# US 2021/0344902 A1 · Parameter derivation for intra prediction

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- Number: US 2021/0344902 A1
- Document ID: US20210344902A1
- Status: Published application
- Kind: A1
- Application number: 17/330,501
- Filed: 2021-05-26
- Published: 2021-11-04
- Earliest claimed: 2018-12-01
- Assignees: Beijing Bytedance Network Technology Co., Ltd.; Bytedance Inc.
- Applicants: Beijing Bytedance Network Technology Co., Ltd.; Bytedance Inc.
- Inventors: Kai ZHANG; Li ZHANG; Hongbin LIU; Jizheng XU; Yue WANG
- Web page: https://patentgrep.com/patent/US20210344902A1

## CPC

- H04N 19/105: Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
- H04N 19/13: Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
- H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635)
- H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
- H04N 19/167: Position within a video image, e.g. region of interest [ROI]
- H04N 19/176: the region being a block, e.g. a macroblock
- H04N 19/186: the unit being a colour or a chrominance component
- H04N 19/189: characterised by the adaptation method, adaptation tool or adaptation type used for the adaptive coding
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A method for video processing is provided. The method includes determining, for a conversion between a current video block of a video and a coded representation of the video, a context that is used to code a flag using arithmetic coding in the coded representation of the current video block, wherein the context is based on whether a top-left neighboring block of the current video block is coded using a cross-component linear model (CCLM) prediction mode; and performing the conversion based on the determining.

## Claims

### Claim 1

A method of processing video data, comprising:
determining, for a conversion between a current video block of a video and a bitstream of the video, parameters for a linear model prediction or cross-color component prediction based on refined neighboring luma samples and chroma samples of the current video block;
deriving prediction values of a chroma component of the current video block based on the parameters and refined internal luma samples of the current video block; and
performing the conversion based on the prediction values.

### Claim 2 (depends on 1)

The method of claim 1, wherein neighboring luma samples and internal luma samples of the current video block are down-sampled before a refinement process, wherein the refinement process comprises a filtering process or a non-linear process.

### Claim 3 (depends on 1)

The method of claim 1, wherein the parameters for the linear model prediction are α and β, wherein α=(C1−C0)/(L1−L0) and β=C0−αL0, wherein C0 and C1 are derived from neighboring chroma samples, and wherein L0 and L1 are derived from neighboring luma samples.

### Claim 4 (depends on 3)

The method of claim 3, wherein C0 and L0 are based on S neighboring chroma and luma samples, denoted {Cx1, Cx2, . . . , CxS} and {Lx1, Lx2, . . . , LxS}, respectively, wherein C1 and L1 are based on T neighboring chroma and luma samples, denoted {Cy1, Cy2, . . . , CyT} and {Ly1, Ly2, . . . , LyT}, respectively, wherein S=T,
wherein {Cx1, Cx2, . . . , CxS} are corresponding to {Lx1, Lx2, . . . , LxS},
wherein {Cy1, Cy2, . . . , CyT} are corresponding to {Ly1, Ly2, . . . , LyT},
wherein C0=f0(Cx1, Cx2, . . . , CxS), L0=f1(Lx1, Lx2, . . . , LxS), C1=f2(Cy1, Cy2, . . . , CyT) and L1=f3(Ly1, Ly2, . . . , LyT), and
wherein f0, f1, f2 and f3 are functions.

### Claim 5 (depends on 4)

The method of claim 4, wherein f0 and f1 are a first function.

### Claim 6 (depends on 4)

The method of claim 4, wherein f2 and f3 are a second function.

### Claim 7 (depends on 4)

The method of claim 4, wherein f0, f1, f2 and f3 are a third function, wherein the third function is an averaging function.

### Claim 8 (depends on 4)

The method of claim 4, wherein {Lx1, Lx2, . . . , LxS} are the smallest samples of a group of luma samples, and {Ly1, Ly2, . . . , LyT} are the largest samples of a group of luma samples,
wherein the group of luma samples comprises all neighboring samples used in VTM-3.0 to derive the parameters of the linear model prediction; or
the group of luma samples comprises a subset of neighboring samples used in VTM-3.0 to derive the parameters of the linear model prediction, and wherein the subset is not identical to all the neighboring samples.

### Claim 9 (depends on 1)

The method of claim 1, wherein parameters for the linear model prediction or cross-color component prediction is further determined by selecting neighboring samples based on a position of a largest or a smallest neighboring sample.

### Claim 10 (depends on 9)

The method of claim 9, wherein the largest neighboring sample is located at a position (x0, y0), samples in a region (x0−d1, y0), (x0, y0−d2), (x0+d3, y0), (x0, y0+d4) are utilized to select the neighboring samples, and wherein {d1, d2, d3, d4} depend on the position (x0, y0); and
the smallest neighboring sample is located at a position (x1, y1), samples in a region (x1−d1, y1), (x1, y1−d2), (x1+d3, y1), (x1, y1+d4) are utilized to select the neighboring samples, and {d1, d2, d3, d4} depend on the position (x1, y1),
wherein the neighboring samples represent a color component.

### Claim 11 (depends on 1)

The method of claim 1, wherein parameters for the linear model prediction or cross-color component prediction is further determined based on a main color component and a dependent color component, the main color component selected as one of a luma color component and a chroma color component and the dependent color component selected as the other of the luma color component and the chroma color component.

### Claim 12 (depends on 1)

The method of claim 1, further comprising:
determining a context that is used to code a flag using arithmetic coding in the bitstream of the current video block, wherein the context is based on whether a top-left neighboring block of the current video block is coded using a cross-component linear model (CCLM) prediction mode, wherein the flag is signaled to indicate whether the CCLM prediction mode is applied on the current video block, and
wherein the CCLM prediction mode uses a linear mode to derive prediction values of a chroma component from another component.

### Claim 13 (depends on 12)

The method of claim 12, wherein the context comprise a first context of the top-left neighboring block uses the CCLM prediction mode and comprises a second context different from the first context if the top-left neighboring block does not use the CCLM prediction mode.

### Claim 14 (depends on 12)

The method of claim 12, wherein the top-left neighboring block is unavailable, and wherein the CCLM prediction mode is considered to be enabled; optionally
the top-left neighboring block is unavailable, and wherein the CCLM prediction mode is considered to be disabled; optionally
the top-left neighboring block is intra-coded, and wherein the CCLM prediction mode is considered to be enabled; optionally
the top-left neighboring block is intra-coded, and wherein the CCLM prediction mode is considered to be disabled.

### Claim 15 (depends on 1)

The method of claim 1, further comprising:
determining a coding order for one or more indications of a derived mode (DM mode) and a linear mode (LM mode) based on a coding mode of one or more neighboring blocks of the current video block,
wherein the LM mode uses a linear mode to derive prediction values of a chroma component from another component, and the DM mode derives intra prediction mode of a chroma component from another component.

### Claim 16 (depends on 15)

The method of claim 15, wherein a top-left neighboring block of the one or more neighboring blocks is coded with the LM mode, and wherein an indication of the LM mode is coded first; optionally
a top-left neighboring block of the one or more neighboring blocks is coded with the DM mode, and wherein an indication of the DM mode is coded first; optionally
a top-left neighboring block of the one or more neighboring blocks is coded with a coding mode that is different from the LM mode, and wherein an indication of the DM mode is coded first,
wherein the one or more indications are signaled in a sequence parameter set (SPS), a video parameter set (VPS), a picture parameter set (PPS), a picture header, a slice header, a tile group header, one or more largest coding units or one or more coding units.

### Claim 17 (depends on 1)

The method of claim 1, wherein the conversion includes encoding the current video block into the bitstream.

### Claim 18 (depends on 1)

The method of claim 1, wherein the conversion includes decoding the current video block from the bitstream.

### Claim 19

An apparatus for processing video data, comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:
determine, for a conversion between a current video block of a video and a bitstream of the video, parameters for a linear model prediction or cross-color component prediction based on refined neighboring luma samples and chroma samples of the current video block;
derive prediction values of a chroma component of the current video block based on the parameters and refined internal luma samples of the current video block; and
perform the conversion based on the prediction values.

### Claim 20

A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises:
determining, for a conversion between a current video block of the video and the bitstream of the video, parameters for a linear model prediction or cross-color component prediction based on refined neighboring luma samples and chroma samples of the current video block;
deriving prediction values of a chroma component of the current video block based on the parameters and refined internal luma samples of the current video block; and
generating the bitstream based on the prediction values.