Determine reference motion vectors

Patent metadata

Field	Value
Publication number	US-9503746-B2
Application number	US-201213647076-A
Country	US
Kind code	B2
Filing date	Oct 8, 2012
Priority date	Oct 8, 2012
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

A method for encoding a video stream having a plurality of blocks including a current block. The method includes identifying, from a plurality of previously coded blocks, a plurality of candidate motion vectors; identifying, for the current block, a set of reconstructed pixel values corresponding to a set of previously coded pixel values; determining, for at least one of the plurality of candidate motion vectors, an error value based on the set of reconstructed pixel values and a set of predicted values for the set of previously coded pixel values; and selecting, from the plurality of candidate motion vectors, a reference motion vector for the current block based on the error value.

First claim

What is claimed is:

1. A method for encoding a current block of a video stream having a plurality of blocks including the current block, comprising:
identifying, from a plurality of blocks coded before the current block, a plurality of candidate motion vectors, each candidate motion vector associated with a respective reference frame;
identifying, for the current block of a current frame, a set of reconstructed pixel values for a set of pixel positions within the current frame, but outside of the current block, coded before the current block;
for each candidate motion vector of the plurality of candidate motion vectors:
generating, by applying the candidate motion vector to the set of pixel positions, a set of predicted pixels for the reconstructed pixels within the respective reference frame associated with the candidate motion vector; and
determining an error value between the set of reconstructed pixel values and values of the set of predicted pixels; and

selecting, from the plurality of candidate motion vectors, a reference motion vector for the current block based on the error value for each candidate motion vector.

2. The method of claim 1 , wherein the set of pixel positions includes at least one of: one or more rows of pixels above the current block or one or more columns of pixels to the left of the current block.

3. The method of claim 1 , wherein the error value is determined using one of the following metrics: sum of absolute difference (SAD), sum of squared error (SSE) or mean squared error (MSE).

4. The method of claim 1 , wherein the reference motion vector is selected from the plurality of candidate motion vectors as the candidate motion vector associated with the lowest error value.

5. The method of claim 1 , further comprising:
encoding, for the current block, a motion vector using the reference motion vector.

6. The method of claim 5 , wherein encoding, for the current block, the motion vector using the reference motion vector includes encoding, for the current block, a difference value based on the reference motion vector and the motion vector for the current block.

7. The method of claim 5 , wherein encoding, for the current block, the motion vector using the reference motion vector includes:
identifying a probability distribution based on the reference motion vector; and
encoding a magnitude value of the motion vector for the current block based on the probability distribution.

8. The method of claim 1 , wherein the reference motion vector is selected as a motion vector for the current block.

9. A method for decoding a current block of an encoded video stream having a plurality of blocks including the current block, comprising:
identifying, from a plurality of blocks decoded before the current block, a plurality of candidate motion vectors, each candidate motion vector associated with a respective reference frame;
identifying, for the current block of a current frame, a set of reconstructed pixel values corresponding to a set of pixel positions within the current frame, but outside of the current block, decoded before the current block;
for each candidate motion vector of the plurality of candidate motion vectors:
generating, by applying the candidate motion vector to the set of pixel positions, a set of predicted pixels within the respective reference frame associated with the candidate motion vector; and
determining an error value between the set of reconstructed pixel values and values of the set of predicted pixels; and

selecting, from the plurality of candidate motion vectors, a reference motion vector for the current block based on the error value for each candidate motion vector.

10. The method of claim 9 , wherein the set of pixel positions includes at least one of: one or more rows of pixels above the current block or one or more columns of pixels to the left of the current block.

11. The method of claim 9 , wherein the error value is determined using one of the following metrics: sum of absolute difference (SAD), sum of squared error (SSE) or mean squared error (MSE).

12. The method of claim 9 , wherein the reference motion vector is selected from the plurality of candidate motion vectors as the candidate motion vector associated with the lowest error value.

13. The method of claim 9 , further comprising:
decoding, for the current block, a motion vector using the reference motion vector.

14. The method of claim 13 , wherein decoding, for the current block, the motion vector using the reference motion vector includes
decoding, from the current block, a difference value based on the reference motion vector and the motion vector for the current block; and
determining the motion vector for the current block based on a sum of the difference value and the reference motion vector.

15. The method of claim 13 , wherein decoding, for the current block, the motion vector using the reference motion vector includes:
identifying a probability distribution based on the reference motion vector; and
decoding a magnitude value of the motion vector for the current block based on the probability distribution.

16. The method of claim 9 , wherein the reference motion vector is selected as a motion vector for the current block.

17. An apparatus for encoding a current block of a video stream having a plurality of blocks including the current block, comprising:
a memory;
a processor configured to execute instructions stored in the memory to:
identify, from a plurality of blocks coded before the current block, a plurality of candidate motion vectors, each candidate motion vector associated with a respective reference frame;
identify, for the current block of a current frame, a set of reconstructed pixel values for a set of pixel positions within the current frame, but outside of the current block, coded before the current block;
for each candidate motion vector of the plurality of candidate motion vectors:
generate, by applying the candidate motion vector to the set of pixel positions, a set of predicted pixels within the respective reference frame associated with the candidate motion vector; and
determine an error value between the set of reconstructed pixel values and values of the set of predicted pixels; and

select, from the plurality of candidate motion vectors, a reference motion vector for the current block based on the error value for each candidate motion vector.

18. The apparatus in claim 17 , wherein the processor is further configured to execute instructions to:
encode, for the current block, a motion vector using the reference motion vector.

Assignees

• Xu Yaowu
• Wilkins Paul Gordon
• Grange Adrian
• Bankoski James
• Google Inc

Inventors

• Xu Yaowu
• Wilkins Paul Gordon
• Grange Adrian
• Bankoski James

Classifications

• H04N19/154

  Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion (use of rate-distortion criteria H04N19/147) · CPC title

• H04N19/61

  in combination with predictive coding · CPC title

• H04N19/463 Primary

  by compressing encoding parameters before transmission · CPC title

• H04N19/105

  Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction · CPC title

• H04N19/56

  Motion estimation with initialisation of the vector search, e.g. estimating a good candidate to initiate a search · CPC title