METHOD AND APPARATUS FOR ENCODING AND DECODING VIDEO

• US 20110243233A1
• Filed: 04/05/2011
• Published: 10/06/2011
• Est. Priority Date: 04/05/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: LEE, Tammy, HAN, Woo-jin, CHEON, Min-su, ALSHIN, Alexander, ALSHINA, Elena
• Granted Patent: US 8,711,939 B2
• Time in Patent Office: Days
• US Class Current: 375/240.16
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/52 by predictive encoding
• CPC Class Codes: H04N 19/523 with sub-pixel accuracy
• CPC Class Codes: H04N 19/53 Multi-resolution motion estimation; Hierarchical motion estimation
• CPC Class Codes: H04N 19/533 Motion estimation using multistep search, e.g. 2D-log search or one-at-a-time search [OTS]
• CPC Class Codes: H04N 19/96 Tree coding, e.g. quad-tree coding

Abstract

Methods and apparatuses for encoding and decoding video are provided. The encoding method includes: performing motion estimation on a current block according to a first sub-pixel unit, and obtaining a motion vector in the first sub-pixel unit with respect to the current block; interpolating a reference picture indicated by the motion vector according to a second sub-pixel unit smaller than the first sub-pixel unit; using the interpolated reference picture, selecting a second sub-pixel in the second sub-pixel unit adjacent to a first sub-pixel in the first sub-pixel unit of the reference picture; selecting a corresponding region that has a smaller error with the current block, from among a first corresponding region of the reference picture and obtained with respect to the first sub-pixel, and a second corresponding region of the current block and obtained with respect to the selected second sub-pixel; and encoding information of the selected corresponding region.

Claims

1. A method of encoding video, the method comprising:

performing motion estimation on a current block according to a first sub-pixel unit, and obtaining a motion vector in the first sub-pixel unit with respect to the current block;

interpolating a reference picture indicated by the obtained motion vector according to a second sub-pixel unit smaller than the first sub-pixel unit;

selecting a second sub-pixel from among sub-pixels in the second sub-pixel unit adjacent to a first sub-pixel in the first sub-pixel unit of the reference picture indicated by the obtained motion vector, wherein the selecting is performed using the interpolated reference picture;

selecting a corresponding region that has a smaller error with the current block from among a first corresponding region and a second corresponding region, wherein the first corresponding region is of the reference picture indicated by the obtained motion vector and is obtained with respect to the first sub-pixel in the first sub-pixel unit, and the second corresponding region is of the current block and is obtained with respect to the selected second sub-pixel in the second sub-pixel unit; and

encoding information of the selected corresponding region.

2. The method of claim 1, wherein the obtaining the motion vector comprises:

selecting, as the first sub-pixel unit, an accuracy from among at least two accuracies;

interpolating the reference picture according to the selected first sub-pixel unit; and

searching, in the interpolated reference picture, a most similar corresponding region to the current block, and obtaining the motion vector indicating a position of the searched corresponding region.

3. The method of claim 2, wherein the encoding the information comprises encoding accuracy information of the motion vector indicating the accuracy selected as the first sub-pixel unit from among the at least two accuracies.

4. The method of claim 2, wherein the at least two accuracies comprise a 1/4 sub-pixel unit and a 1/8 sub-pixel unit.

5. The method of claim 1, wherein, when the first sub-pixel unit is 1/(2̂

p), where p is an integer equal to or greater than 0, and the second sub-pixel unit is a 1/[(2a+1)*(2̂

p)] sub-pixel unit, where a is an integer equal to or greater than 0.

6. The method of claim 5, wherein the second sub-pixel unit is a 1/12 sub-pixel unit.

7. The method of claim 1, wherein the encoding the information comprises encoding information of the motion vector in the first sub-pixel unit, and information indicating whether the second corresponding region is selected.

8. The method of claim 7, wherein, when the second corresponding region is selected as the corresponding region, the encoding the information further comprises encoding position information of the selected second sub-pixel in the second sub-pixel unit.

9. The method of claim 8, wherein the encoding the position information comprises:

estimating the position information of the selected second sub-pixel in the second sub-pixel unit of the current block by using position information of a sub-pixel in the second sub-pixel unit used to estimate and compensate for motion of adjacent blocks to the current block; and

encoding a difference value between the estimated position information of the selected second sub-pixel in the second sub-pixel unit of the current block and the position information of the sub-pixel in the second sub-pixel unit used to estimate and compensate for the motion of adjacent blocks.

10. The method of claim 7, wherein the encoding the information further comprises:

obtaining an estimation motion vector of the current block by using a motion vector of an adjacent block to the current block; and

encoding a difference value between the obtained estimation motion vector of the current block and a motion vector of the current block.

11. A video encoding apparatus comprising:

a motion estimator which performs motion estimation on a current block according to a first sub-pixel unit, and obtains a motion vector in the first sub-pixel unit with respect to the current block;

a motion compensator which interpolates a reference picture indicated by the obtained motion vector according to a second sub-pixel unit smaller than the first sub-pixel unit, which selects, by using the interpolated reference picture, selecting a second sub-pixel from among sub-pixels in the second sub-pixel unit adjacent to a first sub-pixel in the first sub-pixel unit of the reference picture indicated by the obtained motion vector, and which selects a corresponding region that has a smaller error with the current block from among a first corresponding region and a second corresponding region, wherein the first corresponding region is of the reference picture indicated by the obtained motion vector and is obtained with respect to the first sub-pixel in the first sub-pixel unit, and the second corresponding region is of the current block and is obtained with respect to the selected second sub-pixel in the second sub-pixel unit; and

an encoder which encodes information of the selected corresponding region.

12. The video encoding apparatus of claim 11, wherein the motion compensator performs motion estimation by selecting, as the first sub-pixel unit, an accuracy from among at least two accuracies and by interpolating the reference picture according to the selected first sub-pixel unit.

13. The video encoding apparatus of claim 12, wherein the encoder encodes accuracy information of the motion vector indicating the accuracy selected as the first sub-pixel unit from among the at least two accuracies.

14. The video encoding apparatus of claim 12, wherein the at least two accuracies comprise a 1/4 sub-pixel unit and a 1/8 sub-pixel unit.

15. The video encoding apparatus of claim 11, wherein, when the first sub-pixel unit is 1/(2̂

p), where p is an integer equal to or greater than 0, the second sub-pixel unit is a 1/[(2a+1)*(2̂

p)] sub-pixel unit, where a is an integer equal to or greater than 0.

16. The video encoding apparatus of claim 15, wherein the second sub-pixel unit is a 1/12 sub-pixel unit.

17. The video encoding apparatus of claim 11, wherein the encoder encodes information of the motion vector in the first sub-pixel unit, and information indicating whether the second corresponding region is selected.

18. The video encoding apparatus of claim 17, wherein, when the second corresponding region is selected as the corresponding region, the encoder encodes position information of the selected second sub-pixel in the second sub-pixel unit.

19. The video encoding apparatus of claim 17, wherein the encoder:

estimates the position information of the selected second sub-pixel in the second sub-pixel unit of the current block by using position information of a sub-pixel in the second sub-pixel unit used to estimate and compensate for motion of adjacent blocks to the current block; and

encodes a difference value between the estimated position information of the selected second sub-pixel in the second sub-pixel unit of the current block and the position information of the sub-pixel in the second sub-pixel unit used to estimate and compensate for motion of the adjacent blocks.

20. The video encoding apparatus of claim 17, wherein the encoder obtains an estimation motion vector of the current block by using a motion vector of an adjacent block to the current block, and encodes a difference value between the obtained estimation motion vector of the current block and a motion vector of the current block.

21. A method of decoding video, the method comprising:

decoding and obtaining a motion vector in a first sub-pixel unit with respect to a current block from a bitstream;

obtaining information from the bitstream, wherein the information indicates whether motion compensation is performed on the current block by using a corresponding region obtained with respect to a second sub-pixel in a second sub-pixel unit that is smaller than the first sub-pixel unit adjacent to a first sub-pixel in the first sub-pixel unit of a reference picture indicated by the obtained motion vector in the first sub-pixel unit;

if the motion compensation is performed on the current block by using information of the corresponding region obtained with respect to the second sub-pixel in the second sub-pixel unit, extracting position information of the second sub-pixel in the second sub-pixel unit from the bitstream; and

performing the motion compensation on the current block by using the motion vector in the first sub-pixel unit, and the extracted position information of the second sub-pixel in the second sub-pixel unit.

22. The method of claim 21, wherein the obtaining the motion vector comprises:

obtaining an estimation motion vector by using a motion vector of an adjacent block to the current block; and

obtaining the motion vector in the first sub-pixel unit by using the obtained estimation motion vector of the current block, and a difference value between the estimation motion vector comprised in the bitstream and a motion vector of the current block.

23. The method of claim 21, wherein, when the first sub-pixel unit is 1/(2̂

p), where p is an integer equal to or greater than 0, the second sub-pixel unit is a 1/[(2a+1)*(2̂

p)] sub-pixel unit, where a is an integer equal to or greater than 0.

24. The method of claim 23, wherein the second sub-pixel unit is a 1/12 sub-pixel unit.

25. The method of claim 21, wherein the extracting the position information comprises:

estimating the position information of the second sub-pixel in the second sub-pixel unit of the current block by using position information of a sub-pixel in the second sub-pixel unit used to estimate and compensate for motion of adjacent blocks to the current block; and

obtaining the position information of the second sub-pixel in the second sub-pixel unit of the current block by using the estimated position information of the second sub-pixel in the second sub-pixel unit, and a difference value between the estimated position information of the second sub-pixel in the second sub-pixel unit and the extracted position information of the second sub-pixel in the second sub-pixel unit extracted from the bitstream.

26. The method of claim 21, wherein the performing the motion compensation comprises:

interpolating the reference picture indicated by the motion vector in the first sub-pixel unit according to the second sub-pixel unit;

determining the second sub-pixel in the second sub-pixel unit adjacent to the first sub-pixel in the first sub-pixel unit of the reference picture indicated by the motion vector in the first sub-pixel unit, by using the extracted position information of the second sub-pixel in the second sub-pixel unit; and

obtaining a region corresponding to the current block with respect to the determined second sub-pixel in the second sub-pixel unit.

27. A video decoding apparatus comprising:

an entropy decoder which decodes and obtains a motion vector in a first sub-pixel unit with respect to a current block from a bitstream, which obtains information indicating whether motion compensation is performed on the current block by using a corresponding region obtained with respect to a second sub-pixel in a second sub-pixel unit that is smaller than the first sub-pixel unit adjacent to a first sub-pixel in the first sub-pixel unit of a reference picture indicated by the obtained motion vector in the first sub-pixel unit, and which, if the motion estimation is performed on the current block by using information of the corresponding region obtained with respect to the second sub-pixel in the second sub-pixel unit, extracts position information of the second sub-pixel in the second sub-pixel unit from the bitstream; and

a motion compensator which performs the motion compensation on the current block by using the motion vector in the first sub-pixel unit, and the extracted position information of the second sub-pixel in the second sub-pixel unit.

28. The video decoding apparatus of claim 27, wherein the motion compensator obtains an estimation motion vector by using a motion vector of an adjacent block to the current block, and obtains the motion vector in the first sub-pixel unit by using the obtained estimation motion vector of the current block, and a difference value between the estimation motion vector comprised in the bitstream and a motion vector of the current block.

29. The video decoding apparatus of claim 27, wherein, when the first sub-pixel unit is 1/(2̂

p), where p is an integer equal to or greater than 0, the second sub-pixel unit is a 1/[(2a+1)*(2̂

p)] sub-pixel unit, where a is an integer equal to or greater than 0.

30. The video decoding apparatus of claim 29, wherein the second sub-pixel unit is a 1/12 sub-pixel unit.

31. The video decoding apparatus of claim 27, wherein the motion compensator:

estimates the position information of the second sub-pixel in the second sub-pixel unit of the current block by using position information of a sub-pixel in the second sub-pixel unit used to estimate and compensate for motion of adjacent blocks to the current block; and

obtains the position information of the second sub-pixel in the second sub-pixel unit of the current block by using the estimated position information of the second sub-pixel in the second sub-pixel unit, and a difference value between the estimated position information of the second sub-pixel in the second sub-pixel unit and the extracted position information of the second sub-pixel in the second sub-pixel unit extracted from the bitstream.

32. The video decoding apparatus of claim 27, wherein the motion compensator:

interpolates the reference picture indicated by the motion vector in the first sub-pixel unit according to the second sub-pixel unit;

determines the second sub-pixel in the second sub-pixel unit adjacent to the first sub-pixel in the first sub-pixel unit of the reference picture indicated by the motion vector in the first sub-pixel unit, by using the extracted position information of the second sub-pixel in the second sub-pixel unit; and

obtains a region corresponding to the current block with respect to the determined second sub-pixel in the second sub-pixel unit.