Method and apparatus for video coding
Aspects of the disclosure provide methods, apparatuses, and non-transitory computer-readable storage mediums for video encoding/decoding. An apparatus includes processing circuitry that decodes prediction information for a current block in a current picture that is a part of a coded video sequence. The prediction information includes a first syntax element indicating whether both quantization parameter (QP) information of a luma component and QP information of a chroma component of the current block are included in the prediction information. The processing circuitry determines a QP of the chroma component based on the QP information of the luma component and the QP information of the chroma component based on the first syntax element indicating that both the QP information of the luma component and the QP information of the chroma component are included in the prediction information. The processing circuitry reconstructs the current block based on the QP of the chroma component.
1. A method of video decoding in a decoder, comprising:
decoding a first syntax element included in prediction information for a current block in a current picture that is a part of a coded video sequence;
determining whether the first syntax element indicates that quantization parameter (QP) information of a luma component and QP information of a chroma component of the current block are separately included in a picture header of the current picture;
in response to the first syntax element being determined to indicate that the QP information of the luma component and the QP information of the chroma component of the current block are separately included in the picture header of the current picture,
determining a QP of the chroma component based on the QP information of the chroma component included in the picture header of the current picture;
in response to the first syntax element being determined to indicate that the QP information of the luma component and the QP information of the chroma component of the current block are not separately included in the picture header of the current picture,
determining the QP of the chroma component based on the QP information of the chroma component included in a slice header of the current picture; and
reconstructing the current block based on the QP of the chroma component.
2. The method of claim 1 , wherein the slice header of the current picture corresponds to a picture parameter set that does not include the picture header of the current picture.
3. The method of claim 1 , wherein the QP information of the chroma component is included in the picture header of the current picture based on a second syntax element in the prediction information indicating that the current picture is not further partitioned.
4. The method of claim 1 , wherein the QP information of the chroma component is included in the picture header of the current picture based on a third syntax element in the prediction information indicating that the picture header of the current picture is included in the slice header of the current picture.
5. The method of claim 1 , further comprising:
decoding a fourth syntax element in the prediction information indicating whether a QP of the luma component is equal to the QP of the chroma component of the current block; and
determining the QP of the chroma component according to a luma-to-chroma QP mapping table based on the fourth syntax element in the prediction information indicating that the QP of the luma component is not equal to the QP of the chroma component of the current block.
6. The method of claim 5 , further comprising:
determining the QP of the luma component as the QP of the chroma component based on the fourth syntax element indicating that the QP of the luma component is equal to the QP of the chroma component of the current block.
7. The method of claim 5 , wherein the luma-to-chroma QP mapping table is included in the prediction information.
8. An apparatus, comprising processing circuitry configured to:
decode a first syntax element included in prediction information for a current block in a current picture that is a part of a coded video sequence;
determine whether the first syntax element indicates that quantization parameter (QP) information of a luma component and QP information of a chroma component of the current block are separately included in a picture header of the current picture;
in response to the first syntax element being determined to indicate that the QP information of the luma component and the QP information of the chroma component of the current block are separately included in the picture header of the current picture,
determine a QP of the chroma component based on the QP information of the chroma component included in the picture header of the current picture;
in response to the first syntax element being determined to indicate that the QP information of the luma component and the QP information of the chroma component of the current block are not separately included in the picture header of the current picture,
determine the QP of the chroma component based on the QP information of the chroma component included in a slice header of the current picture; and
reconstruct the current block based on the QP of the chroma component.
9. The apparatus of claim 8 , wherein the slice header of the current picture corresponds to a picture parameter set that does not include the picture header of the current picture.
10. The apparatus of claim 8 , wherein the QP information of the chroma component is included in the picture header of the current picture based on a second syntax element in the prediction information indicating that the current picture is not further partitioned.
11. The apparatus of claim 8 , wherein the QP information of the chroma component is included in the picture header of the current picture based on a third syntax element in the prediction information indicating that the picture header of the current picture is included in the slice header of the current picture.
12. The apparatus of claim 8 , wherein the processing circuitry is further configured to:
decode a fourth syntax element in the prediction information indicating whether a QP of the luma component is equal to the QP of the chroma component of the current block; and
determine the QP of the chroma component according to a luma-to-chroma QP mapping table based on the fourth syntax element in the prediction information indicating that the QP of the luma component is not equal to the QP of the chroma component of the current block.
13. The apparatus of claim 12 , wherein the processing circuitry is further configured to:
determine the QP of the luma component as the QP of the chroma component based on the fourth syntax element indicating that the QP of the luma component is equal to the QP of the chroma component of the current block.
14. The apparatus of claim 12 , wherein the luma-to-chroma QP mapping table is included in the prediction information.
15. A non-transitory computer-readable storage medium storing instructions executable by at least one processor to perform:
decoding a first syntax element included in prediction information for a current block in a current picture that is a part of a coded video sequence;
determining whether the first syntax element indicates that quantization parameter (QP) information of a luma component and QP information of a chroma component of the current block are separately included in a picture header of the current picture;
in response to the first syntax element being determined to indicate that the QP information of the luma component and the QP information of the chroma component of the current block are separately included in the picture header of the current picture,
determining a QP of the chroma component based on the QP information of the chroma component included in the picture header of the current picture;
in response to the first syntax element being determined to indicate that the QP information of the luma component and the QP information of the chroma component of the current block are not separately included in the picture header of the current picture,
determining the QP of the chroma component based the QP information of the chroma component included in a slice header of the current picture; and
reconstructing the current block based on the QP of the chroma component.
16. The non-transitory computer-readable storage medium of claim 15 , wherein the slice header of the current picture corresponds to a picture parameter set that does not include the picture header of the current picture.
17. The non-transitory computer-readable storage medium of claim 15 , wherein the QP information of the chroma component is included in the picture header of the current picture based on a second syntax element in the prediction information indicating that the current picture is not further partitioned.
18. The non-transitory computer-readable storage medium of claim 15 , wherein the QP information of the chroma component is included in the picture header of the current picture based on a third syntax element in the prediction information indicating that the picture header of the current picture is included in the slice header of the current picture.
19. The non-transitory computer-readable storage medium of claim 15 , wherein the stored instructions further cause the at least one processor perform:
decoding a fourth syntax element in the prediction information indicating whether a QP of the luma component is equal to the QP of the chroma component of the current block; and
determining the QP of the chroma component according to a luma-to-chroma QP mapping table based on the fourth syntax element in the prediction information indicating that the QP of the luma component is not equal to the QP of the chroma component of the current block.
20. The non-transitory computer-readable storage medium of claim 19 , wherein the stored instructions further cause the at least one processor to perform:
determining the QP of the luma component as the QP of the chroma component based on the fourth syntax element indicating that the QP of the luma component is equal to the QP of the chroma component of the current block.