INTER-LAYER PREDICTION USING SAMPLE-ADAPTIVE ADJUSTMENTS FOR BIT DEPTH SCALABLE VIDEO CODING

• US 20140185664A1
• Filed: 12/20/2013
• Published: 07/03/2014
• Est. Priority Date: 12/28/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: VAN DER AUWERA, Geert, KARCZEWICZ, Marta
• Granted Patent: US 9,532,057 B2
• Time in Patent Office: Days
• US Class Current: 375/240.02
• CPC Class Codes: H04N 19/103 Selection of coding mode or of prediction mode
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/187 the unit being a scalable video layer
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/33 in the spatial domain
• CPC Class Codes: H04N 19/50 using predictive coding H04N19/61 takes precedence

Abstract

An apparatus for coding video data according to certain aspects includes a memory unit and a processor in communication with the memory unit. The memory unit stores video data. The video data may include a base layer comprising samples with a lower bit depth and an enhancement layer comprising samples with a higher bit depth. The processor predicts the values of samples in the enhancement layer based on the values of samples in the base layer. The prediction performed by the processor includes applying a preliminary mapping to the base layer samples to obtain preliminary predictions, and then applying adaptive adjustments to the preliminary predictions to obtain refined predictions. Parameters used for the adaptive adjustments may depend on the values and distribution of base layer samples. The processor may encode or decode the video data.

Claims

1. An apparatus configured to code video data, the apparatus comprising:

a memory unit configured to store video data associated with a base layer and an enhancement layer, the base layer including a base layer sample having a first bit depth; and

a processor in communication with the memory unit, the processor configured to;

apply a function to the base layer sample to produce a preliminary predicted sample;

determine one or more categories associated with the base layer sample;

determine adjustment parameters corresponding to each of the one or more categories associated with the base layer sample; and

perform adjustment calculations using each of the determined adjustment parameters to determine a refined predicted sample from the preliminary predicted sample, the refined predicted sample having a second bit depth that is greater than the first bit depth.

2. The apparatus of claim 1, wherein the first bit depth is 8 bits, and the second bit depth is one of 10 bits, 12 bits, and 14 bits.

3. The apparatus of claim 1, wherein at least one of the one or more categories associated with the base layer sample is determined from one or more luminance or chrominance values of the base layer sample.

4. The apparatus of claim 1, wherein at least one of the one or more categories associated with the base layer sample is determined from one or more luminance or chrominance values of the base layer sample and one or more luminance or chrominance values of at least one other sample from the received video data.

5. The apparatus of claim 1, wherein

the base layer sample represents a luminance value on a scale of possible luminance values;

the scale of possible luminance values is divided into a plurality of luminance bands;

the luminance value represented by the base layer sample lies within one of the luminance bands; and

one of the categories associated with the base layer sample corresponds to the luminance band within which the base layer sample lies.

6. The apparatus of claim 1, wherein

the base layer sample represents a chrominance value on a scale of possible chrominance values;

the scale of possible chrominance values is divided into a plurality of chrominance bands;

the chrominance value represented by the base layer sample lies within one of the chrominance bands; and

one of the categories associated with the base layer sample corresponds to the chrominance band within which the base layer sample lies.

7. The apparatus of claim 1, wherein one of the categories associated with the base layer sample depends on results of a plurality of comparisons between the base layer sample and other samples which are spatially adjacent to the base layer sample in the video data.

8. The apparatus of claim 1, wherein the function comprises at least one logarithmic or exponential operation.

9. The apparatus of claim 1, wherein the function comprises a left bit shift or multiplication by a number greater than or equal to 2.

10. The apparatus of claim 1, wherein the function comprises a look-up table that maps each possible base layer sample value onto a corresponding enhancement layer sample value.

11. The apparatus of claim 1, wherein the preliminary predicted sample has a bit depth equal to the second bit depth.

12. The apparatus of claim 1, wherein the adjustment parameters comprise ratios, coefficients, exponents, or logarithmic bases.

13. The apparatus of claim 1, wherein the adjustment calculations comprise addition, subtraction, multiplication, division, exponentiation, or logarithms.

14. The apparatus of claim 1, wherein the processor is further configured to add a residual value to the refined predicted sample to determine an enhancement layer sample.

15. A method of coding video data, the method comprising:

receiving the video data comprising a base layer sample having a first bit depth;

applying a function to the base layer sample to produce a preliminary predicted sample;

determining one or more categories associated with the base layer sample;

determining adjustment parameters corresponding to each of the one or more categories associated with the base layer sample;

performing adjustment calculations using each of the determined adjustment parameters to determine a refined predicted sample from the preliminary predicted sample, the refined predicted sample having a second bit depth that is greater than the first bit depth.

16. The method of claim 15, wherein the first bit depth is 8 bits, and the second bit depth is one of 10 bits, 12 bits, and 14 bits.

17. The method of claim 15, wherein at least one of the one or more categories associated with the base layer sample is determined from one or more luminance or chrominance values of the base layer sample.

18. The method of claim 15, wherein at least one of the one or more categories associated with the base layer sample is determined from one or more luminance or chrominance values of the base layer sample and one or more luminance or chrominance values of at least one other sample from the received video data.

19. The method of claim 15, wherein

the base layer sample represents luminance value one a scale of possible luminance values;

the scale of possible luminance values is divided into a plurality of luminance bands;

the luminance value represented by the base layer sample lies within one of the luminance bands; and

one of the categories associated with the base layer sample corresponds to the luminance band within which the base layer sample lies.

20. The method of claim 15, wherein

the base layer sample represents a chrominance value on a scale of possible chrominance values;

the scale of possible chrominance values is divided into a plurality of chrominance bands;

the chrominance value represented by the base layer sample lies within one of the chrominance bands; and

one of the categories associated with the base layer sample corresponds to the chrominance band within which the base layer sample lies.

21. The method of claim 15, wherein one of the categories associated with the base layer sample depends on results of a plurality of comparisons between the base layer sample and other samples which are spatially adjacent to the base layer sample in the video data.

22. The method of claim 15, wherein the function comprises at least one logarithmic or exponential operation.

23. The method of claim 15, wherein the function comprises a left bit shift or multiplication by a number greater than or equal to 2.

24. The method of claim 15, wherein the function comprises a look-up table that maps each possible base layer sample value onto a corresponding enhancement layer sample value.

25. The method of claim 15, wherein the preliminary predicted sample has a bit depth equal to the second bit depth.

26. The method of claim 15, wherein the adjustment parameters comprise ratios, coefficients, exponents, or logarithmic bases.

27. The method of claim 15, wherein the adjustment calculations comprise addition, subtraction, multiplication, division, exponentiation, or logarithms.

28. The method of claim 15, wherein the processor is further configured to add a residual value to the refined predicted sample to determine an enhancement layer sample.

29. A non-transitory computer readable medium comprising code that, when executed, causes an apparatus to:

receive video data comprising a base layer sample having a first bit depth;

apply a function to the base layer sample to produce a preliminary predicted sample;

determine one or more categories associated with the base layer sample;

determine adjustment parameters corresponding to each of the one or more categories associated with the base layer sample; and

perform adjustment calculations using each of the determined adjustment parameters to determine a refined predicted sample from the preliminary predicted sample, the refined predicted sample having a second bit depth that is greater than the first bit depth.

30. A video coding device configured to code video data, the video coding device comprising:

means for receiving the video data comprising a base layer sample having a first bit depth;

means for applying a function to the base layer sample to produce a preliminary predicted sample;

means for determining one or more categories associated with the base layer sample;

means for determining adjustment parameters corresponding to each of the one or more categories associated with the base layer sample; and

means for performing adjustment calculations using each of the determined adjustment parameters to determine a refined predicted sample from the preliminary predicted sample, the refined predicted sample having a second bit depth that is greater than the first bit depth.