Selection of phase offsets for interpolation filters for motion compensation

Patent metadata

Field	Value
Publication number	US-9264725-B2
Application number	US-201213532217-A
Country	US
Kind code	B2
Filing date	Jun 25, 2012
Priority date	Jun 24, 2011
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

In one embodiment, a method for encoding or decoding video content is provided. The method determines a plurality of sets of interpolation filters for use in interpolating sub-pel pixel values for a temporal prediction process of video content. Different sets of interpolation filters include different phase offset characteristics. A unit of video content is received. The method then selects one of the set of interpolation filters to interpolate a set of sub-pel pixel values for use in the temporal prediction process for the unit of video content based on characteristics associated with the encoding or decoding of the video content. The one of the set of interpolation filters is selected based on the phase offset characteristic of the one of the set of interpolation filters and the characteristics associated with the encoding or decoding.

First claim

What is claimed is:

1. A method for encoding or decoding video content, the method comprising:
determining a plurality of sets of interpolation filters for use in interpolating sub-pel pixel values for a temporal prediction process of video content, wherein different sets of interpolation filters include different phase offset characteristics;
receiving a unit of video content; and
selecting one of the set of interpolation filters to interpolate a set of sub-pel pixel values for use in the temporal prediction process for the unit of video content based on characteristics associated with the encoding or decoding of the video content, wherein the one of the set of interpolation filters is selected based on the phase offset characteristic of the one of the set of interpolation filters and the characteristics associated with the encoding or decoding,
wherein the phase offset characteristic for the one of the set of interpolation filters comprises a set of sub-pel pixel positions that is non-uniform in spacing between the set of sub-pel pixel positions.

2. The method of claim 1 , wherein the different phase offset characteristics comprise different phase offset spacing between sub-pel pixel positions or a different number of sub-pel pixel positions.

3. The method of claim 1 , wherein the phase offsets for a first set of interpolation filters include sub-pel pixel positions are a different number of sub-pixel positions from a second set of interpolation filters, but the sub-pixel positions for the first set of interpolation filters or the second set of interpolation filters are uniformly spaced between the sub-pel pixel positions.

4. The method of claim 1 , wherein the phase offsets for the set of sub-pel pixel positions is adaptively determined for the unit of the video content.

5. The method of claim 1 , wherein the characteristics associated with the encoding or decoding comprise the video content or a coding condition, the method further comprising:
determining information associated with the video content or a coding condition,
wherein determining the set of interpolation filters comprises adaptively determining which phase offsets for the sub-pel pixel positions are to be used for the one of the plurality of sets of interpolation filters based on the determined information.

6. The method of claim 1 , wherein:
the one of the plurality of sets of interpolation filters is adaptively determined, and
the characteristics associated with the encoding or decoding and the one of the plurality of sets of interpolation filters are determined independently by an encoder and a decoder.

7. The method of claim 1 , wherein:
the interpolation filter is adaptively determined, and
selection information identifying the adaptively determined interpolation filter is sent by an encoder to a decoder.

8. The method of claim 1 , wherein:
the characteristics are determined based on a slice type of the unit of the video content; and
selecting the one of the set of interpolation filters comprises adaptively determining the one of the plurality of sets of interpolation filters based on whether the slice type is a B picture or a P picture.

9. The method of claim 8 , wherein:
a non-uniform spacing for a number of sub-pel pixel positions are determined based on the slice type,
a number of sub-pel pixel positions are determined based on the slice type, or
coefficient values for the set of sub-pel pixel positions are determined based on the slice type.

10. The method of claim 1 , wherein:
the characteristics of encoding or decoding are determined based on a size of the unit of video content; and
selecting the one of the plurality of sets of interpolation filters comprises adaptively determining the one of the plurality of sets of interpolation filters to include phase offsets for a set of sub-pel pixel positions based on the size.

11. The method of claim 1 , wherein:
the characteristics are determined based on motion information for a reference picture for the unit of video content; and
selecting the one of the plurality of sets of interpolation filters comprises adaptively determining the one of the plurality of sets of interpolation filters to include phase offsets for a set of sub-pel pixel positions based on motion information.

12. The method of claim 1 , wherein:
the characteristics are determined based on a motion vector predictor for a reference picture associated with the unit of the video content; and
selecting the one of the plurality of sets of interpolation filters comprises adaptively determining the one of the plurality of sets of interpolation filters to include phase offsets for a set of sub-pel pixel positions based on a phase offset position in which the motion vector predictor is pointing.

13. The method of claim 1 , further comprising:
determining a set of full-pel values for pixels for the video content;
applying the set of full-pel pixel values to a set of taps of the one of the plurality of sets of interpolation filters to interpolate a set of sub-pel pixel values corresponding to a set of sub-pel pixel positions; and
outputting the sub-pel pixel values for use in performing temporal prediction for the unit of video content.

14. The method of claim 1 , wherein the one of the plurality of sets of interpolation filters does not use a zero phase offset.

15. An apparatus configured to encode or decode video content, the apparatus comprising:
one or more computer processors; and
a computer-readable storage medium comprising instructions, that when executed, control the one or more computer processors to be operable to:
determining a plurality of sets of interpolation filters for use in interpolating sub-pel pixel values for a temporal prediction process of video content, wherein different sets of interpolation filters include different phase offset characteristics;
receiving a unit of video content; and
selecting one of the set of interpolation filters to interpolate a set of sub-pel pixel values for use in the temporal prediction process for the unit of video content based on characteristics associated with the encoding or decoding of the video content, wherein the one of the set of interpolation filters is selected based on the phase offset characteristic of the one of the set of interpolation filters and the characteristics associated with the encoding or decoding,
wherein the phase offset characteristic for the one of the set of interpolation filters comprises a set of sub-pel pixel positions that is non-uniform in spacing between the set of sub-pel pixel positions.

16. The apparatus of claim 15 , wherein the different phase offset characteristics comprise different phase offset spacing between sub-pel pixel positions or a different number of sub-pel pixel positions.

17. The apparatus of claim 15 , wherein the phase offsets for a first set of interpolation filters include sub-pel pixel positions are a different number of sub-pixel positions from a second set of interpolation filters, but the sub-pixel positions for the first set of interpolation filters or the second set of interpolation filters are uniformly spaced between the sub-pel pixel positions.

18. The apparatus of claim 15 , wherein:
the characteristics are determined based on a slice type of the unit of the video content; and
selecting the one of the set of interpolation filters comprises adaptively determining the one of the plurality of sets of interpolation filters based on whether the slice type is a B picture or a P picture.

19. A method

Assignees

• Minoo Koohyar
• Baylon David
• Lou Jian
• Luthra Ajay
• Panusopone Krit
• Wang Limin
• Google Inc

Inventors

• Minoo Koohyar
• Baylon David
• Lou Jian
• Luthra Ajay
• Panusopone Krit
• Wang Limin

Classifications

• H04N19/132 Primary

  Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking · CPC title

• H04N19/159

  Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction · CPC title

• H04N19/82

  involving filtering within a prediction loop · CPC title

• H04N19/51 Primary

  Motion estimation or motion compensation · CPC title

• H04N19/182

  the unit being a pixel · CPC title