VIDEO ENCODING METHOD AND DECODING METHOD, APPARATUSES THEREFOR, PROGRAMS THEREFOR, AND STORAGE MEDIA WHICH STORE THE PROGRAMS

• US 20100008422A1
• Filed: 10/24/2007
• Published: 01/14/2010
• Est. Priority Date: 10/30/2006
• Status: Active Grant

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Kamikura, Kazuto, Kimata, Hideaki, Shimizu, Shinya, Yashima, Yoshiyuki
• Granted Patent: US 8,532,190 B2
• Time in Patent Office: Days
• US Class Current: 375/240.160
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/52 by predictive encoding
• CPC Class Codes: H04N 19/577 Motion compensation with bidirectional frame interpolation, i.e. using B-pictures
• CPC Class Codes: H04N 19/597 specially adapted for multi-view video sequence encoding
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards

Abstract

A video encoding method includes selecting a reference vector target frame and a reference frame from among already-encoded frames; encoding information for designating each frame; setting a reference vector for indicating an area in the reference vector target frame with respect to an encoding target area; encoding the reference vector; performing a corresponding area search by using image information of a reference vector target area, which belongs to the reference vector target frame and is indicated by the reference vector, and the reference frame; determining a reference area in the reference frame based on the search result; generating a predicted image by using image information of the reference frame, which corresponds to the reference area; and encoding differential information between image information of the encoding target area and the predicted image.

Claims

1. A video encoding method for encoding a video image by dividing an entire image into areas, generating a predicted image for each area of the divided image based on image information of a plurality of already-encoded frames, and encoding differential information between an image of an encoding target area in an encoding target frame and the predicted image, the video encoding method comprising:

a reference vector target frame selecting step of selecting a reference vector target frame from among the already-encoded frames;

a reference vector target frame designation information encoding step of encoding information which designates the reference vector target frame;

a reference vector setting step of setting a reference vector which indicates an area which belongs to the reference vector target frame and corresponds to the encoding target area;

a reference vector encoding step of encoding the reference vector;

a reference frame selecting step of selecting a reference frame from among the already-encoded frames;

a reference frame designation information encoding step of encoding information which designates the reference frame;

a reference frame area setting step of searching for a corresponding area by using the reference frame and image information of the reference vector target area which belongs to the reference vector target frame and is indicated by the reference vector; and

setting a reference area in the reference frame based on the search result;

a predicted image generating step of generating the predicted image by using image information of the reference frame, which corresponds to the reference area; and

a differential information encoding step of encoding differential information between image information of the encoding target area and the generated predicted image.

2. The video encoding method in accordance with claim 1, wherein:

in the predicted image generating step, the predicted image is generated using image information of the reference area and the image information of the reference vector target area.

3. The video encoding method in accordance with claim 1, wherein:

in the predicted image generating step, it is selected whether the predicted image is generated using image information of the reference area, or using the image information of the reference area and the image information of the reference vector target area, and the predicted image is generated by the selected generating method; and

the video encoding method further comprises;

a predicted image generating method designation information encoding step of encoding information which designates the selected generating method.

4. The video encoding method in accordance with claim 1, wherein:

if the reference frame selected in the reference frame selecting step is a reference frame which was used when encoding the reference vector target area, then the reference area set in the reference frame area setting step is a reference area which was used when encoding the reference vector target area.

5. The video encoding method in accordance with claim 1, wherein:

if the reference frame selected in the reference frame selecting step is a reference vector target frame which was used when encoding the reference vector target area, then the reference area set in the reference frame area setting step is a reference vector target area which was used when encoding the reference vector target area.

6. The video encoding method in accordance with claim 1, wherein:

if the reference frame selected in the reference frame selecting step is an already-encoded frame, where time and viewpoint information relationships between this already-encoded frame and the encoding target frame coincide with those between a reference vector target frame which was used when encoding the reference vector target area and the reference vector target frame set for the encoding target area, then the reference area set in the reference frame area setting step is an area which belongs to the selected reference frame and is indicated by a vector whose starting point is set at the encoding target area and which has the same direction and size as a reference vector which was used when encoding the reference vector target area.

7. The video encoding method in accordance with claim 1, wherein:

if the reference frame selected in the reference frame selecting step is an already-encoded frame, where time and viewpoint information relationships between this already-encoded frame and the encoding target frame coincide with those between a reference frame which was used when encoding the reference vector target area and the reference vector target frame set for the encoding target area, then the reference area set in the reference frame area setting step is an area which belongs to the selected reference frame and is indicated by a vector whose starting point is set at the encoding target area and which has the same direction and size as a vector which indicates a corresponding relationship between the reference vector target area and a reference area which was used when encoding the reference vector target area.

8. The video encoding method in accordance with claim 1, further comprising:

an intermediate frame setting step of setting an intermediate frame which differs from each of the reference vector target frame and the reference frame, and is already encoded, wherein;

in the reference frame area setting step, an intermediate area in the intermediate frame is set using information of the reference vector target area, and the reference area is set using information of the intermediate area or the set of the information of the intermediate area and information of the reference vector target area.

9. The video encoding method in accordance with claim 8, wherein:

the intermediate frame set in the intermediate frame setting step is an already-encoded frame, where time and viewpoint information relationships between this already-encoded frame and the reference vector target frame coincide with those between the encoding target frame and the reference frame; and

in the predicted image generating step, the predicted image is generated using image information of the reference area, image information of the intermediate area, and the image information of the reference vector target area.

10. The video encoding method in accordance with claim 8, wherein:

the intermediate frame set in the intermediate frame setting step is an already-encoded frame, where time and viewpoint information relationships between this already-encoded frame and the reference vector target frame coincide with those between the encoding target frame and the reference frame;

in the predicted image generating step, it is selected whether the predicted image is generated using image information of the reference area, using the image information of the reference area and the image information of the reference vector target area, or using the image information of the reference area, image information of the intermediate area, and the image information of the reference vector target area, and the predicted image is generated by the selected generating method; and

the video encoding method further comprises;

a predicted image generating method designation information encoding step of encoding information which designates the selected generating method.

11. The video encoding method in accordance with claim 3, wherein:

in the reference frame designation information encoding step, a code word table used for encoding the information which designates the reference frame is switched based on encoded data of the reference vector target area; and

in the predicted image generating method designation information encoding step, a code word table used for encoding the information which designates the selected generating method is switched based on at least one of the encoded data of the reference vector target area, the reference frame, and the reference vector target frame.

23. A video encoding apparatus having devices for performing the steps in the video encoding method in accordance with claim 1.

24. A video encoding program by which a computer executes the steps in the video encoding method in accordance with claim 1.

25. A computer-readable storage medium which stores a video encoding program by which a computer executes the steps in the video encoding method in accordance with claim 1.

29. The video encoding method in accordance with claim 10 wherein:

in the reference frame designation information encoding step, a code word table used for encoding the information which designates the reference frame is switched based on encoded data of the reference vector target area; and

in the predicted image generating method designation information encoding step, a code word table used for encoding the information which designates the selected generating method is switched based on at least one of the encoded data of the reference vector target area, the reference frame, and the reference vector target frame.

12. A video decoding method for decoding a video image by dividing an entire image into areas, generating a predicted image for each area of the divided image based on image information of a plurality of already-decoded frames, and decoding differential information between the predicted image and an image of a decoding target area in a decoding target frame, the video decoding method comprising:

a reference vector target frame designation information decoding step of decoding, from encoded data, information which designates a reference vector target frame selected from among the already-decoded frames;

a reference vector decoding step of decoding, from the encoded data, a reference vector which indicates an area which belongs to the reference vector target frame and is set in correspondence to the decoding target area;

a reference frame designation information decoding step of decoding, from the encoded data, information which designates a reference frame selected from among the already-decoded frames;

a reference frame area setting step of searching for a corresponding area by using the reference frame and image information of the reference vector target area which belongs to the reference vector target frame and is indicated by the reference vector; and

setting a reference area in the reference frame based on the search result; and

a predicted image generating step of generating the predicted image by using image information of the reference frame, which corresponds to the reference area.

13. The video decoding method in accordance with claim 12, wherein:

in the predicted image generating step, the predicted image is generated using image information of the reference area and the image information of the reference vector target area.

14. The video decoding method in accordance with claim 12, further comprising:

a predicted image generating method designation information decoding step of decoding, from the encoded data, information which designates whether the predicted image is generated using image information of the reference area, or using the image information of the reference area and the image information of the reference vector target area, wherein;

in the predicted image generating step, the predicted image is generated by the generating method designated by the decoded information.

15. The video decoding method in accordance with claim 12, wherein:

if a frame indicated by reference frame designation information which was decoded when decoding the reference vector target area coincides with the reference frame, then in the reference frame area setting step, a reference area which was used when decoding the reference vector target area is set as the reference area.

16. The video decoding method in accordance with claim 12, wherein:

if a frame indicated by reference vector target frame designation information which was decoded when decoding the reference vector target area coincides with the reference frame, then in the reference frame area setting step, a reference vector target area which was used when decoding the above reference vector target area is set as the reference area.

17. The video decoding method in accordance with claim 12, wherein:

if time and viewpoint information relationships between the reference vector target frame and a frame indicated by reference vector target frame designation information which was decoded when decoding the reference vector target area coincide with those between the decoding target frame and the reference frame, then in the reference frame area setting step, an area, which belongs to the reference frame and is indicated by a vector whose starting point is set at the decoding target area and which has the same direction and size as a reference vector which was used when decoding the reference vector target area, is set as the reference area.

18. The video decoding method in accordance with claim 12, wherein:

if time and viewpoint information relationships between the reference vector target frame and a frame indicated by reference frame designation information which was decoded when decoding the reference vector target area coincide with those between the decoding target frame and the reference frame, then in the reference frame area setting step, an area, which belongs to the reference frame and is indicated by a vector whose starting point is set at the decoding target area and which has the same direction and size as a vector which indicates a corresponding relationship between the reference vector target area and a reference area which was used when decoding the reference vector target area, is set as the reference area.

19. The video decoding method in accordance with claim 12, further comprising:

an intermediate frame setting step of setting an intermediate frame which differs from each of the reference vector target frame and the reference frame, and is already decoded, wherein;

in the reference frame area setting step, an intermediate area in the intermediate frame is set using information of the reference vector target area, and the reference area is set using information of the intermediate area or the set of the information of the intermediate area and information of the reference vector target area.

20. The video decoding method in accordance with claim 19, wherein:

the intermediate frame set in the intermediate frame setting step is an already-decoded frame, where time and viewpoint information relationships between this already-decoded frame and the reference vector target frame coincide with those between the decoding target frame and the reference frame; and

in the predicted image generating step, the predicted image is generated using image information of the reference area, image information of the intermediate area, and the image information of the reference vector target area.

21. The video decoding method in accordance with claim 19, wherein:

the intermediate frame set in the intermediate frame setting step is an already-decoded frame, where time and viewpoint information relationships between this already-decoded frame and the reference vector target frame coincide with those between the decoding target frame and the reference frame;

the video decoding method further comprises;

a predicted image generating method designation information decoding step of decoding, from the encoded data, information which designates whether the predicted image is generated using image information of the reference area, using the image information of the reference area and the image information of the reference vector target area, or using the image information of the reference area, image information of the intermediate area, and the image information of the reference vector target area; and

in the predicted image generating step, the predicted image is generated using the generating method designated by the decoded information.

22. The video decoding method in accordance with claim 14, wherein:

in the reference frame designation information decoding step, a code word table used for decoding the information which designates the reference frame is switched based on decoded data of the reference vector target area; and

in the predicted image generating method designation information decoding step, a code word table used for decoding the information which designates the predicted image generating method is switched based on at least one of the decoded data of the reference vector target area, the reference frame, and the reference vector target frame.

26. A video decoding apparatus having devices for performing the steps in the video decoding method in accordance with claim 12.

27. A video decoding program by which a computer executes the steps in the video decoding method in accordance with claim 12.

28. A computer-readable storage medium which stores a video decoding program by which a computer executes the steps in the video decoding method in accordance with claim 12.

30. The video decoding method in accordance with claim 21, wherein:

in the reference frame designation information decoding step, a code word table used for decoding the information which designates the reference frame is switched based on decoded data of the reference vector target area; and

in the predicted image generating method designation information decoding step, a code word table used for decoding the information which designates the predicted image generating method is switched based on at least one of the decoded data of the reference vector target area, the reference frame, and the reference vector target frame.