Method and apparatus for decoding video data from a bit stream, method and apparatus for encoding video data in a bit stream, and computer program product

Abstract

A method and apparatus for decoding video data from a bitstream, a method and apparatus for encoding video data in a bitstream, and a computer program product are described. The bitstream includes video data corresponding to one or more stripes. The decoding includes parsing the syntactic element and does not permit the use of the sub-picture and / or parsing the sub-picture information in combination with at least one syntactic element indicating that the picture to be decoded contains only one slice. A bitstream is decoded using the syntactic elements.

Description

[0001] (This application is a divisional application of an application filed on March 17, 2021, with application number 2021800227028 and invention name “Advanced Syntax 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 collaborative team consisting of 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 good 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 recommendations showed that compression efficiency was typically improved by 40% or more when compared to using HEVC. Particular results were shown on ultra-high definition (UHD) video test material. Therefore, for the final standard, we can expect compression efficiency improvements far exceeding the 50% target.

[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 that may have an impact on the overall bitrate of the bitstream. Summary of the invention

[0005] The present invention relates to improvements to high-level syntax structures, which enable complexity reduction and / or signaling without any significant 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 comprising video data corresponding to one or more slices, the decoding comprising: parsing one or more syntax elements, and when at least one syntax element indicates that a picture to be decoded contains a slice, not permitting use of sub-pictures and / or parsing sub-picture information; and decoding the bitstream using the syntax elements.

[0007] 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, the decoding including: parsing one or more syntax elements, and not permitting use of sub-pictures and / or parsing sub-picture information in combination with at least one syntax element indicating that a picture to be decoded contains only one slice; and decoding the bitstream using the syntax elements.

[0008] According to yet another aspect of the present invention, a method for decoding video data from a bitstream is provided, the bitstream comprising video data corresponding to one or more slices, the bitstream being constrained so that: in a case where the bitstream comprises a syntax element having a value indicating that a picture to be decoded contains only one slice, the bitstream further comprises a syntax element having a value indicating that a sub-picture is not used and / or sub-picture information does not exist for the picture, the method comprising decoding the bitstream using the syntax element.

[0009] This avoids inconsistencies in the bitstream. Specifically, a picture containing sub-pictures has several slices. If a picture contains only one slice, then the picture is a picture containing only one sub-picture. Furthermore, this simplifies parsing of the slice header for some implementations.

[0010] The method may further include: when at least one syntax element indicates that the picture to be decoded contains one slice, limiting the value of the syntax element indicating the existence of a sub-picture to a value indicating that the sub-picture is not used. The syntax element indicating the existence of a sub-picture may include a flag indicating whether sub-picture information exists.

[0011] The syntax element indicating that the picture to be decoded contains one slice may include a syntax element of a picture header in a slice header, wherein the picture header indicating that the picture contains one slice is signaled in the slice header.

[0012] At least one syntax element indicating that a picture to be decoded contains a slice may include a syntax element indicating that a raster scan slice mode is enabled, may include a syntax element indicating that the number of blocks in the picture is greater than one, and may include a syntax element indicating that the number of blocks in the slice is equal to the number of blocks in the picture.

[0013] According to a second aspect of the present invention, a method for decoding video data from a bitstream is provided, the bitstream comprising video data corresponding to one or more slices, the decoding comprising: parsing one or more syntax elements, and when a picture header is signaled in a slice header, not permitting the use of sub-pictures and / or parsing sub-picture information; and decoding the bitstream using the syntax elements.

[0014] According to a third aspect of the present invention, there is provided a method for decoding video data from a bitstream, the bitstream comprising video data corresponding to one or more slices, the decoding comprising: parsing one or more syntax elements and not allowing separation of color planes of a color picture when the picture contains only one slice; and decoding the bitstream using the syntax elements.

[0015] The advantage of this aspect is that inconsistent bitstreams are avoided. In practice, a picture containing independently coded color planes has several slices. Therefore, it is not possible to have only one slice in the current picture. Furthermore, parsing of the slice headers is simplified for some implementations.

[0016] The disapproval may include enforcing a constraint that a flag indicating whether a color plane of a picture is to be separated has a value indicating that the plane is not to be separated.

[0017] Optionally, the method further comprises parsing a syntax element indicating whether a picture header is signaled in a slice header, wherein signaling the picture header in the slice header indicates that the picture contains one slice.

[0018] Optionally, the method further comprises: permitting parsing of a color plane identifier syntax element when a color plane of the color picture is separated and the picture header is located in a slice header.

[0019] Optionally, the method further comprises: if the raster scan stripe mode is enabled, the number of blocks in the picture is greater than one, and when the number of blocks in the stripe is equal to the number of blocks in the picture, then not permitting separation of the color plane of the current picture.

[0020] Optionally, the method further comprises not permitting the color plane of the picture to be separated by limiting a value of a flag indicating separation of the color plane of the picture to a value indicating not to separate the color plane.

[0021] Optionally, if raster scan slice mode is enabled, the number of tiles in a picture is greater than 1, and when the number of tiles in a slice is equal to the number of tiles in the picture, the color plane identifier syntax element is not decoded.

[0022] According to a fourth aspect of the present invention, a method for decoding video data from a bitstream is provided, the bitstream comprising video data corresponding to one or more slices, the decoding comprising: parsing one or more syntax elements and not allowing separation of color planes of a color picture when a picture header is signaled in a slice header; and decoding the bitstream using the syntax elements.

[0023] According to a fifth aspect of the present invention, a method for decoding video data from a bitstream is provided, the method comprising performing the method according to the first aspect or the second aspect and the method according to the third aspect or the fourth aspect. According to a sixth aspect of the present invention, a method for decoding video data from a bitstream is provided, the bitstream comprising video data corresponding to one or more slices of a picture, the decoding comprising: parsing one or more syntax elements, and forcing separation of color planes of a color picture, and inferring a single color plane identifier of one or more slices in a picture; and decoding the bitstream using the syntax elements.

[0024] This provides the possibility to easily extract only one color plane from a bitstream containing 3 color planes without modifying some syntax elements of the respective slices. Thus, the complexity of such an application is saved.

[0025] Optionally, enforce in case the picture contains only one slice.

[0026] The inferred color plane identity may be brightness.

[0027] Optionally, it is enforced when the picture header is signaled in the slice header.

[0028] Optionally, the forcing is performed when raster scan stripe mode is enabled, the number of tiles in the current picture is greater than 1, and when the number of tiles in a stripe is equal to the number of tiles in the current picture.

[0029] According to a seventh aspect of the present invention, there is provided a method for encoding video data into a bitstream, the bitstream comprising video data corresponding to one or more slices, the encoding comprising: determining one or more syntax elements, and when at least one syntax element indicates that the picture to be encoded contains one slice, the use of sub-pictures and / or the encoding of sub-picture information is not permitted; and encoding the bitstream using the syntax elements. According to another aspect of the present invention, there is provided a method for encoding video data into a bitstream, the bitstream comprising video data corresponding to one or more slices, the encoding comprising: determining one or more syntax elements, and the use of sub-pictures and / or the encoding of sub-picture information is not permitted in combination with at least one syntax element indicating that the picture to be encoded contains only one slice; and encoding the bitstream using the syntax elements. According to another additional aspect of the present invention, there is provided a method of encoding video data into a bitstream, the bitstream comprising video data corresponding to one or more slices, the bitstream being constrained so that in the case where the bitstream comprises a syntax element having a value indicating that a picture to be decoded contains only one slice, the bitstream also comprises a syntax element having a value indicating that sub-pictures are not used and / or that sub-picture information does not exist for the picture, the method comprising encoding the bitstream using the syntax element. This avoids inconsistencies in the bitstream. Specifically, a picture containing sub-pictures has several slices. If a picture contains only one slice, the picture is a picture containing only one sub-picture. Furthermore, this simplifies parsing of slice headers for some implementations.

[0030] Optionally, the method further includes: when at least one syntax element indicates that the picture to be decoded contains one slice, limiting the value of the syntax element indicating the existence of a sub-picture to a value indicating that the sub-picture is not used.

[0031] The syntax element indicating the presence of a sub-picture may include a flag indicating whether sub-picture information exists.

[0032] The syntax element indicating that the picture to be encoded contains one slice may include a syntax element of a picture header in a slice header, wherein the picture header indicating that the picture contains one slice is signaled in the slice header.

[0033] At least one syntax element indicating that the picture to be encoded contains one slice may include a syntax element indicating that a raster scan slice mode is enabled, may include a syntax element indicating that the number of blocks in the picture is greater than one, and may include a syntax element indicating that the number of blocks in the slice is equal to the number of blocks in the picture.

[0034] 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, the decoding including: parsing one or more syntax elements and not allowing the use of sub-pictures and / or parsing sub-picture information and sending a picture header in a slice header; and decoding the bitstream using the syntax elements.

[0035] Optionally, the use of sub-pictures and / or parsing of sub-picture information and whether to send a picture header in a slice header are indicated by a syntax element to be parsed.

[0036] Optionally, a syntax element indicating use of a sub-picture and / or parsing of sub-picture information and a syntax element indicating that a picture header is transmitted in a slice header are not permitted to be combined.

[0037] According to an eighth aspect of the present invention, a method for encoding video data into a bitstream is provided, the bitstream comprising video data corresponding to one or more slices, the encoding comprising: determining one or more syntax elements, and when a picture header is signaled in a slice header, not permitting the use of sub-pictures and / or encoding of sub-picture information; and encoding the video data using the syntax elements.

[0038] In another 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, the decoding including: parsing one or more syntax elements and not allowing the use of sub-pictures and / or parsing sub-picture information and sending a picture header in a slice header; and encoding the bitstream using the syntax elements.

[0039] Optionally, the use of sub-pictures and / or parsing of sub-picture information and whether to send a picture header in a slice header are indicated by a syntax element to be parsed.

[0040] Optionally, a syntax element indicating use of a sub-picture and / or parsing of sub-picture information and a syntax element indicating that a picture header is to be transmitted in a slice header are not permitted to be combined.

[0041] According to a ninth aspect of the invention, there is provided a method for encoding video data into a bitstream, the bitstream comprising video data corresponding to one or more slices, the encoding comprising: determining one or more syntax elements, and not allowing separation of color planes of a color picture when the picture contains only one slice; and encoding the bitstream using the syntax elements. The advantage of this aspect is that inconsistent bitstreams are avoided. In practice, a picture containing independently encoded color planes has several slices. Therefore, it is not possible to have only one slice in the current picture. In addition, parsing of the slice header of some implementations is simplified.

[0042] The disapproval may include enforcing a constraint that a flag indicating whether a color plane of a picture is to be separated has a value indicating that the plane is not to be separated.

[0043] The method may further include determining a syntax element indicating whether to signal a picture header in a slice header, wherein signaling in the slice header that the picture header indicates that the picture contains one slice.

[0044] The method may further include permitting determination of a color plane identifier syntax element when a color plane of the color picture is separated and the picture header is located in a slice header.

[0045] The method may further include not permitting separation of color planes of the current picture if the raster scan stripe mode is enabled, the number of tiles in the picture is greater than one, and when the number of tiles in the stripe is equal to the number of tiles in the picture.

[0046] Optionally, disallowing separation of color planes of a picture is by limiting a value of a flag indicating separation of color planes of the picture to a value indicating not to separate the color planes.

[0047] Optionally, if raster scan stripe mode is enabled, the number of tiles in a picture is greater than one, and when the number of tiles in a stripe is equal to the number of tiles in the picture, the color plane identifier syntax element is not encoded.

[0048] According to a tenth aspect of the present invention, there is provided a method of encoding video data into a bitstream, the bitstream comprising video data corresponding to one or more slices, the encoding comprising: determining one or more syntax elements and not permitting separation of color planes of a color picture when a picture header is to be signaled in a slice header; and encoding the video data using the syntax elements.

[0049] According to an eleventh aspect of the present invention, there is provided a method for encoding video data into a bit stream, comprising performing the method according to the seventh aspect or the eighth aspect and the method according to the ninth aspect or the tenth aspect.

[0050] According to a twelfth aspect of the present invention, there is provided a method of encoding video data into a bitstream, the bitstream comprising video data corresponding to one or more slices of a picture, the encoding comprising: determining one or more syntax elements and forcing color planes of a color picture to be separated and setting a single color plane identifier for one or more slices of the picture; and encoding the bitstream using the syntax elements. In an embodiment, the color plane identifier may be inferred.

[0051] This provides the possibility to easily extract only one color plane from a bitstream containing 3 color planes without modifying some syntax elements of the individual slices. Thus, the complexity of such an application is saved.

[0052] Optionally, enforce in case the picture contains only one slice.

[0053] Optionally, the inferred color plane identity is luminance.

[0054] Optionally, it is enforced when the picture header is signaled in the slice header.

[0055] Optionally, the forcing is performed when raster scan stripe mode is enabled, the number of tiles in the current picture is greater than 1, and when the number of tiles in a stripe is equal to the number of tiles in the current picture.

[0056] According to a thirteenth aspect of the present invention, there is provided a device comprising a decoder, wherein the decoder is configured to perform the method of any one of the first to fourth aspects.

[0057] According to a fourteenth aspect of the present invention, there is provided a device comprising an encoder, wherein the encoder is configured to perform the method of any one of the fifth to eighth aspects.

[0058] 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 the first to eighth aspects to be performed.

[0059] The program may be provided separately or may be on, carried by or 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. Other features of the invention are characterized by independent and dependent claims.

[0060] 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.

[0061] 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.

[0062] 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.).

[0063] It will also be appreciated 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

[0064] Reference will now be made, by way of example, to the accompanying drawings, in which:

[0065] Figure 1 is a diagram for explaining the coding structure used in HEVC and VVC;

[0066] 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;

[0067] Figure 3 is a block diagram illustrating components of a processing device that may implement one or more embodiments of the present invention;

[0068] Figure 4 is a flow chart showing the steps of an encoding method according to an embodiment of the present invention;

[0069] Figure 5 is a flow chart showing the steps of a decoding method according to an embodiment of the present invention;

[0070] Figure 6 shows the structure of a bit stream in an exemplary coding system VVC;

[0071] Figure 7 Another structure of a bit stream in an exemplary coding system VVC is shown;

[0072] Figure 8 Luma Modelling Chroma Scaling (LMCS) is shown;

[0073] Fig. 9 Shows the sub-tools of LMCS;

[0074] Fig.10 This is a diagram of the raster scan strip mode and rectangular strip mode of the current VVC draft standard;

[0075] Fig.11 A diagram showing a system including an encoder or decoder and a communication network according to an embodiment of the present invention;

[0076] Fig.12 is a schematic block diagram of a computing device for implementing one or more embodiments of the present invention;

[0077] Fig.13 is a diagram showing a network camera system; and

[0078] Fig.14 is a diagram showing a smart phone. DETAILED DESCRIPTION

[0079] Figure 1 The 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.

[0080] The images 2 of the sequence may be partitioned into slices 3. In some cases, a slice may constitute the entire image. The 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. The CTU is sometimes also referred to as the largest coding unit (LCU). The CTU has luma and chroma component parts, each of which is called a coding tree block (CTB). These different color components are not in the same Figure 1 Shown in.

[0081] A CTU is typically 64 pixels x 64 pixels in size. Each CTU may be iteratively partitioned into smaller variable-sized coding units (CUs) 5 using a quadtree decomposition.

[0082] The coding unit is the basic coding element and consists 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 for prediction of pixel values. Various different partitions of a CU into PUs are possible, as shown in 606, including a partition into 4 square PUs, and two different partitions into 2 rectangular PUs. A transform unit is a basic unit for spatial transformation using DCT. A CU can be partitioned into TUs based on a quadtree representation 607.

[0083] 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 parameter set NAL units are used: first, the sequence parameter set (SPS) NAL unit, which collects all parameters that remain unchanged during the entire video sequence. Generally, it handles the encoding profile, the size of the video frame, and other parameters. Second, the picture parameter set (PPS) NAL unit, which includes parameters that can be changed 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 describing the overall structure of the bitstream. VPS is a new type of parameter set defined in HEVC and is applied 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 hierarchical extensions for scalability and multi-view, and these extensions will allow multiple layers with a backward compatible version 1 base layer.

[0084] In the current definition of Versatile Video Coding (VVC), there are three high-level possibilities for partitioning of 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 stripes 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, since it splits a picture into independently coded regions of (almost) the same size of the picture. But the tool can also be used for other applications.

[0085] Since these three high-level possible ways of picture partitioning can be used together, there are several modes for their use. As defined in the current draft specification of VVC, two modes of defining slices are defined. For raster scan slice mode, a slice contains a complete sequence of tiles in a raster scan of tiles of a picture. This mode in the current VVC specification is in Fig.10 As shown in (a), the picture contains 18 by 12 luma CTUs shown as partitioned into 12 stripes and 3 raster scan stripes.

[0086] For the second (rectangular strip mode), a strip contains several complete blocks from a rectangular area of ​​the picture. Fig.10 In this example, the picture has 18 by 12 luma TUs shown partitioned into 24 tiles and 9 rectangular strips.

[0087] Figure 2The data communication system in which one or more embodiments of the present invention can be implemented is illustrated. The data communication system includes a transmission device (in this case, a server 201) which is 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 can be a wide area network (WAN) or a local area network (LAN). Such a network can be, for example, a wireless network (Wifi / 802.11a or 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 can be a digital television broadcasting system, in which the server 201 sends the same data content to multiple clients.

[0088] The data stream 204 provided by the server 201 may consist 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.

[0089] 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.

[0090] The client 202 receives the transmitted bitstream and decodes the reconstructed bitstream to reproduce the video image on the display device and reproduce the audio data using the speaker.

[0091] Despite Figure 2 A streaming scenario is considered in the example of , but it will be appreciated that in some embodiments of the invention, data communication between the encoder and the decoder may be carried out using, for example, a media storage device (such as an optical disc).

[0092] 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.

[0093] Figure 3 A 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 light portable device. The device 300 includes a communication bus 313, which is connected to:

[0094] - a central processing unit 311 denoted as CPU, such as a microprocessor or the like;

[0095] - a read-only memory 306, denoted ROM, for storing a computer program implementing the invention;

[0096] - a random access memory 312, represented as a RAM, for storing executable codes of the method of the 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 the embodiment of the present invention; and

[0097] A communication interface 302 connected to a communication network 303, via which digital data to be processed are transmitted or received.

[0098] Optionally, the device 300 may further include the following components:

[0099] - 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;

[0100] a disk drive 305 for a disk 306, which is suitable for reading data from the disk 306 or writing data to said disk;

[0101] - A screen 309 for displaying data and / or serving as a graphical interface for interaction with a user by means of a keyboard 310 or any other pointing means.

[0102] 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 .

[0103] The communication bus provides communication and interoperability between the various elements included in or connected to the 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 the device 300 directly or via other elements of the device 300.

[0104] 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 component 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 present invention.

[0105] 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, a disk 306 as previously described, etc. According to a variant, the executable code of the program may be received via the interface 302 by means of a communication network 303 to be stored in one of the storage means of the device 300, such as a hard disk 304, etc., before being executed.

[0106] The central processing unit 311 is adapted to control and direct the execution of instructions or parts of software code of one or more programs according to the invention, the execution of instructions stored in one of the above-mentioned storage means. At power-on, one or more programs stored in non-volatile memory (e.g., on hard disk 304 or in read-only memory 306) are transferred to random access memory 312 (which then contains the executable code of one or more programs) and registers for storing variables and parameters necessary for implementing the invention.

[0107] 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).

[0108] Figure 4 Block diagram illustrating an encoder according to at least one embodiment of the invention. The encoder is represented by connected modules, each module being adapted to implement, e.g. in the form of programming instructions executed by the CPU 311 of the apparatus 300, at least one corresponding step of a method for implementing at least one embodiment of encoding an image in a sequence of images according to one or more embodiments of the invention.

[0109] The encoder 400 receives a digital image i 0 to i n The original sequence 401 of is taken as input. Each digital image is represented by a set of samples (called pixels).

[0110] 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 an encoding value of an encoding parameter used for slice encoding, and a slice body including encoded video data.

[0111] Module 402 takes the input digital image i 0 to i n401 is partitioned into blocks of pixels. 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 can also be 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.

[0112] Module 403 implements an intra prediction process in which a given block to be encoded is predicted by a predictor calculated from neighboring pixels of the block to be encoded. If intra coding is selected, the selected intra predictor and an indication of the difference between the given block and its predictor are encoded to provide a residual.

[0113] Temporal prediction is implemented by a motion estimation module 404 and a motion compensation module 405. First, a reference image from a reference image set 416 is selected, and a portion of the reference image (also referred to as a reference region or image portion) is selected by the motion estimation module 404, which is the region closest to a given block to be encoded. The motion compensation module 405 then uses the selected region to predict the block to be encoded. The difference between the selected reference region and the given block (also referred to as a residual block) is calculated by the motion compensation module 405. The selected reference region is indicated by a motion vector.

[0114] Thus, in both cases (spatial and temporal prediction), the residual is calculated by subtracting the prediction from the original block.

[0115] In the intra prediction implemented by module 403, the prediction direction is encoded. In the temporal prediction, at least one motion vector is encoded. In the inter 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.

[0116] 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 by the 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.

[0117] The encoder 400 further comprises a selection module 406 for selecting a coding mode by applying a coding cost criterion such as a rate-distortion criterion, etc. To further reduce redundancy, a transform such as DCT is applied to the residual block by a transform module 407, and then the obtained transform data is quantized by a quantization module 408 and entropy encoded by an entropy encoding module 409. Finally, the encoded residual block of the current block being encoded is inserted into a bitstream 410.

[0118] The encoder 400 also performs decoding of the encoded images to produce reference images for motion estimation of subsequent images. This enables 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 area obtained from the reference image set 416.

[0119] Post filtering is then applied by module 415 to filter the reconstructed pixel frame. In an embodiment of the 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.

[0120] 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 suitable for implementing 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.

[0121] The decoder 60 receives a bitstream 600 comprising coding units, each coding unit consisting of a header containing information about the encoded parameters and a body containing the encoded 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 encoded 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.

[0122] Mode data indicating an encoding mode is also entropy-decoded, and based on the mode, an encoding block of the image data is intra-type decoded or inter-type decoded.

[0123] 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.

[0124] 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.

[0125] The motion vector decoding module 70 applies motion vector decoding to each current block encoded 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 reference image portion indicated by the decoded motion vector is extracted from the reference image 68 to apply inverse motion compensation 66. The motion vector field data 71 is updated with the decoded motion vector for inverse prediction of subsequently decoded motion vectors.

[0126] 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.

[0127] Figure 6 The organization of the bitstream in an exemplary coding system VVC as described in JVET_Q2001-vD is shown.

[0128] The bitstream 61 according to the VVC coding system consists of an ordered sequence of syntax elements and encoded data. The syntax elements and the 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 (standing for Real Time Protocol / Internet Protocol), ISO basic media file format, etc.). The network abstraction layer also provides a framework for anti-packet loss.

[0129] NAL units are divided into video coding layer (VCL) NAL units and non-VCL NAL units. VCL NAL units contain actual coded video data. Non-VCL NAL units contain additional information. The additional information can be parameters required for decoding 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 VCL NAL units of the bitstream.

[0130] 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 the parameters of the VPS.

[0131] The sequence parameter set (SPS) NAL unit 603 contains parameters defined for a video sequence. In particular, the SPS NAL unit may define the sub-picture layout and associated parameters of a video sequence. The parameters associated with each sub-picture specify the coding constraints applied to the sub-picture. In particular, a flag indicating that the temporal prediction between sub-pictures is restricted to data from the same sub-picture is included. Another flag may enable or disable the loop filter across sub-picture boundaries.

[0132] 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 mapping with chroma scaling (LMCS) model) or a scaling matrix used at the slice level.

[0133] The syntax of the PPS as proposed in the current version of VVC includes syntax elements that specify the size of the picture in units of luma samples and the partitioning of each picture into blocks and slices.

[0134] The PPS contains syntax elements that allow the slice position in the 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 the sub-picture can be determined from the parameter set NAL unit. The PPS has an ID mechanism like the APS to limit the amount of transmission of the same PPS.

[0135] 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 may be constant for several pictures.

[0136] The bitstream may also contain supplemental enhancement information (SEI) NAL units ( Figure 6The periodicity of the occurrence of these parameter sets in the bitstream is variable. A VPS defined for the entire bitstream may appear only once in the bitstream. In contrast, 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 usually fewer APSs than slices in each picture. In particular, the APS is defined in the picture header. However, the ALF APS may be refined in the slice header.

[0137] 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 in 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 equal to 0, the AU contains only intra slices. If equal to 1, it contains P and I slices. If equal to 2, it contains B, P, or intra slices.

[0138] This NAL unit contains only one syntax element, pic-type.

[0139] Table 1 Syntax AUD

[0140]

[0141]

[0142] In JVET-Q2001-vD, pic-type is defined as follows:

[0143] "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."

[0144] 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.

[0145] Table 2 Explanation of pic_type

[0146] pic_type Possible slice_type values ​​in AU 0 I 1 P,I 2 B,P,I

[0147] 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 slices of the picture.

[0148] Each VCL NAL unit 606 contains a slice. A slice may 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 of comprises several blocks 620. A slice consists of a slice header 610 and a raw byte sequence payload RBSP 611, which contains the encoded pixel data encoded as encoded blocks 640.

[0149] 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.

[0150] 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 blocks belonging to a sub-picture can be determined from the parameter set NAL units.

[0151] NAL unit slice

[0152] The NAL unit slice layer contains a slice header and slice data, as shown in Table 3.

[0153] Table 3 Stripe layer syntax

[0154]

[0155] APS

[0156] The adaptation parameter set (APS) NAL unit 605 is defined in Table 4 showing the syntax elements.

[0157] As depicted in Table 4, there are 3 possible types of APS given by the aps_params_type syntax element:

[0158] ALF_AP: used for ALF parameters

[0159] LMCS_APS: used for LMCS parameters

[0160] SCALLING_APS: used for scaling list related parameters

[0161] Table 4 Adaptive parameter set syntax

[0162]

[0163] These three types of APS parameters are discussed below in turn.

[0164] ALF APS

[0165] The ALF parameters are described in the adaptive loop filter data syntax element (Table 5). First, four flags are dedicated to specify 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. Then, the number of filters signaled is 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.

[0166] If alf_luma_clip_flag is enabled, the clipping index for each coefficient of each enabled filter is decoded.

[0167] In the same way, the ALF chroma coefficients are decoded when needed.

[0168] 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).

[0169] Table 5 Adaptive loop filter data syntax

[0170]

[0171]

[0172]

[0173] LMCS syntax elements for both luma mapping and chroma scaling

[0174] 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.

[0175] These parameters are used to construct the forward and inverse mapping functions for luma and the scaling function for chroma.

[0176] Table 6 Luma mapping with chroma scaling data syntax

[0177]

[0178]

[0179] Zoom List APS

[0180] 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. If the scaling list is used for chroma components (scaling_list_chroma_present_flag), the second one is specified. Then, the syntax elements required to construct the scaling matrix are decoded (scaling_list_copy_mode_flag, scaling_list_pred_mode_flag, scaling_list_pred_id_delta, scaling_list_dc_coef, scaling_list_delta_coef).

[0181] Table 7 Scaling List Data Syntax

[0182]

[0183]

[0184] Image header

[0185] The picture header is sent at the beginning of each picture before the other slice data. This is very large compared to the previous headers in the previous drafts of the standard. A complete description of all these parameters can be found in JVET_Q2001-vD. Table 10 shows these parameters in the current picture header decoding syntax.

[0186] The relevant syntactic elements that can be decoded are:

[0187] Whether to use the image or reference frame

[0188] Type of image

[0189] Output frame

[0190] Number of images

[0191] Use sub-images (if necessary)

[0192] · Reference image list (if required)

[0193] Color plane (if needed)

[0194] Partition update (if the overwrite flag is enabled)

[0195] Incremental QP parameters (if needed)

[0196] Motion information parameters (if required)

[0197] ALF parameters (if required)

[0198] SAO parameters (if required)

[0199] Quantization parameters (if required)

[0200] LMCS parameters (if required)

[0201] Scale list parameters (if needed)

[0202] Image header expansion (if necessary)

[0203] ·etc

[0204] Image "Type"

[0205] 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.

[0206] The ph_inter_slice_allowed_flag is then decoded to identify that inter slices are allowed.

[0207] When they are allowed, the flag ph_infra_slice_allowed_flag is decoded to know whether intra slices are allowed for the current picture.

[0208] 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.

[0209] If the picture is a GDR or IRAP picture, the flag no_output_of_prior_pics_flag is decoded.

[0210] And if the picture is GDR, then decode recovery_poc_cnt. Then, if necessary, decode ph_poc_msb_present_flag and poc_msb_val.

[0211] ALF

[0212] After these parameters describing important information about the current picture, a set of ALF APS ID syntax elements are decoded if ALF is enabled at SPS level and if ALF is enabled at picture header level. ALF is enabled at SPS level due to sps_alf_enabled_flag flag. And ALF is enabled and signaled at picture header level due to alf_info_in_ph_flag equal to 1, otherwise (alf_info_in_ph_flag equal to 0), ALF is signaled at slice level.

[0213] alf_info_in_ph_flag is defined as follows:

[0214] "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."

[0215] 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.

[0216] If ALF is enabled, the pic_num_alf_aps_ids_luma syntax element is used to decode the amount of ALPHA PSD for luma. For each APS ID, the APS ID value "ph_alf_aps_id_luma" for luma is decoded.

[0217] For chroma, the syntax element ph_alf_chroma_idc is decoded to determine whether ALF is enabled for chroma, Cr only, or Cb only. If enabled, the ph_alf_aps_id_chroma syntax element is used to decode the value of the APS ID for chroma.

[0218] In this way, if required by the Cb and / or Cr components, the APS ID for the CC-ALF method is decoded.

[0219] LMCS

[0220] If LMCS is enabled at the SPS level, a set of LMCS APS ID syntax elements are decoded. First, ph_lmcs_enabled_flag is decoded to determine if 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.

[0221] Zoom List

[0222] If scaling list is enabled at SPS level, the set of scaling list APS IDs is decoded. 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.

[0223] Sub-image

[0224] 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. Some information about virtual boundaries is also contained. For sub-picture parameters, eight syntax elements are defined:

[0225] ·ph_virtual_boundaries_present_flag

[0226] ·ph_num_ver_virtual_boundaries

[0227] ·ph_virtual_boundaries_pos_x[i]

[0228] ·ph_num_hor_virtual_boundaries

[0229] ·ph_virtual_boundaries_pos_y[i]

[0230] Output Flags

[0231] These sub-picture parameters are followed by pic_output_flag (if present).

[0232] Reference Image List

[0233] If the reference picture list is signaled in the picture header (because rpl_info_in_ph_flag is equal to 1), the parameters ref_pic_lists() of the reference picture list are decoded, which contains the following syntax elements:

[0234] rpl_sps_flag[]

[0235] ·rpl_idx[]

[0236] ·poc_lsb_lt[][]

[0237] ·delta_poc_msb_present_flag[][]

[0238] delta_poc_msb_cycle_lt[][]

[0239] and is defined in the following syntax table:

[0240] Table 8 Reference picture list syntax

[0241]

[0242] Partition

[0243] If required, a partition parameter set is decoded and contains the following syntax elements:

[0244] ·partition_constraints_override_flag

[0245] ·ph_log2_diff_min_qt_min_cb_intra_slice_luma

[0246] ·ph_max_mtt_hierarchy_depth_intra_slice_luma

[0247] ·ph_log2_diff_max_bt_min_qt_intra_slice_luma

[0248] ·ph_log2_diff_max_tt_min_qt_intra_slice_luma

[0249] ·ph_log2_diff_min_qt_min_cb_intra_slice_chroma

[0250] ·ph_max_mtt_hierarchy_depth_intra_slice_chroma

[0251] ·ph_log2_diff_max_bt_min_qt_intra_slice_chroma

[0252] ·ph_log2_diff_max_tt_min_qt_intra_slice_chroma

[0253] ·ph_log2_diff_min_qt_min_cb_inter_slice

[0254] ·ph_max_mtt_hierarchy_depth_inter_slice

[0255] ·ph_log2_diff_max_bt_min_qt_inter_slice

[0256] ·ph_log2_diff_max_tt_min_qt_inter_slice

[0257] Weighted prediction

[0258] 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 equal to 1), the weighted prediction parameters pred_weight_table() are decoded.

[0259] 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 9), when weighted prediction parameters are sent in the picture header, the number of weights for each list is explicitly sent.

[0260] Table 9 Weighted prediction parameter syntax

[0261]

[0262]

[0263]

[0264] Incremental QP

[0265] 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.

[0266] 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.

[0267] Table 10 Picture header structure

[0268]

[0269]

[0270]

[0271]

[0272]

[0273]

[0274] Strip Header

[0275] A slice header is sent at the beginning of each slice. The slice header contains about 65 syntax elements. This is very large compared to previous slice headers in early video coding standards. A complete description of all slice header parameters can be found in JVET-Q2001-vD. Table 11 shows these parameters in the current slice header decoding syntax.

[0276] Table 11 Partial strip header

[0277]

[0278]

[0279]

[0280]

[0281] First, picture_header_in_slice_header_flag is decoded to know whether picture_header_structure() exists in the slice header.

[0282] If subpic_info_present_flag is set equal to 1 in the SPS, slice_subpic_id is decoded. slice_subpic_id gives the sub-picture id of the current slice. In the current VVC specification, subpic_info_present_flag is defined as follows:

[0283] "subpic_info_present_flag equal to 1 specifies that sub-picture information is present for CLVS and that one or more sub-pictures may be present in each picture of the CLVS. subpic_info_present_flag equal to 0 specifies that sub-picture information is not present for CLVS and that only one sub-picture may be present in each picture of the CLVS.

[0284] When res_change_in_clvs_allowed_flag is equal to 1, the value of subpic_info_present_flag shall be equal to 0. "

[0285] The slice_address is then 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 higher 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 higher than 1 calculated based on the variables defined in the PPS, the slice address may also be decoded.

[0286] 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:

[0287] "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."

[0288] Then decode the slice_type.

[0289] 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 equals 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 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.

[0290] If the color planes are sent independently (when separate_colour_plane_flag is set equal to 1), the colour_plane_id is decoded. In the current VVC draft specification, separate_colour_plane_flag is defined as follows:

[0291] "separate_color_plane_flag equal to 1 specifies that the three color components of the 4:4:4 chroma format are coded separately. separate_color_plane_flag equal to 0 specifies that the color components are not coded separately. When separate_color_plane_flag is not present, it is inferred to be equal to 0. When separate_color_plane_flag is equal to 1, the coded picture consists of three separate components, each component consists of coded samples of one color plane (Y, Cb, or Cr), and the monochrome coding syntax is used. In this case, each color plane is associated with a specific color_plane_id value."

[0292] When the reference picture list ref_pic_lists() is not sent in the picture header (rpl_info_in_ph_flag is 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 is equal to 1), the reference picture list parameters are decoded; these are similar to those in the picture header.

[0293] 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. This flag is defined in the VVC draft specification as follows:

[0294] "num_ref_idx_active_override_flag equal to 1 specifies that the syntax element num_ref_idx_active_minus1[0] is present for P and B slices, and that the syntax element num_ref_idx_active_minus1[1] is present for B slices. num_ref_idx_active_override_flag equal to 0 specifies that the syntax elements num_ref_idx_active_minus1[0] and num_ref_idx_active_minus1[1] are not present. When not present, the value of num_ref_idx_active_override_flag is inferred to be equal to 1."

[0295] If num_ref_idx_active_override_flag is enabled, the number of reference indices num_ref_idx_active_minus1[i] of each list "i" is decoded when needed. The number of reference indices overridden for the current list should be lower 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.

[0296] 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.

[0297] In the same manner, when the slice type is not intra, parameters pred_weight_table() of weighted prediction are decoded.

[0298] If delta QP information is sent in the slice header (qp_delta_info_in_ph_flag is equal to 0), then slice_qp_delta is decoded. If needed, then the syntax elements slice_cb_qp_offset, slice_cr_qp_offset, slice_joint_cbcr_qp_offset, cu_chroma_qp_offset_enabled_flag are decoded.

[0299] If SAO information is sent in the slice header (sao_info_in_ph_flag equal to 0) and if it is enabled at SPS level (sps_sao_enabled_flag), the enabled flags of SAO are decoded for both luma and chroma: slice_sao_luma_flag, slice_sao_chroma_flag.

[0300] 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.

[0301] 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.

[0302] If LMCS is enabled in the picture header (ph_lmcs_enabled_flag is equal to 1), the flag slice_lmcs_enabled_flag is decoded. In the current VVC specification, slice_lmcs_enabled_flag is defined as follows:

[0303] "slice_lmcs_enabled_flag equal to 1 specifies that luma mapping with chroma scaling is enabled for the current slice. slice_lmcs_enabled_flag equal to 0 specifies that luma mapping with chroma scaling is not enabled for the current slice. When slice_lmcs_enabled_flag is not present, it is inferred to be equal to 0."

[0304] 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. In the current VVC specification, slice_scaling_list_present_flag is defined as follows:

[0305] "slice_scaling_list_present_flag equal to 1 specifies that the scaling list data for the current slice is derived based on the scaling list data contained in the referenced scaling list APS with aps_params_type equal to SCALING_APS and adaptation_parameter_set_id equal to ph_scaling_list_aps_id. slice_scaling_list_present_flag equal to 0 specifies that the scaling list data for the current picture is the default scaling list data derived as specified in clause 7.4.3.21. When not present, the value of slice_scaling_list_present_flag is inferred to be equal to 0."

[0306] Then, if necessary, other parameters are decoded.

[0307] Image header in strip header

[0308] By specific signal notification method, such as Figure 7 As depicted in FIG. 7 , the picture header (708) may be signaled within the slice header (710). In this case, there is no NAL unit that contains only the picture header (608). NAL units 701-707 correspond to Figure 6 Similarly, coding block 720 and coding block 740 correspond to Figure 6 620 and 640 of the slice header. 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. Furthermore, when the picture header is signaled within the slice header, the picture shall contain only one slice. Therefore, there is always only one picture header per picture. Furthermore, the flag picture_header_in_slice_header_flag shall 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.

[0309] The flag picture_header_in_slice_header_flag is defined as follows:

[0310] "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.

[0311] 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 a CLVS.

[0312] 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.

[0313] 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.

[0314] picture_header_structure() contains the syntax elements of picture_rbsp() except for the padding bits rbsp_trailing_bits(). "

[0315] Streaming Applications

[0316] Some streaming applications extract only certain parts of the bitstream. These extractions can be spatial (as sub-pictures) or temporal (sub-parts of a video sequence). These extracted parts can then be merged with other bitstreams. Others reduce the frame rate by extracting only some frames. Typically, the main purpose of these streaming applications is to use the maximum allowed bandwidth to produce the highest quality for the end user.

[0317] In VVC, for frame rate reduction, APS ID numbering has been restricted so that new APS ID numbering 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 (because of IRAP) do not reset the numbering of APS IDs.

[0318] LMCS (Luminance Mapping with Chroma Scaling)

[0319] 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.

[0320] 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:

[0321] 1) The first sub-tool is an in-loop mapping of the luminance component based on an adaptive piecewise linear model. The in-loop mapping of the luminance component adjusts the dynamic range of the input signal to improve compression efficiency by redistributing codewords across the dynamic range. The luminance mapping utilizes a forward mapping function into the "mapping domain" and a corresponding inverse mapping function back into the "input domain".

[0322] 2) The second sub-tool is related to the chroma components that apply luma-dependent chroma residual scaling. Chroma residual scaling is designed to compensate for the interaction between luma signals and their corresponding chroma signals. Chroma residual scaling depends on the average of neighboring luma samples reconstructed above and / or to the left of the current block.

[0323] Like most other tools in video encoders (such as VVC), LMCS can be enabled / disabled at the sequence level using the SPS flag. It is also signaled at the slice level whether chroma residual scaling is enabled. 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. In addition, luma-dependent chroma residual scaling is always disabled for chroma blocks of size less than or equal to 4.

[0324] 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 usually 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 process is 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).

[0325] Fig. 9 Shown with Figure 8 Similar diagram, but this time for the Chroma Scaling sub-tool of the LMCS tool. Fig. 9 The shaded blocks in are the 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 chroma samples, only 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, loop filtering are performed in the original domain. Fig. 9As shown, for brightness mapping, there is only a scaling process, and there is no forward and inverse process.

[0326] Brightness mapping using a piecewise linear model

[0327] The Luma Mapping sub-tool uses a piecewise linear model. This means that the piecewise linear model divides the input signal dynamic range into 16 equal sub-ranges, and for each sub-range, its linear mapping parameters are represented using the number of codewords assigned to that range.

[0328] Semantics of brightness mapping

[0329] The syntax element lmcs_min_bin_idx specifies the minimum bin (interval) index used in the construction process of the Luma Map with Chroma Scaling (LMCS). The value of lmcs_min_bin_idx shall be in the range of 0 to 15 (inclusive).

[0330] The syntax element lmcs_delta_max_bin_idx specifies the delta value between 15 and the maximum bin index LmcsMaxBinIdx used in the construction process of luma maps 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 is set equal to 15 - lmcs_delta_max_bin_idx. The value of LmcsMaxBinIdx shall be greater than or equal to lmcs_min_bin_idx.

[0331] 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].

[0332] The syntax element lmcs_delta_abs_cw[i] specifies the absolute delta codeword value for the i-th bin.

[0333] 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.

[0334] LMCS intermediate variable calculation for brightness mapping

[0335] In order to apply the forward and inverse brightness mapping processes, some intermediate variables and data arrays are required.

[0336] First, export the variable OrgCW as follows:

[0337] OrgCW=(1< <BitDepth) / 16

[0338] Then, the variable lmcsDeltaCW[i] (where i=lmcs_min_bin_idx . . . LmcsMaxBinIdx) is calculated as follows:

[0339] lmcsDeltaCW[i]=(1-2*lmcs_delta_sign_cw_flag[i])*lmcs_delta_abs_cw[i]

[0340] The new variable lmcsCW[i] is derived as follows:

[0341] - For i=0...lmcs_min_bin_idx-1, lmcsCW[i] is set equal to 0.

[0342] - For i = lmcs_min_bin_idx ... LmcsMaxBinIdx, the following applies:

[0343] lmcsCW[i]=OrgCW+lmcsDeltaCW[i]

[0344] The value of lmcsCW[i] should be in the range of (OrgCW>>3) to (OrgCW<<3-1) (inclusive).

[0345] - For i=LmcsMaxBinIdx+1...15, lmcsCW[i] is set equal to 0.

[0346] The variable InputPivot[i] (where i=0...16) is derived as follows:

[0347] InputPivot[i]=i*OrgCW

[0348] The variables LmcsPivot[i] (where i=0...16), ScaleCoeff[i] and InvScaleCoeff[i] (where i=0...15) are calculated as follows:

[0349] LmcsPivot[0] = 0;

[0350] for(i=0;i<=15;i++){

[0351] LmcsPivot[i+1]=LmcsPivot[i]+lmcsCW[i]

[0352] ScaleCoeff[i]=(lmcsCW[i]*(1<<11)+(1<<(Log2(OrgCW)-1)))>>(Log2(OrgCW))

[0353] if(lmcsCW[i]==0)

[0354] InvScaleCoeff[i]=0

[0355] else

[0356] InvScaleCoeff[i]=OrgCW*(1<<11) / lmcsCW[i]

[0357] Forward Luminance Map

[0358] 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].

[0359] predMapSamples[i][j] is calculated as follows:

[0360] First, the index idxY is calculated from the prediction sample predSamples[i][j] at position (i, j).

[0361] idxY=predSamples[i][j]>>Log2(OrgCW)

[0362] Then, predMapSamples[i][j] is derived as follows by using the intermediate variable idxY of part 0, LmcsPivot[idxY], and InputPivot[idxY]:

[0363] predMapSamples[i][j]=LmcsPivot[idxY]

[0364] +(ScaleCoeff[idxY]*(predSamples[i][j]-InputPivot[idxY])+(1<<10))>>11

[0365] Brightness reconstruction samples

[0366] The reconstruction process is obtained from the predicted luma samples predMapSample[i][j] and the residual luma samples resiSamples[i][j].

[0367] The reconstructed luma picture sample recSamples[i][j] is simply obtained by adding predMapSample[i][j] to resiSamplei[i][j] as follows:

[0368] recSamples[i][j] = Clip1(predMapSamples[i][j] + resiSamples[i][j]])

[0369] In the above relationship, the Clip1 function is a clipping function to ensure that the reconstructed samples are between 0 and 1<<BitDepth - 1.

[0370] Inverse Luma Mapping

[0371] When applying the inverse luma mapping according to Figure 8 the following operations are applied to each sample recSample[i][j] of the current block being processed:

[0372] First, the index idxY is calculated from the reconstructed sample recSamples[i][j] at position (i, j).

[0373] idxY = recSamples[i][j] >> Log2(OrgCW)

[0374] The inverse mapped luma sample invLumaSample[i][j] is derived based on the following:

[0375] invLumaSample[i][j] =

[0376] InputPivot[idxYInv] + (InvScaleCoeff[idxYInv] *

[0377] (recSample[i][j] - LmcsPivot[idxYInv]) + (1 << 10)) >> 11

[0378] Then a clipping operation is performed to obtain the final sample:

[0379] finalSample[i][j] = Clip1(invLumaSample[i][j])

[0380] Chroma Scaling

[0381] LMCS Semantics for Chroma Scaling

[0382] 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.

[0383] 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.

[0384] LMCS intermediate variable calculation for chroma scaling

[0385] In order to apply the chroma scaling process, some intermediate variables are needed.

[0386] The variable lmcsDeltaCrs is derived as follows:

[0387] lmcsDeltaCrs=(1-2*lmcs_delta_sign_crs_flag)*lmcs_delta_abs_crs

[0388] The variable ChromaScaleCoeff[i] (where i=0...15) is derived as follows:

[0389] if(lmcsCW[i]==0)

[0390] ChromaScaleCoeff[i]=(1<<11)

[0391] else

[0392] ChromaScaleCoeff[i]=OrgCW*(1<<11) / (lmcsCW[i]+lmcsDeltaCrs)

[0393] Chroma Scaling

[0394] 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.

[0395] If no samples are available, the variable invAvgLuma is set as follows:

[0396] invAvgLuma=1<<(BitDepth-1)

[0397] Based on the intermediate array LmcsPivot[] of part 0, the variable idxYInv is then derived as follows:

[0398] For(idxYInv=lmcs_min_bin_idx; idxYInv<=LmcsMaxBinIdx; idxYInv++){

[0399] if(invAvgLuma <LmcsPivot[idxYInv+1])break

[0400] }

[0401] IdxYInv=Min(idxYInv,15)

[0402] The variable varScale is exported as follows:

[0403] varScale=ChromaScaleCoeff[idxYInv]

[0404] When the transform is applied to the current chroma block, the reconstructed chroma picture sample array recSamples is derived as follows:

[0405] recSamples[i][j]=Clip1(predSamples[i][j]+

[0406] Sign(resiSamples[i][j])*((Abs(resiSamples[i][j])*varScale+(1<<10))>>11))

[0407] If no transformation has been applied to the current block, the following is applied:

[0408] recSamples[i][j]=Clip1(predSamples[i][j])

[0409] Encoder Considerations

[0410] The basic principle of the LMCS encoder is to first assign more codewords to those dynamic range segments with codewords with lower variance than the average. In this alternative concept, the main goal of LMCS is to assign 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.

[0411] 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 the local luminance variance and the determination of the LMCS parameters is optimized according to the above basic principles. The optimization is then performed to obtain the best PSNR metric for the final reconstructed samples of a given block.

[0412] Example

[0413] 1. Avoid sub-pictures when there is only one strip

[0414] In one embodiment, when at least one syntax element indicates that the current picture contains only one slice, sub-pictures are not allowed and / or are not signaled. This can be achieved by adding the following sentence to the semantics of subpic_info_present_flag:

[0415] "When one or more syntax elements specify that the current picture contains only one slice, it is a requirement for bitstream conformance that subpic_info_present_flag shall be equal to 0."

[0416] The advantage of this embodiment is that inconsistencies in the bitstream are avoided. In practice, a picture containing sub-pictures has several slices. If a picture contains only one slice, then the picture is a picture containing only one sub-picture. So, in other words, a sub-part of a picture. In addition, the parsing of the slice header is simplified for some implementations.

[0417] 1.1 Avoid sub-images when PH is SH

[0418] In one embodiment, when the picture header is sent in a slice header, sub-pictures are not allowed and / or are not signaled. In fact, when the picture header is in a slice header, the current picture contains only one slice. Therefore, it is not possible to split the current picture into several sub-pictures (since a sub-picture contains at least one slice, this means several slices).

[0419] 1.1.1 Semantics only

[0420] In one embodiment, when the picture header is sent in the slice header, subpic_info_present_flag is set equal to 0. This can be achieved by adding the following sentence to the semantics of subpic_info_present_flag:

[0421] "When the slice header of the referenced PPS contains the PH syntax structure, it is a requirement for bitstream conformance that subpic_info_present_flag shall be equal to 0."

[0422] 1.1.2 Table syntax

[0423] In one embodiment, slice_subpic_id is not decoded when the picture header is in the slice header as depicted in Table 12. In this syntax table, slice_subpic_id is decoded only when subpic_info_present_flag is set equal to 1 and picture_header_in_slice_header_flag is set equal to 0.

[0424] 1.2 Avoid sub-pictures when the blocks in the stripe are equal to the blocks in the picture and the number of blocks in the picture is greater than 1

[0425] In one embodiment, when raster scan stripe mode is enabled, the number of tiles in the current picture is greater than 1, and when the number of tiles in a stripe is equal to the number of tiles in the current picture, sub-pictures are not allowed and / or signaled. In this case, it is determined that the current picture contains only one stripe, and therefore the current picture cannot contain several sub-pictures.

[0426] 1.2.1 Semantics only

[0427] In one embodiment, when raster scan stripe mode is enabled, the number of tiles in the current picture is greater than 1, and when the number of tiles in the stripe is equal to the number of tiles in the current picture, subpic_info_present_flag is set equal to 0. This can be achieved by adding the following sentence to the semantics of subpic_info_present_flag:

[0428] "When raster scan slice mode is enabled and the number of tiles in the current picture is greater than 1, and when the number of tiles in a slice is equal to the number of tiles in the current picture, it is a requirement for bitstream conformance that subpic_info_present_flag shall be equal to 0."

[0429] 1.2.2 Table syntax

[0430] In one embodiment, as depicted in Table 13, when the raster scan slice mode is enabled, the number of blocks in the current picture is greater than 1, and when the number of blocks in the slice is equal to the number of blocks in the current picture, slice_subpic_id is not decoded.

[0431] 1.3 Combination of 1.1+1.2

[0432] In one embodiment, when a picture header is sent in a slice header, or when raster scan slice mode is enabled, the number of tiles in the current picture is greater than 1, and when the number of tiles in the slice is equal to the number of tiles in the current picture, sub-pictures are not allowed and / or signaled.

[0433] 2Avoid separating color planes when there is only one strip

[0434] In one embodiment, when the current picture contains only one slice, the color plane of the current picture is not separated. This can be achieved by adding the following sentence to the semantics of separate_colour_plane_flag:

[0435] "When one or more syntax elements specify that the current picture contains only one slice, it is a requirement for bitstream conformance that separate_colour_plane_flag shall not be equal to 1."

[0436] The advantage of this embodiment is that inconsistent bitstreams are avoided. In practice, a picture containing independently coded color planes has several slices. Therefore, it is not possible to have only one slice in the current picture. Furthermore, parsing of the slice header is simplified for some implementations.

[0437] 2.1 Avoiding separation of color planes when pH is SH

[0438] In one embodiment, when the picture header is sent in the slice header, the color planes of the current picture are not separated. In fact, when the picture header is in the slice header, the current picture contains only one slice.

[0439] 2.1.1 Semantics Only

[0440] In one embodiment, when the picture header is sent in a slice header, separate_colour_plane_flag is set equal to 0. This can be achieved by adding the following sentence to the semantics of separate_colour_plane_flag:

[0441] "When the slice header of the referenced PPS contains the PH syntax structure, it is a requirement for bitstream conformance that separate_colour_plane_flag shall be equal to 0."

[0442] 2.1.2 Table syntax

[0443] In one embodiment, colour_plane_id is not decoded when the picture header is in the slice header as depicted in Table 12. In this syntax table, colour_plane_id is decoded only when separate_colour_plane_flag is set equal to 1 and picture_header_in_slice_header_flag is set equal to 0.

[0444] 2.2 Avoid splitting color planes when the number of blocks in a strip is equal to the number of blocks in the picture and the number of blocks in the picture is greater than 1

[0445] In one embodiment, when raster scan stripe mode is enabled, the number of tiles in the current picture is greater than 1, and when the number of tiles in a stripe is equal to the number of tiles in the current picture, the color planes of the current picture are not separated. In this case, it is ensured that the current picture contains only one stripe, so the current picture cannot contain color planes coded in different stripes.

[0446] 2.2.1 Semantics only

[0447] In one embodiment, when raster scan stripe mode is enabled, the number of tiles in the current picture is greater than 1, and when the number of tiles in a stripe is equal to the number of tiles in the current picture, separate_colour_plane_flag is set equal to 0. This can be achieved by adding the following sentence to the semantics of separate_colour_plane_flag:

[0448] "When raster scan slice mode is enabled and the number of tiles in the current picture is greater than 1, and when the number of tiles in a slice is equal to the number of tiles in the current picture, it is a requirement for bitstream conformance that separate_colour_plane_flag shall be equal to 0."

[0449] 2.2.2 Table syntax

[0450] In one embodiment, as depicted in Table 13, when the raster scan stripe mode is enabled, the number of blocks in the current picture is greater than 1, and when the number of blocks in the stripe is equal to the number of blocks in the current picture, colour_plane_id is not decoded.

[0451] 2.3 Combination of 2.1+2.2

[0452] In one embodiment, when a picture header is sent in a slice header, or when raster scan slice mode is enabled, the number of blocks in the current picture is greater than 1, and when the number of blocks in a slice is equal to the number of blocks in the current picture, the color planes of the current picture are not separated.

[0453] Table 12 shows the modified partial slice header

[0454]

[0455] Table 13 shows the modified partial slice header

[0456]

[0457]

[0458] Combination of 3.1 and 2

[0459] In one embodiment, when at least one syntax element indicates that the current picture contains only one slice, sub-pictures are not allowed and / or signaled and color planes of the current picture are not separated.

[0460] 4. Separate color plane with color plane only

[0461] In one embodiment, the syntax element of the separated color plane is set equal to 1 and the current picture contains one or more slices with only the same color plane id.

[0462] This embodiment provides the possibility to easily extract only one color plane from a bitstream containing 3 color planes without modifying some syntax elements of the respective slices. Thus, the complexity of such an application is saved.

[0463] 4.1 Separate color plane with only one stripe set equal to brightness

[0464] In one embodiment, when at least one syntax element indicates that the current picture contains only one slice, the monochrome of the luma component may be signaled due to the syntax elements of the separated color planes. In this case, colour_plane_id is inferred to be equal to 0. An advantage of this embodiment compared to the previous embodiment is a reduction in bit rate, since the color plane id does not need to be sent.

[0465] This can be achieved by adding the following sentence to the semantics of colour_plane_id:

[0466] "When one or more syntax elements specify that the current picture contains only one slice, and when separate_colour_plane_flag is set equal to 1, colour_plane_id is inferred to be equal to 0."

[0467] 4.1.1 When pH is SH

[0468] In one embodiment, when the picture header is sent in the slice header, the monochrome of the luma component can be signaled due to the syntax elements of the separated color planes. In this case, the colour_plane_id is inferred to be equal to 0. An advantage of this embodiment compared to the previous embodiment is the reduction in bit rate, since the color plane id does not need to be sent.

[0469] This can be achieved by adding the following sentence to the semantics of colour_plane_id:

[0470] "When the slice header of the reference PPS contains the PH syntax structure, and when separate_colour_plane_flag is set equal to 1, colour_plane_id is inferred to be equal to 0."

[0471] In addition, as shown in Table 12, there is no need to send the color plane id.

[0472] 4.1.2 When the blocks in a stripe are equal to the blocks in a picture and the number of blocks in a picture is greater than 1

[0473] In one embodiment, when raster scan stripe mode is enabled, the number of tiles in the current picture is greater than 1, and when the number of tiles in a stripe is equal to the number of tiles in the current picture, a single color of the luma component may be signaled due to the syntax elements of the separated color planes. In this case, colour_plane_id is inferred to be equal to 0. An advantage of this embodiment is a reduction in bit rate, since the color plane id does not need to be sent.

[0474] This can be achieved by adding the following sentence to the semantics of colour_plane_id:

[0475] "When raster scan stripe mode is enabled and the number of tiles in the current picture is greater than 1, and when the number of tiles in a stripe is equal to the number of tiles in the current picture, and when separate_colour_plane_flag is set equal to 1, colour_plane_id is inferred to be equal to 0."

[0476] 4.1.3 Combination of 4.1.1 and 4.1.2

[0477] In one embodiment, when a picture header is sent in a slice header, or when raster scan slice mode is enabled, the number of blocks in the current picture is greater than 1, and when the number of blocks in the slice is equal to the number of blocks in the current picture, the monochrome of the luma component may be signaled due to the syntax elements of the separated color planes.

[0478] accomplish

[0479] Fig.11A system 191, 195 according to an embodiment of the present invention is shown, which includes at least one of the encoder 150 or the decoder 100 and a communication network 199. According to an embodiment, the system 195 is used to process and provide content (e.g., video and audio content for display / output or streaming video / audio content) to a user, who accesses the decoder 100, for example, through a user terminal including the decoder 100 or a user interface of a user terminal that can communicate with the decoder 100. Such a user terminal can be a computer, a mobile phone, a tablet computer, or any other type of device capable of providing / displaying (provided / streamed) content to a user. The system 195 obtains / receives the bitstream 101 (in the form of a continuous stream or signal (e.g., when displaying / outputting earlier video / audio)) via the communication network 199. According to an embodiment, the system 191 is used to process content and store processed content, such as video and audio content processed for display / output / streaming at a later time. The system 191 obtains / receives content including an original image sequence 151, which is received and processed by the encoder 150 (including filtering using a deblocking filter according to the present invention), and the encoder 150 generates a bitstream 101 to be transmitted to the decoder 100 via the communication network 191. The bitstream 101 is then transmitted to the decoder 100 in a variety of ways, for example, it can be pre-generated by the encoder 150 and stored as data in a storage device in the communication network 199 (for example, on a server or cloud storage device) until the user requests the content (i.e., bitstream data) from the storage device, at which time the data is transmitted / streamed from the storage device to the decoder 100. The system 191 may also include a content providing device for providing / streaming to the user (for example, by transmitting data of a user interface to be displayed on a user terminal) content information (for example, the title of the content and other meta / storage location data for identifying, selecting and requesting the content) of the content stored in the storage device, 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 the 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 is then used by the user terminal to provide the requested content to the user.

[0480] Any step of the method / processing according to the present invention or the function 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. Therefore, the term "processor" as used herein may refer to any of the aforementioned structures or any other structures suitable for implementing the technology described herein.

[0481] 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 the apparatus / device configured to perform these embodiments, but 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, which include one or more processors in conjunction with appropriate software / firmware.

[0482] Embodiments of the present invention can be implemented by a computer of a system or device that reads out 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-mentioned embodiments and / or includes one or more processing units or circuits for performing one or more functions in the above-mentioned embodiments, and can be implemented by a method performed by a computer of a system or device, for example, reading out and executing computer executable instructions from a storage medium to perform one or more functions in the above-mentioned embodiments and / or controlling one or more processing units or circuits to perform one or more functions in the above-mentioned embodiments. The computer may include a network of separate computers or separate processing units to read out and execute computer executable instructions. Computer executable instructions may be provided to a 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. A tangible storage medium is a “non-transitory computer-readable storage medium” which may include, for example, a hard disk, a random access memory (RAM), a 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”).

[0483] Fig.122000 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 light 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 part of an image according to the embodiment of the present invention, and its storage capacity can be expanded, for example, by an optional RAM connected to an expansion port; - a read-only memory (ROM) 2003 for storing a computer program for implementing an embodiment of the present invention; - a network interface (NET) 2004, which is usually connected to a communication network through which the digital data to be processed is transmitted or received, and the network interface (NET) 2004 may be a single network interface, or composed of a group of different network interfaces (for example, wired and wireless interfaces, or different kinds of wired or wireless interfaces), which are connected to the CPU when running. 2001, data packets are written to the network interface for transmission or read from the network interface for reception; - User interface (UI) 2005, which can be used to receive input from the user or display information to the user; - Hard disk (HD) 2006, which can be set as a mass storage device; - Input / output module (IO) 2007, which can be used to receive / send data from / to external devices (such as video sources or displays, etc.). The executable code can be stored in ROM 2003, on HD 2006, or on a removable digital medium such as a disk. According to a variant, the executable code of the program can be received via NET 2004 by means of a communication network to be stored in one of the storage components (such as HD 2006, etc.) of the computing device 2000 before being executed. CPU 2001 is suitable for controlling and directing the execution of instructions or parts of the software code of one or more programs according to an embodiment of the present invention, which instructions are 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.

[0484] It should also be understood that according to other embodiments of the present invention, a decoder according to the above embodiments is provided in a user terminal such as a computer, a mobile phone (cellular phone), a tablet or any other type of device (e.g., a display device) capable of providing / displaying content to a user. According to yet another embodiment, an encoder according to the above embodiments is provided in an image capture device, which 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 Fig.13 and 14 Two such examples are provided.

[0485] Network Camera

[0486] Fig.13 21 is a diagram illustrating a network camera system 2100 including a network camera 2102 and a client device 2104 .

[0487] The network camera 2102 includes an imaging unit 2106 , an encoding section 2108 , a communication unit 2110 , and a control unit 2112 .

[0488] The network camera 2102 and the client device 2104 are connected to each other via the network 200 to be able to communicate with each other.

[0489] 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.

[0490] The encoding section 2108 encodes the image data by using the encoding method described above.

[0491] 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 .

[0492] 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.

[0493] The control unit 2112 controls other units in the network camera 2102 according to the command received by the communication unit 2110 .

[0494] The client device 2104 includes a communication unit 2114 , a decoding section 2116 , and a control unit 2118 .

[0495] The communication unit 2114 of the client device 2104 transmits a command to the network camera 2102 .

[0496] Furthermore, the communication unit 2114 of the client device 2104 receives the encoded image data from the network camera 2102 .

[0497] The decoding section 2116 decodes the encoded image data by using the decoding method described above.

[0498] The control unit 2118 of the client device 2104 controls other units in the client device 2104 according to a user operation or command received by the communication unit 2114 .

[0499] The control unit 2118 of the client device 2104 controls the display device 2120 to display the image decoded by the decoding section 2116 .

[0500] 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 ).

[0501] 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 .

[0502] The control unit 2118 of the client device 2104 controls the communication unit 2114 of the client device 2104 according to the 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 .

[0503] Smartphone

[0504] Fig.14 is a diagram illustrating a smartphone 2200 .

[0505] 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 .

[0506] The communication unit 2202 receives the encoded image data via the network 200 .

[0507] The decoding section 2204 decodes the encoded image data received by the communication unit 2202 .

[0508] The decoding section 2204 decodes the encoded image data by using the decoding method described above.

[0509] The control unit 2206 controls other units in the smartphone 2200 according to user operations or commands received by the communication unit 2202 .

[0510] For example, the control unit 2206 controls the display unit 2208 to display the image decoded by the decoding section 2204 .

[0511] Although the present invention has been described with reference to the embodiments, it should be understood that the present invention is not limited to the disclosed embodiments. It will be appreciated by those skilled in the art that various changes and modifications may be made without departing from the scope of the present 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 disclosed method or process may be combined in any combination, except for at least some mutually exclusive combinations of such features and / or steps. Unless otherwise expressly stated, 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 otherwise expressly stated, each feature disclosed is only an example of a general series of equivalent or similar features.

[0512] It should also be understood that any results of the above-described comparison, determination, evaluation, selection, execution, proceeding, or consideration (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 result) or may be determined / inferred from data in the bitstream, such that the indicated or determined / inferred result may be used for processing rather than actually being compared, determined, evaluated, selected, executed, performed, or considered, for example, during a decoding process.

[0513] 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.

[0514] 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 in a picture, a sequence parameter set, a picture header syntax structure, and a slice header, wherein the method comprises: Parsing one or more syntactic elements; as well as decoding video data from the bitstream using the parsed syntax elements, wherein, when the first flag decoded from the slice header indicates that the picture header syntax structure is present in the slice header, the second flag in the sequence parameter set indicating whether sub-picture information related to a sub-picture in the picture exists for a coding layer video sequence, i.e., a CLVS, should have a value indicating that the sub-picture information does not exist for the CLVS, wherein, when (a) the syntax element indicates that raster scan slice mode is enabled, (b) the number of blocks in the picture is greater than one, and (c) the number of blocks in a slice is equal to the number of blocks in the picture, the picture to be decoded contains only one slice, and In which, when the weighted prediction parameters and the adaptive parameter set ID (APS ID) for the adaptive loop filter (ALF) are decoded from the picture header syntax structure, the adaptive parameter set ID (APS ID) for the adaptive loop filter (ALF) is decoded from the picture header syntax structure before the weighted prediction parameters are decoded from the picture header syntax structure.

2. The method according to claim 1, wherein: When the first flag in the slice header indicates that the picture header syntax structure is present in the slice header, the ID of a sub-picture should not be decoded from the slice header.

3. The method according to claim 1, wherein: The sub-picture information includes an ID of the sub-picture, and wherein, when (a) the first flag indicates that the picture header syntax structure does not exist in the slice header and (b) the second flag indicates that sub-picture information exists, the ID of the sub-picture is decoded from the slice header.

4. A method of encoding video data into a bitstream, the bitstream comprising coded video data corresponding to one or more slices in a picture, a sequence parameter set, a picture header syntax structure, and a slice header, the method comprising: Encode one or more syntax elements into a bitstream, wherein, when a first flag to be encoded in the slice header indicates that the picture header syntax structure is present in the slice header, a second flag in the sequence parameter set indicating whether sub-picture information related to a sub-picture in the picture exists for a coding layer video sequence, i.e., a CLVS, should have a value indicating that the sub-picture information does not exist for the CLVS, wherein, when (a) the syntax element indicates that raster scan slice mode is enabled, (b) the number of blocks in the picture is greater than one, and (c) the number of blocks in a slice is equal to the number of blocks in the picture, the picture to be encoded contains only one slice, and Wherein, in a case where the weighted prediction parameters and an adaptive parameter set ID (APS ID) for an adaptive loop filter (ALF) are encoded into the picture header syntax structure, the adaptive parameter set ID (APS ID) for an adaptive loop filter (ALF) is encoded into the picture header syntax structure before the weighted prediction parameters are encoded into the picture header syntax structure; and Slices are encoded into the bitstream.

5. An apparatus for decoding video data from a bitstream, the bitstream comprising coded video data corresponding to one or more slices in a picture, a sequence parameter set, a picture header syntax structure, and a slice header, wherein the apparatus comprises: A component for parsing one or more syntactic elements; as well as means for decoding video data from the bitstream using the parsed syntax elements, wherein, when the first flag decoded from the slice header indicates that the picture header syntax structure is present in the slice header, the second flag in the sequence parameter set indicating whether sub-picture information related to a sub-picture in the picture exists for a coding layer video sequence, i.e., a CLVS, should have a value indicating that the sub-picture information does not exist for the CLVS, wherein, when (a) the syntax element indicates that raster scan slice mode is enabled, (b) the number of blocks in the picture is greater than one, and (c) the number of blocks in a slice is equal to the number of blocks in the picture, the picture to be decoded contains only one slice, and In which, when the weighted prediction parameters and the adaptive parameter set ID (APS ID) for the adaptive loop filter (ALF) are decoded from the picture header syntax structure, the adaptive parameter set ID (APS ID) for the adaptive loop filter (ALF) is decoded from the picture header syntax structure before the weighted prediction parameters are decoded from the picture header syntax structure.

6. An apparatus for encoding video data into a bitstream, the bitstream comprising coded video data corresponding to one or more slices in a picture, a sequence parameter set, a picture header syntax structure, and a slice header, the apparatus comprising: A component used to encode one or more syntax elements into a bitstream. wherein, when a first flag to be encoded in the slice header indicates that the picture header syntax structure is present in the slice header, a second flag in the sequence parameter set indicating whether sub-picture information related to a sub-picture in the picture exists for a coding layer video sequence, i.e., a CLVS, should have a value indicating that the sub-picture information does not exist for the CLVS, wherein, when (a) the syntax element indicates that raster scan slice mode is enabled, (b) the number of blocks in the picture is greater than one, and (c) the number of blocks in a slice is equal to the number of blocks in the picture, the picture to be encoded contains only one slice, and Wherein, in a case where the weighted prediction parameters and an adaptive parameter set ID (APS ID) for an adaptive loop filter (ALF) are encoded into the picture header syntax structure, the adaptive parameter set ID (APS ID) for an adaptive loop filter (ALF) is encoded into the picture header syntax structure before the weighted prediction parameters are encoded into the picture header syntax structure; and Means for encoding said slice into said bitstream.

7. A computer program product, comprising a computer program, which, when executed by a processor, implements the method according to any one of claims 1 to 3.

8. A computer program product comprising a computer program, which, when executed by a processor, implements the method according to claim 4.

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