BETA OFFSET CONTROL FOR DEBLOCKING FILTERS IN VIDEO CODING

• US 20130272425A1
• Filed: 03/14/2013
• Published: 10/17/2013
• Est. Priority Date: 04/13/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: VAN DER AUWERA, Geert, WANG, Xianglin, KARCZEWICZ, Marta
• Granted Patent: US 9,344,723 B2
• Time in Patent Office: Days
• US Class Current: 375/240.24
• 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 19/134 characterised by the element, parameter or criterion affecting or controlling the adaptive coding
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/80 Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation H04N19/635, H04N19/86 take precedence
• 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

Abstract

Techniques are described for providing continuous control of a deblocking filter for a video block using a beta offset parameter. Deblocking filters are defined based on one or more deblocking decisions. Conventionally, a quantization parameter and a beta offset parameter are used to identify a beta parameter (“β”) value that determines threshold values of the deblocking decisions. The value of the beta offset parameter results in a change or increment of the β value. For small increments of the β value, rounding of the threshold values may result in no change and discontinuous control of the deblocking decisions. The techniques include calculating at least one deblocking decision for the deblocking filter according to a threshold value that has been modified based on a multiplier value of the beta offset parameter. The multiplier value applied to the beta offset parameter causes an integer change in the modified threshold value.

Claims

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

decoding a beta offset parameter (“

beta_offset”

) that controls a deblocking filter for a video block;

identifying a beta parameter (“

β

”

) value used to determine a threshold value of at least one deblocking decision for the deblocking filter; and

calculating the deblocking decision for the deblocking filter according to a modified threshold value, wherein the threshold value is modified based on a multiplier value of the beta offset parameter that causes an integer change in the modified threshold value.

2. The method of claim 1, wherein the modified threshold value of the deblocking decision is equal to a sum of an original threshold value and the multiplier value of the beta offset parameter, wherein the multiplier value comprises an integer.

3. The method of claim 2, further comprising:

calculating an index parameter based on a quantization parameter value of the video block; and

identifying the beta parameter value using the index parameter based on one of a deblocking parameter table or equations.

4. The method of claim 2, wherein, when the deblocking decision comprises an on/off deblocking decision with the original threshold value equal to β

, the modified threshold value is equal to β

+A*beta_offset, where A is the multiplier value.

5. The method of claim 2, wherein, when the deblocking decision comprises a strong/weak deblocking decision with the original threshold value equal to β

/8, and the modified threshold value is equal to (β

/8)+B*beta_offset, where B is the multiplier value.

6. The method of claim 2, wherein, when the deblocking decision comprises a weak filter width deblocking decision with the original threshold value equal to 3β

/16, the modified threshold value is equal to (3β

/16)+C*beta_offset, where C is the multiplier value.

7. The method of claim 1, further comprising determining the modified threshold value of the deblocking decision, wherein the determination includes:

calculating an index parameter based on a sum of a quantization parameter value of the video block and the multiplier value of the beta offset parameter, wherein the multiplier value comprises an integer; and

identifying the beta parameter value using the index parameter based on one of a deblocking parameter table or equations, wherein the multiplier value of the beta offset parameter results in an increment of the beta parameter value (“

Δ

β

”

) that causes an integer change in the modified threshold value, the modified threshold value being equal to an original threshold value determined using β

+Δ

β

.

8. The method of claim 7,

wherein calculating the index parameter comprises calculating a separate index parameter for each of several different deblocking decisions based on a different multiplier value of the beta offset parameter selected according to an original threshold value for a particular one of the deblocking decisions;

and

wherein identifying the beta parameter value comprises identifying a separate beta parameter value using the separate index parameter for each of the different deblocking decisions.

9. The method of claim 7,

wherein calculating the index parameter comprises calculating a single index parameter for two or more different deblocking decisions based on a single multiplier value of the beta offset parameter selected according to a smallest original threshold value for the deblocking decisions;

and

wherein identifying the beta parameter value comprises identifying a single beta parameter value using the single index parameter for the two or more different deblocking decisions.

10. The method of claim 7, wherein, when the deblocking decision comprises an on/off deblocking decision with the original threshold value equal to β

, the multiplier value is set equal to N for the beta offset parameter resulting in Δ

β

being equal to 2*N*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to β

+Δ

β

.

11. The method of claim 7, wherein, when the deblocking decision comprises a strong/weak deblocking decision with the original threshold value equal to β

/8, the multiplier value is set equal to 4 for the beta offset parameter resulting in Δ

β

being equal to 8*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to (β

+Δ

β

)/8.

12. The method of claim 7, wherein, when the deblocking decision comprises a weak filter width deblocking decision with the original threshold value equal to 3β

/16, the multiplier value is set equal to 3 for the beta offset parameter resulting in Δ

β

being equal to 6*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to (3(β

+Δ

β

))/16.

13. The method of claim 7, wherein, when the deblocking decision comprises any of an on/off deblocking decision with the original threshold value equal to β

, a weak/strong deblocking decision with the original threshold value equal to β

/8, or a weak filter width deblocking decision with the original threshold value equal to 3β

/16, the multiplier value is set equal to 4 for the beta offset parameter resulting in Δ

β

being equal to 8*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to the original threshold value determined using β

+Δ

β

.

14. The method of claim 1, wherein decoding the beta offset parameter comprises decoding a syntax element received from a video encoder to determine the beta offset parameter.

15. The method of claim 1, further comprising applying the deblocking filter defined according to the at least one deblocking decision to a reconstructed version of the video block for at least one of presentation on a display device or use as a reference block.

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

encoding a beta offset parameter (“

beta_offset”

) that controls a deblocking filter for a video block;

identifying a beta parameter (“

β

”

) value used to determine a threshold value of at least one deblocking decision for the deblocking filter; and

calculating the deblocking decision for the deblocking filter according to a modified threshold value, wherein the threshold value is modified based on a multiplier value of the beta offset parameter that causes an integer change in the modified threshold value.

17. The method of claim 16, wherein the modified threshold value of the deblocking decision is equal to a sum of an original threshold value and the multiplier value of the beta offset parameter, wherein the multiplier value comprises an integer.

18. The method of claim 17, further comprising:

calculating an index parameter based on a quantization parameter value of the video block; and

identifying the beta parameter value using the index parameter based on one of a deblocking parameter table or equations.

19. The method of claim 17, wherein, when the deblocking decision comprises an on/off deblocking decision with the original threshold value equal to β

, the modified threshold value is equal to β

+A*beta_offset, where A is the multiplier value.

20. The method of claim 17, wherein, when the deblocking decision comprises a strong/weak deblocking decision with the original threshold value equal to β

/8, and the modified threshold value is equal to (β

/8)+B*beta_offset, where B is the multiplier value.

21. The method of claim 17, wherein, when the deblocking decision comprises a weak filter width deblocking decision with the original threshold value equal to 3β

/16, the modified threshold value is equal to (3β

/16)+C*beta_offset, where C is the multiplier value.

22. The method of claim 16, further comprising determining the modified threshold value of the deblocking decision, wherein the determination includes:

calculating an index parameter based on a sum of a quantization parameter value of the video block and the multiplier value of the beta offset parameter, wherein the multiplier value comprises an integer; and

identifying the beta parameter value using the index parameter based on one of a deblocking parameter table or equations, wherein the multiplier value of the beta offset parameter results in an increment of the beta parameter value (“

Δ

β

”

) that causes an integer change in the modified threshold value, the modified threshold value being equal to an original threshold value determined using β

+Δ

β

.

23. The method of claim 22,

wherein calculating the index parameter comprises calculating a separate index parameter for each of several different deblocking decisions based on a different multiplier value of the beta offset parameter selected according to an original threshold value for a particular one of the deblocking decisions;

and

wherein identifying the beta parameter value comprises identifying a separate beta parameter value using the separate index parameter for each of the different deblocking decisions.

24. The method of claim 22,

wherein calculating the index parameter comprises calculating a single index parameter for two or more different deblocking decisions based on a single multiplier value of the beta offset parameter selected according to a smallest original threshold value for the deblocking decisions;

and

wherein identifying the beta parameter value comprises identifying a single beta parameter value using the single index parameter for the two or more different deblocking decisions.

25. The method of claim 22, wherein, when the deblocking decision comprises an on/off deblocking decision with the original threshold value equal to β

, the multiplier value is set equal to N for the beta offset parameter resulting in Δ

β

being equal to 2*N*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to β

+Δ

β

.

26. The method of claim 22, wherein, when the deblocking decision comprises a strong/weak deblocking decision with the original threshold value equal to β

/8, the multiplier value is set equal to 4 for the beta offset parameter resulting in Δ

β

being equal to 8*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to (β

+Δ

β

)/8.

27. The method of claim 22, wherein, when the deblocking decision comprises a weak filter width deblocking decision with the original threshold value equal to 3β

/16, the multiplier value is set equal to 3 for the beta offset parameter resulting in Δ

β

being equal to 6*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to (3(β

+Δ

β

))/16.

28. The method of claim 22, wherein, when the deblocking decision comprises any of an on/off deblocking decision with the original threshold value equal to β

, a weak/strong deblocking decision with the original threshold value equal to β

/8, or a weak filter width deblocking decision with the original threshold value equal to 3β

/16, the multiplier value is set equal to 4 for the beta offset parameter resulting in Δ

β

being equal to 8*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to the original threshold value determined using β

+Δ

β

.

29. The method of claim 16, wherein encoding the beta offset parameter comprises encoding a syntax element to indicate the beta offset parameter to a video decoder.

30. The method of claim 16, further comprising applying the deblocking filter defined according to the at least one deblocking decision to a reconstructed version of the video block for use as a reference block.

31. A video coding device comprising:

a memory that stores video data; and

a processor configured to code a beta offset parameter (“

beta_offset”

) that controls a deblocking filter for a video block, identify a beta parameter (“

β

”

) value used to determine a threshold value of at least one deblocking decision for the deblocking filter, and calculate the deblocking decision for the deblocking filter according to the threshold value modified based on a multiplier value of the beta offset parameter that causes an integer change in the modified threshold value.

32. The video coding device of claim 31, wherein the modified threshold value of the deblocking decision is equal to a sum of an original threshold value and the multiplier value of the beta offset parameter, wherein the multiplier value comprises an integer.

33. The video coding device of claim 32, wherein the processor is configured to:

calculate an index parameter based on a quantization parameter value of the video block; and

identify the beta parameter value using the index parameter based on one of a deblocking parameter table or equations.

34. The video coding device of claim 32, wherein, when the deblocking decision comprises an on/off deblocking decision with the original threshold value equal to β

, the modified threshold value is equal to β

+A*beta_offset, where A is the multiplier value.

35. The video coding device of claim 32, wherein, when the deblocking decision comprises a strong/weak deblocking decision with the original threshold value equal to β

/8, and the modified threshold value is equal to (β

/8)+B*beta_offset, where B is the multiplier value.

36. The video coding device of claim 32, wherein, when the deblocking decision comprises a weak filter width deblocking decision with the original threshold value equal to 3β

/16, the modified threshold value is equal to (3β

/16)+C*beta_offset, where C is the multiplier value.

37. The video coding device of claim 31, wherein the processor is configured to determine the modified threshold value of the deblocking decision, including:

calculating an index parameter based on a sum of a quantization parameter value of the video block and the multiplier value of the beta offset parameter, wherein the multiplier value comprises an integer; and

identifying the beta parameter value using the index parameter based on one of a deblocking parameter table or equations, wherein the multiplier value of the beta offset parameter results in an increment of the beta parameter value (“

Δ

β

”

) that causes an integer change in the modified threshold value, the modified threshold value being equal to an original threshold value determined using β

+Δ

β

.

38. The video coding device of claim 37, wherein the processor is configured to:

calculate a separate index parameter for each of several different deblocking decisions based on a different multiplier value of the beta offset parameter selected according to an original threshold value for a particular one of the deblocking decisions; and

identify a separate beta parameter value using the separate index parameter for each of the different deblocking decisions.

39. The video coding device of claim 37, wherein the processor is configured to:

calculate a single index parameter for two or more different deblocking decisions based on a single multiplier value of the beta offset parameter selected according to a smallest original threshold value for the deblocking decisions; and

identify a single beta parameter value using the single index parameter for the two or more different deblocking decisions.

40. The video coding device of claim 37, wherein, when the deblocking decision comprises an on/off deblocking decision with the original threshold value equal to β

, the multiplier value is set equal to N for the beta offset parameter resulting in Δ

β

being equal to 2*N*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to β

+Δ

β

.

41. The video coding device of claim 37, wherein, when the deblocking decision comprises a strong/weak deblocking decision with the original threshold value equal to β

/8, the multiplier value is set equal to 4 for the beta offset parameter resulting in Δ

β

being equal to 8*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to (β

+Δ

β

)/8.

42. The video coding device of claim 37, wherein, when the deblocking decision comprises a weak filter width deblocking decision with the original threshold value equal to 3β

/16, the multiplier value is set equal to 3 for the beta offset parameter resulting in Δ

β

being equal to 6*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to (3(β

+Δ

β

))/16.

43. The video coding device of claim 37, wherein, when the deblocking decision comprises any of an on/off deblocking decision with the original threshold value equal to β

, a weak/strong deblocking decision with the original threshold value equal to β

/8, or a weak filter width deblocking decision with the original threshold value equal to 3β

/16, the multiplier value is set equal to 4 for the beta offset parameter resulting in Δ

β

being equal to 8*beta_offset when the index parameter is greater than 27, and the modified threshold value is equal to the original threshold value determined using β

+Δ

β

.

44. A video coding device comprising:

means for coding a beta offset parameter (“

beta_offset”

) that controls a deblocking filter for a video block;

means for identifying a beta parameter (“

β

”

) value used to determine a threshold value of at least one deblocking decision for the deblocking filter; and

means for calculating the deblocking decision for the deblocking filter according to the threshold value modified based on a multiplier value of the beta offset parameter that causes an integer change in the modified threshold value.

45. The video coding device of claim 44, wherein the modified threshold value of the deblocking decision is equal to a sum of an original threshold value and the multiplier value of the beta offset parameter, wherein the multiplier value comprises an integer.

46. The video coding device of claim 45, further comprising:

means for calculating an index parameter based on a quantization parameter value of the video block; and

means for identifying the beta parameter value using the index parameter based on one of a deblocking parameter table or equations.

47. The video coding device of claim 44, further comprising means for determining the modified threshold value of the deblocking decision, wherein the means for determining includes:

means for calculating an index parameter based on a sum of a quantization parameter value of the video block and the multiplier value of the beta offset parameter, wherein the multiplier value comprises an integer; and

means for identifying the beta parameter value using the index parameter based on one of a deblocking parameter table or equations, wherein the multiplier value of the beta offset parameter results in an increment of the beta parameter value (“

Δ

β

”

) that causes an integer change in the modified threshold value, the modified threshold value being equal to an original threshold value determined using β

+Δ

β

.

48. The video coding device of claim 47, further comprising:

means for calculating a separate index parameter for each of several different deblocking decisions based on a different multiplier value of the beta offset parameter selected according to an original threshold value for a particular one of the deblocking decisions; and

means for identifying a separate beta parameter value using the separate index parameter for each of the different deblocking decisions.

49. The video coding device of claim 47, further comprising:

means for calculating a single index parameter for two or more different deblocking decisions based on a single multiplier value of the beta offset parameter selected according to a smallest original threshold value for the deblocking decisions; and

means for identifying a single beta parameter value using the single index parameter for the two or more different deblocking decisions.

50. A computer readable medium comprising instructions for coding video data that when executed cause one or more processors to:

code a beta offset parameter (“

beta_offset”

) that controls a deblocking filter for a video block;

identify a beta parameter (“

β

”

) value used to determine a threshold value of at least one deblocking decision for the deblocking filter; and

calculate the deblocking decision for the deblocking filter according to the threshold value modified based on a multiplier value of the beta offset parameter that causes an integer change in the modified threshold value.