Methods and apparatus of video coding in 4:4:4 chroma format
An electronic apparatus performs a method of decoding video data, including receiving, from bitstream, a first syntax element in a slice header of a slice that indicates whether luma mapping with chroma scaling (LMCS) is applied to a coding unit in the slice; receiving a second syntax element for the coding unit that indicates whether the coding unit has been coded using adaptive color-space transform (ACT); if the second syntax element has a non-zero value, decoding the coding unit by applying inverse ACT to convert luma and chroma residuals of the coding unit from a transformed color space to an original color space of the video data; and if the first syntax element has a non-zero value, decoding the coding unit by performing inverse luma mapping to the luma samples and inverse scaling to the chroma residuals of the coding unit after performing the inverse ACT.
1 . A method of video encoding, comprising:
determining whether a coding unit has been coded using adaptive color-space transform (ACT), wherein the coding unit is coded by intra-prediction mode;
in accordance with a determination that the coding unit has not been coded using ACT:
determining whether chroma components of the coding unit have been coded using block differential pulse coded modulation (BDPCM); and
decoding chroma components of the coding unit based on the determination of whether the chroma components of the coding unit have been coded using BDPCM; and in accordance with a determination that the coding unit has been coded using ACT:
decoding the coding unit by applying inverse ACT.
2 . The method of claim 1 , wherein the method further comprises:
signaling a first syntax element, wherein the first syntax element indicates whether the coding unit has been coded using ACT;
in accordance with a determination that the first syntax element has a zero value:
signaling one or more syntax elements, wherein the one or more syntax elements indicate whether the chroma components of the coding unit have been coded using BDPCM; and
in accordance with a determination that the first syntax element has a non-zero value:
not signaling the one or more syntax elements,
wherein when the one or more syntax elements are not signaled, default values are assigned to the one or more syntax elements.
3 . The method of claim 2 , wherein the method further comprises:
signaling a second syntax element, wherein the second syntax element indicates whether video data has a predefined chroma format,
wherein the signaling the first syntax element comprises:
in response to the second syntax element indicating that the video data has the predefined chroma format, signaling the first syntax element.
4 . The method of claim 3 , wherein the predefined chroma format is 4:4:4 chroma format.
5 . The method of claim 3 , wherein the first syntax element is signaled only when the video data has the predefined chroma format.
6 . The method of claim 1 , wherein the default values indicate that the chroma components of the coding unit are decoded without using inverse BDPCM.
7 . The method of claim 1 , wherein the coding unit is decoded using inverse BDPCM when the coding unit is coded without applying transforms.
8 . An electronic apparatus comprising:
one or more processing units;
a memory coupled to the one or more processing units; and
a plurality of programs stored in the memory that, when executed by the one or more processing units, cause the electronic apparatus to perform operations comprising:
determining whether a coding unit has been coded using adaptive color-space transform (ACT), wherein the coding unit is coded by intra-prediction mode;
in accordance with a determination that the coding unit has not been coded using ACT:
determining whether chroma components of the coding unit have been coded using block differential pulse coded modulation (BDPCM); and
decoding chroma components of the coding unit based on the determination of whether the chroma components of the coding unit have been coded using BDPCM; and
in accordance with a determination that the coding unit has been coded using ACT:
decoding the coding unit by applying inverse ACT.
9 . The electronic apparatus of claim 8 , wherein the operations further comprise:
signaling a first syntax element, wherein the first syntax element indicates whether the coding unit has been coded using ACT;
in accordance with a determination that the first syntax element has a zero value:
signaling one or more syntax elements, wherein the one or more syntax elements indicate whether the chroma components of the coding unit have been coded using BDPCM; and
in accordance with a determination that the first syntax element has a non-zero value:
not signaling the one or more syntax elements,
wherein when the one or more syntax elements are not signaled, default values are assigned to the one or more syntax elements.
10 . The electronic apparatus of claim 9 , wherein the operations further comprise:
signaling a second syntax element, wherein the second syntax element indicates whether video data has a predefined chroma format,
wherein the signaling the first syntax element comprises:
in response to the second syntax element indicating that the video data has the predefined chroma format, signaling the first syntax element.
11 . The electronic apparatus of claim 10 , wherein the predefined chroma format is 4:4:4 chroma format.
12 . The electronic apparatus of claim 10 , wherein the first syntax element is signaled only when the video data has the predefined chroma format.
13 . The electronic apparatus of claim 9 , wherein the default values indicate that the chroma components of the coding unit are decoded without using inverse BDPCM.
14 . The electronic apparatus of claim 8 , wherein the coding unit is decoded using inverse BDPCM when the coding unit is coded without applying transforms.
15 . A non-transitory computer readable storage medium having stored therein a bitstream comprising video information generated by a method of video encoding, the method comprising:
determining whether a coding unit has been coded using adaptive color-space transform (ACT), wherein the coding unit is coded by intra-prediction mode;
in accordance with a determination that the coding unit has not been coded using ACT:
determining whether chroma components of the coding unit have been coded using block differential pulse coded modulation (BDPCM); and
decoding chroma components of the coding unit based on the determination of whether the chroma components of the coding unit have been coded using BDPCM; and
in accordance with a determination that the coding unit has been coded using ACT:
decoding the coding unit by applying inverse ACT.
16 . The non-transitory computer readable storage medium of claim 15 , wherein the method further comprises:
signaling a first syntax element, wherein the first syntax element indicates whether the coding unit has been coded using ACT;
in accordance with a determination that the first syntax element has a zero value:
signaling one or more syntax elements, wherein the one or more syntax elements indicate whether the chroma components of the coding unit have been coded using BDPCM; and
in accordance with a determination that the first syntax element has a non-zero value:
not signaling the one or more syntax elements,
wherein when the one or more syntax elements are not signaled, default values are assigned to the one or more syntax elements.
17 . The non-transitory computer readable storage medium of claim 16 , wherein the method further comprises:
signaling a second syntax element, wherein the second syntax element indicates whether video data has a predefined chroma format,
wherein the signaling the first syntax element comprises:
in response to the second syntax element indicating that the video data has the predefined chroma format, signaling the first syntax element.
18 . The non-transitory computer readable storage medium of claim 17 , wherein the predefined chroma format is 4:4:4 chroma format.
19 . The non-transitory computer readable storage medium of claim 17 , wherein the first syntax element is signaled only when the video data has the predefined chroma format.
20 . The non-transitory computer readable storage medium of claim 16 , wherein the default values indicate that the chroma components of the coding unit are decoded without using inverse BDPCM.