Method of video encoding using windows and system thereof

• US 20040141556A1
• Filed: 01/16/2003
• Published: 07/22/2004
• Est. Priority Date: 01/16/2003
• Status: Active Grant

• Current Assignee: VIXS Systems Incorporated (Pixelworks Incorporated)
• Original Assignee: VIXS Systems Incorporated (Pixelworks Incorporated)
• Inventors: Zeng, Zhihua, Rault, Patrick
• Granted Patent: US 7,408,989 B2
• Time in Patent Office: Days
• US Class Current: 375/240.16
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51

Abstract

A first search window within a reference frame of video data is identified along with a first correlation threshold value for the first window. The first correlation threshold value is a value to which correlation factors between a pixel set being encoded and pixels sets of the first search window are compared. For example, if a correlation factor between a specific pixel set of the first search window and a pixel set being encoded meets the first threshold value, a successful match between the two pixel sets has been found, and a corresponding motion vector can be assigned to the pixel set being encoded. If none of the pixel sets within the first window meet the first threshold value, a second search window within the first frame is selected along with a second correlation threshold value. The correlation factors for pixel sets in the second window are compared to the second correlation threshold value.

Claims

1. A method of processing a video signal, the method comprising:

selecting a first search window of a first frame of video data, the first search window having a first window size;

determining a first correlation factor between a first set of pixels within the first search window with respect to a second set of pixels in a second frame of video data;

comparing the first correlation factor to a first threshold value;

selecting a second search window of the first frame, the second search window having a second window size, the second window size greater than the first window size;

determining a second correlation factor between a third set of pixels within the second search window with respect to the second set of pixels; and

comparing the second correlation factor to a second threshold value, the second threshold value being different than the first threshold value.

2. The method of claim 1, wherein selecting the second search window comprises the first set of pixels being within the second search window.

3. The method of claim 1, further comprising selecting a third search window of the first frame, the third search window having a third window size, the third window size greater than the second window size.

4. The method of claim 3, further comprising determining a third correlation factor between a third fourth of pixels within the third search window with respect to the second set of pixels.

5. The method of claim 4, further comprising comparing the third correlation factor to a third threshold having a third correlation threshold value, the third correlation threshold value being different than the second correlation threshold value and different than the first correlation threshold value.

6. The method of claim 1, further comprising determining a motion vector based on at least one of the pixels within the third set of pixels within the third search window.

7. The method of claim 1 further comprising:

saving the first correlation factor; and

comparing the first correlation factor to the second threshold value.

8. The method of claim 7 wherein comparing the first correlation factor to the second threshold value occurs before comparing the second correlation factor to the second threshold value.

9. The method of claim 1, wherein determining the first correlation factor is determined based on a first correlation technique and determining the second correlation factor is determined based on a second correlation technique different than the first correlation technique.

10. The method of claim 2, wherein determining the first correlation factor is determined based on a first correlation technique and determining the second correlation factor is determined based on the first correlation technique.

11. The method of claim 1 further comprising:

selecting a third search window of the first frame, the third search window having a third window size, the third window size greater than the first window size;

determining a third correlation factor between the fourth set of pixels within the third search window with respect to the second set of pixels;

when the fourth set of pixels has a best correlation factor of sets of pixels in the third search window, identifying the fourth set of pixels as a set of pixels with the best correlation factor in the third window.

17. The method of claim 1, wherein comparing the first set of pixels includes the first correlation being determined based on a first correlation technique and comparing the second set of pixels includes the second correlation being determined based on a second correlation technique different than the first correlation technique.

18. The method of claim 1, wherein comparing the first set of pixels includes the first correlation being determined based on a first correlation technique and comparing the second set of pixels includes the second correlation being determined based on the first correlation technique.

12. A method comprising:

selecting a first search window of a first frame of video data, the first search window having a first window size;

comparing a first set of pixels within the first search window to a set of pixels in a second frame of video data to determine a first correlation;

selecting a second search window of the first frame of video data, the second search window having a second window size, the second window size greater than the first window size; and

comparing a second set of pixels within the second search window to the set of pixels in a second frame of video data to determine a second correlation.

13. The method of claim 12, further comprising evaluating the first correlation using a first threshold and evaluating the second correlation using a second threshold, the first threshold value being more stringent than the second threshold value.

14. The method of claim 12, further comprising selecting a third search window of the first frame of video data, the third search window having a third window size, the third window size greater than the second window size.

15. The method of claim 14, further comprising comparing a third set of pixels within the third search window to the set of pixels in the second frame of video data to determine a third correlation.

16. The method of claim 12, wherein the first window size is a equal to a size of the second set of pixels.

19. The method of claim 12, wherein selecting the second search window comprises the first set of pixels being within the second search window.

20. A system comprising:

a video data processing element;

a memory coupled to the video data processing element, the memory comprising;

a video data storage region to store a first frame of video data and a second frame of video data; and

a program storage region to store program instructions, the program instructions to facilitate

selecting a first search window of a first frame of video data, the first search window having a first window size;

comparing a first set of pixels within the first search window to a set of pixels in a second frame of video data to determine a first correlation;

selecting a second search window of the first frame of video data, the second search window having a second window size, the second window size greater than the first window size; and

comparing a second set of pixels within the second search window to the set of pixels in a second frame of video data to determine a second correlation.

21. The system of claim 20, wherein the program instructions further comprise facilitating

evaluating the first correlation using a first threshold;

evaluating the second correlation using a second threshold, the first threshold being different than the second threshold.

22. The system of claim 20, wherein the program instructions further comprise facilitating

selecting a third search window of the first frame of video data, the third search window having a third window size, wherein the third window size is greater than the second window size.

23. The system of claim 20, wherein the program instructions selecting the first window size comprise the first window size being a single pixel and the second window size includes a plurality of pixels.

24. A method of determining a motion vector for a pixel set being encoded comprising:

selecting a first search window of a first frame of video data, the first search window having a first window size;

determining if any pixel set associated with the first search window meets a first correlation requirement with respect to the pixel set being encoded;

determining a motion vector for the pixel set being encoded when any pixel set associated the first search window meets the first correlation requirement; and

when no pixel set associated the first search window meets the first correlation requirement;

selecting a second search window of the first frame of video data, the second search window having a first window size larger than the first window size;

determining if any pixel set associated with the first search window meets a second correlation requirement with respect to the pixel set being encoded, the second correlation requirement being different than the first correlation requirement;

determining a motion vector for the pixel set being encoded when any pixel set associated the second search window meets the second correlation requirement.

25. The method of claim 24, wherein the step of determining a motion vector for the pixel set being encoded comprises the second correlation requirement being less stringent than the first correlation requirement.