# US 11,451,826 B2 · Lossless coding mode and switchable residual coding

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- Number: US 11,451,826 B2
- Document ID: US11451826B2
- Status: Granted
- Kind: B2
- Application number: 16/848,612
- Filed: 2020-04-14
- Published: 2020-10-15
- Granted: 2022-09-20
- Earliest claimed: 2019-04-15
- Assignees: Tencent America LLC
- Applicants: Tencent America LLC
- Inventors: Xin Zhao; Xiang Li; Shan Liu; Cheung Auyeung; Liang Zhao; Ling Li
- Web page: https://patentgrep.com/patent/US11451826B2

## CPC

- H04N 19/615: using motion compensated temporal filtering [MCTF]
- H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards
- H04N 19/124: Quantisation
- H04N 19/176: the region being a block, e.g. a macroblock
- H04N 19/127: Prioritisation of hardware or computational resources
- H04N 19/157: Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

An apparatus of video decoding can include circuitry configured to receive a lossless mode flag associated with a current block indicating whether a lossless coding mode is applied to the current block, determine that a lossy coding mode is not applied to the current block when the lossless mode flag indicates that the lossless coding mode is applied to the current block, and reconstruct the current block with the lossy coding mode disabled.

## Claims

### Claim 1

A method of video decoding at a video decoder, comprising:
receiving a coding unit (CU) level lossless mode flag associated with a current block of a current picture comprising plural blocks, the CU level lossless mode flag indicating at a CU level whether a lossless coding mode is applied to the current block;
in response to a determination that (i) a slice level flag indicates that a luma mapping with chroma scaling (LMCS) coding mode is enabled for a current slice of the current block and that (ii) the CU level lossless mode flag indicates that the lossless coding mode is applied to the current block, disabling the LMCS coding mode for the current block;
in response to a determination that (i) the slice level flag indicates that the LMCS coding mode is enabled for the current slice of the current block and that (ii) the CU level lossless mode flag indicates that the lossless coding mode is not applied to the current block, enabling the LMCS coding mode for the current block; and
reconstructing the current block with the LMCS coding mode disabled or enabled.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
receiving a high level syntax element indicating whether the lossless coding mode is allowed for current video data referencing the high level syntax element, the high level syntax element being signaled in a video parameter set, a sequence parameter set, a picture parameter set, a slice header, a tile header, or a tile group header,
wherein the CU level lossless mode flag associated with the current block is received based on the high level syntax element indicating the lossless coding mode is allowed for the current video data.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
in response to the CU level lossless mode flag indicating that the lossless coding mode is not applied to the current block, receiving a syntax element indicating whether joint chroma residual coding mode is applied to the current block.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
in response to the CU level lossless mode flag indicating that the lossless coding mode is applied to the current block, determining that (i) a lossy coding mode is not applied to the current block or that (ii) a syntax element indicating whether the lossy coding mode is applied to the current block is not signaled, wherein
the lossy coding mode is one of:
joint chroma residual coding mode,
a combined intra and inter prediction (CIIP) coding mode,
a quantized residual block-based delta pulse code modulation (BDPCM) coding mode,
a multiple transform selection (MTS) coding mode,
a secondary transform (ST) coding mode,
a dependent quantization coding mode,
a transform skip (TS) coding mode, or
a sub-block transform (SBT) coding mode.

### Claim 5 (depends on 1)

The method of claim 1, wherein the disabling the LMCS coding mode is performed further in response to a determination that (iii) a color component index is equal to 0, in addition to conditions (i) and (ii).

### Claim 6

An apparatus of video decoding, comprising circuitry configured to:
receive a coding unit (CU) level lossless mode flag associated with a current block of a current picture comprising plural blocks, the CU level lossless mode flag indicating at a CU level whether a lossless coding mode is applied to the current block;
in response to a determination that (i) a slice level flag indicates that a luma mapping with chroma scaling (LMCS) coding mode is enabled for a current slice of the current block and that (ii) the CU level lossless mode flag indicates that the lossless coding mode is applied to the current block, disable the LMCS coding mode for the current block ;
in response to a determination that (i) the slice level flag indicates that the LMCS coding mode is enabled for the current slice of the current block and that (ii) the CU level lossless mode flag indicates that the lossless coding mode is not applied to the current block, enable the LMCS coding mode for the current block; and
reconstruct the current block with the LMCS coding mode disabled or enabled.

### Claim 7 (depends on 6)

The apparatus of claim 6, wherein the circuitry is further configured to:
receive a high level syntax element indicating whether the lossless coding mode is allowed for current video data referencing the high level syntax element, the high level syntax element being signaled in a video parameter set, a sequence parameter set, a picture parameter set, a slice header, a tile header, or a tile group header,
wherein the CU level lossless mode flag associated with the current block is received based on the high level syntax element indicating the lossless coding mode is allowed for the current video data.

### Claim 8 (depends on 6)

The apparatus of claim 6, wherein the circuitry is further configured to:
in response to the CU level lossless mode flag indicating that the lossless coding mode is not applied to the current block, receive a syntax element indicating whether joint chroma residual coding mode is applied to the current block.

### Claim 9 (depends on 6)

The apparatus of claim 6, wherein the circuitry is configured to, in response to the CU level lossless mode flag indicating that the lossless coding mode is applied to the current block, determine that (i) a lossy coding mode is not applied to the current block or that (ii) a syntax element indicating whether the lossy coding mode is applied to the current block is not signaled, and
the second lossy coding mode is one of:
joint chroma residual coding mode,
a combined intra and inter prediction (CIIP) coding mode,
a quantized residual block-based delta pulse code modulation (BDPCM) coding mode,
a multiple transform selection (MTS) coding mode,
a secondary transform (ST) coding mode,
a dependent quantization coding mode, a transform skip (TS) coding mode, or
a sub-block transform (SBT) coding mode.

### Claim 10

A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform a method of video decoding, the method comprising:
receiving a coding unit (CU) level lossless mode flag associated with a current block of a current picture comprising plural blocks, the CU level lossless mode flag indicating at a CU level whether a lossless coding mode is applied to the current block;
in response to a determination that (i) a slice level flag indicates that a luma mapping with chroma scaling (LMCS) coding mode is enabled for a current slice of the current block and that (ii) the CU level lossless mode flag indicates that the lossless coding mode is applied to the current block, disabling the LMCS coding mode for the current block ;
in response to a determination that (i) the slice level flag indicates that the LMCS coding mode is enabled for a current slice of the current block and that (ii) the CU level lossless mode flag indicates that the lossless coding mode is not applied to the current block, enabling the LMCS coding mode for the current block; and
reconstructing the current block with the LMCS coding mode disabled or enabled.

### Claim 11 (depends on 10)

The non-transitory computer-readable medium of claim 10, wherein the method further comprises:
receiving a high level syntax element indicating whether the lossless coding mode is allowed for current video data referencing the high level syntax element, the high level syntax element being signaled in a video parameter set, a sequence parameter set, a picture parameter set, a slice header, a tile header, or a tile group header,
wherein the CU level lossless mode flag associated with the current block is received based on the high level syntax element indicating the lossless coding mode is allowed for the current video data.

### Claim 12 (depends on 10)

The non-transitory computer-readable medium of claim 10, wherein the method further comprises:
in response to the CU level lossless mode flag indicating that the lossless coding mode is not applied to the current block, receiving a syntax element indicating whether joint chroma residual coding mode is applied to the current block.

### Claim 13 (depends on 10)

The non-transitory computer-readable medium of claim 10, wherein the method further comprises:
in response to the CU level lossless mode flag indicating that the lossless coding mode is applied to the current block, determining that (i) a lossy coding mode is not applied to the current block or that (ii) a syntax element indicating whether the lossy coding mode is applied to the current block is not signaled, wherein
the lossy coding mode is one of:
joint chroma residual coding mode,
a combined intra and inter prediction (CIIP) coding mode,
a quantized residual block-based delta pulse code modulation (BDPCM) coding mode,
a multiple transform selection (MTS) coding mode,
a secondary transform (ST) coding mode,
a dependent quantization coding mode,
a transform skip (TS) coding mode, or
a sub-block transform (SBT) coding mode.