Apparatus, and associated method, for forming a compressed motion vector field utilizing predictive motion coding
View Patent ↗Apparatus, and an associated method, motion compensates coding of video sequences. Motion compensated prediction is utilized in the representation of motion vector fields. Reduced numbers of bits are required to represent the motion vector field while maintaining a low prediction error, thereby facilitating improved communication of, and recreation of, video frames forming a video sequence.
1. A method of decoding encoded information representative of a video sequence, said video sequence comprising a plurality of video frames, said decoding method comprising the steps of:
receiving encoded information representative of a segment of a current frame of said video sequence;
identifying a coding mode of the encoded information, the coding mode being one of at least a first coding mode and a second coding mode; and
reconstructing the segment of the current frame of the video sequence;
wherein the reconstructing step is performed using a first motion field model derived using motion compensated prediction with respect to a previously-encoded frame of the video sequence if the identified coding mode is the first coding mode; and
wherein the reconstructing step is performed using a second motion field model based on a motion field model determined for an adjacent previously-encoded segment of the current frame if the identified coding mode is the second coding mode.
2. The method according to claim 1 , further comprising the step of forming a prediction motion field model for the segment based on the motion field model determined for the adjacent previously-encoded segment of the current frame.
3. The method according to claim 2 , wherein the prediction motion field model is formed by projecting the motion field model determined for the adjacent previously-encoded segment from the adjacent previously-encoded segment into the segment being reconstructed.
4. The method according to claim 2 , wherein the second motion field model is formed as a combination of the prediction motion field model and a refinement motion field model.
5. The method according to claim 4 , wherein the refinement motion field model represents a difference between the first motion field model and the prediction motion field model.
6. The method according to claim 4 , wherein in the second coding mode the encoded information representative of the segment of the current frame comprises motion coefficient information representative of the refinement motion field model.
7. The method according to claim 6 , wherein the motion coefficient information comprises an indication of a non-zero coefficient pattern and at least one non-zero coefficient value.
8. The method according to claim 2 , wherein in the second coding mode the encoded information representative of the segment of the current frame comprises an indication of the adjacent previously-encoded segment whose motion field model is to be used to form the prediction motion field model for the segment.
9. The method according to claim 8 , wherein the indication of the adjacent previously-encoded segment comprises information about the position of the adjacent previously-encoded segment with respect to the segment being reconstructed.
10. The method according to claim 8 , wherein the indication of the adjacent previously-encoded segment comprises information about a sub-segment within the adjacent previously encoded segment.
11. The method according to claim 1 , wherein in the first coding mode the encoded information representative of the segment of the current frame comprises motion coefficient information.
12. The method according to claim 11 , wherein the motion coefficient information comprises an indication of a non-zero coefficient pattern and at least one non-zero coefficient value.
13. A video decoder for decoding encoded information representative of a video sequence, said video sequence comprising a plurality of video frames, said decoder including:
an input for receiving encoded information representative of a segment of a current frame of the video sequence;
means for identifying a coding mode of the encoded information, the coding mode being one of at least a first coding mode and a second coding mode;
means for reconstructing the segment of the current frame of the video sequence using a first motion field model derived using motion compensated prediction with respect to a previously-encoded frame of the video sequence if the identified coding mode is the first coding mode; and
means for reconstructing the segment of the current frame of the video sequence using a second motion field model based on a motion field model determined for an adjacent previously-encoded segment of the current frame if the identified coding mode is the second coding mode.
14. The video decoder according to claim 13 , arranged to form a prediction motion field model for the segment from the motion field model determined for the adjacent previously-encoded segment of the current frame.
15. The video decoder according to claim 14 , arranged to form the prediction motion field model by projecting the motion field model determined, for the adjacent previously-encoded segment from the adjacent previously-encoded segment into the segment being reconstructed.
16. The A video decoder according to claim 14 , arranged to form the second motion field model as a combination of the prediction motion field model and a refinement motion field model.
17. The video decoder according to claim 16 , wherein the refinement motion field model represents a difference between the first motion field model and said prediction motion field model.
18. The video decoder according to claim 16 , wherein in the second coding mode said decoder is arranged to decode the encoded information representative of the segment of the current frame to recover motion coefficient information representative of the refinement motion field model.
19. The video decoder according to claim 13 , wherein in said first coding mode said decoder is arranged to decode the encoded information representative of the segment of the current frame to recover motion coefficient information.
20. The video decoder according to claim 13 , wherein in the second coding mode said decoder is arranged to decode the encoded information representative of the segment of the current frame to recover an indication of the adjacent previously-encoded segment.
21. The video decoder according to claim 20 , wherein the indication of the adjacent previously-encoded segment, comprises information about the position of the adjacent previously-encoded segment with respect to the segment being reconstructed.
22. The video decoder according to claim 20 , wherein the indication of the adjacent previously-encoded segment comprises information about a sub-segment within the adjacent previously-encoded segment.
23. The video decoder according to claim 20 , wherein in the second coding mode the means for reconstructing the segment of the current frame is arranged to derive the prediction motion field model from the motion field model for the indicated adjacent previously-encoded segment.
24. The video decoder according to claim 23 , wherein in the second coding mode the means for reconstructing the segment of the current frame is further arranged to reconstruct the segment of the current frame by combining the prediction motion field model with the refinement motion field model.