Modified quantizer

1. A method of video encoding using at least one processor, the method comprising:

obtaining a quantization index;

adding an offset value to the quantization index;

obtaining a quantization step size from a lookup table based on the quantization index and the offset value, wherein the quantization step size is scaled by 2 to the power of an integer that is obtained by subtracting a constant from an internal bit depth value; and

encoding video data based on the quantization step size, wherein the encoded video data includes a syntax element indicating the quantization index.

2. The method of claim 1 , wherein the constant is 8.

3. The method of claim 1 , wherein the offset value is determined based on the internal bit depth value of the video data.

4. The method of claim 1 , wherein the offset value is a negative integer.

5. The method of claim 1 , wherein the syntax element comprises a 9-bit integer.

6. The method of claim 1 , wherein a value of the 9-bit integer is equal to a result of adding the offset value to the quantization index.

7. The method of claim 1 , wherein a size of the lookup table is 255 values of the quantization step size.

8. A device for video encoding, the device comprising:

at least one memory configured to store program code; and

at least one processor configured to read the program code and operate as instructed by the program code, the program code including:

first obtaining code configured to cause the at least one processor to obtain a quantization index;

adding code configured to cause the at least one processor to add an offset value to the quantization index;

second obtaining code configured to cause the at least one processor to obtain a quantization step size from a lookup table based on the quantization index and the offset value, wherein the quantization step size is scaled by 2 to the power of an integer that is obtained by subtracting a constant from an internal bit depth value; and

encoding code configured to cause the at least one processor to encode the video data based on the quantization step size, wherein the encoded video data includes a syntax element indicating the quantization index.

9. The device of claim 8 , wherein the constant is 8.

10. The device of claim 8 , wherein the offset value is determined based on the internal bit depth value of the video data.

11. The device of claim 8 , wherein the offset value is a negative integer.

12. The device of claim 8 , wherein the syntax element comprises a 9-bit integer.

13. The device of claim 12 , wherein a value of the 9-bit integer is equal to a result of adding the offset value to the quantization index.

14. The device of claim 8 , wherein a size of the lookup table is 255 values of the quantization step size.

15. A non-transitory computer-readable medium storing instructions, the instructions comprising: one or more instructions that, when executed by one or more processors of a device for video encoding, cause the one or more processors to:

obtain a quantization index;

add an offset value to the quantization index;

obtain a quantization step size from a lookup table based on the quantization index and the offset value, wherein the quantization step size is scaled by 2 to the power of an integer that is obtained by subtracting a constant from the an internal bit depth value; and

encode video data based on the quantization step size, wherein the encoded video data includes a syntax element indicating the quantization index.

16. The non-transitory computer-readable medium of claim 15 , wherein the constant is 8.

17. The non-transitory computer-readable medium of claim 15 , wherein the offset value is determined based on the internal bit depth value of the video data.

18. The non-transitory computer-readable medium of claim 15 , wherein the syntax element comprises a 9-bit integer.