Method and apparatus for coding video data in palette mode
Methods for performing palette coding of video data may include: determining whether a luma component of a coding unit (CU) and chroma components of the CU are coded jointly or separately in a palette mode; and in response to the luma component and the chroma components being coded separately in the palette mode, determining a maximum separate palette-table size for the CU; determining a maximum separate palette-predictor size for the CU; and predicting the CU based on the maximum separate palette-table size and the maximum separate palette-predictor size.
1. A palette coding method implemented in a decoder, comprising:
determining whether a luma component of a coding unit (CU) and chroma components of the CU are coded jointly or separately in a palette mode; and
in response to the luma component and the chroma components being coded separately in the palette mode,
determining a maximum separate palette-table size for the CU to be smaller than a maximum joint palette-table size,
determining a maximum separate palette-predictor size for the CU, and
predicting the CU based on the maximum separate palette-table size and the maximum separate palette-predictor size.
2. The method of claim 1 , wherein the maximum separate palette-table size or the maximum separate palette-predictor size is for the luma component or the chroma component.
3. The method of claim 1 , wherein determining the maximum separate palette-table size for the CU comprises: determining the maximum separate palette-table size for the CU based on a value of a first syntax element signaled in a video bitstream, and determining the maximum separate palette-predictor size for the CU comprises:
determining the maximum separate palette-predictor size for the CU based on the value of the first syntax element and a value of a second syntax element signaled in the video bitstream.
4. The method of claim 3 , wherein determining the maximum separate palette-predictor size for the CU comprises:
determining the maximum separate palette-predictor size for the CU to be a sum of the value of the first syntax element and the value of the second syntax element.
5. The method of claim 3 , wherein the first syntax element and second syntax element are signaled in a sequence parameter set (SPS) or a picture header (PH) associated with the CU.
6. The method of claim 1 , wherein determining the maximum separate palette-table size for the CU comprises:
determining the maximum separate palette-table size for the CU based on the maximum joint palette-table size.
7. The method of claim 6 , wherein determining the maximum separate palette-predictor size for the CU comprises:
determining the maximum separate palette-predictor size for the CU based on a maximum joint palette-predictor size.
8. The method of claim 7 , wherein, in response to the CU being part of a single-tree slice, the determining the maximum separate palette-table size for the CU comprises: determining the maximum separate palette-table size to be smaller than the maximum joint palette-table size, and
predicting the CU comprises: predicting the CU based on the maximum joint palette-predictor size.
9. The method of claim 7 , wherein, in response to the CU being not part of a single-tree slice, the determining the maximum separate palette-predictor size for the CU comprises: determining the maximum separate palette-predictor size to be smaller than the maximum joint palette-predictor size, and
predicting the CU comprises: predicting the CU based on the maximum separate palette-predictor size.
10. The method of claim 7 , further comprising:
determining whether a picture slice comprising the CU is a single-tree slice or a dual-tree slice; and
in response to the picture slice being a single-tree slice,
determining the maximum joint palette-table size for the CU in the picture slice, based on a value of a first syntax element signaled in a slice header of the picture slice; and
determining the maximum joint palette-predictor size for the CU, based on the value of the first syntax element and a value of a second syntax element signaled in the slice header.
11. The method of claim 10 , wherein determining the maximum joint palette-predictor size for the CU comprises:
determining the maximum joint palette-predictor size for the CU to be a sum of the value of the first syntax element and the value of the second syntax element.
12. The method of claim 10 , further comprising:
in response to the picture slice being a dual-tree slice,
determining the maximum separate palette-table size for the CU, based on a value of a third syntax element signaled in the slice header, and
determining the maximum separate palette-predictor size for the CU, based on the value of the third syntax element and a value of a fourth syntax element signaled in the slice header.
13. The method of claim 12 , wherein determining the maximum separate palette-predictor size for the CU comprises:
determining the maximum separate palette-predictor size for the CU to be a sum of the value of the third syntax element and the value of the fourth syntax element.
14. The method of claim 1 , wherein the maximum separate palette-table size is 15.
15. The method of claim 14 , wherein the maximum joint palette-table size is 31.
16. A video processing apparatus implemented in an encoder, comprising:
at least one memory for storing instructions; and
at least one processor configured to execute the instructions to cause the apparatus to perform:
determining whether a luma component of a coding unit (CU) and chroma components of the CU are coded jointly or separately in a palette mode; and
in response to the luma component and the chroma components being coded separately in the palette mode,
determining a maximum separate palette-table size for the CU to be smaller than a maximum joint palette-table size,
determining a maximum separate palette-predictor size for the CU, and
predicting the CU based on the maximum separate palette-table size and the maximum separate palette-predictor size.
17. A non-transitory computer readable storage medium storing a video bitstream for processing according to an operation comprising:
determining whether a luma component of a coding unit (CU) and chroma components of the CU are coded jointly or separately in a palette mode; and
in response to the luma component and the chroma components being coded separately in the palette mode,
determining a maximum separate palette-table size for the CU to be smaller than a maximum joint palette-table size,
determining a maximum separate palette-predictor size for the CU, and
predicting the CU based on the maximum separate palette-table size and the maximum separate palette-predictor size.
18. The non-transitory computer readable storage medium of claim 17 , wherein the operation further comprises:
determining the maximum separate palette-table size for the CU based on a value of a first syntax element signaled in the video bitstream; and
determining the maximum separate palette-predictor size for the CU based on the value of the first syntax element and a value of a second syntax element signaled in the video bitstream.
19. The non-transitory computer readable storage medium of claim 18 , wherein the operation further comprises:
determining the maximum separate palette-predictor size for the CU to be a sum of the value of the first syntax element and the value of the second syntax element.
20. The non-transitory computer readable storage medium of claim 17 , wherein the operation further comprises:
determining the maximum separate palette-table size for the CU based on the maximum joint palette-table size; and
determining the maximum separate palette-predictor size for the CU based on a maximum joint palette-predictor size.