Entropy coding for palette escape symbol
Methods, systems, and devices for performing entropy coding for the palette escape symbol in palette mode coding and decoding are described. An example method for video processing includes performing a conversion between a video comprising one or more video regions comprising a current video block and a bitstream representation of the video, wherein the bitstream representation conforms to a format rule that the current video block is coded using a palette mode coding tool, wherein a binarization of an escape symbol for the current video block uses an exponential-Golomb (EG) code of order K, wherein K is a non-negative integer that is unequal to three, and wherein the palette mode coding tool represents the current video block using a palette of representative color values and wherein the escape symbol is used for a sample of the current video block coded without using the representative color values.
1. A method for processing video data, comprising:
determining, for a conversion between a current video block of a video and a bitstream of the video, that a prediction mode is applied to the current video block, wherein in the prediction mode, reconstructed samples are represented by a set of representative color values, and the set of representative color values comprises at least one of 1) palette predictors, 2) escaped samples, or 3) palette information included in the bitstream; and
performing the conversion at least based on the prediction mode,
wherein a first syntax element specifying a quantized value of the escaped sample is included in the bitstream, and wherein a binarization of the first syntax element uses an exponential-Golomb (EG) code of order K, K a non-negative integer that is unequal to three,
wherein the escaped sample is reconstructed based on a Clip function and the quantized value of the escaped sample to generate a reconstructed escape sample,
wherein the reconstructed escape sample is determined based on Clip3(0, (1<<BitDepth)−1, tmpVal), wherein tmpVal is determined based on (m<<(qP/6)+32) >>6, wherein qP specifies a quantization parameter, and wherein m is determined based on the quantized value of the escaped sample.
2. The method of claim 1 , wherein K=5.
3. The method of claim 1 , wherein the qP is determined based on Max(QpPrimeTsMin, Qp′Y),
wherein QpPrimeTsMin denotes a minimum allowed quantization parameter for transform skip mode, and
wherein Qp′Y denotes a luma quantization parameter.
4. The method of claim 3 , wherein QpPrimeTsMin is defined as 6*n+4, wherein n is the value of a second syntax element included in the bitstream.
5. The method of claim 4 , wherein the second syntax element is included in a sequence level of the bitstream.
6. The method of claim 1 , wherein the conversion includes encoding the current video block into the bitstream.
7. The method of claim 1 , wherein the conversion includes decoding the current video block from the bitstream.
8. An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:
determine, for a conversion between a current video block of a video and a bitstream of the video, that a prediction mode is applied to the current video block, wherein in the prediction mode, reconstructed samples are represented by a set of representative color values, and the set of representative color values comprises at least one of 1) palette predictors, 2) escaped samples, or 3) palette information included in the bitstream; and
perform the conversion at least based on the prediction mode,
wherein a first syntax element specifying a quantized value of the escaped sample is included in the bitstream, and wherein a binarization of the first syntax element uses an exponential-Golomb (EG) code of order K, K a non-negative integer that is unequal to three,
wherein the escaped sample is reconstructed based on a Clip function and the quantized value of the escaped sample to generate a reconstructed escape sample,
wherein the reconstructed escape sample is determined based on Clip3(0, (1<<BitDepth) −1, tmpVal), wherein tmpVal is determined based on (m<<(qP/6)+32) >>6, wherein qP specifies a quantization parameter, and wherein m is determined based on the quantized value of the escaped sample.
9. The apparatus of claim 8 , wherein K=5.
10. The apparatus of claim 8 , wherein the qP is determined based on Max(QpPrimeTsMin, Qp′Y),
wherein QpPrimeTsMin denotes a minimum allowed quantization parameter for transform skip mode, and
wherein Qp′Y denotes a luma quantization parameter.
11. The apparatus of claim 10 , wherein QpPrimeTsMin is defined as 6*n+4, wherein n is the value of a second syntax element included in the bitstream.
12. The apparatus of claim 11 , wherein the second syntax element is included in a sequence level of the bitstream.
13. A non-transitory computer-readable storage medium storing instructions that cause a processor to:
determine, for a conversion between a current video block of a video and a bitstream of the video, reconstructed samples are represented by a set of representative color values, and the set of representative color values comprises at least one of 1) palette predictors, 2) escaped samples, or 3) palette information included in the bitstream; and
perform the conversion at least based on the prediction mode,
wherein a first syntax element specifying a quantized value of the escaped sample is included in the bitstream, and wherein a binarization of the first syntax element uses an exponential-Golomb (EG) code of order K, K a non-negative integer that is unequal to three,
wherein the escaped sample is reconstructed based on a Clip function and the quantized value of the escaped sample to generate a reconstructed escape sample,
wherein the reconstructed escape sample is determined based on Clip3(0, (1<<BitDepth)−1, tmpVal), wherein tmpVal is determined based on (m<<(qP/6)+32) >>6, wherein qP specifies a quantization parameter, and wherein m is determined based on the quantized value of the escaped sample.
14. The non-transitory computer-readable storage medium of claim 13 , wherein K=5.
15. A non-transitory computer-readable recording medium storing a bitstream which is generated by a method performed by a video processing apparatus, wherein the method comprises:
determining, for a current video block of a video, that a prediction mode is applied to the current video block, wherein in the prediction mode, reconstructed samples are represented by a set of representative color values, and the set of representative color values comprises at least one of 1) palette predictors, 2) escaped samples, or 3) palette information included in the bitstream; and
generating the bitstream at least based on the prediction mode,
wherein a first syntax element specifying a quantized value of the escaped sample is included in the bitstream, and wherein a binarization of the first syntax element uses an exponential-Golomb (EG) code of order K, K a non-negative integer that is unequal to three,
wherein the escaped sample is reconstructed based on a Clip function and the quantized value of the escaped sample to generate a reconstructed escape sample,
wherein the reconstructed escape sample is determined based on Clip3(0, (1<<BitDepth)−1, tmpVal), wherein tmpVal is determined based on (m<<(qP/6)+32) >>6, wherein qP specifies a quantization parameter, and wherein m is determined based on the quantized value of the escaped sample.
16. The non-transitory computer-readable recording medium of claim 15 , wherein the qP is determined based on Max(QpPrimeTsMin, Qp′Y),
wherein QpPrimeTsMin denotes a minimum allowed quantization parameter for transform skip mode, and
wherein Qp′Y denotes a luma quantization parameter.
17. The non-transitory computer-readable storage medium of claim 13 , wherein the qP is determined based on Max(QpPrimeTsMin, Qp′Y),
wherein QpPrimeTsMin denotes a minimum allowed quantization parameter for transform skip mode, and
wherein Qp′Y denotes a luma quantization parameter.