BLOCK ADAPTIVE COLOR-SPACE CONVERSION CODING

• US 20150358631A1
• Filed: 06/03/2015
• Published: 12/10/2015
• Est. Priority Date: 06/04/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zhang, Li, Chen, Jianle, Sole Rojals, Joel, Karczewicz, Marta
• Granted Patent: US 10,142,642 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/52 by predictive encoding
• CPC Class Codes: H04N 19/573 Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction
• CPC Class Codes: H04N 19/577 Motion compensation with bidirectional frame interpolation, i.e. using B-pictures
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/82 involving filtering within a prediction loop
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding

Abstract

A video coder decodes a coding unit (CU) of video data. In decoding the video data, the video coder determines that the CU was encoded using the color space conversion. The video coder determines the initial quantization parameter (QP), determines the final QP that is equal to a sum of the initial QP and a QP offset, and inverse quantizes, based on the final QP, a coefficient block, then reconstructs the CU based on the inverse quantized coefficient blocks.

Claims

1. A method of decoding video data, the method comprising:

determining a coding unit (CU) of the video data was encoded using a color space conversion;

determining an initial quantization parameter (QP) for a color component;

based on the CU being encoded using the color space conversion, determining a final QP for the color component such that the final QP for the color component is equal to a sum of the initial QP of the color component and a non-zero QP offset for the color component; and

inverse quantizing, based on the final QP for the color component, a coefficient block for the CU, the coefficient block for the CU being based on sample values of the color component; and

reconstructing the CU based on the inverse quantized coefficient blocks for the CU.

2. The method of claim 1, wherein the QP offset for the color component is signaled in one of:

a picture parameter set, a sequence parameter set, and a slice header.

3. The method of claim 1, wherein the color component is a first color component of a plurality of color components, wherein the quantization parameter offset is a first quantization parameter offset, wherein the quantization parameter is a first quantization parameter, and wherein the first quantization parameter offset for the first quantization parameter for the first color component is equal to a second quantization parameter offset for a second quantization parameter for a second color component and wherein the first quantization parameter offset is less than a third quantization parameter offset for a third quantization parameter for a third color component.

4. The method of claim 1, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprises a luma component and a chroma component, the method further comprising:

determining, based at least in part on the final QP for the luma component, a boundary strength of a luma edge;

determining, based at least in part on the final QP for the chroma component, a boundary strength of a chroma edge;

in response to determining the boundary strength of the luma edge does not meet a first threshold, performing a deblocking filtering process on the luma edge; and

in response to determining the boundary strength of the chroma edge does not meet a second threshold, performing the deblocking filtering process on the chroma edge.

5. The method of claim 1, further comprising:

performing a deblocking filtering process on the CU using the initial QP for the color component.

6. The method of claim 1, wherein the CU is a first CU, the method further comprising:

determining a second QP for a color component of a second CU; and

in response to the second CU not being encoded using the color space conversion, inverse quantizing, based on the second QP for the color component, a coefficient block of the second CU, the coefficient block of the second CU based on sample values of the color component; and

reconstructing the second CU based on each of the one or more inverse quantized coefficient blocks of the second CU.

7. The method of claim 1, wherein the QP offset for the color component is dependent on an encoding mode of the CU.

8. The method of claim 7, further comprising determining the QP offset for the component such that the QP offset for the color component is equal to a first value when the encoding mode of the CU is an intra mode or an intra block copy (BC) mode, and equal to a second value when the encoding mode of the CU is an inter mode, the first value being different from the second value.

9. The method of claim 7, further comprising determining the QP offset for the component such that the QP offset for the color component is equal to a first value when the encoding mode of the CU is an intra mode, and equal to a second value when the encoding mode of the CU is an intra block copy (BC) mode or an inter mode, the first value being different from the second value.

10. The method of claim 1, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprises three color components, wherein each of the three color components is associated with a respective QP offset, and wherein the respective QP offsets are equal to (−

5+6*BitInc, −

5+6*BitInc, −

3+6*BitInc), wherein BitInc is equal to one of 0, 1, or 2.

11. The method of claim 1, wherein the QP offset for the color component is dependent on whether a slice type of the CU an I-slice type, a P-slice type, or a B-slice type.

12. The method of claim 11, further comprising:

determining the QP offset for the color component is equal to a first value when the slice type of the CU is the I-slice type and equal to a second value when the slice type of the CU is the P-slice type or the B-slice type, the first value being different from the second value.

13. The method of claim 11, further comprising:

determining the QP offset for the color component is equal to a first value when the slice type of the CU is the I-slice type, equal to a second value when the slice type of the CU is the P-slice type, and equal to a third value when the slice type of the CU is the B-slice type, the first value being different from the second value, the second value being different from the third value, and the first value being different from the third value.

14. The method of claim 1, wherein input data of the color space conversion has N-bit precision, and residual data for the CU after intra/inter prediction is in a range of [−

2^N, 2^N−

1], the method further comprising;

after performing the color space conversion process, clipping the transformed residual data such that the transformed residual data is within the range.

15. The method of claim 1, further comprising:

in response to determining the CU is coded with an intra coding mode;

predicting all chroma blocks of the CU using a same chroma prediction mode;

in response to the CU having only one prediction unit (PU), predicting all luma blocks of the CU using a same luma prediction mode, wherein the same luma prediction mode is the same as the same chroma prediction mode; and

in response to the CU having a plurality of PUs, predicting a first luma block of a first PU of the plurality of PUs using the same luma prediction mode.

16. A device for decoding video data, the device comprising:

a memory configured to store the video data; and

one or more processors configured to;

determine a coding unit (CU) of the video data was encoded using a color space conversion;

determine an initial quantization parameter (QP) for the color component;

based on the CU being encoded using the color space conversion, determine a final QP for the color component such that the final QP for the color component is equal to a sum of the initial QP of the color component and a non-zero QP offset for the color component; and

inverse quantize, based on the final QP for the color component, a coefficient block for the CU, the coefficient block for the CU being based on sample values of the color component; and

reconstructing the coding unit based on the inverse quantized coefficient blocks for the CU.

17. The device of claim 16, wherein, the QP offset for the color component is signaled in one of:

a picture parameter set, a sequence parameter set, and a slice header.

18. The device of claim 16, wherein the color component is a first color component of a plurality of color components, wherein the quantization parameter offset is a first quantization parameter offset, wherein the quantization parameter is a first quantization parameter, and wherein the first quantization parameter offset for the first quantization parameter for the first color component is equal to a second quantization parameter offset for a second quantization parameter for a second color component and wherein the first quantization parameter offset is less than a third quantization parameter offset for a third quantization parameter for a third color component.

19. The device of claim 16, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprises a luma component and a chroma component, wherein the one or more processors are further configured to:

determine, based at least in part on the final QP for the luma component, a boundary strength of a luma edge;

determine, based at least in part on the final QP for the chroma component, a boundary strength of a chroma edge;

in response to determining the boundary strength of the luma edge does not meet a first threshold, perform a deblocking filtering process on the luma edge; and

in response to determining the boundary strength of the chroma edge does not meet a second threshold, perform the deblocking filtering process on the chroma edge.

20. The device of claim 16, wherein the one or more processors are further configured to:

perform a deblocking filtering process on the CU using the initial QP for the color component.

21. The device of claim 16, wherein the CU is a first CU, wherein the one or more processors are further configured to:

determine a second QP for a color component of a second CU; and

in response to the second CU not being encoded using the color space conversion, inverse quantize, based on the second QP for the color component, a coefficient block of the second CU, the coefficient block of the second CU based on sample values of the color component; and

reconstruct the second CU based on each of the one or more inverse quantized coefficient blocks of the second CU.

22. The device of claim 16, wherein the QP offset for the color component is dependent on an encoding mode of the CU.

23. The device of claim 22, wherein the one or more processors are further configured to, determine the QP offset for the color component such that the QP offset for the color component is equal to a first value when the encoding mode of the CU is an intra mode or an intra block copy (BC) mode, and equal to a second value when the encoding mode of the CU is an inter mode, the first value being different from the second value.

24. The device of claim 22, wherein the one or more processors are further configured to determine the QP offset for the color component such that the QP offset for the color component is equal to a first value when the encoding mode of the CU is an intra mode, and equal to a second value when the encoding mode of the CU is an intra block copy (BC) mode or an inter mode, the first value being different from the second value.

25. The device of claim 16, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprises three color components, wherein each of the three color components is associated with a respective QP offset, and wherein the respective QP offsets are equal to (−

5+6*BitInc, −

5+6*BitInc, −

3+6*BitInc), wherein BitInc is equal to one of 0, 1, or 2.

26. The device of claim 16, wherein the QP offset for the color component is dependent on whether a slice type of the CU an I-slice type, a P-slice type, or a B-slice type.

27. The device of claim 26, wherein the one or more processors are further configured to:

determine the QP offset for the color component is equal to a first value when the slice type of the CU is the I-slice type and equal to a second value when the slice type of the CU is the P-slice type or the B-slice type, the first value being different from the second value.

28. The device of claim 26, wherein the one or more processors are further configured to:

determine the QP offset for the color component is equal to a first value when the slice type of the CU is the I-slice type, equal to a second value when the slice type of the CU is the P-slice type, and equal to a third value when the slice type of the CU is the B-slice type, the first value being different from the second value, the second value being different from the third value, and the first value being different from the third value.

29. The device of claim 16, wherein input data of the color space conversion has N-bit precision, and residual data for the CU after intra/inter prediction is in a range of [−

2^N, 2^N−

1], wherein the one or more processors are further configured to;

after performing the color space conversion process, clip the transformed residual data such that the transformed residual data is within the range.

30. The device of claim 16, wherein the one or more processors are further configured to:

in response to determining the CU is coded with an intra coding mode;

predict all chroma blocks of the CU using a same chroma prediction mode;

in response to the CU having only one prediction unit (PU), predict all luma blocks of the CU using a same luma prediction mode, wherein the same luma prediction mode is the same as the same chroma prediction mode; and

in response to the CU having a plurality of PUs, predict a first luma block of a first PU of the plurality of PUs using the same luma prediction mode.

31. The device of claim 16, wherein the device comprises at least one of:

an integrated circuit;

a microprocessor;

or

a wireless communication device.

32. The device of claim 16, further comprising a display configured to display decoded pictures of the video data.

33. A device for decoding video data, the device comprising:

means for determining that a coding unit (CU) of the video data was encoded using a color space conversion;

means for determining an initial quantization parameter (QP) for the color component;

based on the CU being encoded using the color space conversion, means for determining a final QP for the color component such that the final QP for the color component is equal to a sum of the initial QP of the color component and a non-zero QP offset for the color component; and

means for inverse quantizing, based on the final QP for the color component, a coefficient block for the CU, the coefficient block for the CU being based on sample values of the color component; and

means for reconstructing the coding unit based on the inverse quantized coefficient blocks for the CU.

34. The device of claim 33, wherein the QP offset for the color component is signaled in one of:

a picture parameter set, a sequence parameter set, and a slice header.

35. The device of claim 33, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprises a luma component and a chroma component, the device further comprising:

means for determining, based at least in part on the final QP for the luma component, a boundary strength of a luma edge;

means for determining, based at least in part on the final QP for the chroma component, a boundary strength of a chroma edge;

in response to determining the boundary strength of the luma edge does not meet a first threshold, means for performing a deblocking filtering process on the luma edge; and

in response to determining the boundary strength of the chroma edge does not meet a second threshold, means for performing the deblocking filtering process on the chroma edge.

36. The device of claim 33, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprises three color components, wherein each of the three color components is associated with a respective QP offset, and wherein the respective QP offsets are equal to (−

5+6*BitInc, −

5+6*BitInc, −

3+6*BitInc), wherein BitInc is equal to one of 0, 1, or 2.

37. The device of claim 33, further comprising:

in response to determining the CU is coded with an intra coding mode;

means for predicting all chroma blocks of the CU using a same chroma prediction mode; and

in response to the CU having only one prediction unit (PU), means for predicting all luma blocks of the CU using a same luma prediction mode, wherein the same luma prediction mode is the same as the same chroma prediction mode; and

in response to the CU having a plurality of PUs, means for predicting a first luma block of a first PU of the plurality of PUs using the same luma prediction mode.

38. The device of claim 33, further comprising:

means for performing a deblocking filtering process on the CU using the initial QP for the color component.

39. A computer-readable storage medium encoded with instructions that, when executed, cause one or more processors to:

determine a coding unit (CU) of the video data was encoded using a color space conversion;

determine an initial quantization parameter (QP) for the color component;

based on the CU being encoded using the color space conversion, determine a final QP for the color component such that the final QP for the color component is equal to a sum of the initial QP of the color component and a non-zero QP offset for the color component; and

inverse quantize, based on the final QP for the color component, a coefficient block for the CU, the coefficient block for the CU being based on sample values of the color component; and

reconstructing the coding unit based on the inverse quantized coefficient blocks for the CU.

40. The computer-readable storage medium of claim 39, wherein the QP offset for the color component is signaled in one of:

a picture parameter set, a sequence parameter set, and a slice header.

41. The computer-readable storage medium of claim 39, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprise a luma component and a chroma component, wherein the instructions further cause the one or more processors to:

determine, based at least in part on the final QP for the luma component, a boundary strength of a luma edge;

determine, based at least in part on the final QP for the chroma component, a boundary strength of a chroma edge;

in response to determining the boundary strength of the luma edge does not meet a first threshold, perform a deblocking filtering process on the luma edge; and

in response to determining the boundary strength of the chroma edge does not meet a second threshold, perform the deblocking filtering process on the chroma edge.

42. The computer-readable storage medium of claim 39, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprises three color components, wherein each of the three color components is associated with a respective QP offset, and wherein the respective QP offsets are equal to (−

5+6*BitInc, −

5+6*BitInc, −

3+6*BitInc), wherein BitInc is equal to one of 0, 1, or 2.

43. The computer-readable storage medium of claim 39, wherein the instructions further cause the one or more processors to:

in response to determining the CU is coded with an intra coding mode;

predict all chroma blocks of the CU using a same chroma prediction mode; and

in response to the CU having only one prediction unit (PU), predicting all luma blocks of the CU using a same luma prediction mode, wherein the same luma prediction mode is the same as the same chroma prediction mode; and

in response to the CU having a plurality of PUs, predicting a first luma block of a first PU of the plurality of PUs using the same luma prediction mode.

44. The computer-readable storage medium of claim 39, wherein the instructions further cause the one or more processors to:

perform a deblocking filtering process on the CU using the initial QP for the color component.

45. A method of encoding video data, the method comprising:

determining to encode a coding unit (CU) of the video data using a color space conversion;

determining an initial quantization parameter (QP) for a color component;

based on the CU being encoded using the color space conversion, setting a final QP for the color component such that the final QP for the color component is equal to a sum of the initial QP of the color component and a non-zero QP offset for the color component; and

quantizing, based on the final QP for the color component, a coefficient block for the CU, the coefficient block for the CU being based on sample values of the color component; and

outputting a video data bitstream comprising one or more entropy encoded syntax elements representative of each of the quantized coefficient blocks.

46. The method of claim 45, wherein the QP offset for the color component is signaled in one of:

a picture parameter set, a sequence parameter set, and a slice header.

47. The method of claim 45, wherein the color component is a first color component of a plurality of color components, wherein the quantization parameter offset is a first quantization parameter offset, wherein the quantization parameter is a first quantization parameter, and wherein the first quantization parameter offset for the first quantization parameter for the first color component is equal to a second quantization parameter offset for a second quantization parameter for a second color component and wherein the first quantization parameter offset is less than a third quantization parameter offset for a third quantization parameter for a third color component.

48. The method of claim 45, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprises a luma component and a chroma component, the method further comprising:

determining, based at least in part on the final QP for the luma component, a boundary strength of a luma edge;

determining, based at least in part on the final QP for the chroma component, a boundary strength of a chroma edge;

in response to determining the boundary strength of the luma edge does not meet a first threshold, performing a deblocking filtering process on the luma edge; and

in response to determining the boundary strength of the chroma edge does not meet a second threshold, performing the deblocking filtering process on the chroma edge.

49. The method of claim 45, further comprising:

performing a deblocking filtering process on the CU using the initial QP for the color component.

50. The method of claim 45, wherein the CU is a first CU, the method further comprising:

determining a second QP for a color component of a second CU;

in response to the second CU not being encoded using the color space conversion, quantizing, based on the second QP for the color component, a coefficient block of the second CU, the coefficient block of the second CU based on sample values of the color component; and

outputting the video data bitstream comprising a second set of one or more entropy encoded syntax elements representative of each of the quantized second coefficient blocks.

51. The method of claim 45, wherein the QP offset for the color component is dependent on an encoding mode of the CU.

52. The method of claim 51, further comprising determining the QP offset for the component such that the QP offset is equal to a first value when the encoding mode of the CU is an intra mode or an intra block copy (BC) mode, and equal to a second value when the encoding mode of the CU is an inter mode, the first value being different from the second value.

53. The method of claim 51, further comprising determining the QP offset for the component such that the QP offset is equal to a first value when the encoding mode of the CU is an intra mode, and equal to a second value when the encoding mode of the CU is an intra block copy (BC) mode or an inter mode, the first value being different from the second value.

54. The method of claim 45, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprises three color components, wherein each of the three color components is associated with a respective QP offset, and wherein the respective QP offsets are equal to (−

5+6*BitInc, −

5+6*BitInc, −

3+6*BitInc), wherein BitInc is equal to one of 0, 1, or 2.

55. The method of claim 45, wherein, for the color component, the QP offset for the color component is dependent on whether a slice type of the CU an I-slice type, a P-slice type, or a B-slice type.

56. The method of claim 45, wherein input data of the color space conversion has N-bit precision, and residual data for the CU after intra/inter prediction is in a range of [−

2^N, 2^N−

1], the method further comprising;

after performing the color space conversion process, clipping the transformed residual data such that the transformed residual data is within the range.

57. The method of claim 45, further comprising:

in response to determining the CU is coded with an intra coding mode;

predicting all chroma blocks of the CU using a same chroma prediction mode;

in response to the CU having only one prediction unit (PU), predicting all luma blocks of the CU using a same luma prediction mode, wherein the same luma prediction mode is the same as the same chroma prediction mode; and

in response to the CU having a plurality of PUs, predicting a first luma block of a first PU of the plurality of PUs using the same luma prediction mode.

58. A device for encoding video data, the device comprising:

a data storage medium configured to store the video data; and

one or more processors configured to;

determine to encode a coding unit (CU) of the video data using a color space conversion;

determine an initial quantization parameter (QP) for the color component;

based on the CU being encoded using the color space conversion, set a final QP for the color component such that the final QP for the color component is equal to a sum of the initial QP of the color component and a non-zero QP offset for the color component; and

quantize, based on the final QP for the color component, a coefficient block for the CU, the coefficient block for the CU being based on sample values of the color component; and

output a video data bitstream comprising one or more entropy encoded syntax elements representative of each of the quantized coefficient blocks.

59. The device of claim 58, wherein the QP offset for the color component is signaled in one of:

a picture parameter set, a sequence parameter set, and a slice header.

60. The device of claim 58, wherein the color component is a first color component of a plurality of color components, wherein the quantization parameter offset is a first quantization parameter offset, wherein the quantization parameter is a first quantization parameter, and wherein the first quantization parameter offset for the first quantization parameter for the first color component is equal to a second quantization parameter offset for a second quantization parameter for a second color component and wherein the first quantization parameter offset is less than a third quantization parameter offset for a third quantization parameter for a third color component.

61. The device of claim 58, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprises a luma component and a chroma component, wherein the one or more processors are further configured to:

determine, based at least in part on the final QP for the luma component, a boundary strength of a luma edge;

determine, based at least in part on the final QP for the chroma component, a boundary strength of a chroma edge;

in response to determining the boundary strength of the luma edge does not meet a first threshold, perform a deblocking filtering process on the luma edge; and

in response to determining the boundary strength of the chroma edge does not meet a second threshold, perform the deblocking filtering process on the chroma edge.

62. The device of claim 58, wherein the one or more processors are further configured to:

perform a deblocking filtering process on the CU using the initial QP for the color component.

63. The device of claim 58, wherein the CU is a first CU, wherein the one or more processors are further configured to:

determine a second QP for a color component of a second CU; and

in response to the second CU not being encoded using the color space conversion, quantize, based on the second QP for the color component, a coefficient block of the second CU, the coefficient block of the second CU based on sample values of the color component; and

output the video data bitstream comprising a second set of one or more entropy encoded syntax elements representative of each of the quantized second coefficient blocks.

64. The device of claim 58, wherein the QP offset for the color component is dependent on an encoding mode of the CU.

65. The device of claim 64, wherein the one or more processors are further configured to determine the QP offset for the component such that the QP offset is equal to a first value when the encoding mode of the CU is an intra mode or an intra block copy (BC) mode, and equal to a second value when the encoding mode of the CU is an inter mode, the first value being different from the second value.

66. The device of claim 64, wherein the one or more processors are further configured to determine the QP offset for the component such that the QP offset is equal to a first value when the encoding mode of the CU is an intra mode, and equal to a second value when the encoding mode of the CU is an intra block copy (BC) mode, the first value being different from the second value.

67. The device of claim 58, wherein the color component is a first color component of a plurality of color components, wherein the plurality of color components comprises three color components, wherein each of the three color components is associated with a respective QP offset, and wherein the respective QP offsets are equal to (−

5+6*BitInc, −

5+6*BitInc, −

3+6*BitInc), wherein BitInc is equal to one of 0, 1, or 2.

68. The device of claim 58, wherein the one or more processors are further configured to:

determine the QP offset for the color component is equal to a first value when the slice type of the CU is the I-slice type, equal to a second value when the slice type of the CU is the P-slice type, and equal to a third value when the slice type of the CU is the B-slice type, the first value being different from the second value, the second value being different from the third value, and the first value being different from the third value.

69. The device of claim 58, wherein input data of the color space conversion has N-bit precision, and residual data for the CU after intra/inter prediction is in a range of [−

2^N, 2^N−

1], wherein the one or more processors are further configured to;

after performing the color space conversion process, clip the transformed residual data such that the transformed residual data is within the range.

70. The device of claim 58, wherein the one or more processors are further configured to:

in response to determining the CU is coded with an intra coding mode;

predict all chroma blocks of the CU using a same chroma prediction mode;

in response to the CU having only one prediction unit (PU), predict all luma blocks of the CU using a same luma prediction mode, wherein the same luma prediction mode is the same as the same chroma prediction mode; and

in response to the CU having a plurality of PUs, predict a first luma block of a first PU of the plurality of PUs using the same luma prediction mode.

71. The device of claim 58, wherein the device comprises at least one of:

an integrated circuit;

a microprocessor;

or

a wireless communication device.

72. The device of claim 58, further comprising a camera configured to capture the video data.

73. A device for encoding video data, the device comprising:

means for determining to encode a coding unit (CU) of the video data using a color space conversion;

means for determining an initial quantization parameter (QP) for the color component;

based on the CU being encoded using the color space conversion, means for setting a final QP for the color component such that the final QP for the color component is equal to a sum of the initial QP of the color component and a non-zero QP offset for the color component; and

means for quantizing, based on the final QP for the color component, a coefficient block for the CU, the coefficient block for the CU being based on sample values of the color component; and

means for outputting a video data bitstream comprising one or more entropy encoded syntax elements representative of each of the quantized coefficient blocks.

74. A computer-readable storage medium encoded with instructions that, when executed, cause one or more processors to:

determine to encode a coding unit (CU) of the video data using a color space conversion;

determine an initial quantization parameter (QP) for the color component;

based on the CU being encoded using the color space conversion, set a final QP for the color component such that the final QP for the color component is equal to a sum of the initial QP of the color component and a non-zero QP offset for the color component; and

quantize, based on the final QP for the color component, a coefficient block for the CU, the coefficient block for the CU being based on sample values of the color component; and

output a video data bitstream comprising one or more entropy encoded syntax elements representative of each of the quantized coefficient blocks.