Methods and apparatus of video coding using palette mode
An electronic apparatus performs a method of decoding video data. The method comprises, receiving, from bitstream, video data corresponding to a palette-mode coded block; determining a quantization parameter value from information included in a parameter set associated with the palette-mode coded block; identifying escape samples in the palette-mode coded block; in accordance with a determination that the quantization parameter value is greater than a threshold value: performing de-quantization on quantized escape samples according to a predefined formula to obtain reconstructed escape sample values; and in accordance with a determination that the quantization parameter value is less than or equal to the threshold value: setting the reconstructed escape samples to be the quantized escape sample values.
1 . A method for video decoding, comprising:
receiving, from a bitstream, a coding block in a palette mode;
determining a quantization parameter according to information parsed from a sequence parameter set associated with the coding block; wherein the quantization parameter is limited according to a formula: MAX (4, QPcu), wherein QPcu represents a quantization parameter value corresponding to the coding block;
identifying an escape sample in the coding block;
in accordance with a determination that the quantization parameter is greater than a threshold value:
obtaining a reconstructed sample based on the escape sample using a predefined formula; and
in accordance with a determination that the quantization parameter is equal to the threshold value:
setting the reconstructed sample to be a value of the escape sample.
2 . The method of claim 1 , wherein:
in accordance with a determination that the quantization parameter is greater than the threshold value, the reconstructed sample is obtained through a lossy process; and
in accordance with a determination that the quantization parameter is equal to the threshold value, the reconstructed sample is obtained through a lossless process.
3 . The method of claim 1 , wherein the predefined formula is associated with a look-up table defined as
QP %6
0
1
2
3
4
5
decScale[QP %6]
40
45
51
57
64
72.
4 . The method of claim 1 , wherein the escape sample is associated with additional overhead in the bitstream.
5 . The method of claim 1 , wherein the threshold value is equal to 4.
6 . 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 acts comprising:
receiving, from a bitstream, a coding block in a palette mode;
determining a quantization parameter according to information parsed from a sequence parameter set associated with the coding block; wherein the quantization parameter is limited according to a formula: MAX (4, QPcu), wherein QPcu represents a quantization parameter value corresponding to the coding block;
identifying an escape sample in the coding block;
in accordance with a determination that the quantization parameter is greater than a threshold value:
obtaining a reconstructed sample based on the escape sample using a predefined formula; and
in accordance with a determination that the quantization parameter is equal to the threshold value:
setting the reconstructed sample to be a value of the escape sample.
7 . The electronic apparatus of claim 6 , wherein:
in accordance with a determination that the quantization parameter is greater than the threshold value, the reconstructed sample is obtained through a lossy process; and
in accordance with a determination that the quantization parameter is equal to the threshold value, the reconstructed sample is obtained through a lossless process.
8 . The electronic apparatus of claim 6 , wherein the predefined formula is associated with a look-up table defined as
QP %6
0
1
2
3
4
5
decScale[QP %6]
40
45
51
57
64
72.
9 . The electronic apparatus of claim 6 , wherein the escape sample is associated with additional overhead in the bitstream.
10 . The electronic apparatus of claim 6 , wherein the threshold value is equal to 4.
11 . A non-transitory computer readable storage medium storing a bitstream to be decoded by a method for video decoding comprising:
receiving, from a bitstream, a coding block in a palette mode;
determining a quantization parameter according to information parsed from a sequence parameter set associated with the coding block; wherein the quantization parameter is limited according to a formula: MAX (4, QPcu), wherein QPcu represents a quantization parameter value corresponding to the coding block;
identifying an escape sample in the coding block;
in accordance with a determination that the quantization parameter is greater than a threshold value:
obtaining a reconstructed sample based on the escape sample using a predefined formula; and
in accordance with a determination that the quantization parameter is equal to the threshold value:
setting the reconstructed sample to be a value of the escape sample.
12 . The non-transitory computer readable storage medium of claim 11 , wherein:
in accordance with a determination that the quantization parameter is greater than the threshold value, the reconstructed sample is obtained through a lossy process; and
in accordance with a determination that the quantization parameter is equal to the threshold value, the reconstructed sample is obtained through a lossless process.
13 . The non-transitory computer readable storage medium of claim 11 , wherein the predefined formula is associated with a look-up table defined as
QP %6
0
1
2
3
4
5
decScale[QP %6]
40
45
51
57
64
72.
14 . The non-transitory computer readable storage medium of claim 11 , wherein the threshold value is equal to 4.