# US 12,771,880 B2 · Quantization parameter signaling

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- Number: US 12,771,880 B2
- Document ID: US12771880B2
- Status: Granted
- Kind: B2
- Application number: 18/936,809
- Filed: 2024-11-04
- Published: 2025-02-20
- Granted: 2026-10-20
- Earliest claimed: 2019-05-28
- Assignees: Dolby Laboratories Licensing Corporation
- Applicants: Dolby Laboratories Licensing Corporation
- Inventors: Fangjun Pu; Taoran Lu; Peng Yin; Sean Thomas McCarthy
- Web page: https://patentgrep.com/patent/US12771880B2

## CPC

- H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards
- H04N 19/172: the region being a picture, frame or field
- H04N 19/186: the unit being a colour or a chrominance component
- H04N 19/46: Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A quantization parameter signaling mechanism for both SDR and HDR content in video coding is described using two approaches. The first approach is to send the user-defined QpC table directly in high level syntax. This leads to more flexible and efficient QP control for future codec development and video content coding. The second approach is to signal luma and chroma QPs independently. This approach eliminates the need for QpC tables and removes the dependency of chroma quantization parameter on luma QP.

## Claims

### Claim 1

An apparatus to reconstruct coded data, the apparatus comprising:
means for receiving a coded bitstream comprising one or more coded pictures, wherein each picture comprises a luminance component, a first chroma component, and a second chroma component;
means for extracting syntax parameters from the coded bitstream to determine a chroma quantization parameter (QP) table, wherein the chroma QP table maps input luminance QP values to corresponding chroma QP values; and
means for decoding the one or more coded pictures based on the chroma QP table, wherein the syntax parameters comprise a start luminance QP value and one or more offset parameters to determine a mapping of the luminance QP values to corresponding chroma QP values using a piece-wise linear representation, wherein for luminance quantization values qP[i] for i larger than an end index value, corresponding chroma quantization values (Qpc[i]) are determined as Qpc[i]=qP[i]-offset, where offset denotes a fixed value.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the one or more offset parameters comprise a delta QP chroma parameter dQpc[i]=Qpc[i]−Qpc[i−1], wherein i denotes an index and Qpc[i−1] and Qpc[i] denote consecutive chroma QP values.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein the syntax parameters further comprise a flag indicating whether the first chroma component and the second chroma component share a common chroma QP table or whether the first chroma component and the second chroma component have different chroma QP tables.

### Claim 4

A apparatus to encode a sequence of video pictures to generate a coded video bitstream, the apparatus comprising:
means for receiving a sequence of pictures wherein each picture comprises a luminance component, a first chroma component, and a second chroma component;
means for encoding the sequence of video pictures using luminance quantization parameters (QP) values and chroma QP values to generate a coded video bitstream; and
means for encoding signal parameters in the coded video bitstream for a decoder to determine a chroma QP table, wherein the chroma QP table maps input luminance QP values to corresponding chroma QP values, wherein the signal parameters comprise a start luminance QP value and one or more offset parameters to determine a mapping of the luminance QP values to the corresponding chroma QP values using a piece-wise linear representation, wherein for luminance quantization values qP[i] for i larger than an end index value, corresponding chroma quantization values (Qpc[i]) are determined as Qpc[i]=qP[i]-offset, where offset denotes a fixed value.

### Claim 5 (depends on 4)

The apparatus of claim 4, wherein the one or more offset parameters comprise a delta QP chroma parameter dQpc[i]=Qpc[i]−Qpc[i−1], wherein i denotes an index and Qpc[i−1] and Qpc[i] denote consecutive chroma QP values.

### Claim 6 (depends on 4)

The apparatus of claim 4, wherein the signal parameters further comprise a flag indicating whether the first chroma component and the second chroma component share a common chroma QP table or whether the first chroma component and the second chroma component have different chroma QP tables.

### Claim 7

A method for transmitting a bitstream which is generated by a video encoding apparatus and used to reconstruct a video, wherein the method comprises:
transmitting the bitstream, wherein generating the bitstream comprises:
receiving a sequence of pictures wherein each picture comprises a luminance component, a first chroma component, and a second chroma component;
encoding the sequence of video pictures using luminance quantization parameters (QP) values and chroma QP values to generate a coded video bitstream; and
encoding signal parameters in the coded video bitstream for a decoder to determine a chroma QP table, wherein the chroma QP table maps input luminance QP values to corresponding chroma QP values, wherein the signal parameters comprise a start luminance QP value and one or more offset parameters to determine a mapping of the luminance QP values to the corresponding chroma QP values using a piece-wise linear representation, wherein for luminance quantization values qP[i] for i larger than an end index value, corresponding chroma quantization values (Qpc[i]) are determined as Qpc[i]=qP[i]-offset, where offset denotes a fixed value.