that allow the slice positions in a frame to be determined. Since a sub-picture forms a rectangular area in a frame, the set of slices, tile parts or tiles belonging to a sub-picture can be determined from the parameter set NAL units.

[0132] NAL unit slice

[0133] The NAL unit slice layer contains a slice header and slice data, as shown in Table 3.

[0134] Table 3 Stripe layer syntax

[0135]

[0136] APS

[0137] The adaptation parameter set (APS) NAL unit 605 is defined in Table 4 showing the syntax elements.

[0138] As depicted in Table 4, there are 3 possible types of APS given by the aps_params_type syntax element:

[0139] ALF_AP: used for ALF parameters

[0140] LMCS_APS: used for LMCS parameters

[0141] SCALLING_APS: used for scaling list related parameters

[0142] Table 4 Adaptive parameter set syntax

[0143]

[0144]

[0145] The following discusses these three types of APS parameters in turn.

[0146] ALF APS

[0147] The ALF parameters are described in the adaptive loop filter data syntax element (Table 5). First, four flags are dedicated to specifying whether the ALF filter is sent for luma and / or for chroma and whether CC-ALF (cross-component adaptive loop filtering) is enabled for the Cb component and the Cr component. If the luma filter flag is enabled, another flag is decoded to know whether the clipping value (alf_luma_clip_flag) is signaled. The number of filters signaled is then decoded using the alf_luma_num_filters_signalled_minus1 syntax element. If necessary, the syntax element representing the ALF coefficient increment "alf_luma_coeff_delta_idx" is decoded for each enabled filter. The absolute value and sign of each coefficient of each filter are then decoded.

[0148] If alf_luma_clip_flag is enabled, the clipping index of each coefficient of each enabled filter is decoded.

[0149] In the same way, the ALF chroma coefficients are decoded when needed.

[0150] If CC-ALF is enabled for Cr or Cb, the number of filters is decoded (alf_cc_cb filters_signalled minus1 or alf_cc_cr filters_signalled_minus1) and the related coefficients are decoded (alf_cc_cb_mapped_coeff_abs and alf_cc_cb_coeff_sign or alf_cc_cr_mapped_coeff_abs and alf_cc_cr_coeff_sign respectively).

[0151] Table 5 Adaptive loop filter data syntax

[0152]

[0153]

[0154]

[0155] LMCS syntax elements for both luma mapping and chroma scaling

[0156] Table 6 below gives all LMCS syntax elements (LMCS_APS) encoded in the Adaptation Parameter Set (APS) syntax structure when the aps_params_type parameter is set to 1. Up to four LMCS APSs may be used in a coded video sequence, however, for a given picture only a single LMCS APS may be used.

[0157] These parameters are used to construct the forward and inverse mapping functions for luma and the scaling function for chroma.

[0158] Table 6 Luma Mapping with Chroma Scaling Data Syntax

[0159]

[0160] Zoom List APS

[0161] The scaling list provides the possibility to update the quantization matrix used for quantization. In VVC, the scaling matrix is signaled in the APS as described in the scaling list data syntax element (Table 7 Scaling list data syntax). The first syntax element specifies whether the scaling matrix is used for the LFNST (Low Frequency Non-separable Transform) tool based on the flag scaling_matrix_for_lfnst_disabled_flag. The second is specified if the scaling list is used for chroma components (scaling_list_chroma_present_flag). Then, the syntax elements required to construct the scaling matrix (scaling_list_copy_mode_flag, scaling_list_pred_mode_flag, scaling_list_pred_id_delta, scaling_list_dc_coef, scaling_list_delta_coef) are decoded.

[0162] Table 7: Scaling List Data Syntax

[0163]

[0164]

[0165] Image header

[0166] A picture header is sent at the beginning of each picture before the other slice data. This is very large compared to previous headers in previous drafts of the standard. A complete description of all these parameters can be found in JVET_Q2001-vD. Table 9 shows these parameters in the current picture header decoding syntax.

[0167] The relevant syntactic elements that can be decoded are:

[0168] Whether to use the image or reference frame

[0169] Type of image

[0170] Output frame

[0171] Number of images

[0172] Use sub-images (if needed)

[0173] List of reference images (if required)

[0174] Color plane (if needed)

[0175] Partition update (if overwrite flag is enabled)

[0176] Incremental QP parameters (if needed)

[0177] Motion information parameters (if necessary)

[0178] ALF parameters (if required)

[0179] SAO parameters (if needed)

[0180] Quantization parameters (if needed)

[0181] LMCS parameters (if required)

[0182] Scale list parameters (if needed)

[0183] Image header expansion (if necessary)

[0184] ·etc

[0185] Image "Type"

[0186] The first flag is grd_or_irap_pic_flag, which indicates whether the current picture is a resynchronization picture (IRAP or GDR). If this flag is true, gdr_pic_flag is decoded to know whether the current picture is an IRAP picture or a GDR picture.

[0187] The ph_inter_slice_allowed_flag is then decoded to identify that inter slices are allowed.

[0188] When they are allowed, the flag ph_infra_slice_allowed_flag is decoded to know whether intra slices are allowed for the current picture.

[0189] Then decode non_reference_picture_flag, ph_pic_parameter_set_id indicating PPS ID, and picture order count ph_pic_order_cnt_lsb. The picture order count gives the number of the current picture.

[0190] If the picture is a GDR or IRAP picture, the flag no_output_of_prior_pics_flag is decoded.

[0191] And if the picture is GDR, decode recovery_poc_cnt. Then, decode ph_poc_msb_present_flag and poc_msb_val if necessary.

[0192] ALF

[0193] After these parameters that describe important information about the current picture, a set of ALF APS ID syntax elements are decoded if ALF is enabled at the SPS level and if ALF is enabled at the picture header level. ALF is enabled at the SPS level due to the sps_alf_enabled_flag flag. ALF is signaled at the picture header level due to alf_info_in_ph_flag being 1, otherwise (alf_info_in_ph_flag being 0), ALF is signaled at the slice level.

[0194] alf_info_in_ph_flag is defined as follows:

[0195] "alf_info_in_ph_flag equal to 1 specifies that ALF information is present in the PH syntax structure and is not present in slice headers referencing PPSs that do not contain a PH syntax structure. alf_info_in_ph_flag equal to 0 specifies that ALF information is not present in the PH syntax structure and may be present in slice headers referencing PPSs that do not contain a PH syntax structure."

[0196] First, ph_alf_enabled_present_flag is decoded to determine whether ph_alf_enabled_flag should be decoded. If ph_alf_enabled_present_flag is enabled, ALF is enabled for all slices of the current picture.

[0197] If ALF is enabled, the pic_num_alf_aps_ids_luma syntax element is used to decode the amount of ALF APS ID for luma. For each APS ID, the APS ID value "ph_alf_aps_id_luma" for luma is decoded.

[0198] For chroma, the syntax element ph_alf_chroma_idc is decoded to determine whether ALF is enabled for chroma, only for Cr, or only for Cb. If enabled, the value of the APS ID for chroma is decoded using the ph_alf_aps_id_chroma syntax element.

[0199] In this way, if required by the Cb and / or Cr components, the APS ID for the CC-ALF method is decoded.

[0200] LMCS

[0201] If LMCS is enabled at the SPS level, the set of LMCS APS ID syntax elements is decoded. First, ph_lmcs_enabled_flag is decoded to determine whether LMCS is enabled for the current picture. If LMCS is enabled, the ID value ph_lmcs_aps_id is decoded. For chroma, only ph_chroma_residual_scale_flag is decoded to enable or disable the method for chroma.

[0202] Zoom List

[0203] If scaling lists are enabled at the SPS level, the set of scaling list APS IDs is decoded. The ph_scaling_list_present_flag is decoded to determine whether the scaling matrix is enabled for the current picture. And then the value of the APS ID (ph_scaling_list_aps_id) is decoded.

[0204] Sub-image

[0205] When sub-picture parameters are enabled at the SPS and if the sub-picture ID is signaled to be disabled, the sub-picture parameters are enabled. Also contains some information about the virtual boundaries. For sub-picture parameters, eight syntax elements are defined:

[0206] · ph_virtual_boundaries_present_flag

[0207] · ph_num_ver_virtual_boundaries

[0208] · ph_virtual_boundaries_pos_x[i]

[0209] · ph_num_hor_virtual_boundaries

[0210] · ph_virtual_boundaries_pos_y[i]

[0211] Output Flag

[0212] These sub-picture parameters are followed by pic_output_flag (if present).

[0213] Reference Image List

[0214] If the reference picture list is signaled in the picture header (due to rpl_info_in_ph_flag being equal to 1), the parameter ref_pic_lists() of the reference picture list is decoded, which contains the following syntax elements:

[0215] rpl_sps_flag[]

[0216] rpl_idx[]

[0217] ·poc_lsb_lt[][]

[0218] ·delta_poc_msb_present_flag[][]

[0219] delta_poc_msb_cycle_lt[][]

[0220] Partition

[0221] If required, a partition parameter set is decoded and contains the following syntax elements:

[0222] ·partition_constraints_override_flag

[0223] ·ph_log2_diff_min_qt_min_cb_intra_slice_luma

[0224] ·ph_max_mtt_hierarchy_depth_intra_slice_luma

[0225] ·ph_log2_diff_max_bt_min_qt_intra_slice_luma

[0226] ·ph_log2_diff_max_tt_min_qt_intra_slice_luma

[0227] ·ph_log2_diff_min_qt_min_cb_intra_slice_chroma

[0228] ·ph_max_mtt_hierarchy_depth_intra_slice_chroma

[0229] ·ph_log2_diff_max_bt_min_qt_intra_slice_chroma

[0230] ·ph_log2_diff_max_tt_min_qt_intra_slice_chroma

[0231] ·ph_log2_diff_min_qt_min_cb_inter_slice

[0232] ·ph_max_mtt_hierarchy_depth_inter_slice

[0233] ·ph_log2_diff_max_bt_min_qt_inter_slice

[0234] ·ph_log2_diff_max_tt_min_qt_inter_slice

[0235] Weighted prediction

[0236] If the weighted prediction method is enabled at the PPS level and if the weighted prediction parameters are signaled in the picture header (wp_info_in_ph_flag is equal to 1), the weighted prediction parameters pred_weight_table() are decoded.

[0237] When bi-predictive weighted prediction is enabled, pred_weight_table() contains weighted prediction parameters for list L0 and list L1. As depicted in the pred_weight_table() syntax table (Table 8), when weighted prediction parameters are sent in the picture header, the number of weights for each list is explicitly sent.

[0238] Table 8 Weighted prediction parameter syntax

[0239]

[0240]

[0241] Incremental QP

[0242] When the picture is intra, ph_cu_qp_delta_subdiv_intra_slice and ph_cu_chroma_qp_offset_subdiv_intra_slice are decoded if needed. And if inter slices are allowed, ph_cu_qp_delta_subdiv_inter_slice and ph_cu_chroma_qp_offset_subdiv_inter_slice are decoded if needed. Finally, the picture header extension syntax element is decoded if needed.

[0243] All parameters alf_info_in_ph_flag, rpl_info_in_ph_flag, qp_delta_info_in_ph_flag, sao_info_in_ph_flag, dbf_info_in_ph_flag, wp_info_in_ph_flag are signaled in the PPS.

[0244] Table 9 Picture header structure

[0245]

[0246]

[0247]

[0248]

[0249]

[0250]

[0251]

[0252] Strip header

[0253] A slice header is sent at the beginning of each slice. The slice header contains approximately 65 syntax elements. This is very large compared to previous slice headers in earlier video coding standards. A complete description of all slice header parameters can be found in JVET-Q2001-vD. Table 10 shows these parameters in the current slice header decoding syntax.

[0254] Table 10 Partial strip header

[0255]

[0256]

[0257]

[0258]

[0259]

[0260] First, picture_header_in_slice_header_flag is decoded to know whether picture_header_structure() exists in the slice header.

[0261] Then, if necessary, slice_subpic_id is decoded to determine the sub-picture ID of the current slice. Then, slice_address is decoded to determine the address of the current slice. If the current slice mode is rectangular slice mode (rest_slice_flag is equal to 1) and if the number of slices in the current sub-picture is greater than 1, the slice address is decoded. If the current slice mode is raster scan mode (rest_slice_flag is equal to 0) and if the number of blocks in the current picture is greater than 1 calculated based on the variables defined in the PPS, the slice address may also be decoded.

[0262] If the number of tiles in the current picture is greater than 1 and if the current slice mode is not a rectangular slice mode, num_tiles_in_slice_minus1 is decoded. In the current VVC draft specification, num_tiles_in_slice_minus1 is defined as follows:

[0263] "num_tiles_in_slice_minus1 plus 1, when present, specifies the number of tiles in a slice. The value of num_tiles_in_slice_minus1 should be in the range of 0 to NumTilesInPic-1, inclusive."

[0264] Then decode the slice_type.

[0265] If ALF is enabled at the SPS level (sps_alf_enabled_flag) and if ALF is signaled in the slice header (alf_info_in_ph_flag is equal to 0), the ALF information is decoded. This includes a flag indicating that ALF is enabled for the current slice (slice_alf_enabled_flag). If enabled, the number of APS ALF IDs for luma (slice_num_alf_aps_ids_luma) is decoded, followed by the APS ID (slice_alf_aps_id_luma[i]). Then, slice_alf_chroma_idc is decoded to know if ALF is enabled for the chroma components and which chroma component is enabled. Then, if necessary, the APS ID for chroma (slice_alf_aps_id_chroma) is decoded. In the same way, if necessary, slice_cc_alf_cb_enabled_flag is decoded to know if the CC ALF method is enabled. If CC ALF is enabled, if CC ALF is enabled for Cr and / or Cb, decode the relevant APS ID for Cr and / or Cb.

[0266] If the colour planes are sent independently (separate_colour_plane_flag equal to 1), colour_plane_id is decoded.

[0267] When the reference picture list is not sent in the picture header (rpl_info_in_ph_flag equal to 0) and when the NAL unit is not IDR or if the reference picture list is sent for an IDR picture (sps_idr_rpl_present_flag equal to 1), the reference picture list parameters are decoded; these are similar to those in the picture header.

[0268] If a reference picture list is sent in the picture header (rpl_info_in_ph_flag is equal to 1) or the NAL unit is not IDR, or if a reference picture list is sent for an IDR picture (sps_idr_rpl_present_flag is equal to 1), and if the number of references of at least one list is higher than 1, the override flag num_ref_idx_active_override_flag is decoded.

[0269] If this flag is enabled, the reference indices of the individual lists are decoded.

[0270] If num_ref_idx_active_override_flag is enabled, the number of reference indices num_ref_idx_active_minus1[i] for each list "i" is decoded when needed. The number of reference indices overridden for the current list should be lower than or equal to the number of reference frame indices signaled in ref_pic_lists(). Thus, the overriding reduces or does not reduce the maximum number of reference frames for each list.

[0271] When the slice type is not intra, and if necessary, decode cabac_init_flag. If the reference picture list is sent in the slice header and other conditions occur, decode slice_collocated_from_l0_flag and slice_collocated_ref_idx. These data are related to CABAC coding and collocated motion vectors.

[0272] In the same manner, when the slice type is not intra, parameters pred_weight_table() of weighted prediction are decoded.

[0273] If delta QP information is sent in the slice header (qp_delta_info_in_ph_flag is equal to 0), decode slice_qp_delta. If needed, decode the syntax elements slice_cb_qp_offset, slice_cr_qp_offset, slice_joint_cbcr_qp_offset, and cu_chroma_qp_offset_enabled_flag.

[0274] If SAO information is sent in the slice header (sao_info_in_ph_flag equal to 0) and if it is enabled at the SPS level (sps_sao_enabled_flag), then the SAO enablement flags are decoded for both luma and chroma: slice_sao_luma_flag, slice_sao_chroma_flag.

[0275] Then, if the deblocking filter parameters are signaled in the slice header (dbf_info_in_ph_flag equal to 0), the deblocking filter parameters are decoded.

[0276] The flag slice_ts_residual_coding_disabled_flag is system-decoded to know whether the transform skip residual coding method is enabled for the current slice.

[0277] If LMCS is enabled in the picture header (ph_lmcs_enabled_flag is equal to 1), the flag slice_lmcs_enabled_flag is decoded.

[0278] In the same way, if the scaling list is enabled in the picture header (phpic_scaling_list_presentenabled_flag is equal to 1), the flag slice_scaling_list_present_flag is decoded.

[0279] Then, if necessary, other parameters are decoded.

[0280] Image header in strip header

[0281] In a specific signal notification manner, such as Figure 7 As depicted in FIG, the picture header (708) may be signaled within the slice header (710). In this case, there is no NAL unit containing only the picture header (608). NAL units 701-707 correspond to Figure 6 Similarly, coding block 720 and coding block 740 correspond to the corresponding NAL units 601-607 in Figure 6 620 and 640. Therefore, the description of these units and blocks will not be repeated here. Due to the flag picture_header_in_slice_header_flag, it can be enabled in the slice header. In addition, when the picture header is signaled in the slice header, the picture should only contain one slice. Therefore, each picture always has only one picture header. In addition, the flag picture_header_in_slice_header_flag should have the same value for all pictures of a CLVS (Coding Layer Video Sequence). This means that all pictures between two IRAPs including the first IRAP have only one slice per picture.

[0282] The flag picture_header_in_slice_header_flag is defined as follows:

[0283] "picture_header_in_slice_header_flag equal to 1 specifies that the PH syntax structure is present in the slice header. picture_header_in_slice_header_flag equal to 0 specifies that the PH syntax structure is not present in the slice header.

[0284] It is a requirement for bitstream conformance that the value of picture_header_in_slice_header_flag should be the same in all coded slices in CLVS.

[0285] When picture_header_in_slice_header_flag is equal to 1 for a coded slice, it is a requirement for bitstream conformance that no VCL NAL units with nal_unit_type equal to PH_NUT shall be present in the CLVS.

[0286] When picture_header_in_slice_header_flag is equal to 0, all coded slices in the current picture shall have picture_header_in_slice_header_flag equal to 0, and the current PU shall have a PH NAL unit.

[0287] picture_header_structure() contains the syntax elements of picture_rbsp() except for the padding bits rbsp_trailing_bits(). "

[0288] Streaming applications

[0289] Some streaming applications extract only certain portions of the bitstream. These extractions can be spatial (as sub-pictures) or temporal (sub-portions of a video sequence). These extracted portions can then be merged with the rest of the bitstream. Others reduce the frame rate by extracting only some frames. Typically, the primary goal of these streaming applications is to use the maximum allowed bandwidth to produce the highest quality for the end user.

[0290] In VVC, for frame rate reduction, APS ID numbering is already restricted so that new APS ID numbers for a frame cannot be used for frames in upper layers in the temporal hierarchy. However, for streaming applications that extract portions of a bitstream, it is necessary to track APS IDs to determine which APSs should be retained for a sub-portion of the bitstream, since frames (due to IRAP) do not reset the APS ID numbering.

[0291] LMCS (Luminance Mapping with Chroma Scaling)

[0292] The Luma Mapping with Chroma Scaling (LMCS) technique is a sample value conversion method applied to a block before applying a loop filter in a video decoder such as VVC.

[0293] LMCS can be divided into two sub-tools. The first sub-tool is applied to luma blocks, while the second sub-tool is applied to chroma blocks, as described below:

[0294] 1) The first sub-tool is an in-loop mapping of the luma component based on an adaptive piecewise linear model. Luma component in-loop mapping adjusts the dynamic range of the input signal to improve compression efficiency by redistributing codewords across the dynamic range. Luma mapping utilizes a forward mapping function into the "mapping domain" and a corresponding inverse mapping function back into the "input domain."

[0295] 2) The second sub-tool is related to the chroma components, which apply luma-dependent chroma residual scaling. Chroma residual scaling is designed to compensate for the interaction between the luma signal and its corresponding chroma signal. Chroma residual scaling depends on the average of the neighboring luma samples reconstructed above and / or to the left of the current block.

[0296] Like most other tools in video encoders such as VVC, LMCS can be enabled / disabled at the sequence level using an SPS flag. Whether chroma residual scaling is enabled is also signaled at the slice level. If luma mapping is enabled, an additional flag is signaled to indicate whether luma-dependent chroma residual scaling is enabled. When luma mapping is not used, luma-dependent chroma residual scaling is completely disabled. Additionally, luma-dependent chroma residual scaling is always disabled for chroma blocks of size less than or equal to 4.

[0297] Figure 8 The principle of LMCS as described above for the Luma Mapping Sub-Tool is shown. Figure 8 The shaded blocks in the figure are the new LMCS functional blocks, which include the forward and inverse mapping of the luminance signal. It is important to note that when LMCS is used, some decoding operations are applied in the "mapping domain". These operations are performed by the Figure 8 They generally correspond to the inverse quantization, inverse transform, luma intra prediction and reconstruction steps (which consists in adding the luma prediction to the luma residual). Figure 8 The solid blocks in indicate where the decoding processes are applied in the original (ie non-mapped) domain, and this includes loop filtering such as deblocking, ALF and SAO, motion compensated prediction, and storage of decoded pictures as reference pictures (DPB).

[0298] Figure 9 Shown with Figure 8 Similar diagram, but this time for the Chroma Scaling sub-tool of the LMCS tool. Figure 9 The shaded blocks in the figure are new LMCS functional blocks, which include the luma-dependent chroma scaling process. However, in terms of chroma, there are some important differences compared to the luma case. Here, for the chroma samples, only the inverse quantization and inverse transform, represented by the blocks in the dashed line, are performed in the "mapped domain". All other steps of intra chroma prediction, motion compensation, and loop filtering are performed in the original domain. Figure 9 As shown, for brightness mapping, there is only a scaling process, and no forward and inverse processes.

[0299] Brightness mapping using a piecewise linear model

[0300] The Luma Mapping sub-tool uses a piecewise linear model, which means that the piecewise linear model divides the input signal dynamic range into 16 equal sub-ranges and, for each sub-range, uses the number of codewords assigned to that range to represent its linear mapping parameters.

[0301] Semantics of brightness mapping

[0302] The syntax element lmcs_min_bin_idx specifies the minimum bin (interval) index used in the construction process of the Luma Map with Chroma Scale (LMCS). The value of lmcs_min_bin_idx shall be in the range of 0 to 15 (inclusive).

[0303] The syntax element lmcs_delta_max_bin_idx specifies the delta value between 15 and the maximum bin index LmcsMaxBinIdx used in the construction of the luma map with chroma scaling. The value of lmcs_delta_max_bin_idx shall be in the range of 0 to 15, inclusive. The value of LmcsMaxBinIdx shall be set equal to 15 - lmcs_delta_max_bin_idx. The value of LmcsMaxBinIdx shall be greater than or equal to lmcs_min_bin_idx.

[0304] The syntax element lmcs_delta_cw_prec_minus1 plus 1 specifies the number of bits used to represent the syntax lmcs_delta_abs_cw[i].

[0305] The syntax element lmcs_delta_abs_cw[i] specifies the absolute delta codeword value for the i-th bin.

[0306] The syntax element lmcs_delta_sign_cw_flag[i] specifies the sign of the variable lmcsDeltaCW[i]. When lmcs_delta_sign_cw_flag[i] is not present, it is inferred to be equal to 0.

[0307] LMCS intermediate variable calculation for brightness mapping

[0308] In order to apply the forward and inverse brightness mapping processes, some intermediate variables and data arrays are required.

[0309] First, export the variable OrgCW as follows:

[0310] OrgCW=(1< <BitDepth) / 16

[0311] Then, the variable lmcsDeltaCW[i] (where i=lmcs_min_bin_idx . . . LmcsMaxBinIdx) is calculated as follows:

[0312] lmcsDeltaCW[i]=(1-2*lmcs_delta_sign_cw_flag[i])*lmcs_delta_abs_cw[i]

[0313] The new variable lmcsCW[i] is derived as follows:

[0314] - For i=0...lmcs_min_bin_idx-1, lmcsCW[i] is set equal to 0.

[0315] - For i = lmcs_min_bin_idx ... LmcsMaxBinIdx, the following applies:

[0316] lmcsCW[i]=OrgCW+lmcsDeltaCW[i]

[0317] The value of lmcsCW[i] should be in the range of (OrgCW>>3) to (OrgCW<<3-1) (inclusive).

[0318] - For i=LmcsMaxBinIdx+1...15, lmcsCW[i] is set equal to 0.

[0319] The variable InputPivot[i] (where i=0...16) is derived as follows:

[0320] InputPivot[i]=i*OrgCW

[0321] The variables LmcsPivot[i] (where i=0...16), ScaleCoeff[i] and InvScaleCoeff[i] (where i=0...15) are calculated as follows:

[0322]

[0323] Forward Luminance Map

[0324] like Figure 8 As shown, when LMCS is applied to luma, luma remap samples called predMapSamples[i][j] are obtained from the prediction samples predSamples[i][j].

[0325] predMapSamples[i][j] is calculated as follows:

[0326] First, calculate the index idxY from the predicted sample predSamples[i][j] at position (i, j).

[0327] idxY = predSamples[i][j] >> Log2(OrgCW)

[0328] Then, derive predMapSamples[i][j] as follows by using the intermediate variables idxY, LmcsPivot[idxY], and InputPivot[idxY] with part 0:

[0329] predMapSamples[i][j] = LmcsPivot[idxY]

[0330] +(ScaleCoeff[idxY] * (predSamples[i][j] - InputPivot[idxY]) + (1 << 10)) >> 11

[0331] Luminance reconstruction sample

[0332] Obtain the reconstruction process from the predicted luminance sample predMapSample[i][j] and the residual luminance sample resiSamples[i][j].

[0333] Simply obtain the reconstructed luminance picture sample recSamples[i][j] by adding predMapSample[i][j] to resiSamplei[i][j] as follows:

[0334] recSamples[i][j] = Clip1(predMapSamples[i][j] + resiSamples[i][j]])

[0335] In the above relationship, the Clip 1 function is a clipping function to ensure that the reconstructed sample is between 0 and 1 << BitDepth - 1.

[0336] Inverse luminance mapping

[0337] When applying the inverse luminance mapping according to Figure 8 the following operations are applied to each sample recSample[i][j] of the current block being processed:

[0338] First, calculate the index idxY from the reconstructed sample recSamples[i][j] at position (i, j).

[0339] idxY=recSamples[i][j]>>Log2(OrgCW)

[0340] The inverse mapped luma samples invLumaSample[i][j] are derived based on:

[0341] invLumaSample[i][j]=

[0342] InputPivot[idxYInv]+(InvScaleCoeff[idxYInv]*

[0343] (recSample[i][j]-LmcsPivot[idxYInv])+(1<<10))>>11

[0344] Then perform a clipping operation to obtain the final sample:

[0345] finalSample[i][j]=Clip1(invLumaSample[i][j])

[0346] Chroma Scaling

[0347] LMCS semantics for chroma scaling

[0348] The syntax element lmcs_delta_abs_crs in Table 6 specifies the absolute codeword value of the variable lmcsDeltaCrs. The value of lmcs_delta_abs_crs shall be in the range of 0 to 7 (inclusive). When not present, lmcs_delta_abs_crs is inferred to be equal to 0.

[0349] The syntax element lmcs_delta_sign_crs_flag specifies the sign of the variable lmcsDeltaCrs. When not present, lmcs_delta_sign_crs_flag is inferred to be equal to 0.

[0350] LMCS intermediate variable calculation for chroma scaling

[0351] In order to apply the chroma scaling process, some intermediate variables are needed.

[0352] The variable lmcsDeltaCrs is derived as follows:

[0353] lmcsDeltaCrs=(1-2*lmcs_delta_sign_crs_flag)*lmcs_delta_abs_crs

[0354] The variable ChromaScaleCoeff[i] (where i=0...15) is derived as follows:

[0355]

[0356] Chroma scaling

[0357] In the first step, the variable invAvgLuma is derived to calculate the average luma value of the reconstructed luma samples around the current corresponding chroma block. The average luma is calculated from the left and top luma blocks surrounding the corresponding chroma block.

[0358] If no samples are available, the variable invAvgLuma is set as follows:

[0359] invAvgLuma=1<<(BitDepth-1)

[0360] Based on the intermediate array LmcsPivot[] of part 0, the variable idxYInv is then derived as follows:

[0361]

[0362] The variable varScale is exported as follows:

[0363] varScale=ChromaScaleCoeff[idxYInv]

[0364] When the transform is applied to the current chroma block, the reconstructed chroma picture sample array recSamples is derived as follows:

[0365] recSamples[i][j]=Clip1(predSamples[i][j]+

[0366] Sign(resiSamples[i][j])*((Abs(resiSamples[i][j])*varScale+(1<<10))>>11))

[0367] If no transform has been applied to the current block, the following is applied:

[0368] recSamples[i][j]=Clip1(predSamples[i][j])

[0369] Encoder Considerations

[0370] The basic principle of the LMCS encoder is to first allocate more codewords to those dynamic range segments with codewords with lower variance than the average. In an alternative concept, the main goal of LMCS is to allocate fewer codewords to those dynamic range segments with codewords with higher variance than the average. In this way, smooth areas of the picture will be encoded with more codewords than the average, and vice versa.

[0371] All parameters of the LMCS tool stored in the APS are determined on the encoder side (see Table 6). The LMCS encoder algorithm is based on the evaluation of local luminance variance and optimizes the determination of LMCS parameters according to the basic principles described above. The optimization is then performed to obtain the best PSNR metric for the final reconstructed samples of a given block.

[0372] Example

[0373] Avoid striping address syntax elements when not needed

[0374] In one embodiment, when the picture header is signaled in the slice header, the slice address syntax element (slice_address) is inferred to be equal to the value 0, even if the number of tiles is greater than 1. Table 11 shows this embodiment.

[0375] An advantage of this embodiment is that the slice address is not parsed when the picture header is in the slice header, which reduces the bit rate, especially for low latency and low bit rate applications, and reduces the parsing complexity of some implementations when the picture is signaled in the slice header.

[0376] In an embodiment, this only applies to raster scan striping mode (rect_slice_flag equal to 0). This reduces parsing complexity for some implementations.

[0377] Table 11 shows the modified portion of the slice header

[0378]

[0379] Avoid sending the number of chunks in a stripe when not needed

[0380] In one embodiment, when the picture header is sent in the slice header, the number of tiles in the slice is not sent. Table 12 shows this embodiment, where the num_tiles_in_slice_minus1 syntax element is not sent when the flag picture_header_in_slice_header_flag is set equal to 1. An advantage of this embodiment is that the bit rate is reduced, especially for low-latency and low-bit-rate applications, because the number of tiles does not need to be sent.

[0381] In an embodiment, this only applies to raster scan striping mode (rect_slice_flag equal to 0). This reduces parsing complexity for some implementations.

[0382] Table 12 shows the modified portion of the slice header

[0383]

[0384] Predicted by PPS value NumTilesInPic (semantic)

[0385] In an additional embodiment, when a picture header is sent in a slice header, the number of tiles in the current slice is inferred to be equal to the number of tiles in the picture. This can be set by adding the following sentence to the semantics of the syntax element num_tiles_in_slice_minus1: "When not present, the variable num_tiles_in_slice_minus1 is set equal to NumTilesInPic - 1".

[0386] The variable NumTilesInPic gives the maximum number of tiles in a picture and is calculated based on the syntax elements sent in the PPS.

[0387] Set the number of blocks before the stripe address and avoid unnecessary sending of slice_address

[0388] In one embodiment, a syntax element dedicated to the number of blocks in a slice is sent before the slice address, and its value is used to determine whether the slice address needs to be decoded. More precisely, the number of blocks in a slice is compared with the number of blocks in the picture to determine whether the slice address needs to be decoded. In fact, if the number of blocks in a slice is equal to the number of blocks in the picture, it is guaranteed that the current picture contains only one slice.

[0389] In an embodiment, this only applies to raster scan striping mode (rect_slice_flag equal to 0). This reduces parsing complexity for some implementations.

[0390] This embodiment is shown in Table 13, where the syntax element slice_address is not decoded if the value of the syntax element num_tiles_in_slice_minus1 is equal to the variable NumTilesInPic minus 1. When num_tiles_in_slice_minus1 is equal to the variable NumTilesInPic minus 1, slice_address is inferred to be equal to 0.

[0391] Table 13 shows the modified portion of the slice header

[0392]

[0393] An advantage of this embodiment is that when the condition is set equal to true, the bit rate is reduced and the parsing complexity is reduced because the stripe address is not sent.

[0394] In one embodiment, when a picture header is sent in a slice header, the syntax element indicating the number of blocks in the current slice is not decoded, and the number of blocks in the slice is inferred to be equal to 1. Also, when the number of blocks in the slice is equal to the number of blocks in the picture, the slice address is inferred to be equal to 0, and the relevant syntax element is not decoded. Table 14 shows this embodiment.

[0395] This increases the bit rate reduction obtained by combining these two embodiments.

[0396] Table 14 shows the modified partial slice header

[0397]

[0398] Remove the unnecessary condition NumTilesInPic>1

[0399] In one embodiment, when raster scan stripe mode is enabled, there is no need to test whether the number of tiles in the current picture is actually greater than 1 in order to decode the syntax element slice_address and / or the number of tiles in the current slice. Specifically, when the number of tiles in the current picture is equal to 1, the rect_slice_flag value is inferred to be equal to 1. Therefore, raster scan stripe mode cannot be enabled in this case. Table 15 shows this embodiment.

[0400] This embodiment reduces the parsing complexity of the slice header.

[0401] Table 15 shows the modified portion of the slice header

[0402]

[0403] In one embodiment, when a picture header is sent in a slice header and when raster scan slice mode is enabled, the syntax element indicating the number of tiles in the current slice is not decoded, and the number of tiles in the slice is inferred to be equal to 1. Also, when the number of tiles in the slice is equal to the number of tiles in the picture and when raster scan slice mode is enabled, the slice address is inferred to be equal to 0, and the related syntax element slice_address is not decoded. Table 16 shows this embodiment.

[0404] The advantages are reduced bit rate and reduced parsing complexity.

[0405] Table 16 shows the modified partial slice header

[0406]

[0407] accomplish

[0408] Figure 11 Systems 191 and 195 according to embodiments of the present invention are shown, comprising at least one of encoder 150 or decoder 100 and a communication network 199. According to embodiments, system 195 is configured to process and provide content (e.g., video and audio content for display / output or streaming) to a user, who accesses decoder 100, for example, via a user terminal including decoder 100 or a user interface of a user terminal capable of communicating with decoder 100. Such a user terminal may be a computer, mobile phone, tablet computer, or any other type of device capable of providing / displaying (provided / streamed) content to a user. System 195 obtains / receives bitstream 101 (in the form of a continuous stream or signal (e.g., when displaying / outputting earlier video / audio)) via communication network 199. According to embodiments, system 191 is configured to process content and store processed content, such as video and audio content processed for display / output / streaming at a later time. System 191 obtains / receives content comprising a raw image sequence 151, which is received and processed by encoder 150 (including filtering using a deblocking filter according to the present invention), and encoder 150 generates a bitstream 101 to be transmitted to decoder 100 via communication network 199. Bitstream 101 is then transmitted to decoder 100 in a variety of ways. For example, it can be pre-generated by encoder 150 and stored as data in a storage device in communication network 199 (e.g., on a server or cloud storage device) until a user requests content (i.e., bitstream data) from the storage device, at which point the data is transmitted / streamed from the storage device to decoder 100. System 191 may also include a content providing device for providing / streaming content information (e.g., the title of the content and other metadata / storage location data used to identify, select, and request the content) of the content stored in the storage device to the user (e.g., by transmitting data for a user interface to be displayed on a user terminal), and for receiving and processing user requests for content so that the requested content can be transmitted / streamed from the storage device to the user terminal. Alternatively, the encoder 150 generates the bitstream 101 and transmits / streams it directly to the decoder 100 when the user requests content. The decoder 100 then receives the bitstream 101 (or signal) and filters it using the deblocking filter according to the present invention to obtain / generate a video signal 109 and / or an audio signal, which the user terminal then uses to provide the requested content to the user.

[0409] Any step of the method / process according to the present invention or the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the step / function may be stored as one or more instructions or codes or programs or computer-readable media on one or more hardware-based processing units or sent via one or more hardware-based processing units and executed by one or more hardware-based processing units, such as a programmable computing machine, which may be a PC ("personal computer"), a DSP ("digital signal processor"), a circuit, a circuit system, a processor and memory, a general-purpose microprocessor or central processing unit, a microcontroller, an ASIC ("application-specific integrated circuit"), a field programmable logic array (FPGA), or other equivalent integrated or discrete logic circuit system. Thus, the term "processor" as used herein may refer to any of the foregoing structures or any other structure suitable for implementing the techniques described herein.

[0410] Embodiments of the present invention may also be implemented by various devices or apparatuses, including wireless handsets, integrated circuits (ICs), or JC collections (e.g., chipsets). Various components, modules, or units are described herein to illustrate functional aspects of apparatuses / devices configured to perform these embodiments, but they do not necessarily need to be implemented by different hardware units. Instead, the various modules / units may be combined in a codec hardware unit or provided by a collection of interoperable hardware units, including one or more processors in conjunction with appropriate software / firmware.

[0411] The embodiments of the present invention can be implemented by a computer of a system or device that reads and executes computer-executable instructions (e.g., one or more programs) recorded on a storage medium to perform one or more modules / units / functions in the above-described embodiments and / or includes one or more processing units or circuits for performing one or more functions in the above-described embodiments, and can be implemented by a method performed by a computer of the system or device, for example, reading and executing computer-executable instructions from a storage medium to perform one or more functions in the above-described embodiments and / or controlling one or more processing units or circuits to perform one or more functions in the above-described embodiments. The computer may include a network of separate computers or separate processing units to read and execute computer-executable instructions. The computer-executable instructions may be provided to the computer from a computer-readable medium such as a communication medium, for example, via a network or a tangible storage medium. The communication medium may be a signal / bit stream / carrier. Tangible storage media are “non-transitory computer-readable storage media” and may include, for example, a hard disk, random access memory (RAM), read-only memory (ROM), a storage device of a distributed computing system, an optical disk (such as a compact disk (CD), a digital versatile disk (DVD), or a Blu-ray disk (BD)). TM ), one or more of a flash memory device, a memory card, etc. At least some steps / functions may also be implemented in hardware by a machine or dedicated components such as an FPGA (“field programmable gate array”) or an ASIC (“application-specific integrated circuit”).

[0412] Figure 122 is a schematic block diagram of a computing device 2000 for implementing one or more embodiments of the present invention. The computing device 2000 may be a device such as a microcomputer, a workstation, or a lightweight portable device. The computing device 2000 includes a communication bus connected to the following: - a central processing unit (CPU) 2001, such as a microprocessor; - a random access memory (RAM) 2002 for storing executable code of the method of the embodiment of the present invention and registers suitable for recording variables and parameters required to implement the method for encoding or decoding at least a portion of an image according to the embodiment of the present invention, the storage capacity of which may be expanded, for example, by an optional RAM connected to an expansion port; - a read-only memory (ROM) 2003 for storing computer programs for implementing the embodiment of the present invention; - a network interface (NET) 2004, which is typically connected to a communication network through which digital data to be processed is transmitted or received. The network interface (NET) 2004 may be a single network interface, or may be composed of a group of different network interfaces (e.g., wired and wireless interfaces, or different kinds of wired or wireless interfaces). Under the control of a software application in 2001, data packets are written to a network interface for transmission or read from the network interface for reception; a user interface (UI) 2005, which can be used to receive input from a user or display information to a user; a hard disk (HD) 2006, which can be configured as a mass storage device; and an input / output module (IO) 2007, which can be used to receive and send data from and to external devices (such as a video source or display). Executable code can be stored in ROM 2003, on HD 2006, or on a removable digital medium such as a disk. According to a variation, the executable code of a program can be received via NET 2004 via a communications network for storage in one of the storage components of computing device 2000 (such as HD 2006) prior to execution. CPU 2001 is adapted to control and direct the execution of instructions or portions of software code of one or more programs according to embodiments of the present invention, the instructions being stored in one of the aforementioned storage components. For example, after power-up, CPU 2001 is capable of executing those instructions relating to a software application from main RAM memory 2002 after loading instructions from program ROM 2003 or HD 2006. Such a software application, when executed by CPU 2001, causes the steps of the method according to the invention to be performed.

[0413] It will also be appreciated that, according to other embodiments of the present invention, a decoder according to the above-described embodiments is provided in a user terminal such as a computer, a mobile phone (cellular phone), a tablet, or any other type of apparatus capable of providing / displaying content to a user (e.g., a display device). According to yet another embodiment, an encoder according to the above-described embodiments is provided in an image capture device that also includes a camera, a video camera, or a webcam (e.g., a closed-circuit television or video surveillance camera) for capturing and providing content for encoding by the encoder. See below. Figure 13 and 14 Two such examples are provided.

[0414] Web camera

[0415] Figure 13 21 is a diagram illustrating a network camera system 2100 including a network camera 2102 and a client device 2104 .

[0416] The network camera 2102 includes an imaging unit 2106 , an encoding section 2108 , a communication unit 2110 , and a control unit 2112 .

[0417] The network camera 2102 and the client device 2104 are connected to each other via the network 200 so as to be able to communicate with each other.

[0418] The camera unit 2106 includes a lens and an image sensor (eg, a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS)), and captures an image of a subject and generates image data based on the image. The image may be a still image or a video image.

[0419] The encoding section 2108 encodes the image data by using the encoding method described above.

[0420] The communication unit 2110 of the network camera 2102 transmits the encoded image data encoded by the encoding section 2108 to the client device 2104 .

[0421] Furthermore, the communication unit 2110 receives commands from the client device 2104. The commands include commands for setting parameters for encoding by the encoding section 2108.

[0422] The control unit 2112 controls other units in the network camera 2102 according to the commands received by the communication unit 2110 .

[0423] The client device 2104 includes a communication unit 2114 , a decoding section 2116 , and a control unit 2118 .

[0424] The communication unit 2114 of the client device 2104 transmits a command to the network camera 2102 .

[0425] Furthermore, the communication unit 2114 of the client device 2104 receives the encoded image data from the network camera 2102 .

[0426] The decoding section 2116 decodes the encoded image data by using the decoding method described above.

[0427] The control unit 2118 of the client device 2104 controls other units in the client device 2104 according to user operations or commands received by the communication unit 2114 .

[0428] The control unit 2118 of the client device 2104 controls the display device 2120 to display the image decoded by the decoding section 2116 .

[0429] The control unit 2118 of the client device 2104 also controls the display device 2120 to display a GUI (Graphical User Interface) for specifying values of parameters of the network camera 2102 (including parameters used for encoding by the encoding section 2108 ).

[0430] The control unit 2118 of the client device 2104 also controls other units in the client device 2104 according to user operation input to the GUI displayed by the display device 2120 .

[0431] The control unit 2118 of the client device 2104 controls the communication unit 2114 of the client device 2104 according to user operation input to the GUI displayed by the display device 2120 to transmit a command for specifying the value of the parameter of the network camera 2102 to the network camera 2102 .

[0432] smartphone

[0433] Figure 14 2 is a diagram illustrating a smartphone 2200 .

[0434] The smartphone 2200 includes a communication unit 2202 , a decoding section 2204 , a control unit 2206 , a display unit 2208 , an image recording device 2210 , and a sensor 2212 .

[0435] The communication unit 2202 receives the encoded image data via the network 200 .

[0436] The decoding section 2204 decodes the encoded image data received by the communication unit 2202 .

[0437] The decoding section 2204 decodes the encoded image data by using the decoding method described above.

[0438] The control unit 2206 controls other units in the smartphone 2200 according to user operations or commands received by the communication unit 2202 .

[0439] For example, the control unit 2206 controls the display unit 2208 to display the image decoded by the decoding section 2204 .

[0440] Although the present invention has been described with reference to the embodiments, it will be understood that the present invention is not limited to the disclosed embodiments. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the appended claims. All features disclosed in this specification (including any appended claims, abstracts and drawings), and / or all steps of any method or process disclosed, may be combined in any combination, except for at least some mutually exclusive combinations of such features and / or steps. Unless expressly stated otherwise, each feature disclosed in this specification (including any appended claims, abstracts and drawings) may be replaced by alternative features for the same, equivalent or similar purposes. Therefore, unless expressly stated otherwise, each feature disclosed is merely an example of a general series of equivalent or similar features.

[0441] It should also be understood that any results of the above-described comparisons, determinations, evaluations, selections, performance, performance, or considerations (e.g., selections made during an encoding or filtering process) may be indicated in data in the bitstream (e.g., a flag or data indicating the results) or may be determined / inferred from data in the bitstream, such that the indicated or determined / inferred results may be used in processing rather than actually being compared, determined, evaluated, selected, performed, performed, or considered, for example, during a decoding process.

[0442] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.

[0443] Reference signs appearing in the claims are by way of illustration only and shall have no limiting effect on the scope of the claims.

Claims

1. A method of decoding video data from a bitstream, the bitstream comprising coded video data corresponding to one or more slices, wherein: Each stripe can include one or more blocks. wherein the bitstream comprises a picture header and a slice header, the picture header comprising syntax elements to be used when decoding one or more slices, the slice header comprising syntax elements to be used when decoding a slice, and The method comprises: Parsing syntactic elements; decoding a weighted prediction parameter from the picture header according to a value of a first flag, the first flag being a flag in a picture parameter set in the bitstream and being associated with the presence of the weighted prediction parameter in the picture header; and decoding the video data from the bitstream using the parsed syntax elements, Wherein, when the second syntax element parsed from the slice header indicates that the picture header exists in the slice header, (a) parsing of the first syntax element indicating the address of a slice included in a picture is constrained to be omitted, (b) when the second syntax element indicates that the picture header is present in the slice header, by not satisfying one of two conditions, omitting parsing of a third syntax element, the third syntax element being a syntax element to be parsed based on satisfying the two conditions and being a syntax element representing a result of subtracting 1 from the number of blocks in the slice; and (c) The value of the third syntax element is inferred to be equal to 0 regardless of the number of blocks in the picture.

2. The method according to claim 1, wherein If the second syntax element indicates that the picture header is present in the slice header, the value of the first syntax element is inferred to be 0.

3. The method according to claim 1 or 2, wherein: The logical operator && is not included in each of the two conditions.

4. The method according to claim 1, wherein When the value of the first flag is 1, the weighted prediction parameters can be decoded from the picture header, and when the value of the first flag is 0, the weighted prediction parameters are not decoded from the picture header.

5. The method according to claim 1, wherein The picture header is picture_header_structure().

6. A method of encoding video data into a bitstream, the bitstream comprising encoded video data corresponding to one or more slices, wherein: Each stripe can include one or more blocks. wherein the bitstream comprises a picture header and a slice header, the picture header comprising syntax elements to be used when decoding one or more slices, the slice header comprising 0 syntax elements to be used when decoding a slice, and The method comprises: Encode one or more syntactic elements; encoding the weighted prediction parameters in the picture header according to a value of a first flag, the first flag being a flag in a picture parameter set in the bitstream and being associated with the presence of the weighted prediction parameters in the picture header; and encoding the video data using the one or more syntax elements, Wherein, in a case where a second syntax element encoded in the slice header indicates that the picture header is present in the slice header, (a) a value of a first syntax element indicating an address of a slice included in a picture is constrained to be 0, (b) when the second syntax element indicates that the picture header is present in the slice header, a third syntax element is not encoded due to one of two conditions not being satisfied, the third syntax element being a syntax element to be parsed based on satisfying the two conditions and being a syntax element representing a result of subtracting 1 from the number of blocks in the slice, and (c) the value of the third syntax element is inferred to be equal to 0 regardless of the number of blocks in the picture.

7. The method according to claim 6, wherein: The logical operator && is not included in each of the two conditions.

8. The method according to claim 6, wherein: If the second syntax element indicates that the picture header is present in the slice header, the value of the first syntax element is inferred to be 0.

9. The method according to claim 6, wherein: When the value of the first flag is 1, the weighted prediction parameter can be encoded into the picture header, and when the value of the first flag is 0, the weighted prediction parameter is not encoded into the picture header.

10. The method according to claim 6, wherein: The picture header is picture_header_structure().

11. A decoder for decoding video data from a bitstream, the decoder being configured to perform the method according to any one of claims 1 to 5.

12. An encoder for encoding video data into a bitstream, the encoder being configured to perform the method according to any one of claims 6 to 10.

13. A computer program product comprising a computer program which, when executed, causes the method according to any one of claims 1 to 10 to be performed.

14. A computer-readable storage medium storing a computer program which, when executed, causes the method according to any one of claims 1 to 10 to be performed.

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