Video encoding method and decoding method, apparatuses therefor, programs therefor, and storage media which store the programs

• US 8,532,190 B2
• Filed: 10/24/2007
• Issued: 09/10/2013
• Est. Priority Date: 10/30/2006
• Status: Active Grant

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Shimizu, Shinya, Kimata, Hideaki, Kamikura, Kazuto, Yashima, Yoshiyuki
• Primary Examiner(s): Czekaj, David
• Assistant Examiner(s): Beck, Leron
• Application Number:
  US12/445,446
• Publication Number:
  US 20100008422A1
• Time in Patent Office: 2,148 Days
• Field of Search: None
• US Class Current: 375/240.16
• 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 indicated by a reference vector of the encoding target area, from among the already-encoded frames, where the reference vector indicates an area which belongs to the reference vector target frame and corresponds to the encoding target area;

a matching step of selecting a reference frame from among the already-encoded frames, and setting a reference vector target area which belongs to the reference vector target frame and has the same size as the encoding target area, where the image information of a reference area in the reference frame corresponds to image information of the reference vector target area;

a predicted reference vector generating step of generating a predicted reference vector as a predicted vector of the reference vector of the encoding target area, by using the reference vector target frame of the encoding target area and a reference vector and a reference vector target frame which are used when encoding an adjacent area of the encoding target area;

a predicted image generating step of generating the predicted image by using the image information of the reference area in the reference frame; and

a differential information encoding step of encoding differential information between the image information of the encoding target area and the generated predicted image, wherein;

the reference frame selected in the matching step is one of a reference frame and a reference vector target frame, which was used when encoding the reference vector target area, where;

if said one of a reference frame and a reference vector target frame is a reference frame, the reference area in the reference frame is a reference area which was used when encoding the reference vector target area, and

if said one of a reference frame and a reference vector target frame is a reference vector target frame, the reference area in the reference frame is a reference vector target area which was used when encoding the reference vector target area; and

each of the steps are performed by a computer processor.

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

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

7. A non-transitory 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.

13. The video encoding method in accordance with any one of claims 1 and 2, wherein:

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

14. The video encoding method in accordance with any one of claims 1 and 2, wherein:

in the predicted image generating step, it is selected whether the predicted image is generated using the 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.

2. 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 indicated by a reference vector of the encoding target area, from among the already-encoded frames, where the reference vector indicates an area which belongs to the reference vector target frame and corresponds to the encoding target area;

a matching step of selecting a reference frame from among the already-encoded frames, and setting a reference vector target area which belongs to the reference vector target frame and has the same size as the encoding target area, where the image information of a reference area in the reference frame corresponds to image information of the reference vector target area;

a predicted reference vector generating step of generating a predicted reference vector as a predicted vector of the reference vector of the encoding target area, by using the reference vector target frame of the encoding target area and a reference vector and a reference vector target frame which are used when encoding an adjacent area of the encoding target area;

a predicted image generating step of generating the predicted image by using the image information of the reference area in the reference frame; and

a differential information encoding step of encoding differential information between the image information of the encoding target area and the generated predicted image, wherein;

the reference frame selected in the matching 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 one of a reference vector target frame and a reference frame, which was used when encoding the reference vector target area, where;

if said one of a reference vector target frame and a reference frame is a reference vector target frame, the reference vector target frame set for the encoding target area, and the reference area in the reference frame 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, and

if said one of a reference vector target frame and a reference frame is a reference frame, the reference area in the reference frame 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; and

each of the steps are performed by a computer processor.

11. A video encoding apparatus having devices for performing the steps in the video encoding method in accordance with claim 2.

3. 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 predicted reference vector generating step of generating a predicted reference vector as a predicted vector of a reference vector of the decoding target area, by using a reference vector and a reference vector target frame which are used when decoding an adjacent area of the decoding target area;

a reference vector generating step of generating the reference vector of the decoding target area by using the predicted reference vector, where the reference vector indicates an area which corresponds to the decoding target area and belongs to a reference vector target frame that is one of the already-decoded frames;

a reference frame area setting step of selecting a reference frame from among the already-decoded frames, and setting a reference area which belongs to the reference frame and has the same size as the decoding target area, where the image information of the reference area corresponds to image information of the reference vector target area; 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, wherein;

the reference frame selected in the reference frame area setting step is one of a reference frame and a reference vector target frame, which was used when decoding the reference vector target area, where;

if said one of a reference frame and a reference vector target frame is a reference frame, 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, and

if said one of a reference frame and a reference vector target frame is a reference vector target frame, 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; and

each of the steps are performed by a computer processor.

8. A video decoding apparatus having devices for performing the steps in the video decoding method in accordance with claim 3.

9. A video decoding program by which a computer executes the steps in the video decoding method in accordance with claim 3.

10. A non-transitory 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 3.

15. The video decoding method in accordance with any one of claims 3 and 4, wherein:

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

16. The video decoding method in accordance with any one of claims 3 and 4, 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 the 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.

4. 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 predicted reference vector generating step of generating a predicted reference vector as a predicted vector of a reference vector of the decoding target area, by using a reference vector and a reference vector target frame which are used when decoding an adjacent area of the decoding target area;

a reference vector generating step of generating the reference vector of the decoding target area by using the predicted reference vector, where the reference vector indicates an area which corresponds to the decoding target area and belongs to a reference vector target frame that is one of the already-decoded frames;

a reference frame area setting step of selecting a reference frame from among the already-decoded frames, and setting a reference area which belongs to the reference frame and has the same size as the decoding target area, where the image information of the reference area corresponds to image information of the reference vector target area; 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, wherein;

the reference frame selected in the reference frame area setting step is an already-decoded frame, where time and viewpoint information relationships between this already-decoded frame and the decoding target frame coincide with those between the reference vector target frame and one of a reference frame which was used when decoding the reference vector target area and a frame indicated by reference vector target frame designation information which was decoded when decoding the reference vector target area, where;

if said one of a reference frame and a frame is a reference frame, 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, and

if said one of a reference frame and a frame is a frame, 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; and

each of the steps are performed by a computer processor.

12. A video decoding apparatus having devices for performing the steps in the video decoding method in accordance with claim 4.