Escape color coding for palette coding mode
Systems, methods, and instrumentalities are disclosed for escape color coding for palette coding mode. A video bitstream may be received. The video bitstream may comprise a quantization parameter (QP) and/or a quantized escape color value that corresponds to an escape color pixel. A scaled escape color value may be generated by scaling the quantized escape color value by a scaling factor. A left-shift parameter may be determined based on the QP. A left-shifted escape color value may be generated by left-shifting the scaled escape color value based on the left-shift parameter. A right-shifted escape color value may be generated by right-shifting the left-shifted escape color value based on a constant parameter. A reconstructed escape color value may be determined based on the right-shifted escape color value. The device may decode the video bitstream based on the reconstructed escape color value.
1. A method for decoding a video bitstream, the method comprising:
receiving a video bitstream comprising a quantization parameter and a quantized escape color value that defines an escape color;
generating a scaled escape color value by scaling the quantized escape color value by a scaling factor;
determining a left-shift parameter based on the quantization parameter;
generating a left-shifted escape color value by left-shifting the scaled escape color value based on the left-shift parameter;
generating a right-shifted escape color value by right-shifting the left-shifted escape color value by a constant parameter; and
determining a reconstructed escape color value based on the right-shifted escape color value.
2. The method of claim 1 , further comprising decoding the video bitstream based on the reconstructed escape color value.
3. The method of claim 1 , wherein the constant parameter is equal to 6.
4. The method of claim 1 , wherein the right-shifting of the left-shifted escape color value is independent of the quantization parameter.
5. The method of claim 1 , wherein the left-shift parameter is determined by dividing the quantization parameter by 6; and wherein the left-shifted escape color value is generated by adding 32 to the left-shift parameter.
6. The method of claim 1 , wherein the escape color is associated with a coding unit that comprises at least one major color and at least one escape color.
7. The method of claim 1 , wherein the quantized escape color value is associated with a lossy coding.
8. The method of claim 1 , further comprising determining the scaling factor based on the quantization parameter.
9. The method of claim 1 , wherein the quantized escape color value corresponds to an escape color pixel.
10. A video coding device comprising:
a processor configured to:
receive a video bitstream that comprises a quantization parameter and a quantized escape color value, wherein the quantized escape color value defines an escape color;
generate a scaled escape color value by scaling the quantized escape color value by a scaling factor;
determine a left-shift parameter based on the quantization parameter;
generate a left-shifted escape color value by left-shifting the scaled escape color value based on the left-shift parameter;
generate a right-shifted escape color value by right-shifting the left-shifted escape color value by a constant parameter; and
determine a reconstructed escape color value based on the right-shifted escape color value.
11. The video coding device of claim 10 , wherein the processor is further configured to decode the video bitstream based on the reconstructed escape color value.
12. The video coding device of claim 10 , wherein the constant parameter is equal to 6.
13. The video coding device of claim 10 , wherein the right-shifting of the left-shifted escape color value is independent of the quantization parameter.
14. The video coding device of claim 10 , wherein the left-shift parameter is determined by dividing the quantization parameter by 6; and wherein the left-shifted escape color value is generated by adding 32 to the left-shift parameter.
15. The video coding device of claim 10 , wherein the escape color is associated with a coding unit that comprises at least one major color and at least one escape color.
16. The video coding device of claim 10 , wherein the quantized escape color value is associated with a lossy coding.
17. The video coding device of claim 10 , wherein the processor is further configured to determine the scaling factor based on the quantization parameter.
18. The video coding device of claim 10 , wherein the quantized escape color value corresponds to an escape color pixel.