Residual coding constraint flag signaling
In a method of video decoding, a no transform skip residual coding rice constraint flag in a general constraint information (GCI) syntax structure for coded video data in a bitstream is determined. The no transform skip residual coding rice constraint flag is associated with a residual coding tool. When the no transform skip residual coding rice constraint flag in the GCI syntax structure is equal to 1, the coded video data is decoded without invoking the residual coding tool. When the no transform skip residual coding rice constraint flag is equal to 0, a value of a transform skip residual coding rice present in slice header flag for one of one or more coded layer video sequences (CLVSs) in the coded video data is determined. The coded video data in the bitstream is determined based on the value of the transform skip residual coding rice present in slice header flag.
1 . A method of video decoding, comprising:
decoding a syntax element in a general constraint information (GCI) syntax structure, the syntax element indicating a total number of additional constraint syntax elements in the GCI syntax structure to provide additional constraint information;
when the syntax element indicates that the total number of additional constraint syntax elements in the GCI syntax structure is larger than zero, determining a no transform skip residual coding Rice constraint flag in the GCI syntax structure for coded video data in a bitstream, the no transform skip residual coding Rice constraint flag being associated with a residual coding tool;
when the no transform skip residual coding Rice constraint flag in the GCI syntax structure is equal to 1, decoding, by a processor, the coded video data without invoking the residual coding tool; and
when the no transform skip residual coding Rice constraint flag is equal to 0, determining a value of a transform skip residual coding Rice present in slice header flag for one of one or more coded layer video sequences (CLVSs) in the coded video data in the bitstream, and
decoding, by the processor, the coded video data in the bitstream based on the value of the transform skip residual coding Rice present in slice header flag.
2 . The method of claim 1 , further comprising:
determining statistics of coefficients decoded from one or more transform units prior to a current transform unit;
determining an initial value of a Rice parameter for the current transform unit based on the statistics; and decoding coefficients of the current transform unit based on the Rice parameter, wherein
the decoding the coded video data in the bitstream based on the value includes decoding the coded video data in the bitstream based on the value of the transform skip residual coding Rice present in slice header flag and the decoded coefficients of the current transform unit.
3 . The method of claim 1 , wherein the no transform skip residual coding Rice constraint flag is a GCI syntax element in the GCI syntax structure that defines a constraint applied to the one or more CLVSs.
4 . The method of claim 1 , wherein the no transform skip residual coding Rice constraint flag being equal to 1 is indicative of disabling the residual coding tool in each of the one or more CLVSs.
5 . The method of claim 1 , wherein
the transform skip residual coding Rice present in slice header flag for coding control of the one of the one or more CLVSs is constrained to have the value indicative of not using the residual coding tool for decoding the one of the one or more CLVSs, the transform skip residual coding Rice present in slice header flag being a sequence parameter set (SPS) syntax element in an SPS syntax structure.
6 . The method of claim 1 , further comprising:
when the no transform skip residual coding Rice constraint flag is equal to 0, determining the value of the transform skip residual coding Rice present in slice header flag for coding control of the one of the one or more CLVSs, the transform skip residual coding Rice present in slice header flag being indicative of whether the residual coding tool is used in the one of the one or more CLVSs and being a sequence parameter set (SPS) syntax element in an SPS syntax structure.
7 . The method of claim 6 , wherein the determining the value of the transform skip residual coding Rice present in slice header flag further comprises:
inferring, when the transform skip residual coding Rice present in slice header flag is not present in the SPS syntax structure for the one of the one or more CLVSs, the value of the transform skip residual coding Rice present in slice header flag as indicating no use of the residual coding tool in the one of the one or more CLVSs.
8 . The method of claim 1 , wherein the determining the no transform skip residual coding Rice constraint flag further comprises:
decoding the no transform skip residual coding Rice constraint flag from the GCI syntax structure when a syntax element in the GCI syntax structure indicating that additional bits for general constraint information is included in the GCI syntax structure.
9 . A method of video encoding, comprising:
determining, by a processor, whether a residual coding tool is enabled for video data;
encoding the video data in a bitstream using the residual coding tool based on whether the residual coding tool is enabled for the video data;
when a total number of additional constraint syntax elements in a general constraint information (GCI) syntax structure for the video data in the bitstream is larger than zero, encoding a no transform skip residual coding Rice constraint flag in the GCI syntax structure for the video data in the bitstream, the no transform skip residual coding Rice constraint flag being associated with the residual coding tool; and
encoding a syntax element in the GCI syntax structure for the video data in the bitstream, the syntax element indicating the total number of the additional constraint syntax elements in the GCI syntax structure, wherein
the no transform skip residual coding Rice constraint flag in the GCI syntax structure is equal to 1 when the video data is encoded without invoking the residual coding tool; and
a transform skip residual coding Rice present in slice header flag for one of one or more coded layer video sequences (CLVSs) is encoded in the bitstream when the no transform skip residual coding Rice constraint flag is equal to 0.
10 . The method of claim 9 , further comprising:
determining statistics of coefficients from one or more transform units coded prior to a current transform unit;
determining an initial value of a Rice parameter for the current transform unit based on the statistics; and
encoding coefficients of the current transform unit based on the Rice parameter, wherein
the encoding the video data includes encoding the video data based on whether the residual coding tool is enabled for the video data and the encoded coefficients of the current transform unit.
11 . The method of claim 9 , wherein the no transform skip residual coding Rice constraint flag is a GCI syntax element in the GCI syntax structure that defines a constraint applied to the one or more CLVSs.
12 . The method of claim 9 , wherein the no transform skip residual coding Rice constraint flag being equal to 1 is indicative of disabling the residual coding tool in each of the one or more CLVSs.
13 . The method of claim 9 , wherein
the transform skip residual coding Rice present in slice header flag for coding control of the one of the one or more CLVSs is constrained to have a value indicative of not using the residual coding tool for decoding the one of the one or more CLVSs, the transform skip residual coding Rice present in slice header flag being a sequence parameter set (SPS) syntax element in an SPS syntax structure.
14 . The method of claim 9 , further comprising:
when the no transform skip residual coding Rice constraint flag is equal to 0, encoding a value of the transform skip residual coding Rice present in slice header flag for coding control of the one of the one or more CLVSs, the transform skip residual coding Rice present in slice header flag being indicative of whether the residual coding tool is used in the one of the one or more CLVSs and being a sequence parameter set (SPS) syntax element in an SPS syntax structure.
15 . The method of claim 14 , wherein
when the transform skip residual coding Rice present in slice header flag is not present in the SPS syntax structure for the one of the one or more CLVSs, the value of the transform skip residual coding Rice present in slice header flag is inferred as indicating no use of the residual coding tool in the one of the one or more CLVSs.
16 . The method of claim 9 , wherein the encoding the no transform skip residual coding Rice constraint flag comprises:
encoding the no transform skip residual coding Rice constraint flag in the GCI syntax structure when a syntax element in the GCI syntax structure indicating that additional bits for general constraint information is included in the GCI syntax structure.
17 . A non-transitory computer-readable storage medium storing instructions which when executed by a processor cause the processor to perform an encoding method comprising:
determining whether a residual coding tool is enabled for video data;
encoding the video data in a bitstream using the residual coding tool based on whether the residual coding tool is enabled for the video data;
when a total number of additional constraint syntax elements in a general constraint information (GCI) syntax structure for the video data in the bitstream is larger than zero, encoding a no transform skip residual coding Rice constraint flag in the GCI syntax structure for the video data in the bitstream, the no transform skip residual coding Rice constraint flag being associated with the residual coding tool;
encoding a syntax element in the GCI syntax structure for the video data in the bitstream, the syntax element indicating the total number of the additional constraint syntax elements in the GCI syntax structure; and
transmitting the encoded bitstream, wherein
the no transform skip residual coding Rice constraint flag in the GCI syntax structure is equal to 1 when the video data is encoded without invoking the residual coding tool; and
a transform skip residual coding Rice present in slice header flag for one of one or more coded layer video sequences (CLVSs) is encoded in the bitstream when the no transform skip residual coding Rice constraint flag is equal to 0.
18 . The non-transitory computer-readable storage medium of claim 17 , wherein the encoding method comprises:
determining statistics of coefficients decoded from one or more transform units prior to a current transform unit;
determining an initial value of a Rice parameter for the current transform unit based on the statistics; and
encoding coefficients of the current transform unit based on the Rice parameter, wherein
the video data in the bitstream is coded based on the value of the transform skip residual coding Rice present in slice header flag and the encoded coefficients of the current transform unit.
19 . The non-transitory computer-readable storage medium of claim 17 , wherein the no transform skip residual coding Rice constraint flag is a GCI syntax element in the GCI syntax structure that defines a constraint applied to the one or more CLVSs.
20 . The non-transitory computer-readable storage medium of claim 17 , wherein the no transform skip residual coding Rice constraint flag being equal to 1 is indicative of disabling the residual coding tool in each of the one or more CLVSs.