Parameterized filters and signaling techniques

• US 20080232452A1
• Filed: 03/20/2007
• Published: 09/25/2008
• Est. Priority Date: 03/20/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Srinivasan, Sridhar, Sullivan, Gary J., Regunathan, Shankar, Tu, Chengjie
• Granted Patent: US 8,107,571 B2
• Time in Patent Office: Days
• US Class Current: 375/232
• CPC Class Codes: H03H 17/0294 Variable filters; Programmable filters
• CPC Class Codes: H03H 2017/0297 Coefficients derived from input parameters

Abstract

Filter taps for filters are specified by filter coefficient parameters. The filter taps are greater in number than the coefficient parameters from which the filter taps are calculated. For example, two coefficient parameters are used to specify a four-tap filter. Filter information can be signaled in a bitstream, such as by signaling one or more family parameters for a filter family and, for each filter in a family, signaling one or more filter tap parameters from which filter taps can be derived. Family parameters can include a number of filters parameter, a resolution parameter, a scaling bits parameter, and/or a full integer position filter present parameter that indicates whether or not the filters include an integer position filter. Filter parameters can be signaled and used to determine coefficient parameters from which filter taps are calculated.

Claims

1. A method of filtering media information, the method comprising:

receiving filter information for one or more filters;

for each of the one or more filters, calculating plural filter taps using the filter information, wherein the plural filter taps for the filter are specified by one or more filter coefficient parameters for the filter, and wherein the plural filter taps are greater in number than the one or more filter coefficient parameters from which the plural filter taps are calculated; and

filtering media information using the one or more filters.

2. The method of claim 1 wherein the one or more filters comprise filters with different phases or fractional sample delays in a filter family.

3. The method of claim 2 wherein the one or more filter coefficient parameters consist of two parameters for each of the one or more filters.

4. The method of claim 1 wherein the one or more filter coefficient parameters are calculated by:

identifying a constraint for the filter; and

based on the identified constraint, identifying the one or more filter coefficient parameters.

5. The method of claim 4 wherein the identifying the constraint comprises identifying a constraint matrix for the filter, and wherein the constraint matrix constrains the filter to be a linear interpolator.

6. The method of claim 1 wherein the filter information includes:

one or more filter family parameters selected from the group comprising number of filters parameter, resolution parameter, scaling bits parameter, and full integer position filter present parameter; and

for each of the one or more filters, one or more signaled filter parameters used to determine the one or more filter coefficient parameters from which the plural filter taps are calculated.

7. A method of upsampling spatially scalable video information, the method comprising:

receiving upsampling filter information for plural upsampling filters,

using the upsampling filter information, determining at least two effective filter tap calculation parameters for each of the plural upsampling filters;

receiving encoded video sample information; and

upsampling the video sample information using the plural upsampling filters, each of the plural upsampling filters having at least four filter taps, wherein for each of the plural upsampling filters;

the at least four filter taps are calculated with the at least two effective filter tap calculation parameters prior to the upsampling, and

the at least four filter taps are greater in number than the at least two effective filter tap calculation parameters from which the plural filter taps are calculated.

8. The method of claim 7 wherein each of the plural upsampling filters is a 1/16-sample resolution upsampling filter.

9. A method comprising:

signaling filter information in a bitstream, wherein the filter information comprises information for a set of plural filters in a filter family, wherein each of the plural filters comprises plural filter taps, and wherein the signaling of the filter information comprises;

signaling one or more family parameters for the filter family; and

for each of the plural filters, signaling one or more filter tap parameters from which the plural filter taps of the filter can be derived, wherein the one or more filter tap parameters for the filter are fewer in number than the plural filter taps of the filter.

10. The method of claim 9 wherein the one or more family parameters include a number of filters in the set of plural filters.

11. The method of claim 9 wherein the one or more family parameters include a resolution parameter.

12. The method of claim 9 wherein the one or more family parameters include a scaling bits parameter.

13. The method of claim 9 wherein the one or more family parameters include one or more of a resolution parameter, a scaling bits parameter, and a number of filters parameter, and wherein any of the resolution parameter, the scaling bits parameter and the number of filters that is not signaled is implied.

14. The method of claim 9 wherein the one or more family parameters include a integer position filter present parameter that indicates whether or not the plural filters for which one or more filter tap parameters are signaled include an integer position filter.

15. The method of claim 9 wherein the plural filters are usable for resampling and/or sub-sample interpolation in motion compensation.

16. The method of claim 9 wherein the filter family further includes plural mirrored filters, each of the plural mirrored filters having plural filter taps derived from the plural filter taps of one of the plural filters for which filter information is signaled.

17. The method of claim 9 further comprising, before the signaling the one or more filter tap parameters, differentially coding the filter tap parameters for at least one of the plural filters relative to the filter tap parameters of another of the plural filters such that the signaled filter tap parameters are differentially coded values for the at least one of the plural filters.

18. The method of claim 17 wherein the differential coding is second degree differential coding.

19. The method of claim 9 further comprising, before the signaling the one or more filter tap parameters, fixed-length coding the one or more filter tap parameters.

20. The method of claim 9 further comprising, before the signaling the one or more filter tap parameters, variable-length coding the one or more filter tap parameters.