Method and device for video processing and medium

Abstract

Embodiments of the present disclosure provide a scheme for video processing. A method for video processing is presented. The method comprises: for a conversion between a current video block of the video and a bitstream of the video, determining at least one context model based on initial information of at least one context model associated with the current video block, the initial information of the at least one context model being included in the bitstream; and performing the conversion based on the at least one context model.

Description

Technical Field

[0001] Embodiments of the present invention generally relate to video coding techniques, and more particularly, to context model determination. Background Art

[0002] Nowadays, digital video functions are being applied to all aspects of people's lives. For video encoding / decoding, various types of video compression technologies have been proposed, such as MPEG-2, MPEG-4, ITU-TH.263, ITU-TH.264 / MPEG-4 Part 10 Advanced Video Codec (AVC), ITU-TH.265 High Efficiency Video Codec (HEVC) standard, and Versatile Video Codec (VVC) standard. However, the encoding and decoding efficiency of conventional video encoding and decoding technologies is usually very low, which is undesirable. Summary of the invention

[0003] Embodiments of the present disclosure provide a solution for video processing.

[0004] In a first aspect, a method for video processing is proposed. The method comprises: for conversion between a current video block of a video and a bitstream of the video, determining at least one context model based on initial information of at least one context model associated with the current video block, the initial information of the at least one context model being included in the bitstream; and performing conversion based on at least one context model. The method according to the first aspect of the present disclosure determines a context model based on initial information of the context model in the bitstream. Compared with conventional schemes, the method proposed in the first aspect can advantageously improve coding and decoding effects and coding and decoding efficiency.

[0005] In a second aspect, a device for processing video data is provided. The device for processing video data includes a processor and a non-volatile memory having instructions thereon. The instructions, when executed by the processor, cause the processor to perform the method according to the first aspect of the present disclosure.

[0006] In a third aspect, a non-transitory computer-readable storage medium is provided, wherein the non-transitory computer-readable storage medium stores instructions that cause a processor to execute the method according to the first aspect of the present disclosure.

[0007] In a fourth aspect, another non-transitory computer-readable recording medium is provided. The non-transitory computer-readable recording medium stores a bitstream of a video, the bitstream of the video being generated by a method performed by an apparatus for video processing, wherein the method comprises: determining at least one context model based on initial information of at least one context model associated with a current video block of the video, the initial information of the at least one context model being included in the bitstream; and generating the bitstream based on the at least one context model

[0008] In a fifth aspect, a method for storing a bitstream of a video is provided. The method comprises: determining at least one context model based on initial information of at least one context model associated with a current video block of the video, the initial information of the at least one context model being included in the bitstream; generating a bitstream based on the at least one context model; and storing the bitstream in a non-transitory computer-readable recording medium.

[0009] This summary is provided to introduce a selection of concepts that are further described below in the specific embodiments in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other purposes, features and advantages of the exemplary embodiments of the present disclosure will become more apparent through the following detailed description with reference to the accompanying drawings. In the exemplary embodiments of the present disclosure, the same reference numerals generally refer to the same components.

[0011] Figure 1 A block diagram illustrating an example video encoding and decoding system according to some embodiments of the present disclosure is shown;

[0012] Figure 2 A block diagram illustrating a first example video encoder according to some embodiments of the present disclosure is shown;

[0013] Figure 3 A block diagram illustrating an example video decoder according to some embodiments of the present disclosure is shown;

[0014] Figure 4 A flowchart for decoding binary bits in HEVC is shown;

[0015] Figure 5 A flow chart for decoding binary bits in VVC is shown;

[0016] Figure 6 A flowchart showing a method for video processing according to some embodiments of the present disclosure; and

[0017] Figure 7 A block diagram of a computing device is shown in which various embodiments of the present disclosure may be implemented.

[0018] In the drawings, same or similar reference numbers generally refer to same or similar elements. Specific embodiments

[0019] The principle of the present disclosure will now be described with reference to some embodiments. It should be understood that these embodiments are described only for the purpose of illustrating and helping those skilled in the art to understand and implement the present disclosure, without implying any limitation on the scope of the present disclosure. In addition to the methods described below, the disclosure described herein can also be implemented in various ways.

[0020] In the following description and claims, unless defined otherwise, all scientific and technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs.

[0021] References in this disclosure to "one embodiment," "an embodiment," "an example embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment must include the particular feature, structure, or characteristic. Furthermore, these phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an example embodiment, whether or not explicitly described, it is considered to be within the knowledge of those skilled in the art to affect such feature, structure, or characteristic in relation to other embodiments.

[0022] It should be understood that although the terms "first" and "second" etc. can be used to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish one element from another element. For example, a first element can be referred to as a second element, and similarly, a second element can be referred to as a first element without departing from the scope of the exemplary embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0023] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms "including", "comprising", and / or "having" when used herein indicate the presence of the features, elements, and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Example Environment

[0024] Figure 11 is a block diagram illustrating an example video codec system 100 that may utilize the techniques of the present disclosure. As shown, the video codec system 100 may include a source device 110 and a destination device 120. The source device 110 may also be referred to as a video encoding device, and the destination device 120 may also be referred to as a video decoding device. In operation, the source device 110 may be configured to generate encoded video data, and the destination device 120 may be configured to decode the encoded video data generated by the source device 110. The source device 110 may include a video source 112, a video encoder 114, and an input / output (I / O) interface 116.

[0025] Video source 112 may include a source such as a video capture device. Examples of a video capture device include, but are not limited to, an interface that receives video data from a video content provider, a computer graphics system for generating video data, and / or combinations thereof.

[0026] The video data may include one or more pictures. The video encoder 114 encodes the video data from the video source 112 to generate a code stream. The code stream may include a bit sequence that forms a coded representation of the video data. The code stream may include coded pictures and associated data. The coded picture is a coded representation of the picture. The associated data may include a sequence parameter set, a picture parameter set, and other grammatical structures. The I / O interface 116 may include a modulator / demodulator and / or a transmitter. The coded video data may be directly transmitted to the destination device 120 via the network 130A via the I / O interface 116. The coded video data may also be stored on a storage medium / server 130B for access by the destination device 120.

[0027] The destination device 120 may include an I / O interface 126, a video decoder 124, and a display device 122. The I / O interface 126 may include a receiver and / or a modem. The I / O interface 126 may obtain encoded video data from the source device 110 or the storage medium / server 130B. The video decoder 124 may decode the encoded video data. The display device 122 may display the decoded video data to the user. The display device 122 may be integrated with the destination device 120, or may be outside the destination device 120, which is configured to be connected to an external display device interface.

[0028] The video encoder 114 and the video decoder 124 may operate according to a video compression standard, such as the High Efficiency Video Codec (HEVC) standard, the Versatile Video Codec (VVC) standard, and other existing and / or additional standards.

[0029] Figure 2 is a block diagram showing an example of a video encoder 200 according to some embodiments of the present disclosure, which may be Figure 1 An example of a video encoder 114 in the system 100 is shown.

[0030] Video encoder 200 may be configured to implement any or all of the techniques of this disclosure. Figure 2 In the example of , video encoder 200 includes multiple functional components. The techniques described in this disclosure can be shared between the various components of video encoder 200. In some examples, a processor can be configured to perform any or all of the techniques described in this disclosure.

[0031] In some embodiments, the video encoder 200 may include a partitioning unit 201, a prediction unit 202, a residual generation unit 207, a transformation unit 208, a quantization unit 209, an inverse quantization unit 210, an inverse transformation unit 211, a reconstruction unit 212, a buffer 213 and an entropy coding unit 214, and the prediction unit 202 may include a mode selection unit 203, a motion estimation unit 204, a motion compensation unit 205 and an intra-frame prediction unit 206.

[0032] In other examples, the video encoder 200 may include more, fewer, or different functional components. In one example, the prediction unit 202 may include an intra-block copy (IBC) unit. The IBC unit may perform prediction in an IBC mode, where at least one reference picture is a picture where the current video block is located.

[0033] Furthermore, although some components (such as the motion estimation unit 204 and the motion compensation unit 205) may be integrated, for the purpose of explanation, these components are described in detail below. Figure 2 are shown separately in the example.

[0034] The partitioning unit 201 may partition a picture into one or more video blocks. The video encoder 200 and the video decoder 300 may support various video block sizes.

[0035] The mode selection unit 203 may select one of a plurality of coding modes (intra-frame coding or inter-frame coding), for example, based on the error result, and provide the generated intra-frame coding block or inter-frame coding block to the residual generation unit 207 to generate residual block data, and to the reconstruction unit 212 to reconstruct the coding block for use as a reference picture. In some examples, the mode selection unit 203 may select a combination of intra-frame and inter-frame prediction (CIIP) modes, where the prediction is based on an inter-frame prediction signal and an intra-frame prediction signal. In the case of inter-frame prediction, the mode selection unit 203 may also select a resolution for the motion vector (e.g., sub-pixel precision or integer pixel precision) for the block.

[0036] To perform inter-frame prediction on the current video block, the motion estimation unit 204 may generate motion information for the current video block by comparing the current video block with one or more reference frames from the buffer 213. The motion compensation unit 205 may determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from the buffer 213 other than the picture associated with the current video block.

[0037] The motion estimation unit 204 and the motion compensation unit 205 may perform different operations on the current video block, for example, depending on whether the current video block is in an I slice, a P slice, or a B slice. As used herein, an "I slice" may refer to a portion of a picture consisting of macroblocks, all of which are based on macroblocks within the same picture. Furthermore, as used herein, in some aspects, a "P slice" and a "B slice" may refer to a portion of a picture consisting of macroblocks that are independent of macroblocks in the same picture.

[0038] In some examples, the motion estimation unit 204 may perform unidirectional prediction on the current video block, and the motion estimation unit 204 may search the reference pictures of list 0 or list 1 to find the reference video block for the current video block. The motion estimation unit 204 may then generate a reference index and a motion vector, the reference index indicating the reference picture in list 0 or list 1 containing the reference video block, and the motion vector indicating the spatial displacement between the current video block and the reference video block. The motion estimation unit 204 may output the reference index, the prediction direction indicator, and the motion vector as the motion information of the current video block. The motion compensation unit 205 may generate a predicted video block for the current video block based on the reference video block indicated by the motion information of the current video block.

[0039] Alternatively, in other examples, the motion estimation unit 204 may perform bidirectional prediction on the current video block. The motion estimation unit 204 may search the reference pictures in list 0 for a reference video block for the current video block, and may also search the reference pictures in list 1 for another reference video block for the current video block. The motion estimation unit 204 may then generate a plurality of reference indexes and a plurality of motion vectors, the plurality of reference indexes indicating a plurality of reference pictures in list 0 and list 1 containing a plurality of reference video blocks, and the plurality of motion vectors indicating a plurality of spatial displacements between the plurality of reference video blocks and the current video block. The motion estimation unit 204 may output the plurality of reference indexes and the plurality of motion vectors of the current video block as motion information of the current video block. The motion compensation unit 205 may generate a predicted video block for the current video block based on the plurality of reference video blocks indicated by the motion information of the current video block.

[0040] In some examples, motion estimation unit 204 may output a complete set of motion information for use in a decoding process by a decoder. Alternatively, in some embodiments, motion estimation unit 204 may signal motion information of a current video block with reference to motion information of another video block. For example, motion estimation unit 204 may determine that motion information of a current video block is sufficiently similar to motion information of a neighboring video block.

[0041] In one example, motion estimation unit 204 may indicate to video decoder 300 a value in a syntax structure associated with the current video block that indicates that the current video block has the same motion information as another video block.

[0042] In another example, the motion estimation unit 204 may identify another video block and a motion vector difference (MVD) in a syntax structure associated with the current video block. The motion vector difference indicates the difference between the motion vector of the current video block and the motion vector of the indicated video block. The video decoder 300 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[0043] As discussed above, the video encoder 200 may signal motion vectors in a predictive manner.Two examples of prediction signaling techniques that may be implemented by the video encoder 200 include Advanced Motion Vector Prediction (AMVP) and merge mode signaling.

[0044] The intra prediction unit 206 may perform intra prediction on the current video block. When the intra prediction unit 206 performs intra prediction on the current video block, the intra prediction unit 206 may generate prediction data for the current video block based on decoded samples of other video blocks in the same picture. The prediction data for the current video block may include a prediction video block and various syntax elements.

[0045] The residual generation unit 207 may generate residual data for the current video block by subtracting (e.g., indicated by a minus sign) the prediction video block(s) of the current video block from the current video block. The residual data of the current video block may include residual video blocks corresponding to different sample portions of samples in the current video block.

[0046] In other examples, such as in skip mode, there may be no residual data for the current video block, and the residual generation unit 207 may not perform a subtraction operation.

[0047] Transform processing unit 208 may generate one or more transform coefficient video blocks for a current video block by applying one or more transforms to the residual video block associated with the current video block.

[0048] After transform processing unit 208 generates a transform coefficient video block associated with the current video block, quantization unit 209 may quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values ​​associated with the current video block.

[0049] The inverse quantization unit 210 and the inverse transform unit 211 may apply inverse quantization and inverse transform to the transform coefficient video block, respectively, to reconstruct a residual video block from the transform coefficient video block. The reconstruction unit 212 may add the reconstructed residual video block to corresponding samples from one or more prediction video blocks generated by the prediction unit 202 to generate a reconstructed video block associated with the current video block for storage in the buffer 213.

[0050] After reconstruction unit 212 reconstructs the video block, a loop filtering operation may be performed to reduce video blocking artifacts in the video block.

[0051] The entropy coding unit 214 may receive data from other functional components of the video encoder 200. When the entropy coding unit 214 receives data, the entropy coding unit 214 may perform one or more entropy coding operations to generate entropy coded data and output a code stream including the entropy coded data.

[0052] Figure 3 is a block diagram showing an example of a video decoder 300 according to some embodiments of the present disclosure, which may be Figure 1 An example of a video decoder 124 in the system 100 is shown.

[0053] Video decoder 300 may be configured to perform any or all of the techniques of this disclosure. Figure 3 In the example of , video decoder 300 includes multiple functional components. The techniques described in this disclosure can be shared between the various components of video decoder 300. In some examples, a processor can be configured to perform any or all of the techniques described in this disclosure.

[0054] exist Figure 3 In the example of , the video decoder 300 includes an entropy decoding unit 301, a motion compensation unit 302, an intra prediction unit 303, an inverse quantization unit 304, an inverse transform unit 305, and a reconstruction unit 306 and a buffer 307. In some examples, the video decoder 300 can perform a decoding process that is generally opposite to the encoding process described with respect to the video encoder 200.

[0055] The entropy decoding unit 301 can retrieve the encoded code stream. The encoded code stream may include entropy encoded video data (e.g., encoded video data blocks). The entropy decoding unit 301 can decode the entropy encoded video data, and the motion compensation unit 302 can determine motion information from the entropy decoded video data, the motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. The motion compensation unit 302 can determine the information, for example, by performing AMVP and merge mode. AMVP is used, including deriving several most likely candidates based on data and reference pictures of neighboring PBs. The motion information typically includes horizontal and vertical motion vector displacement values, one or two reference picture indexes, and in the case of prediction areas in B stripes, also includes an identification of which reference picture list is associated with each index. As used herein, in some aspects, "merge mode" may refer to deriving motion information from blocks that are adjacent in space or time.

[0056] The motion compensation unit 302 may generate motion compensated blocks, possibly performing interpolation based on interpolation filters.Identifiers for the interpolation filters used with sub-pixel precision may be included in the syntax elements.

[0057] The motion compensation unit 302 may calculate interpolated values ​​for sub-integer pixels of a reference block using interpolation filters used by the video encoder 200 during encoding of the video block. The motion compensation unit 302 may determine the interpolation filters used by the video encoder 200 based on received syntax information, and the motion compensation unit 302 may use the interpolation filters to generate a prediction block.

[0058] The motion compensation unit 302 may use at least part of the syntax information to determine the size of blocks used to encode (multiple) frames and / or (multiple) slices of the encoded video sequence, partition information describing how each macroblock of a picture of the encoded video sequence is partitioned, a mode indicating how each partition is encoded, one or more reference frames (and reference frame lists) for each inter-coded block, and other information for decoding the encoded video sequence. As used herein, in some aspects, a "slice" may refer to a data structure that can be decoded independently of other slices of the same picture in terms of entropy coding, signal prediction, and residual signal reconstruction. A slice may be an entire picture, or it may be a region of a picture.

[0059] The intra prediction unit 303 may use, for example, an intra prediction mode received in a bitstream to form a prediction block from spatially neighboring blocks. The inverse quantization unit 304 inversely quantizes (i.e., dequantizes) the quantized video block coefficients provided in the bitstream and decoded by the entropy decoding unit 301. The inverse transform unit 305 applies an inverse transform.

[0060] The reconstruction unit 306 may obtain the decoded block, for example, by adding the residual block to the corresponding prediction block generated by the motion compensation unit 302 or the intra prediction unit 303. If necessary, a deblocking filter may also be applied to filter the decoded block in order to remove blocking artifacts. The decoded video block is then stored in a buffer 307, which provides reference blocks for subsequent motion compensation / intra prediction, and the buffer 307 also generates the decoded video for presentation on a display device.

[0061] Some exemplary embodiments of the present disclosure will be described in detail below. It should be noted that the section titles used in this document are for ease of understanding, rather than limiting the embodiments disclosed in the section to that section. In addition, although some embodiments are described with reference to general video codecs or other specific video codecs, the disclosed technology is also applicable to other video codec technologies. In addition, although some embodiments describe the video encoding steps in detail, it should be understood that the corresponding decoding steps of the unencoding will be implemented by the decoder. In addition, the term video processing includes video encoding or compression, video decoding or decompression, and video transcoding, in which video pixels are represented from one compression format to another compression format or at different compression bit rates. 1. Brief Overview The present disclosure relates to video coding techniques. Specifically, the present disclosure relates to context signaling and initialization methods in video coding. These ideas can be applied to any video coding standard or non-standard video codec alone or in various combinations. 2. Introduction 2.1. Entropy encoding and decoding Entropy coding aims to remove entropy redundancy in video signals, which is usually achieved by utilizing conditional entropy and joint entropy. Accurate probability distribution estimation of source symbols (i.e., context modeling) is a key prerequisite for efficient entropy coding. Existing entropy coding techniques can be roughly classified into variable length coding (VLC) and arithmetic coding (AC), wherein Huffman coding is a typical VLC method and has been adopted in early video coding standards such as mpeg_1, mpeg-2 and h.263. The basic idea of ​​VLC is to assign shorter codewords to those symbols with high probability of occurrence, and thus reduce the average codec bit. In addition to Huffman coding, some other VLC methods, such as exponential Golomb coding (ECG), Golombreth coding (GRC) and context-based variable length coding (CAVLC), are also widely studied in various video coding standards. Unlike VLC, arithmetic coding maps source symbol sequences to positive real numbers from 0 to 1, and uses binary decimals to represent symbol sequences within this range. As a successful application of arithmetic coding in the field of video compression, context-adaptive binary arithmetic coding (CABAC) has been thoroughly studied in modern video coding standards, which can effectively remove the entropy redundancy of source symbols by utilizing context information during the coding and decoding process. 2.2. CABAC in HEVC The CABAC engine in HEVC uses a table-based probability conversion process between 64 different representative probability states. In particular, for each context variable, two variables pStateIdx and valMps are initialized. From the 8-bit table entry initValue, two 4-bit variables slopeIdx and offsetIdx are derived as follows: slopeIdx=initValue>>4 offsetIdx=initValue&15 (1). The variables m and n used in the initialization of the context variables are derived from slopeIdx and offsetIdx as follows: mslopeIdx*5-45 n=(offsetIdx<<3)-16 (2). The two values ​​assigned to pStateIdx and valMps for initialization are derived from SliceQpY, which is derived in formula (3). Given the variables m and n, the initialization is specified as follows. In HEVC, the range ivlCurrRange representing the state of the codec engine is quantized to a set of 4 values ​​before the calculation of the new interval range. HEVC state transitions can be implemented using a table containing all 64×4 8-bit pre-calculated values ​​to approximate the value of ivlCurrRange*pLPS(pStateIdx), where pLPS is the probability of the least likely symbol (LPS) and pStateIdx is the index of the current state. In addition, decoding decisions can be implemented using a pre-calculated LUT. First, the LUT is used to obtain ivlLpsRange, that is, ivlLpsRange=rangeTabLps[pStateIdx][qRangeIdx]. Then, ivlLpsRange is used to update ivlCurrRange and calculate the output binVal. In particular, the variable ivlCurrRange is set equal to ivlCurrRange-ivlLpsRange, and the following is applied: a) If ivlOffset is greater than or equal to ivlCurrRange, then the variable binVal is set equal to 1-valMps, ivlOffset minus ivlCurrRange, and ivlCurrRange is set equal to ivlLpsRange. b) Otherwise, the variable binVal is set equal to valMps. Figure 4 A flowchart 400 is shown for decoding binary bits in HEVC. At block 401, the process DecodeDecision(ctxTable, ctxIdx) begins. At block 410, the following calculations are performed: qRangeIdx=(ivlCurrRange>>6)&3; ivlLpsRange=rangeTabLps[pStateIdx][qRangeIdx]; ivlCurrRange=ivlCurrRange-ivlLpsRange. At block 420, it is determined whether ivlOffset is greater than or equal to ivlCurrRange. If ivlOffset is greater than or equal to ivlCurrRange, then at block 430, the following calculation is performed: binVal = !valMps; ivlOffset=ivlOffset-ivlCurrRange; ivlCurrRange=ivlLpsRange. If ivlOffset is less than ivlCurrRange, then at block 440, the following calculation is performed: binVal=valMps pStateIdx=transIdxMps[pStateIdx]. At block 450, it is determined whether pStateIdx is equal to 0. If pStateIdx is equal to 0, then at block 460, valMps = 1 - valMps. If pStateIdx is not equal to 0, then at block 470, pStateIdx = transIdxLps[pStateIdx]. At block 480, a normalization process such as RemormD is performed. At block 490, the procedure DecodeDecision(ctxTable, ctxIdx) is completed. CABAC in VVC In VVC, probabilities are represented linearly by probability indexes pStateIdx. Therefore, all calculations can be done using equations that do not require LUT operations. In order to improve the accuracy of probability estimates, a multi-hypothesis probability update model is applied. The pStateIdx used in interval subdivision in the binary arithmetic codec is a combination of two probabilities pStateIdx0 and pStateIdxl. The two probabilities are associated with each context model and are updated independently at different adaptation rates. The adaptation rates of pStateIdx0 and pStateIdx1 for each context model are pre-trained based on the statistics of the associated binary bits. The probability estimate pStateIdx is the average of the estimates from the two hypotheses. As done in HEVC, VVC CABAC also has a QP-dependent initialization process that is called at the beginning of each slice. For a slice with a given initial value of the luma QP, the initial probability state of the context model (denoted as preCtxState) is derived as follows: m=slopeIdx×5-45 (4) n=(offsetIdx<<3)+7 (5) preCtxState=Clip3(1,127,((m×(QP-32))>>4)+n) (6) Where slopeIdx and offsetIdx are limited to 3 bits, and the total initialization value is represented by 6-bit precision. The probability state preCtxState directly represents the probability in the linear domain. Therefore, preCtxState only requires appropriate shift operations before input to the arithmetic codec engine, and the logarithmic to linear domain mapping and 256-byte table are saved. pStateIdx0=preCtxState<<3 (7) pStateIdx1=preCtxState<<7 (8). Figure 5 A flow chart 500 is shown for decoding binary bits in a VVC. At block 501, the procedure DecodeDecision(ctx Table, ctxIdx) begins. At block 510, the following calculations are performed. Once pStateIdx0 and pStateIdx1 are derived, the value of the variable ivlLpsRange is derived as follows. Given the current value of ivlCurrRange, the variable qRangeIdx is derived as follows: qRangeIdx=ivlCurrRange>>5 (9). Given qRangeIdx, pStateIdx0, and pStateIdx1 associated with ctxTable and ctxIdx, valMps and ivlLpsRange are derived as follows: The variable ivlCurrRange is then set equal to ivlCurrRange - ivlLpsRange and at block 520 it is determined whether ivlOffset is greater than or equal to ivlCurrRange and the following is applied: 1. If ivlOffset is greater than or equal to ivlCurrRange, then at block 530, the variable binVal is set equal to 1-valMps, ivlOffset minus ivlCurrRange, and ivlCurrRange is set equal to ivlLpsRange. For example, binVal = !valMps; ivlOffset = ivlOffset - ivlCurrRange; and ivlCurrRange = ivlLpsRange. 2. Otherwise, if ivlOffset is less than ivlCurrRange, then at block 540, the variable binVal is set equal to valMps. At block 550 , the multi-hypothesis probability model is then independently updated using two different adaptation rates shift0 and shift1 derived based on the shiftIdx value in ctxTable and ctxIdx. shift0=(shiftIdx>>2)+2 shift1=(shiftIdx&3)+3+shift0 (11). Based on the decoded value binVal, the updated variables pStateIdx0 and pStateIdx1 associated with ctxTable and ctxIdx are obtained as follows: pStateIdx0=pStateIdx0-(pStateIdx0>>shift0)+(1023*binVal>>shift0) pStateIdx1=pStateIdx1-(pStateIdx1>>shift1)+(16383*binVal>>shift1) (12) At block 560, a normalization process such as RemormD is performed. At block 570, the procedure DecodeDecision(ctxTable, ctxIdx) is completed. 2.4. CABAC Improvements in Enhanced Compression Model (ECM) In ECM, adaptive weights are assigned to probability models based on multiple hypotheses. In particular, two separate probability models p 0 and p1 are maintained for each context and updated according to their own adaptation rates. Unlike VVC which uses a simple average to obtain the resulting context state, multiple weights are introduced as shown below: p=((3 2-ω)·p 0 +ω·p 1 )>>5 (13) where ω is a weight selected from a predefined set ω∈{0, 6, 11, 16, 21, 26, 32}. In ECM, context initialization based on temporal inheritance is applied to inter slices. The probabilities and weights of the context model of the inter slice (i.e., B- or P-slice type) containing the last CTU in the previously coded picture are stored. The stored state is used to initialize the context model in the next inter slice with the same slice type, QP value, and temporal layer ID. 2.5. Adaptive Parameter Set (APS) VVC introduces Adaptive Parameter Sets (APS) to convey picture- and / or slice-level information that can be shared by multiple slices of a picture and / or by slices of different pictures, but this may change frequently from picture to picture, and the total number of variants for it may be very high, so it is not suitable for inclusion in the PPS. Three types of parameters are included in the APS: Adaptive Loop Filter (ALF) parameters, Luma Mapping and Chroma Scaling (LMCS) parameters, and Quantization Scaling List parameters. Depending on the type of data it carries, the APS can be carried in two different Network Abstraction Layer (NAL) unit types, as a prefix or suffix before or after the associated slice. Using a suffix NAL unit can help with ALF parameters, because the typical way for encoder operation (especially in low-latency use cases) is to use statistics of the current picture to generate ALF parameters to apply to subsequent pictures in the decoding sequence. 3. Question In ECM, context initialization based on temporal inheritance is adopted to facilitate better CABAC context modeling, where the context state of a frame to be coded can be inherited from the context state of an already coded frame with the same slice type and / or QP value and / or temporal layer ID. To this end, context buffers are managed in both the encoder and decoder to store and update context model information that can be inherited for subsequent frames. However, this inheritance strategy raises a critical issue in terms of frame / slice dependency, because the frame to be coded can only be decoded when the frame of the reference context is decoded, but the frame of the reference context may not even be in the reference frame list of the frame to be coded. 4. Detailed solution In the present disclosure, it is proposed to optimize the context initialization based on time inheritance by signaling the information (or parameters) of the context model in SPS / APS / PPS / picture header / slice header / CTU line / CTU. Instead of managing the context buffer based on the coded / decoded frame / slice information, the inherited context model information and the corresponding frame / slice are separated by signaling the context model information in SPS / APS / PPS / picture header / slice header / CTU line / CTU, so that the decoding of the frame to be coded and decoded will not depend on the video codec layer (VCL) network abstraction layer (NAL) of the non-reference frame. The following detailed embodiments should be considered as examples for explaining the general concept. These embodiments should not be interpreted in a narrow sense. In addition, these embodiments can be combined in any way. The combination between this patent application and other patent applications is also applicable. In the present disclosure, the information of the context model may include at least one parameter or value, and the at least one parameter or value may be used to initialize at least one context model. 1. It is proposed that specific information of at least one context model can be signaled in the video unit, such as in SPS / APS / PPS / Picture header / slice header / CTU row / CTU center. a) In one example, when the last CTU in any B / P frame / slice is encoded, information of at least one context model may be encoded in the video unit. i. In one example, alternatively, when a central CTU or a CTU in an arbitrary position is encoded, information of at least one context model may be encoded in a video unit. b) In one example, the decoder may initialize the context of at least one model based on information of the context model signaled in the video unit. c) In one example, information of at least one context model may be signaled in the APS. i. In one example, this information may be signaled (or encoded) in the prefix APS or the suffix APS. d) In one example, a first syntax element (SE) may be signaled to indicate the type of information carried in the video unit (eg, APS). i. In one example, the first index may indicate whether specific information is carried in the video codec. ii. For example, specific information is signaled only when it is indicated that the specific information is carried. e) In one example, specific information may be signaled in the extended part of the APS. i. In one example, a SE indicating whether APS extension exists is signaled. Only when the SE indicates that APS extension data exists, specific information can be signaled in the APS extension data. f) In one example, specific information may be signaled in the first video unit (such as PPS / picture header / slice header / APS / etc.). i. In one example, an SE (referred to as A) indicating whether the information (or parameters) of the context model is signaled in the PPS is signaled, and if this SE indicates that the information is signaled in the PPS, the information will be signaled in the PPS. 1) In one example, whether SE A is signaled in the first video unit may depend on SE B in the second video unit, such as SPS / VPS / etc. a) In one example, SE B may indicate whether the codec tools that need to signal this information are enabled. b) In one example, SE B may indicate whether this information may be signaled in the first video unit. 2) In one example, whether SE A is signaled in the first video unit may depend on multiple SE B 1 …B n , the multiple SEs can be signaled in different video units. a) In one example, B 1 …B n The SE in may indicate whether the codec tools required to signal this information are enabled, or whether this information can be signaled in the first video unit. b) In one example, multiple SEs are combined to mutually determine whether the information can be signaled in the first video unit. g) In one example, whether to signal specific information of at least one context model may be controlled by one or more syntaxes. i. In one example, the syntax in the SPS / VPS / PPS / picture header / slice header may be used to indicate whether it needs to signal this specific information. ii. In one example, specific information may be signaled in PPS, picture header, slice header or any other high-level syntax module. 1) In one example, whether certain information is signaled in the PPS depends on the syntax of one or more SPS / VPS / PPS levels. 2) In one example, whether specific information is signaled in the picture header depends on the syntax of one or more SPS / VPS / PPS levels. 3) In one example, whether specific information is signaled in the slice header depends on the syntax of one or more SPS / VPS / PPS levels. 2. In one example, specific information of at least one context model to be signaled (or encoded) may include probability parameters, update speed (ie, window size), indicators of initialization probability values, and / or any other parameters related to the context model. 3. It is proposed to manage the context parameter buffer in the encoder and / or decoder. Let M (M>0) denote the number of context models considered, then: a) In one example, K (K>=0) groups of context information or parameters (here a set of information / parameters including all or part of the parameters associated with a specific context model) can be stored for N (N<=M) different contexts, where one or more groups of context model parameters are stored for certain context models. i. In one example, alternatively, for at least one context model, information / parameters of the context model are not stored. b) In one example, for different QPs or / and slice types or / and temporal layers, different sets of context parameters are stored in the buffer. i. In one example, when certain frames / slices complete the encoding process, all or part of the context model parameters are signaled. At the decoder, these context model parameters are decoded and used to update the context buffer, which is then used to initialize the context state for subsequent frames. 1) In one example, for certain QPs or / and slice types or / and temporal layers, only one set of context model parameters is stored. 2) In one example, alternatively, for certain QPs and / or slice types and / or temporal layers, multiple sets of context model parameters are stored. c) In one example, a context buffer is constructed to provide a reference context for predictive context coding. 4. In one example, specific information of at least one context model that can be used to initialize the context model can be signaled for all or part of the B / P frames. a) In one example, only information for part of the B / P frames is signaled. i. In one example, whether the information of the current slice / frame is signaled may depend on the QP value. ii. In one example, whether the information of the current slice / frame is signaled may depend on the slice type. iii. In one example, whether the information of the current slice / frame is signaled may depend on the temporal layer index. b) In one example, the information of the context model is signaled in a fixed or adaptively determined POC interval. 5. In one example, for a frame or slice that needs to signal specific information of at least one context model (the specific information of the at least one context model can be used to initialize the context), all or part of the context model information / parameters in this frame can be signaled. Let M (M>0) represent the number of different context models used in the encoding and decoding process, then: a) In one example, K (M>=K>=0) context states are signaled. i. In one example, M context models are ranked based on some metric and information / parameters of the top K contexts are signaled. 1) In one example, K may be a constant for all frames / slices, or may be different between different frames / slices. ii. In one example, alternatively, only information / parameters of certain contexts that satisfy certain conditions are signaled. 1) In one example, specifically, the number of contexts requiring signaling model parameters may be a constant, It can also be determined adaptively in each frame / slice. iii. In one example, only information / parameters of some predefined contexts are signaled. iv. In one example, for those contexts without signaling model parameters, the CABAC context initialization table is used to initialize the context state. b) In one example, context parameters for all context models are signaled. 6. It is proposed to use a predictive coding and decoding method to encode and decode specific information of at least one context model, which specific information can be used to initialize the context model. a) In one example, the encoding and decoding process of the context model that requires signaling model parameters may depend on the parameters of the reference model. b) In one example, for context models that require signaling model parameters, a reference context model is acquired, and the difference (or residual) between the parameters of the reference model and the parameters of the current model is signaled. i. In one example, the reference model can be derived based on the CABAC initialization table. ii. In one example, the reference model may be derived based on context information / parameters stored in a context buffer. 1) In one example, context model information / parameters for the same QP, slice type or temporal layer are used as reference context. 2) In one example, alternatively, any model information / parameters in the context buffer may be used as a reference. a) In one example, specifically, a context index and / or a QP index and / or a slice type index and / or a temporal layer index may be used to identify a reference context. c) The difference (or residual) of the context parameters can be decoded using truncated Rice (TR) codec, truncated binary (TB) codec The codec can be coded using the kth exponential Golomb (EGk) codec or the fixed length (FL) codec. d) The difference (or residual) of the context parameters can be encoded and decoded by CABAC. e) The difference (or residual) of the context parameters can be encoded after quantization, and the decoder needs to perform dequantization to derive a different signal. 7. In one example, the context model used in the first frame or slice may be initialized using initialization information of the context model, and the initialization information may be signaled in the second frame or slice. a) In one example, the second frame / slice must be or belong to a reference frame of the first frame / slice. b) In one example, it may be possible to indicate via signaling which reference frame the initialization information of the context model is associated with. i. For example, a reference list and / or a reference index may be signaled to indicate a reference frame. 5. Examples In one example, when all or part of the B / P frame / slice completes the encoding process, the context model parameters of the last CTU are encoded and signaled in the APS, and the syntax is signaled in the picture header / slice header / PPS / SPS to indicate whether the context parameters for the current frame / slice are signaled. And these context model parameters are also stored in a local buffer. In order to efficiently encode the context parameters, the reference context is first obtained from the context buffer, where the context model parameters for the same QP or slice type or time layer are used as the reference context model by default. Alternatively, any model parameter in the context buffer can be used as a reference. In the latter case, the reference index is signaled to identify the reference context. Afterwards, the difference (or residual) of the context parameters can be quantized first before being encoded using truncated Rice (TR) codec / truncated binary (TB) codec / kth order exponential Golomb (EGk) codec / fixed length (FL) codec. At the decoder side, when a frame / slice with the same QP / slice type / temporal layer index is encoded and decoded, the syntax at the picture header / slice header / PPS / SPS level is first parsed to indicate whether the context parameters are signaled in the APS. If so, the corresponding parameters are first decoded by identifying the APS that conveys the context parameters, and the decoded context parameters are then used to initialize the CABAC context. The difference (or residual) of the context parameters can be decoded using truncated Rice (TR) codec / truncated binary (TB) codec / kth order exponential Golomb (EGk) codec / fixed length (FL) codec and then dequantized. The recovery of the context model parameters is achieved by adding the decoded context parameter differences (or residuals) to the reference context parameters, which default to the context with the same QP / slice type / temporal layer index in the context buffer, or to any context model specified by the reference index. These decoded and recovered context model parameters are used to initialize the context in the current frame / slice. Once the context model parameters for the current frame / slice are decoded and recovered, they are then used to update the context buffer, which provides a reference context to facilitate more efficient context model parameter signaling. An example of a syntax that signals specific information of at least one context model in an APS is provided below in a tabular form. Specifically, aps_params_type indicates the APS type, which can be adaptive loop filter (ALF) parameters (ALF_APS), luma mapping and chroma scaling (LMCS) parameters (LMCS_APS) and quantization scaling list parameters (SCALING_APS) or CABAC context model parameters (CABAC_APS). If aps_params_type is parsed and indicates that context model parameters are signaled, CABAC_model_data() will be parsed, which contains specific information to be used for the context of the current or subsequent frame / slice.

[0062] Embodiments of the present disclosure relate to determining or initializing a context model. As used herein, the term "block" may refer to a codec tree block (CTB), a codec tree unit (CTU), a codec block (CB), a codec unit (CU), a prediction unit (PU), a transform unit (TU), a prediction block (PB), a transform block (TB), or a video processing unit including multiple samples or pixels. A block may be rectangular or non-rectangular.

[0063] Figure 6 A flow chart of a method 600 for video processing according to an embodiment of the present disclosure is shown. The method 600 is implemented for conversion between a current video block of a video and a bitstream of the video.

[0064] At block 610, at least one context model is determined based on initial information of at least one context model associated with the current video block. The initial information of the at least one context model is included in the bitstream. As used herein, the term "initial information of at least one context model" may also be referred to as "specific information of at least one context model". In an example, at least one context model is initiated based on the initial information. For example, the initial information of the context model may include at least one parameter or value, which may be used to initialize at least one context model.

[0065] At block 620, conversion is performed based on at least one context model. In some embodiments, conversion between the current video block and the bitstream may include encoding the current video block into the bitstream. Alternatively or additionally, conversion may include decoding the current video block from the bitstream.

[0066] The method 600 enables initiation of at least one context model based on initial information in a bitstream. In this way, the coding effect and coding efficiency can be advantageously improved.

[0067] In some embodiments, the initial information of at least one context model includes at least one of the following: a probability parameter, an update speed of the probability parameter, an indicator of an initialization value of the probability parameter, or another parameter associated with the at least one context model. For example, the update speed may be a window size.

[0068] In some embodiments, initial information of at least one context model is included in a first video unit in a bitstream. As an example, the first video unit includes at least one of the following: a sequence parameter set (SPS), an adaptation parameter set (APS), a picture parameter set (PPS), a picture header, a slice header, a codec tree unit (CTU), or a CTU row. For example, initial information of at least one context model can be signaled in a video unit (such as in an SPS / APS / PPS / picture header / slice header / CTU row / CTU).

[0069] In some embodiments, the first video unit includes at least one of: a prefix adaptation parameter set (APS), or a suffix APS. In one example, the information may be signaled (or encoded) in the prefix APS or the suffix APS.

[0070] In some embodiments, a first syntax element is included in the bitstream, the first syntax element indicating the type of information included in the video unit. In one example, a first syntax element (SE) may be signaled to indicate the type of information carried in the video unit (e.g., APS).

[0071] In one example, the syntax element aps_params_type indicates the APS type, which may be adaptive loop filter (ALF) parameters (ALF_APS), luma mapping and chroma scaling (LMCS) parameters (LMCS_APS), and quantization scaling list parameters (SCALING_APS), or CABAC context model parameters (CABAC_APS). If aps_params_type is parsed and indicates that context model parameters are signaled, CABAC_model_data() will be parsed, which contains specific information to be used for the context of the current or subsequent frame / slice.

[0072] In some embodiments, the first syntax element further indicates whether initial information of at least one context model is included in the first video unit. For example, the first syntax element may indicate whether specific information is carried in the video codec.

[0073] In some embodiments, if the first syntax element indicates initial information of at least one context model, the initial information is included in the first video unit.

[0074] In some embodiments, at least one second syntax element indicating whether the first syntax element is included in the first video unit is included in at least one second video unit in the bitstream.

[0075] In some embodiments, the at least one second syntax element comprises a single second syntax element in a single second video unit.

[0076] In some embodiments, the first video unit comprises a picture parameter set (PPS), and the single second video unit comprises one of: a sequence parameter set (SPS), or a video parameter set (VPS).

[0077] In some embodiments, the single second syntax element indicates whether a codec tool is enabled, and initial information of at least one context model is included in the first video unit by the codec tool.

[0078] In some embodiments, the single second syntax element indicates whether initial information for at least one context model is included in the first video unit.

[0079] In some embodiments, the at least one at least one second syntax element comprises a plurality of second syntax elements in a plurality of second video units, the plurality of second video units being different video units.

[0080] In some embodiments, one second syntax element among the plurality of second syntax elements indicates whether a codec tool is enabled, initial information of at least one context model is included in the first video unit by the codec tool, and another second syntax element among the plurality of second syntax elements indicates whether initial information of at least one context model is included in the first video unit.

[0081] In some embodiments, a combination of a plurality of second syntax elements indicates whether initial information of at least one context model is included in the first video unit. That is, a plurality of SEs are combined to mutually determine whether the information can be signaled in the first video unit.

[0082] In some embodiments, the first video unit comprises an extended portion of an adaptation parameter set (APS).

[0083] In some embodiments, a first syntax element indicating whether an extended part of the APS exists is included in the bitstream. In some embodiments, if the first syntax element indicates that the extended part exists, initial information of at least one context model is included in the extended part.

[0084] In some embodiments, if a codec tree unit (CTU) in a frame or a slice is coded, initial information of at least one context model is included in the bitstream, the frame includes a B frame or a P frame, and the slice includes a B slice or a B frame.

[0085] In some embodiments, the CTU includes at least one of the following: the last CTU in a frame or a slice, the central CTU in a frame or a slice, or a CTU in a predefined position in a frame or a slice. For example, when the last CTU in any B / P frame / slice is encoded, information of at least one context model can be encoded in the first video unit. For another example, when the central CTU or a CTU in an arbitrary position is encoded, information of at least one context model can be encoded in the first video unit.

[0086] In some embodiments, determining at least one context model comprises: initiating at least one context of the at least one context model based on initial information. For example, the decoder may initialize the context of the at least one model based on information of the context model signaled in the first video unit.

[0087] In some embodiments, the method 600 further comprises: determining whether to include initial information of at least one context model in the bitstream based on at least one syntax element in the bitstream.

[0088] In some embodiments, the at least one syntax element is in at least one video unit, the at least one video unit comprising at least one of: a sequence parameter set (SPS), a video parameter set (VPS), a picture parameter set (PPS), a picture header, or a slice header.

[0089] In some embodiments, at least one syntax element indicates whether at least one video unit includes initial information for at least one context model.

[0090] In some embodiments, initial information of at least one context model is included in a high-level syntax module, the high-level syntax module comprising at least one of the following: a picture parameter set (PPS), a picture header, or a slice header.

[0091] In some embodiments, at least one syntax element in at least one of a sequence parameter set (SPS), a video parameter set (VPS), or a picture parameter set (PPS) indicates whether initial information of at least one context model is included in a high-level syntax module.

[0092] In some embodiments, method 600 further includes storing context information of at least one context model in a context parameter buffer.

[0093] In some embodiments, the context parameter buffer is in at least one of: an encoder associated with a coding conversion from a current video block to a bitstream, or a decoder associated with a decoding conversion from a bitstream to the current video block. That is, the context parameter buffer can be managed in the encoder or the decoder.

[0094] In some embodiments, the context information includes multiple sets of context parameters associated with at least one context model, and a set of context parameters includes multiple contexts associated with one context model in the at least one context model. In some embodiments, the number of at least one context model is less than or equal to the number of multiple sets of context parameters. In other words, K (K>=0) sets of context information or parameters (here a set of information / parameters including all or part of the parameters associated with a specific context model) can be stored for N (N<=M) different contexts, where one or more sets of context model parameters are stored for certain context models.

[0095] In some embodiments, the plurality of sets of context parameters include a first set of context parameters associated with a first quantization parameter (QP) and a second set of context parameters associated with a second QP. For example, different sets of context parameters are stored in a buffer for different QPs and / or slice types and / or temporal layers.

[0096] In some embodiments, the multiple sets of context parameters include a third set of context parameters associated with the first slice type and a fourth set of context parameters associated with the second slice type.

[0097] In some embodiments, the multiple sets of context parameters include a fifth set of context parameters associated with the first temporal layer and a sixth set of context parameters associated with the second temporal layer.

[0098] In some embodiments, a single set of context parameters in the plurality of sets of context parameters is associated with at least one of: a first quantization parameter (QP), a first slice type, or a first temporal layer.

[0099] In some embodiments, more than one set of context parameters in the plurality of sets of context parameters are associated with at least one of: a first quantization parameter (QP), a first slice type, or a first temporal layer.

[0100] In some embodiments, if the encoding and decoding process of the current frame or the current slice is completed, context information of at least part of context parameters of at least one context model is included in the bitstream.

[0101] In some embodiments, the method 600 further comprises: encoding and decoding context information of at least part of the context parameters; and updating the context parameter buffer based on the context information.

[0102] In some embodiments, the context information is used to initialize the context state of subsequent frames after the current frame. For example, when certain frames / strips complete the encoding process, all or part of the context model parameters are signaled. At the decoder, these context model parameters are decoded and used to update the context buffer, which is then used to initialize the context state for subsequent frames.

[0103] In some embodiments, context information of one context model in at least one context model is not stored in the context parameter buffer. For example, for at least one context model, information / parameters of the context model are not stored.

[0104] In some embodiments, the context parameter buffer includes a reference context for predictive context coding and decoding. For example, the context buffer is constructed to provide a reference context for predictive context coding and decoding.

[0105] In some embodiments, initial information of at least one context model is included for at least part of the B frame or at least part of the P frame. For example, specific information of at least one context model that can be used to initialize the context model can be signaled for all or part of the B / P frame.

[0106] In some embodiments, whether initial information of at least one context model associated with a current slice or a current frame is included in the bitstream is based on at least one of: a quantization parameter (QP) value, a slice type, or a temporal layer index.

[0107] In some embodiments, initial information of at least one context model is included in the bitstream based on a picture order count (POC) interval.

[0108] In some embodiments, the POC interval is predefined or determined during a switch. That is, the context model is signaled in a fixed or adaptively determined POC interval.

[0109] In some embodiments, if initial information of at least one context model associated with a frame or a slice is included in the bitstream, at least part of the context information in the frame or the slice is included in the bitstream.

[0110] In some embodiments, the at least one context model includes a first number of context models, a second number of context states are included in the bitstream, the second number being less than or equal to the first number.

[0111] In some embodiments, method 600 further includes: sorting the first number of context models based on a metric; determining a second number of context models from the first number of context models based on the sorting; and including in the bitstream a second number of context states associated with the second number of context models. For example, the M context models are sorted based on some metric, and information / parameters of the first K contexts are signaled.

[0112] In some embodiments, the second number is the same or different for multiple frames or multiple slices. For example, K may be a constant for all frames / slices, or may be different between different frames / slices.

[0113] In some embodiments, if the context state of one of the at least one context model satisfies a condition, the context state is included in the bitstream. For example, only information / parameters of certain contexts that satisfy certain conditions are signaled.

[0114] In some embodiments, the second number is a predefined value, or is determined for a frame or a slice. For example, the number of contexts requiring signaling model parameters may be a constant, or may be adaptively determined in each frame / slice.

[0115] In some embodiments, the second number of context states includes a plurality of predefined contexts. For example, only information / parameters of some predefined contexts are signaled.

[0116] In some embodiments, if context information associated with the first context model is not included in the bitstream, the context state of the first context model is initialized according to a context-based adaptive binary arithmetic coding (CABAC) context initialization table. For example, for contexts without signaling model parameters, the CABAC context initialization table is used to initialize the context state.

[0117] In some embodiments, context information associated with at least one context model is included in the bitstream.

[0118] In some embodiments, method 600 further includes: determining initial information of at least one context model by using predictive coding.

[0119] In some embodiments, the encoding and decoding process associated with the current video block is based on parameters of a reference model, and context information of at least one context model is included in the bitstream during the encoding and decoding process. For example, an encoding and decoding process of a context model that requires signaling model parameters may depend on parameters of the reference model.

[0120] In some embodiments, a difference between a first value of a context parameter of a reference model and a second value of a context parameter of a current context model of at least one context model is included in the bitstream. As used herein, the term "difference" may also be referred to as a "residual." For example, for a context model that requires signaling model parameters, a reference context model is obtained, and the difference (or residual) between the parameters of the reference model and the parameters of the current model is signaled.

[0121] In some embodiments, the method 600 further includes: determining a reference model according to a context-based adaptive binary arithmetic coding and decoding (CABAC) context initialization table.

[0122] In some embodiments, the difference is encoded by at least one of: a truncated Rice (TR) codec, a truncated binary (TB) codec, a kth exponential Golomb (EGk) codec, or a fixed length (FL) codec.

[0123] In some embodiments, the difference is encoded by context-based adaptive binary arithmetic coding (CABAC).For example, the reference model may be derived based on a CABAC initialization table.

[0124] In some embodiments, the method 600 further includes updating the difference by applying a quantization or dequantization process to the difference.

[0125] In some embodiments, method 600 further includes: determining a reference model based on context information stored in a context parameter buffer.

[0126] In some embodiments, the method 600 further comprises: determining a reference model from a context parameter buffer based on at least one of a context index, a quantization parameter (QP) index, a slice type index, and a temporal layer index.

[0127] In some embodiments, the reference model includes reference context information associated with at least one of: a quantization parameter (QP) of at least one context model, a slice type of at least one context model, and a temporal layer of at least one context model.

[0128] In some embodiments, initial information of at least one context model is included in a first frame or a first slice, and at least one context model is used in a second frame or a second slice. In some embodiments, the first frame or the first slice is a reference frame for the second frame or the second slice.

[0129] In some embodiments, an association between a reference frame and information of at least one context model is included in the bitstream. For example, it may be signaled to indicate which reference frame the initialization information of the context model is associated with.

[0130] In some embodiments, at least one of a reference list or a reference index associated with a reference frame is included in the bitstream.For example, the reference list and / or the reference index may be signaled to indicate the reference frame.

[0131] According to another embodiment of the present disclosure, a non-transitory computer-readable recording medium is provided. The non-transitory computer-readable recording medium stores a bitstream of a video, which is generated by a method performed by a device for video processing. In the method, at least one context model associated with a current video block of the video is determined based on initial information of at least one context model. The initial information of at least one context model is included in the bitstream. The bitstream is generated based on at least one context model.

[0132] According to some other embodiments of the present disclosure, a method for storing a bitstream of a video is provided. In the method, based on initial information of at least one context model associated with a current video block of the video, at least one context model is determined. Initial information of at least one context model is included in the bitstream. Based on at least one context model, a bitstream is generated. The bitstream is stored in a non-transitory computer-readable recording medium.

[0133] Implementations of the present disclosure may be described with reference to the following clauses, features of which may be combined in any reasonable manner.

[0134] Clause 1. A method for video processing, comprising: for conversion between a current video block of a video and a bitstream of the video, determining at least one context model based on initial information of at least one context model associated with the current video block, the initial information of the at least one context model being included in the bitstream; and performing the conversion based on the at least one context model.

[0135] Clause 2. A method according to clause 1, wherein the initial information of the at least one context model comprises at least one of the following: a probability parameter, an update speed of the probability parameter, an indicator of the initialization value of the probability parameter, or another parameter associated with the at least one context model.

[0136] Clause 3. A method according to clause 1 or clause 2, wherein the initial information of the at least one context model is included in a first video unit in the bitstream.

[0137] Clause 4. A method according to clause 3, wherein the first video unit comprises at least one of the following: a sequence parameter set (SPS), an adaptation parameter set (APS), a picture parameter set (PPS), a picture header, a slice header, a codec tree unit (CTU) or a CTU row.

[0138] Clause 5. The method of clause 3 or clause 4, wherein the first video unit comprises at least one of: a prefix adaptation parameter set (APS), or a suffix APS.

[0139] Clause 6. The method of any of clauses 3 to 5, wherein a first syntax element is included in the bitstream, the first syntax element indicating a type of information included in the video unit.

[0140] Clause 7. The method of clause 6, wherein the first syntax element further indicates whether the initial information for the at least one context model is included in the first video unit.

[0141] Clause 8. A method according to clause 6 or clause 7, wherein if the first syntax element indicates the initial information of the at least one context model, the initial information is included in the first video unit.

[0142] Clause 9. The method of any of clauses 6 to 8, wherein at least one second syntax element indicating whether the first syntax element is included in the first video unit is included in at least one second video unit in the bitstream.

[0143] Clause 10. The method of Clause 9, wherein the at least one second syntax element comprises a single second syntax element in a single second video unit.

[0144] Clause 11. The method of clause 10, wherein the first video unit comprises a picture parameter set (PPS), and the single second video unit comprises one of: a sequence parameter set (SPS), or a video parameter set (VPS).

[0145] Clause 12. A method according to clause 10 or clause 11, wherein the single second syntax element indicates whether a codec tool is enabled, and the initial information of the at least one context model is included in the first video unit by the codec tool.

[0146] Clause 13. A method according to clause 10 or clause 11, wherein the single second syntax element indicates whether the initial information of the at least one context model is included in the first video unit.

[0147] Clause 14. The method of Clause 9, wherein the at least one second syntax element comprises a plurality of second syntax elements in a plurality of second video units, the plurality of second video units being different video units.

[0148] Clause 15. A method according to clause 14, wherein one second syntax element among the multiple second syntax elements indicates whether the codec tool is enabled, the initial information of the at least one context model is included in the first video unit by the codec tool, and another second syntax element among the multiple second syntax elements indicates whether the initial information of the at least one context model is included in the first video unit.

[0149] Clause 16. The method of clause 14, wherein a combination of the plurality of second syntax elements indicates whether the initial information for the at least one context model is included in the first video unit.

[0150] Clause 17. The method of any one of clauses 3 to 16, wherein the first video unit comprises an extended portion of an adaptation parameter set (APS).

[0151] Clause 18. The method of clause 17, wherein a first syntax element indicating whether the extended portion of the APS is present is included in the bitstream.

[0152] Clause 19. The method according to clause 18, wherein if the first syntax element indicates that the extension part exists, the initial information of the at least one context model is included in the extension part.

[0153] Clause 20. A method according to any one of clauses 1 to 19, wherein the initial information of the at least one context model is included in the bitstream if a codec tree unit (CTU) in a frame or a slice is encoded and decoded, the frame includes a B frame or a P frame, and the slice includes a B slice or a B frame.

[0154] Clause 21. The method of clause 20, wherein the CTU comprises at least one of: the last CTU in the frame or the slice, the center CTU in the frame or the slice, or a CTU in a predefined position in the frame or the slice.

[0155] Clause 22. The method of any one of clauses 1 to 21, wherein determining the at least one context model comprises initiating at least one context of the at least one context model based on the initial information.

[0156] Clause 23. The method according to any one of clauses 1 to 22 further comprises: determining whether to include the initial information of the at least one context model in the bitstream based on at least one syntax element in the bitstream.

[0157] Clause 24. A method according to clause 23, wherein the at least one syntax element is in at least one video unit, and the at least one video unit includes at least one of the following: a sequence parameter set (SPS), a video parameter set (VPS), a picture parameter set (PPS), a picture header or a slice header.

[0158] Clause 25. The method of clause 24, wherein the at least one syntax element indicates whether the at least one video unit includes the initial information for the at least one context model.

[0159] Clause 26. A method according to clause 23, wherein the initial information of the at least one context model is included in a high-level syntax module, the high-level syntax module comprising at least one of the following: a picture parameter set (PPS), a picture header or a slice header.

[0160] Clause 27. A method according to clause 26, wherein the at least one syntax element in at least one of a sequence parameter set (SPS), a video parameter set (VPS) or a picture parameter set (PPS) indicates whether the initial information of the at least one context model is included in the high-level syntax module.

[0161] Clause 28. The method according to any one of clauses 1 to 27, further comprising: storing context information of the at least one context model in a context parameter buffer.

[0162] Clause 29. A method according to clause 28, wherein the context parameters are buffered in at least one of: an encoder associated with an encoding conversion from the current video block to the bitstream, or a decoder associated with a decoding conversion from the bitstream to the current video block.

[0163] Clause 30. A method according to clause 28 or clause 29, wherein the context information includes multiple sets of context parameters associated with the at least one context model, a set of context parameters including multiple contexts associated with one context model of the at least one context model.

[0164] Clause 31. The method of clause 30, wherein the number of the at least one context model is less than or equal to the number of the plurality of sets of context parameters.

[0165] Clause 32. The method of clause 30 or clause 31, wherein the multiple sets of context parameters include a first set of context parameters associated with a first quantization parameter (QP) and a second set of context parameters associated with a second QP.

[0166] Clause 33. The method of any of clauses 30 to 32, wherein the plurality of sets of context parameters comprises a third set of context parameters associated with a first slice type and a fourth set of context parameters associated with a second slice type.

[0167] Clause 34. The method of any of clauses 30 to 33, wherein the plurality of sets of context parameters comprises a fifth set of context parameters associated with a first temporal layer and a sixth set of context parameters associated with a second temporal layer.

[0168] Clause 35. A method according to any of clauses 30 to 34, wherein a single set of context parameters in the plurality of sets of context parameters is associated with at least one of: a first quantization parameter (QP), a first slice type, or a first temporal layer.

[0169] Clause 36. A method according to any of clauses 30 to 34, wherein more than one of the plurality of sets of context parameters are associated with at least one of: a first quantization parameter (QP), a first slice type, or a first temporal layer.

[0170] Clause 37. A method according to any one of clauses 28 to 36, wherein if the encoding and decoding process of the current frame or the current slice is completed, the context information of at least part of the context parameters of the at least one context model is included in the bitstream.

[0171] Clause 38. The method according to clause 37 further includes: encoding and decoding the context information of the at least part of the context parameters; and updating the context parameter buffer based on the context information.

[0172] Clause 39. A method according to clause 37 or clause 38, wherein the context information is used to initialize the context state of subsequent frames after the current frame.

[0173] Clause 40. The method of Clause 28, wherein context information for one of the at least one context model is not stored in the context parameter buffer.

[0174] Clause 41. A method according to any of clauses 28 to 40, wherein the context parameter buffer comprises a reference context for predictive context coding.

[0175] Clause 42. A method according to any one of clauses 1 to 40, wherein the initial information of the at least one context model is included for at least part of a B frame or at least part of a P frame.

[0176] Clause 43. A method according to clause 42, wherein whether the initial information of the at least one context model associated with the current slice or the current frame is included in the bitstream is based on at least one of the following: a quantization parameter (QP) value, a slice type, or a temporal layer index.

[0177] Clause 44. A method according to any one of clauses 1 to 43, wherein the initial information of the at least one context model is included in the bitstream based on a picture order count (POC) interval.

[0178] Clause 45. The method of clause 44, wherein the POC interval is predefined or determined during the conversion.

[0179] Clause 46. A method according to any one of clauses 1 to 45, wherein if the initial information of the at least one context model associated with a frame or a slice is included in the bitstream, then at least part of the context information in the frame or the slice is included in the bitstream.

[0180] Clause 47. The method of clause 46, wherein the at least one context model comprises a first number of context models, a second number of context states are included in the bitstream, the second number being less than or equal to the first number.

[0181] Clause 48. The method according to Clause 47 further includes: sorting the first number of context models based on a metric; determining the second number of context models from the first number of context models based on the sorting; and including the second number of context states associated with the second number of context models in the bitstream.

[0182] Clause 49. The method of clause 47 or clause 48, wherein the second number is the same or different for multiple frames or multiple slices.

[0183] Clause 50. The method of any one of clauses 47 to 49, wherein if a context state of one of the at least one context model satisfies a condition, the context state is included in the bitstream.

[0184] Clause 51. The method of any one of clauses 47 to 50, wherein the second number is a predefined value, or is determined for a frame or a slice.

[0185] Clause 52. The method of any one of clauses 47 to 51, wherein the second number of context states comprises a plurality of predefined contexts.

[0186] Clause 53. A method according to any one of clauses 1 to 52, wherein if context information associated with a first context model is not included in the bitstream, the context state of the first context model is initialized according to a context-based adaptive binary arithmetic coding and decoding (CABAC) context initialization table.

[0187] Clause 54. A method according to any one of clauses 1 to 53, wherein context information associated with the at least one context model is included in the bitstream.

[0188] Clause 55. The method according to any one of clauses 1 to 54, further comprising: determining the initial information of the at least one context model by using predictive coding.

[0189] Clause 56. A method according to any one of clauses 1 to 55, wherein a coding process associated with the current video block is based on parameters of a reference model, and context information of the at least one context model is included in the bitstream during the coding process.

[0190] Clause 57. A method according to any one of clauses 1 to 56, wherein a difference between a first value of a context parameter of a reference model and a second value of the context parameter of a current context model of the at least one context model is included in the bitstream.

[0191] Clause 58. The method according to clause 56 or clause 57 further includes: determining the reference model based on a context-based adaptive binary arithmetic coding and decoding (CABAC) context initialization table.

[0192] Clause 59. A method according to clause 57, wherein the difference is encoded by at least one of the following: a truncated Rice (TR) codec, a truncated binary (TB) codec, a kth exponential Golomb (EGk) codec, or a fixed length (FL) codec.

[0193] Clause 60. The method of clause 57, wherein the difference is encoded by context-based adaptive binary arithmetic coding and decoding (CABAC).

[0194] Clause 61. The method of any one of clauses 57 to 60, further comprising: updating the difference by applying a quantization or dequantization process to the difference.

[0195] Clause 62. The method according to any one of clauses 56 to 61, further comprising: determining the reference model based on context information stored in a context parameter buffer.

[0196] Clause 63. The method according to Clause 62 further includes: determining the reference model from the context parameter buffer based on at least one of a context index, a quantization parameter (QP) index, a slice type index, and a temporal layer index.

[0197] Clause 64. A method according to any one of clauses 56 to 63, wherein the reference model includes reference context information, and the reference context information is associated with at least one of the following: a quantization parameter (QP) of the at least one context model, a slice type of the at least one context model, and a temporal layer of the at least one context model.

[0198] Clause 65. A method according to any one of clauses 1 to 64, wherein the initial information of the at least one context model is included in a first frame or a first slice, and the at least one context model is used in a second frame or a second slice.

[0199] Clause 66. The method of clause 65, wherein the first frame or the first slice is a reference frame for the second frame or the second slice.

[0200] Clause 67. The method of clause 66, wherein an association between the reference frame and the information of the at least one context model is included in the bitstream.

[0201] Clause 68. The method of clause 65 or clause 66, wherein at least one of a reference list or a reference index associated with the reference frame is included in the bitstream.

[0202] Clause 69. The method of any one of clauses 1 to 68, wherein the converting comprises encoding the current video block into the bitstream.

[0203] Clause 70. The method of any one of clauses 1 to 68, wherein the converting comprises decoding the current video block from the bitstream.

[0204] Clause 71. An apparatus for video processing, comprising a processor and a non-transitory memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform the method of any one of clauses 1 to 70.

[0205] Clause 72. A non-transitory computer-readable storage medium storing instructions that cause a processor to perform the method of any one of clauses 1 to 70.

[0206] Clause 73. A non-transitory computer-readable recording medium storing a bitstream of a video, the bitstream of the video being generated by a method performed by a device for video processing, wherein the method comprises: determining at least one context model based on initial information of at least one context model associated with a current video block of the video, the initial information of the at least one context model being included in the bitstream; and generating the bitstream based on the at least one context model.

[0207] Clause 74. A method for storing a bitstream of a video, comprising: determining at least one context model based on initial information of at least one context model associated with a current video block of the video, the initial information of the at least one context model being included in the bitstream; generating the bitstream based on the at least one context model; and storing the bitstream in a non-transitory computer-readable recording medium. Example Device

[0208] Figure 7 A block diagram of a computing device 700 in which various embodiments of the present disclosure may be implemented is shown. The computing device 700 may be implemented as a source device 110 (or video encoder 114 or 200) or a destination device 120 (or video decoder 124 or 300), or may be included in a source device 110 (or video encoder 114 or 200) or a destination device 120 (or video decoder 124 or 300).

[0209] It should be understood that Figure 7 The computing device 700 shown in the figure is for illustration purposes only and is not intended to in any way imply any limitation on the functionality and scope of the embodiments of the present disclosure.

[0210] like Figure 7 As shown, computing device 700 includes a general computing device 700. Computing device 700 may include at least one or more processors or processing units 710, memory 720, storage unit 730, one or more communication units 740, one or more input devices 750, and one or more output devices 760.

[0211] In some embodiments, the computing device 700 can be implemented as any user terminal or server terminal with computing power. The server terminal can be a server provided by a service provider, a large computing device, etc. The user terminal can be, for example, any type of mobile terminal, fixed terminal or portable terminal, including a mobile phone, a station, a unit, a device, a multimedia computer, a multimedia tablet computer, an Internet node, a communicator, a desktop computer, a laptop computer, a notebook computer, a netbook computer, a personal communication system (PCS) device, a personal navigation device, a personal digital assistant (PDA), an audio / video player, a digital camera / camcorder, a positioning device, a television receiver, a radio broadcast receiver, an electronic book device, a gaming device, or any combination thereof, and includes the accessories and peripherals of these devices, or any combination thereof. It is conceivable that the computing device 700 can support any type of interface to the user (such as a "wearable" circuit device, etc.).

[0212] The processing unit 710 may be a physical processor or a virtual processor and may implement various processes based on a program stored in the memory 720. In a multi-processor system, multiple processing units execute computer executable instructions in parallel to improve the parallel processing capability of the computing device 700. The processing unit 710 may also be referred to as a central processing unit (CPU), a microprocessor, a controller, or a microcontroller.

[0213] The computing device 700 typically includes various computer storage media. Such media can be any media accessible by the computing device 700, including but not limited to volatile media and non-volatile media, or removable media and non-removable media. The memory 720 can be a volatile memory (e.g., a register, a cache, a random access memory (RAM)), a non-volatile memory (such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM) or flash memory) or any combination thereof. The storage unit 730 can be any removable or non-removable medium, and can include machine-readable media, such as a memory, a flash drive, a disk, or other media that can be used to store information and / or data and can be accessed in the computing device 700.

[0214] The computing device 700 may also include additional removable / non-removable storage media, volatile / non-volatile storage media. Figure 7 Although not shown in the figure, a magnetic disk drive for reading from and / or writing to a removable nonvolatile magnetic disk and an optical disk drive for reading from and / or writing to a removable nonvolatile optical disk may be provided. In this case, each drive may be connected to the bus (not shown) via one or more data medium interfaces.

[0215] The communication unit 740 communicates with another computing device via a communication medium. In addition, the functions of the components in the computing device 700 can be implemented by a single computing cluster or multiple computing machines that can communicate via a communication connection. Therefore, the computing device 700 can operate in a networked environment using logical connections to one or more other servers, networked personal computers (PCs), or other general network nodes.

[0216] The input device 750 may be one or more of various input devices, such as a mouse, keyboard, trackball, voice input device, etc. The output device 760 may be one or more of various output devices, such as a display, a speaker, a printer, etc. With the aid of the communication unit 740, the computing device 700 may also communicate with one or more external devices (not shown), such as storage devices and display devices, and the computing device 700 may also communicate with one or more devices that enable a user to interact with the computing device 700, or any device that enables the computing device 700 to communicate with one or more other computing devices (e.g., a network card, a modem, etc.), if necessary. Such communication may be performed via an input / output (I / O) interface (not shown).

[0217] In some embodiments, some or all components of the computing device 700 may also be arranged in a cloud computing architecture rather than being integrated in a single device. In a cloud computing architecture, components may be provided remotely and work together to implement the functions described in the present disclosure. In some embodiments, cloud computing provides computing, software, data access and storage services, which will not require the end user to know the physical location or configuration of the system or hardware that provides these services. In various embodiments, cloud computing provides services via a wide area network (e.g., the Internet) using a suitable protocol. For example, a cloud computing provider provides applications via a wide area network, which can be accessed through a web browser or any other computing component. The software or components of the cloud computing architecture and the corresponding data may be stored on a remote server. The computing resources in a cloud computing environment may be merged or distributed at the location of a remote data center. Cloud computing infrastructures may provide services through a shared data center, although they appear as a single access point for users. Therefore, cloud computing architectures may be used to provide components and functions described herein from a service provider at a remote location. Alternatively, they may be provided by a conventional server, or installed directly or otherwise on a client device.

[0218] In an embodiment of the present disclosure, the computing device 700 may be used to implement video encoding / decoding. The memory 720 may include one or more video encoding / decoding modules 725 having one or more program instructions. These modules can be accessed and executed by the processing unit 710 to perform the functions of the various embodiments described herein.

[0219] In an example embodiment of performing video encoding, the input device 750 may receive video data as input 770 to be encoded. The video data may be processed by, for example, the video codec module 725 to generate an encoded bitstream. The encoded bitstream may be provided as output 780 via the output device 760.

[0220] In an example embodiment of performing video decoding, the input device 750 may receive an encoded bitstream as input 770. The encoded bitstream may be processed by, for example, the video codec module 725 to generate decoded video data. The decoded video data may be provided as output 780 via the output device 760.

[0221] Although the present disclosure has been specifically shown and described with reference to the preferred embodiments of the present disclosure, it will be understood by those skilled in the art that various changes can be made in form and detail without departing from the spirit and scope of the present application as defined by the appended claims. These changes are intended to be encompassed by the scope of the present application. Therefore, the foregoing description of the embodiments of the present application is not intended to be limiting.

Claims

1. A method for video processing, comprising: For conversion between a current video block of a video and a bitstream of the video, determine at least one context model based on initial information of at least one context model associated with the current video block, the initial information of the at least one context model being included in the bitstream; as well as The converting is performed based on the at least one context model.

2. The method according to claim 1, wherein the initial information of the at least one context model comprises at least one of the following: Probability parameter, The update speed of the probability parameters, an indicator of an initialization value for the probability parameter, or Another parameter associated with the at least one context model.

3. The method according to claim 1 or claim 2, wherein the initial information of the at least one context model is included in a first video unit in the bitstream.

4. The method according to claim 3, wherein the first video unit comprises at least one of the following: a sequence parameter set (SPS), an adaptation parameter set (APS), a picture parameter set (PPS), a picture header, a slice header, a codec tree unit (CTU) or a CTU row.

5. The method according to claim 3 or claim 4, wherein the first video unit comprises at least one of the following: Prefix Adaptation Parameter Set (APS), or suffix APS.

6. The method of any one of claims 3 to 5, wherein a first syntax element is included in the bitstream, the first syntax element indicating a type of information included in the video unit. 7 . The method according to claim 6 , wherein the first syntax element further indicates whether the initial information of the at least one context model is included in the first video unit.

8. The method according to claim 6 or claim 7, wherein if the first syntax element indicates the initial information of the at least one context model, the initial information is included in the first video unit.

9. The method of any one of claims 6 to 8, wherein at least one second syntax element indicating whether the first syntax element is included in the first video unit is included in at least one second video unit in the bitstream.

10. The method of claim 9, wherein the at least one second syntax element comprises a single second syntax element in a single second video unit.

11. The method of claim 10, wherein the first video unit comprises a picture parameter set (PPS), and the single second video unit comprises one of: a sequence parameter set (SPS), or a video parameter set (VPS).

12. The method according to claim 10 or claim 11, wherein the single second syntax element indicates whether a codec tool is enabled, and the initial information of the at least one context model is included in the first video unit by the codec tool.

13. The method according to claim 10 or claim 11, wherein the single second syntax element indicates whether the initial information of the at least one context model is included in the first video unit.

14. The method of claim 9, wherein the at least one second syntax element comprises a plurality of second syntax elements in a plurality of second video units, the plurality of second video units being different video units.

15. The method of claim 14, wherein one of the plurality of second syntax elements indicates whether the codec tool is enabled, the initial information of the at least one context model is included in the first video unit by the codec tool, and another second syntax element of the plurality of second syntax elements indicates whether the initial information of the at least one context model is included in the first video unit. 16 . The method according to claim 14 , wherein a combination of the plurality of second syntax elements indicates whether the initial information of the at least one context model is included in the first video unit.

17. The method of any one of claims 3 to 16, wherein the first video unit comprises an extended portion of an Adaptation Parameter Set (APS).

18. The method of claim 17, wherein a first syntax element indicating whether the extended part of the APS exists is included in the bitstream.

19. The method according to claim 18, wherein if the first syntax element indicates that the extended part exists, the initial information of the at least one context model is included in the extended part.

20. The method according to any one of claims 1 to 19, wherein the initial information of the at least one context model is included in the bitstream if a codec tree unit (CTU) in a frame or a slice is encoded and decoded, the frame includes a B frame or a P frame, and the slice includes a B slice or a B frame.

21. The method of claim 20, wherein the CTU comprises at least one of the following: The last CTU in the frame or slice, the central CTU in the frame or the slice, or A CTU in a predefined position in the frame or the slice.

22. The method according to any one of claims 1 to 21, wherein determining the at least one context model comprises: At least one context of the at least one context model is initiated based on the initial information.

23. The method according to any one of claims 1 to 22, further comprising: Based on at least one syntax element in the bitstream, it is determined whether to include the initial information of the at least one context model in the bitstream.

24. The method of claim 23, wherein the at least one syntax element is in at least one video unit, and the at least one video unit comprises at least one of the following: a sequence parameter set (SPS), a video parameter set (VPS), a picture parameter set (PPS), a picture header, or a slice header.

25. The method of claim 24, wherein the at least one syntax element indicates whether the at least one video unit includes the initial information of the at least one context model.

26. The method of claim 23, wherein the initial information of the at least one context model is included in a high-level syntax module, the high-level syntax module comprising at least one of the following: a picture parameter set (PPS), a picture header, or a slice header.

27. The method of claim 26, wherein the at least one syntax element in at least one of a sequence parameter set (SPS), a video parameter set (VPS), or a picture parameter set (PPS) indicates whether the initial information of the at least one context model is included in the high-level syntax module.

28. The method according to any one of claims 1 to 27, further comprising: Context information of the at least one context model is stored in a context parameter buffer.

29. The method of claim 28, wherein the context parameters are buffered in at least one of: an encoder associated with transcoding the current video block to the bitstream, or A decoder associated with decoding conversion from the bitstream to the current video block.

30. The method of claim 28 or claim 29, wherein the context information comprises a plurality of sets of context parameters associated with the at least one context model, a set of context parameters comprising a plurality of contexts associated with one of the at least one context model.

31. The method of claim 30, wherein the number of the at least one context model is less than or equal to the number of the plurality of groups of context parameters.

32. The method of claim 30 or claim 31, wherein the plurality of sets of context parameters comprises a first set of context parameters associated with a first quantization parameter (QP) and a second set of context parameters associated with a second QP.

33. The method of any one of claims 30 to 32, wherein the plurality of sets of context parameters comprises a third set of context parameters associated with a first slice type and a fourth set of context parameters associated with a second slice type.

34. The method of any one of claims 30 to 33, wherein the plurality of sets of context parameters comprises a fifth set of context parameters associated with a first temporal layer and a sixth set of context parameters associated with a second temporal layer.

35. The method of any one of claims 30 to 34, wherein a single set of context parameters in the plurality of sets of context parameters is associated with at least one of: a first quantization parameter (QP), a first slice type, or a first temporal layer.

36. The method of any one of claims 30 to 34, wherein more than one of the plurality of sets of context parameters are associated with at least one of: a first quantization parameter (QP), a first slice type, or a first temporal layer.

37. The method according to any one of claims 28 to 36, wherein if the encoding and decoding process of the current frame or the current slice is completed, the context information of at least part of the context parameters of the at least one context model is included in the bitstream.

38. The method of claim 37, further comprising: encoding and decoding the context information of at least a portion of the context parameters; as well as The context parameter buffer is updated based on the context information.

39. A method according to claim 37 or claim 38, wherein the context information is used to initialize the context state of subsequent frames after the current frame.

40. The method of claim 28, wherein context information for one of the at least one context model is not stored in the context parameter buffer.

41. A method according to any one of claims 28 to 40, wherein the context parameter buffer comprises a reference context for predictive context coding and decoding.

42. The method according to any one of claims 1 to 40, wherein the initial information of the at least one context model is included for at least part of a B frame or at least part of a P frame.

43. The method of claim 42, wherein whether the initial information of the at least one context model associated with a current slice or a current frame is included in the bitstream is based on at least one of: a quantization parameter (QP) value, a slice type, or a temporal layer index.

44. The method according to any one of claims 1 to 43, wherein the initial information of the at least one context model is included in the bitstream based on a picture order count (POC) interval.

45. The method of claim 44, wherein the POC interval is predefined or determined during the conversion.

46. ​​The method according to any one of claims 1 to 45, wherein if the initial information of the at least one context model associated with a frame or a slice is included in the bitstream, at least part of the context information in the frame or the slice is included in the bitstream.

47. The method of claim 46, wherein the at least one context model comprises a first number of context models, a second number of context states are included in the bitstream, the second number being less than or equal to the first number.

48. The method of claim 47, further comprising: sorting the first number of context models based on the metric; Based on the ranking, determining the second number of context models from the first number of context models; as well as The second number of context states associated with the second number of context models are included in the bitstream.

49. The method of claim 47 or claim 48, wherein the second number is the same or different for multiple frames or multiple slices.

50. The method according to any one of claims 47 to 49, wherein if a context state of one context model among the at least one context model satisfies a condition, the context state is included in the bitstream.

51. The method according to any one of claims 47 to 50, wherein the second number is a predefined value, or is determined for a frame or a slice.

52. The method of any one of claims 47 to 51, wherein the second number of context states comprises a plurality of predefined contexts.

53. A method according to any one of claims 1 to 52, wherein if context information associated with a first context model is not included in the bitstream, the context state of the first context model is initialized according to a context-based adaptive binary arithmetic coding and decoding (CABAC) context initialization table.

54. The method of any one of claims 1 to 53, wherein context information associated with the at least one context model is included in the bitstream.

55. The method according to any one of claims 1 to 54, further comprising: The initial information of the at least one context model is determined by using predictive coding.

56. The method according to any one of claims 1 to 55, wherein a coding process associated with the current video block is based on parameters of a reference model, and context information of the at least one context model is included in the bitstream during the coding process.

57. A method according to any one of claims 1 to 56, wherein a difference between a first value of a context parameter of a reference model and a second value of the context parameter of a current context model of the at least one context model is included in the bitstream.

58. The method of claim 56 or claim 57, further comprising: The reference model is determined according to a context-based adaptive binary arithmetic coding and decoding (CABAC) context initialization table.

59. The method of claim 57, wherein the difference is encoded by at least one of: a truncated Rice (TR) codec, a truncated binary (TB) codec, a kth exponential Golomb (EGk) codec, or a fixed length (FL) codec.

60. The method of claim 57, wherein the difference is encoded by context-based adaptive binary arithmetic coding and decoding (CABAC).

61. The method according to any one of claims 57 to 60, further comprising: The difference is updated by applying a quantization or dequantization process to the difference.

62. The method according to any one of claims 56 to 61, further comprising: The reference model is determined based on context information stored in a context parameter buffer.

63. The method of claim 62, further comprising: The reference model is determined from the context parameter buffer based on at least one of a context index, a quantization parameter (QP) index, a slice type index, and a temporal layer index.

64. A method according to any one of claims 56 to 63, wherein the reference model includes reference context information, and the reference context information is associated with at least one of the following: a quantization parameter (QP) of the at least one context model, a slice type of the at least one context model, and a temporal layer of the at least one context model.

65. The method according to any one of claims 1 to 64, wherein the initial information of the at least one context model is included in a first frame or a first stripe, and the at least one context model is used in a second frame or a second stripe.

66. The method of claim 65, wherein the first frame or the first slice is a reference frame for the second frame or the second slice.

67. The method of claim 66, wherein an association between the reference frame and the information of the at least one context model is included in the bitstream.

68. The method of claim 65 or claim 66, wherein at least one of a reference list or a reference index associated with the reference frame is included in the bitstream.

69. The method of any one of claims 1 to 68, wherein the converting comprises encoding the current video block into the bitstream.

70. The method of any one of claims 1 to 68, wherein the converting comprises decoding the current video block from the bitstream.

71. An apparatus for video processing, comprising a processor and a non-volatile memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform a method according to any one of claims 1 to 70.

72. A non-transitory computer readable storage medium storing instructions that cause a processor to perform the method according to any one of claims 1 to 70.

73. A non-transitory computer-readable recording medium storing a bit stream of a video, the bit stream of the video being generated by a method performed by an apparatus for video processing, wherein the method comprises: determining, based on initial information of at least one context model associated with a current video block of the video, the at least one context model, the initial information of the at least one context model being included in the bitstream; as well as Based on the at least one context model, the bitstream is generated.

74. A method for storing a bitstream of a video, comprising: determining, based on initial information of at least one context model associated with a current video block of the video, the at least one context model, the initial information of the at least one context model being included in the bitstream; generating the bitstream based on the at least one context model; as well as The bit stream is stored in a non-transitory computer-readable recording medium.

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