Encoding video signals using multi-phase motion estimation

• US 5,778,190 A
• Filed: 09/29/1995
• Issued: 07/07/1998
• Est. Priority Date: 07/21/1995
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Agarwal, Rohit
• Primary Examiner(s): Voeltz, Emanuel Todd
• Assistant Examiner(s): PEESO, THOMAS R
• Application Number:
  US08/537,298
• Time in Patent Office: 1,012 Days
• Field of Search: 348/394, 348/403, 348/407, 348/415, 348/416, 395/114, 395/888, 395/200.18, 395/200.77, 382/236, 382/238
• US Class Current: 709/247
• CPC Class Codes: H04N 1/415 in which the picture-elements are subdivided or grouped into fixed one-dimensional or two-dimensional blocks

Abstract

Video signals are encoded using motion compensation based on motion vectors generated using multi-phase motion estimation. In a first phase, a first subset of video signals of each block is compared to the reference frame at locations corresponding to a first set of motion vectors. In a second phase, a second subset of video signals of each block is compared to the reference frame at locations corresponding to a second set of motion vectors, where the resolution of the first subset of video signals in the spatial domain is lower than the resolution of the second subset of video signals. In an alternative embodiment, in the first phase, each block is compared to the reference frame at locations corresponding to a first set of motion vectors. In the second phase, each block is compared to the reference frame at locations corresponding to a second set of motion vectors, where the second set of motion vectors is based on at least two best matches from the first phase.

Claims

1. A computer-implemented process for encoding video signals, comprising the steps of:

(a) generating a motion vector for a current block of video signals of a current frame by performing motion estimation relative to a reference frame; and

(b) generating encoded video signals for the current block using motion compensation based on the motion vector, wherein;

the motion estimation of step (a) comprises a first phase and a second phase;

the first phase comprises the step of comparing a first subset of video signals of the current block to the reference frame at locations corresponding to a first set of motion vectors;

the second phase comprises the step of comparing a second subset of video signals of the current block to the reference frame at locations corresponding to a second set of motion vectors; and

the resolution of the first subset of video signals in the spatial domain is lower than the resolution of the second subset of video signals.

2. The process of claim 1, wherein the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors.

3. The process of claim 1, wherein the second set of motion vectors is based on at least two best matches from the first phase.

4. The process of claim 1, wherein the number of motion vectors in the second set is less than the number of motion vectors in the first set.

5. The process of claim , wherein:

the motion estimation of step (a) further comprises a third phase;

the third phase comprises the step of comparing a third subset of video signals of the current block to the reference frame at locations corresponding to a third set of motion vectors; and

the resolution of the second subset of video signals in the spatial domain is lower than the resolution of the third subset of video signals.

6. The process of claim 5, wherein:

the third subset of video signals comprises all of the video signals of the current block;

the third set of motion vectors is based on at least two best matches from the second phase; and

the number of motion vectors in the third set is less than the number of motion vectors in the second set.

7. The process of claim wherein:

the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors;

the resolution of the second set of motion vectors in the velocity domain is lower than the resolution of the third set of motion vectors;

the second set of motion vectors is based on at least two best matches from the first phase; and

the number of motion vectors in the second set is less than the number of motion vectors in the first set.

8. An apparatus for encoding video signals, comprising:

(a) means for generating a motion vector for a current block of video signals of a current frame by performing motion estimation relative to a reference frame; and

(b) means for generating encoded video signals for the current block using motion compensation based on the motion vector, wherein;

the motion estimation of means (a) comprises a first phase and a second phase;

the first phase comprises comparing a first subset of video signals of the current block to the reference frame at locations corresponding to a first set of motion vectors;

the second phase comprises comparing a second subset of video signals of the current block to the reference frame at locations corresponding to a second set of motion vectors; and

the resolution of the first subset of video signals in the spatial domain is lower than the resolution of the second subset of video signals.

9. The apparatus of claim 8, wherein the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors.

10. The apparatus of claim 8, wherein the second set of motion vectors is based on at least two best matches from the first phase.

11. The apparatus of claim 8, wherein the number of motion vectors in the second set is less than the number of motion vectors in the first set.

12. The apparatus of claim 8, wherein:

the motion estimation of means (a) further comprises a third phase;

the third phase comprises comparing a third subset of video signals of the current block to the reference frame at locations corresponding to a third set of motion vectors; and

the resolution of the second subset of video signals in the spatial domain is lower than the resolution of the third subset of video signals.

13. The apparatus of claim 12, wherein:

the third subset of video signals comprises all of the video signals of the current block;

the third set of motion vectors is based on at least two best matches from the second phase; and

the number of motion vectors in the third set is less than the number of motion vectors in the second set.

14. The apparatus of claim 13, wherein:

the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors;

the resolution of the second set of motion vectors in the velocity domain is lower than the resolution of the third set of motion vectors;

the second set of motion vectors is based on at least two best matches from the first phase; and

the number of motion vectors in the second set is less than the number of motion vectors in the first set.

15. A storage medium having stored thereon a plurality of instructions for encoding video signals, wherein the plurality of instructions when executed by a processor, cause the processor to perform the steps of:

(a) generating a motion vector for a current block of video signals of a current frame by performing motion estimation relative to a reference frame; and

(b) generating encoded video signals for the current block using motion compensation based on the motion vector, wherein;

the motion estimation of step (a) comprises a first phase and a second phase;

the first phase comprises comparing a first subset of video signals of the current block to the reference frame at locations corresponding to a first set of motion vectors;

the second phase comprises comparing a second subset of video signals of the current block to the reference frame at locations corresponding to a second set of motion vectors; and

the resolution of the first subset of video signals in the spatial domain is lower than the resolution of the second subset of video signals.

16. The storage medium of claim 15, wherein the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors.

17. The storage medium of claim 15, wherein the second set of motion vectors is based on at least two best matches from the first phase.

18. The storage medium of claim 15, wherein the number of motion vectors in the second set is less than the number of motion vectors in the first set.

19. The storage medium of claim 15, wherein:

the motion estimation of step (a) further comprises a third phase;

the third phase comprises comparing a third subset of video signals of the current block to the reference frame at locations corresponding to a third set of motion vectors; and

the resolution of the second subset of video signals in the spatial domain is lower than the resolution of the third subset of video signals.

20. The storage medium of claim 19, wherein:

the third subset of video signals comprises all of the video signals of the current block;

the third set of motion vectors is based on at least two best matches from the second phase; and

the number of motion vectors in the third set is less than the number of motion vectors in the second set.

21. The storage medium of claim 20, wherein:

the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors;

the resolution of the second set of motion vectors in the velocity domain is lower than the resolution of the third set of motion vectors;

the second set of motion vectors is based on at least two best matches from the first phase; and

the number of motion vectors in the second set is less than the number of motion vectors in the first set.

22. A computer-implemented process for encoding video signals, comprising the steps of:

(a) generating a motion vector for a current block of video signals of a current frame by performing motion estimation relative to a reference frame; and

(b) generating encoded video signals for the current block using motion compensation based on the motion vector, wherein;

the motion estimation of step (a) comprises a first phase and a second phase;

the first phase comprises the step of comparing the current block to the reference frame at locations corresponding to a first set of motion vectors;

the second phase comprises the step of comparing the current block to the reference frame at locations corresponding to a second set of motion vectors; and

the second set of motion vectors is based on at least two best matches from the first phase.

23. The process of claim 22, wherein the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors.

24. The process of claim 22, wherein the number of motion vectors in the second set is less than the number of motion vectors in the first set.

25. The process of claim 22, wherein:

the motion estimation of step (a) further comprises a third phase;

the third phase comprises the step of comparing the current block to the reference frame at locations corresponding to a third set of motion vectors; and

the third set of motion vectors is based on at least two best matches from the second phase.

26. The process of claim 25, wherein:

the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors;

the resolution of the second set of motion vectors in the velocity domain is lower than the resolution of the third set of motion vectors;

the number of motion vectors in the second set is less than the number of motion vectors in the first set; and

the number of motion vectors in the third set is less than the number of motion vectors in the second set.

27. An apparatus for encoding video signals, comprising:

(a) means for generating a motion vector for a current block of video signals of a current frame by performing motion estimation relative to a reference frame; and

(b) means for generating encoded video signals for the current block using motion compensation based on the motion vector, wherein;

the motion estimation of means (a) comprises a first phase and a second phase;

the first phase comprises comparing the current block to the reference frame at locations corresponding to a first set of motion vectors,

the second phase comprises comparing the current block to the reference frame at locations corresponding to a second set of motion vectors; and

the second set of motion vectors is based on at least two best matches from the first phase.

28. The apparatus of claim 27, wherein the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors.

29. The apparatus of claim 27, wherein the number of motion vectors in the second set is less than the number of motion vectors in the first set.

30. The apparatus of claim 27, wherein:

the motion estimation of means (a) further comprises a third phase;

the third phase comprises comparing the current block to the reference frame at locations corresponding to a third set of motion vectors; and

the third set of motion vectors is based on at least two best matches from the second phase.

31. The apparatus of claim 30, wherein:

the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors;

the resolution of the second set of motion vectors in the velocity domain is lower than the resolution of the third set of motion vectors;

the number of motion vectors in the second set is less than the number of motion vectors in the first set; and

the number of motion vectors in the third set is less than the number of motion vectors in the second set.

32. A storage medium having stored thereon a plurality of instructions for encoding video signals, wherein the plurality of instructions when executed by a processor cause the processor to perform the steps of:

(a) generating a motion vector for a current block of video signals of a current frame by performing motion estimation relative to a reference frame; and

(b) generating encoded video signals for the current block using motion compensation based on the motion vector, wherein;

the motion estimation of step (a) comprises a first phase and a second phase;

the first phase comprises comparing the current block to the reference frame at locations corresponding to a first set of motion vectors;

the second phase comprises comparing the current block to the reference frame at locations corresponding to a second set of motion vectors; and

the second set of motion vectors is based on at least two best matches from the first phase.

33. The storage medium of claim 32, wherein the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors.

34. The storage medium of claim 32, wherein the number of motion vectors in the second set is less than the number of motion vectors in the first set.

35. The storage medium of claim 32, wherein:

the motion estimation of step (a) further comprises a third phase;

the third phase comprises comparing the current block to the reference frame at locations corresponding to a third set of motion vectors; and

the third set of motion vectors is based on at least two best matches from the second phase.

36. The storage medium of claim 35, wherein:

the resolution of the first set of motion vectors in the velocity domain is lower than the resolution of the second set of motion vectors;

the resolution of the second set of motion vectors in the velocity domain is lower than the resolution of the third set of motion vectors;

the number of motion vectors in the second set is less than the number of motion vectors in the first set; and

the number of motion vectors in the third set is less than the number of motion vectors in the second set.