Coding Unit Quantization Parameters in Video Coding

1 . A method comprising:

receiving a coded largest coding unit in a video decoder, wherein the coded largest coding unit comprises a coded coding unit structure and a plurality of coded quantization parameters; and

decoding the coded largest coding unit based on the coded coding unit structure and the plurality of coded quantization parameters.

2 . The method of claim 1 , wherein the coded largest coding unit comprises a plurality of coding units as indicated by the coded coding unit structure, wherein at least a first coding unit and a second coding unit are different sizes.

3 . The method of claim 1 , wherein decoding the coded largest coding unit further comprises:

receiving, at least one of a sequence level, a picture level, a slice level, and a largest coding unit level, a minimum quantization parameter coding unit size; and

decoding the coded largest coding unit based on the minimum quantization parameter coding unit size.

4 . The method of claim 1 , wherein decoding the coded largest coding unit further comprises reconstructing a quantization parameter for a coding unit in the coded largest coding unit by adding a coded quantization parameter corresponding to the coding unit and a reconstructed quantization parameter for a coding unit preceding the coding unit in a coding order.

5 . The method of claim 1 , wherein decoding the coded largest coding unit further comprises reconstructing a quantization parameter for a coding unit in the coded largest coding unit by adding a coded quantization parameter corresponding to the coding unit and a reconstructed quantization parameter for a left spatially neighboring coding unit of the coding unit.

6 . The method of claim 1 , wherein decoding the coded largest coding unit further comprises reconstructing a quantization parameter for a coding unit in the coded largest coding unit by adding a coded quantization parameter corresponding to the coding unit and a function of one or more reconstructed quantization parameters of spatially neighboring coding units of the coding unit.

7 . The method of claim 1 , further comprising:

receiving a coded indicator of a first mode used to compute a first coded quantization parameter;

reconstructing the first coded quantization parameter according to the first mode;

receiving a coded indicator of a second mode used to compute a second coded quantization parameter; and

reconstructing the second coded quantization parameter according to the second mode.

8 . A method comprising:

receiving a largest coding unit in a video encoder;

determining a coding unit structure comprising a plurality of coding units for the largest coding unit;

computing a plurality of quantization parameters for the largest coding unit, wherein there is a one-to-one correspondence between each quantization parameter and a coding unit in the coding unit structure;

coding coding units in the plurality of coding units based on the corresponding quantization parameters to generate a portion of a compressed bit stream; and

coding the coding unit structure and the plurality of quantization parameters in the compressed bit stream.

9 . The method of claim 8 , wherein at least a first coding unit and a second coding unit are different sizes.

10 . The method of claim 8 , wherein determining a coding unit structure further comprises:

determining the coding unit structure based on a minimum quantization parameter coding unit size, wherein the minimum quantization parameter coding unit size is larger than a smallest coding unit size allowed in the coding unit structure.

11 . The method of claim 10 , further comprising signaling the minimum quantization parameter coding unit size in the compressed bit stream at least one of a sequence level, a picture level, a slice level, and a largest coding unit level.

12 . The method of claim 8 , wherein a quantization parameter is coded as a difference between a quantization parameter for a coding unit in the largest coding unit and a quantization parameter for a coding unit preceding the coding unit in a coding order.

13 . The method of claim 8 , wherein a quantization parameter is coded as a difference between a quantization parameter for a coding unit in the largest coding unit and a quantization parameter for a left spatially neighboring coding unit of the coding unit.

14 . The method of claim 8 , wherein a quantization parameter is coded as a difference between a quantization parameter for a coding unit in the largest coding unit and a function of one or more quantization parameters of spatially neighboring coding units of the coding unit.

15 . The method of claim 8 , further comprising:

selecting a mode for coding quantization parameters from a plurality of modes for coding quantization parameters; and

signaling the selected mode in the compressed bit stream at least one of a sequence level, a picture level, a slice level, and a largest coding unit level.

16 . A digital system comprising a video decoder configured to:

receive a coded largest coding unit, wherein the coded largest coding unit comprises a coded coding unit structure and a plurality of coded quantization parameters; and

decode the coded largest coding unit based on the coded coding unit structure and the plurality of coded quantization parameters.

17 . The digital system of claim 16 , wherein the coded largest coding unit comprises a plurality of coding units as indicated by the coded coding unit structure, wherein at least a first coding unit and a second coding unit are different sizes.

18 . The digital system of claim 16 , wherein the video decoder is further configured to:

receive, at least one of a sequence level, a picture level, a slice level, and a largest coding unit level, a minimum quantization parameter coding unit size; and

decode the largest coding unit based on the minimum quantization parameter coding unit size.

19 . The digital system of claim 16 , wherein the video decoder is further configured to decode the coded largest coding unit by reconstructing a quantization parameter for a coding unit in the coded largest coding unit by adding a coded quantization parameter corresponding to the coding unit and one selected from a group consisting of a reconstructed quantization parameter for a coding unit preceding the coding unit in a coding order, a reconstructed quantization parameter for a left spatially neighboring coding unit of the coding unit, and a function of one or more reconstructed quantization parameters of spatially neighboring coding units of the coding unit.

20 . The digital system of claim 16 , wherein the video decoder is further configured to:

receive a coded indicator of a first mode used to code a first coded quantization parameter;

reconstruct the first coded quantization parameter according to the first mode;

receive a coded indicator of a second mode used to code a second coded quantization parameter; and

reconstruct the second coded quantization parameter according to the second mode.