# US 9,883,184 B2 · QP derivation and offset for adaptive color transform in video coding

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 9,883,184 B2
- Document ID: US9883184B2
- Status: Granted
- Kind: B2
- Application number: 14/876,574
- Filed: 2015-10-06
- Published: 2016-04-07
- Granted: 2018-01-30
- Earliest claimed: 2014-10-07
- Assignees: QUALCOMM Incorporated
- Applicants: QUALCOMM Incorporated
- Inventors: Krishnakanth Rapaka; Li Zhang; Rajan Laxman Joshi; Marta Karczewicz
- Web page: https://patentgrep.com/patent/US9883184B2

## CPC

- H04N 19/124: Quantisation
- H04N 19/12: Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
- H04N 19/176: the region being a block, e.g. a macroblock
- H04N 19/18: the unit being a set of transform coefficients
- H04N 19/186: the unit being a colour or a chrominance component
- H04N 19/44: Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
- H04N 19/60: using transform coding
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A device for decoding video data is configured to determine for one or more blocks of the video data that adaptive color transform is enabled; determine a quantization parameter for the one or more blocks; in response to a value of the quantization parameter being below a threshold, modify the quantization parameter to determine a modified quantization parameter; and dequantize transform coefficients based on the modified quantization parameter.

## Claims

### Claim 1

A method of decoding video data, the method comprising:
receiving an offset value in the video data;
determining for one or more blocks of the video data that adaptive color transform is enabled;
determining a red, green, and blue (RGB)-color space quantization parameter for the one or more blocks, wherein determining the RGB-color space quantization parameter comprises adding the offset value to a luma-chroma (YCbCr)-color space quantization parameter;
in response to a value of the RGB-color space quantization parameter being below a threshold, modifying the RGB-color space quantization parameter to determine a modified RGB-color space quantization parameter; and
dequantizing transform coefficients of a block from the one or more blocks based on the modified RGB-color space quantization parameter.

### Claim 2 (depends on 1)

The method of claim 1, wherein determining for the one or more blocks of the video data that adaptive color transform is enabled comprises determining a chroma format for the video data.

### Claim 3 (depends on 2)

The method of claim 2, wherein determining for the one or more blocks of the video data that adaptive color transform is enabled comprises:
in response to determining a chroma format for the one or more blocks of the video data is 4:4:4, determining that adaptive color transform is enabled for the one or more blocks.

### Claim 4 (depends on 2)

The method of claim 2, further comprising:
for one or more additional blocks, in response to determining a chroma format of the one or more additional blocks is other than 4:4:4, determining that adaptive color transform is disabled for the one or more additional blocks.

### Claim 5

The method of 1, wherein determining for the one or more blocks of the video data that adaptive color transform is enabled comprises parsing a syntax element in the video data, wherein the syntax element indicates if adaptive color transform is enabled.

### Claim 6 (depends on 5)

The method of claim 5 wherein the syntax element is signalled in a picture parameter set (PPS).

### Claim 7 (depends on 1)

The method of claim 1, wherein the threshold is zero and wherein a value of the modified quantization parameter is greater than or equal to zero.

### Claim 8 (depends on 1)

The method of claim 1, wherein the modified RGB-color space quantization parameter is less than or equal to 51 plus the offset value.

### Claim 9 (depends on 1)

The method of claim 1, further comprising:
receiving a flag indicating the offset value is to be added to the quantization parameter.

### Claim 10 (depends on 1)

The method of claim 1, further comprising:
based on the dequantized transform coefficients, determining a residual block for the video data;
determining a predictive block;
adding the residual block to a predictive block to determine a reconstructed block of video data.

### Claim 11 (depends on 1)

The method of claim 1, wherein the method of decoding the video data is performed as part of a video encoding process.

### Claim 12 (depends on 1)

The method of claim 1, further comprising:
receiving the video data at a receiver of a wireless communication device;
storing the video data in a memory of the wireless communication device; and
processing the video data on one or more processors of the wireless communication device.

### Claim 13

A device for decoding video data, the device comprising:
a video data memory;
one or more processors configured to:
receive an offset value in the video data;
determine for one or more blocks of the video data that adaptive color transform is enabled;
determine a red, green, and blue (RGB)-color space quantization parameter for the one or more blocks, wherein determining the RGB-color space quantization parameter comprises adding the offset value to a luma-chroma (YCbCr)-color space quantization parameter;
in response to a value of the RGB-color space quantization parameter being below a threshold, modify the RGB-color space quantization parameter to determine a modified RGB-color space quantization parameter; and
dequantize transform coefficients of a block from the one or more blocks based on the modified RGB-color space quantization parameter.

### Claim 14 (depends on 13)

The device of claim 13, wherein to determine for the one or more blocks of the video data that adaptive color transform is enabled, the one or more processors are further configured to determine a chroma format for the video data.

### Claim 15 (depends on 14)

The device of claim 14, wherein to determine for the one or more blocks of the video data that adaptive color transform is enabled, the one or more processors are further configured to:
in response to determining a chroma format for the one or more blocks of the video data is 4:4:4, determine that adaptive color transform is enabled for the one or more blocks.

### Claim 16 (depends on 14)

The device of claim 14, wherein the one or more processors are further configured to:
for one or more additional blocks, in response to determining a chroma format for the one or more additional blocks is other than 4:4:4, determine that adaptive color transform is disabled for the one or more additional blocks.

### Claim 17 (depends on 13)

The device of claim 13, wherein to determine for the one or more blocks of the video data that adaptive color transform is enabled, the one or more processors are further configured to parse a syntax element in the video data, wherein the syntax element indicates if adaptive color transform is enabled.

### Claim 18 (depends on 17)

The device of claim 17, wherein the syntax element is signalled in a picture parameter set (PPS).

### Claim 19 (depends on 13)

The device of claim 13, wherein the threshold is zero and wherein a value of the modified quantization parameter is greater than or equal to zero.

### Claim 20 (depends on 13)

The device of claim 13, wherein the modified RGB-color space quantization parameter is less than or equal to 51 plus the offset value.

### Claim 21 (depends on 13)

The device of claim 13, wherein the one or more processors are further configured to receive a flag indicating the offset value is to be added to the quantization parameter.

### Claim 22 (depends on 13)

The device of claim 13, wherein the one or more processors are further configured to:
based on the dequantized transform coefficients, determining a residual block for the video data;
determining a predictive block;
adding the residual block to a predictive block to determine a reconstructed block of video data.

### Claim 23 (depends on 13)

The device of claim 13, where the one or more processors are further confiugred to decode the video data, and wherein the device further comprises a display configured to display the decoded video data.

### Claim 24 (depends on 13)

The device of claim 13, where the one or more processors are further confiugred to encode the video data, and wherein the device further comprises a camera configured to acquire the video data.

### Claim 25 (depends on 13)

The device of claim 13, wherein the device comprises a wireless communication device, the device further comprising a receiver configured to receive the video data.

### Claim 26 (depends on 25)

The device of claim 25, wherein the wireless communication device comprises a telephone handset and wherein the receiver is configured to demodulate, according to a wireless communication standard, a signal comprising the video data.

### Claim 27

An apparatus for decoding video data, the apparatus comprising:
means for receiving an offset value in the video data;
means for determining for one or more blocks of the video data that adaptive color transform is enabled;
means for determining a red, green, and blue (RGB)-color space quantization parameter for the one or more blocks, wherein determining the RGB-color space quantization parameter comprises adding the offset value to a luma-chroma (YCbCr)-color space quantization parameter;
means for modifying the RGB-color space quantization parameter to determine a modified RGB-color space quantization parameter in response to a value of the RGB-color space quantization parameter being below a threshold; and
means for dequantizing transform coefficients of a block from the one or more blocks based on the modified RGB-color space quantization parameter.

### Claim 28

A non-transitory computer-readable storage medium storing instructions that when executed by one or more processors cause the one or more processors to:
receive in the video data an offset value;
determine for one or more blocks of the video data that adaptive color transform is enabled;
determine a red, green, and blue (RGB)-color space quantization parameter for the one or more blocks, wherein determining the RGB-color space quantization parameter comprises adding an offset to a luma-chroma (YCbCr)-color space quantization parameter;
modify the RGB-color space quantization parameter to determine a modified RGB-color space quantization parameter in response to a value of the RGB-color space quantization parameter being below a threshold; and
dequantize transform coefficients of a block from the one or more blocks based on the modified RGB-color space quantization parameter.