Method of identifying target synchronization point pair through scan-line image matching scheme

• US 8,104,055 B2
• Filed: 11/14/2007
• Issued: 01/24/2012
• Est. Priority Date: 11/14/2007
• Status: Expired due to Fees

• Current Assignee: MAVS Lab Incorporated
• Original Assignee: MAVS Lab Incorporated
• Inventors: Wang, Bei, Yeh, Chia-Hung, Shih, Hsuan-Huei, Kuo, Chung-Chieh
• Primary Examiner(s): Kumar, Pankaj
• Assistant Examiner(s): BROWN, RUEBEN M
• Application Number:
  US11/940,300
• Publication Number:
  US 20090122189A1
• Time in Patent Office: 1,532 Days
• Field of Search: 725/81, 725/17, 725/19, 348/500, 382/193, 382/222
• US Class Current: 725/19
• CPC Class Codes: H04N 5/05 Synchronising circuits with arrangements for extending range of synchronisation, e.g. by using switching between several time constants

Abstract

A method of identifying a target synchronization point pair including a source synchronization point corresponding to a source end and a destination synchronization point corresponding to a destination end is provided. The method includes receiving a source scan-line image corresponding to a first video source from the source end; selecting at least a comparing frame out of the source scan-line image; providing a destination scan-line image corresponding to a second video source at the destination end; and determining the target synchronization point pair by comparing the comparing frame and the destination scan-line image.

Claims

1. A method of identifying a target synchronization point pair including a source synchronization point corresponding to a source end and a destination synchronization point corresponding to a destination end, the method comprising:

utilizing the destination end for receiving a source scan-line image corresponding to a first video source from the source end, wherein the source scan-line image is created by extracting one scan-line from each frame of the first video source, the first video source having a plurality of frames and the created source scan-line image comprising a plurality of scan-lines;

utilizing the destination end for selecting at least a comparing frame out of the source scan-line image;

utilizing the destination end for providing a destination scan-line image corresponding to a second video source at the destination end, wherein the destination scan-line image is created by extracting one scan-line from each frame of the second video source, the second video source having a plurality of frames and the created destination scan-line image comprising a plurality of scan-lines; and

utilizing the destination end for determining the target synchronization point pair by comparing the comparing frame and the destination scan-line image and finding matching image correlation values.

2. The method of claim 1, wherein the step of receiving the source scan-line image comprises:

receiving a compressed scan-line image from the source end; and

decompressing the compressed scan-line image to get the source scan-line image at the destination end.

3. The method of claim 1, wherein the step of receiving the source scan-line image comprises:

requesting the source end for at least a scan-line image segment according to information of an electronic program guide (EPG); and

receiving the scan-line image segment as the source scan-line image from the source end.

4. The method of claim 3, wherein the step of requesting the source end for at least the scan-line image segment according to information of the EPG comprises:

determining a time error between a starting time point of the second video source and a reference starting time point provided by the EPG;

referring to the time error to determine a time duration after the starting time point of the second video source; and

requesting the source end for the scan-line image segment corresponding to the time duration.

5. The method of claim 1, wherein the step of providing the destination scan-line image comprises:

applying a black margin detection to the second video source to identify a black margin inserted to each frame of the second video source;

obtaining black margin removed frames according to results of the black margin detection; and

generating the destination scan-line image according to the black margin removed frames.

6. The method of claim 5, wherein the step of applying the black margin detection to the second video source comprises:

generating a black image having an image size equal to a frame size corresponding to the second video source;

performing an XOR operation to combine the black image and a frame in the second video source to generate a binary image;

performing a NOT operation upon the binary image to generate an updated binary image;

for each row of the updated binary image, performing an AND operation upon pixels located at the same row; and

identifying the black margin according to results of the AND operation applied to pixels at rows of the updated binary image.

7. The method of claim 6, wherein the step of applying the black margin detection to the second video source further comprises:

before executing the XOR operation, pre-processing the frame by making each pixel having an original pixel value equal to or smaller than a predetermined value to have an updated pixel value equal to zero.

8. The method of claim 5, wherein the step of generating the destination scan-line image according to the black margin removed frames comprises:

adjusting the black margin removed frames to generate adjusted black margin removed frames according to an image resolution discrepancy or a frame rate discrepancy between the black margin removed frames and the first video source; and

generating the destination scan-line image according to the adjusted black margin removed frames.

9. The method of claim 5, wherein the step of generating the destination scan-line image according to the black margin removed frames comprises:

generating a scan-line image according to the black margin removed frames;

adjusting the scan-line image to generate the destination scan-line image according to an image resolution discrepancy or a frame rate discrepancy between the black margin removed frames and the first video source.

10. The method of claim 5, wherein the step of receiving the source scan-line image further comprises:

adjusting the source scan-line image according to an image resolution discrepancy or a frame rate discrepancy between the black margin removed frames and the first video source.

11. The method of claim 5, wherein the step of providing the destination scan-line image comprises:

generating a scan-line image according to frames of the second video source;

adjusting the scan-line image to generate the destination scan-line image according to an image resolution discrepancy or a frame rate discrepancy between the second video source and the first video source.

12. The method of claim 1, wherein the step of providing the destination scan-line image comprises:

adjusting frames of the second video source to generate adjusted frames according to an image resolution discrepancy or a frame rate discrepancy between the second video source and the first video source; and

generating the destination scan-line image according to the adjusted frames.

13. The method of claim 1, wherein the step of receiving the source scan-line image further adjusts the source scan-line image according to an image resolution discrepancy or a frame rate discrepancy between the second video source and the first video source.

14. The method of claim 1, wherein the step of selecting at least the comparing frame from the source scan-line image comprises selecting a plurality of comparing frames from the source scan-line image;

and the step of determining the target synchronization point pair comprises;

respectively comparing the comparing frames and the destination scan-line image for identifying a plurality of candidate matching point pairs;

checking the candidate matching point pairs to select a rough synchronization point pair out of the candidate matching point pairs, wherein the rough synchronization point pair includes a rough source synchronization point and a rough destination synchronization point;

selecting a comparing portion out of a specific comparing frame corresponding to the rough source synchronization point; and

comparing the comparing portion with a portion of the destination scan-line image that corresponds to the rough destination synchronization point to determine the target synchronization point pair.

15. The method of claim 14, wherein the comparing portion is a middle portion of the specific comparing frame corresponding to the rough source synchronization point.

16. The method of claim 14, wherein the step of checking the candidate matching point pairs comprises:

calculating a slope index for each candidate matching point pair according to the corresponding candidate matching point pair, a starting time point of the second video source, and a starting time point of the first video source;

checking the slope index to determine if the corresponding candidate matching point pair is a valid matching point pair or an invalid matching point pair; and

selecting one of valid matching point pairs as the rough synchronization point pair.

17. The method of claim 16, further comprising:

checking a ratio of valid matching point pairs to invalid matching point pairs for determining similarity between the first video source and the second video source.

18. The method of claim 14, wherein the step of comparing the comparing portion with the portion of the destination scan-line image comprises:

providing a sliding window for the destination scan-line image, wherein a size of the sliding window is equal to a size of the comparing portion;

calculating a plurality of image difference values according to the comparing portion and the sliding window; and

determining the target synchronization point pair according to a destination image defined by the sliding window and having a minimum value of the image difference values.

19. The method of claim 14, wherein the step of comparing the comparing portion with the portion of the destination scan-line image comprises:

providing a sliding window for the destination scan-line image, wherein a size of the sliding window is equal to a size of the comparing portion;

calculating a plurality of image correlation values according to the comparing portion and the sliding window; and

determining the target synchronization point pair according to a destination image defined by the sliding window and having a maximum value of the image correlation values.

20. The method of claim 14, wherein the step of comparing the comparing portion with the portion of the destination scan-line image comprises:

providing a sliding window for the destination scan-line image, wherein a size of the sliding window is equal to a size of the comparing portion;

calculating a plurality of image difference values according to the comparing portion and the sliding window;

calculating a plurality of image correlation values according to the comparing portion and the sliding window; and

determining the target synchronization point pair according to a destination image defined by the sliding window and having a minimum value of the image difference values and a maximum value of the image correlation values.

21. The method of claim 14, wherein the step of respectively comparing the comparing frames and the destination scan-line image for identifying the candidate matching point pairs comprises:

for each of the comparing frames;

providing a sliding window for the destination scan-line image, wherein a size of the sliding window is equal to a size of the comparing frame;

calculating a plurality of image difference values according to the comparing frame and the sliding window; and

determining a candidate matching point pair according to a destination image defined by the sliding window and having a minimum value of the image difference values.

22. The method of claim 14, wherein the step of respectively comparing the comparing frames and the destination scan-line image for identifying the candidate matching point pairs comprises:

for each of the comparing frames;

providing a sliding window for the destination scan-line image, wherein a size of the sliding window is equal to a size of the comparing frame;

calculating a plurality of image correlation values according to the comparing frame and the sliding window; and

determining a candidate matching point pair according to a destination image defined by the sliding window and having a maximum value of the image correlation values.

23. The method of claim 14, wherein the step of respectively comparing the comparing frames and the destination scan-line image for identifying the candidate matching point pairs comprises:

for each of the comparing frames;

providing a sliding window for the destination scan-line image, wherein a size of the sliding window is equal to a size of the comparing portion;

calculating a plurality of image difference values according to the comparing frame and the sliding window;

calculating a plurality of image correlation values according to the comparing frame and the sliding window; and

determining a candidate matching point pair according to a destination image defined by the sliding window and having a minimum value of the image difference values and a maximum value of the image correlation values.

24. The method of claim 1, further comprising:

estimating a time shift between the source end and the destination end according to the target synchronization point pair.

25. A method of identifying a target synchronization point pair including a source synchronization point corresponding to a source end and a destination synchronization point corresponding to a destination end, the method comprising:

utilizing the destination end for receiving a source scan-line image corresponding to a first video source from the source end;

utilizing the destination end for selecting at least a comparing frame out of the source scan-line image;

utilizing the destination end for providing a destination scan-line image corresponding to a second video source at the destination end, comprising;

applying a black margin detection to the second video source to identify a black margin inserted to each frame of the second video source, comprising;

generating a black image having an image size equal to a frame size corresponding to the second video source;

performing an XOR operation to combine the black image and a frame in the second video source to generate a binary image;

performing a NOT operation upon the binary image to generate an updated binary image;

for each row of the updated binary image, performing an AND operation upon pixels located at the same row; and

identifying the black margin according to results of the AND operation applied to pixels at rows of the updated binary image;

obtaining black margin removed frames according to results of the black margin detection; and

generating the destination scan-line image according to the black margin removed frames; and

utilizing the destination end for determining the target synchronization point pair by comparing the comparing frame and the destination scan-line image.