SYSTEMS AND METHODS FOR FAST RANDOM ACCESS AND BACKWARD PLAYBACK OF VIDEO FRAMES USING DECODED FRAME CACHE

• US 20030133694A1
• Filed: 06/18/1999
• Published: 07/17/2003
• Est. Priority Date: 06/18/1999
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: YEO, BOON-LOCK
• Granted Patent: US 7,190,883 B2
• Time in Patent Office: Days
• US Class Current: 386/68
• CPC Class Codes: H04N 21/4325 by playing back content from the storage medium reproduction of recorded television signals H04N5/76; reproduction of recorded television signals H04N9/79
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/6587 Control parameters, e.g. trick play commands, viewpoint selection
• CPC Class Codes: H04N 5/783 Adaptations for reproducing at a rate different from the recording rate
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends
• CPC Class Codes: H04N 9/8042 involving data reduction

Abstract

In some embodiments, the invention includes a method of processing a video stream. The method involves detecting a request to playback a particular frame. It is determined whether a decoded version of the particular frame is in a decoded frame cache. If it is not, the method includes(i) determining a frame dependency for the particular frame; (ii) determining which of the frames in the frame dependency are in the decoded frame cache; (iii) decoding any frame in the frame dependency that is not in the decoded frame cache and placing it in the decoded frame cache; and (iv) using at least some of the decoded frames in the frame dependency to decode the particular frame to create a decoded version of the particular frame. In some embodiments, the request to playback a particular frame is part of a request to perform frame-by-frame backward playback and the method is performed for successively earlier frames with respect to the particular frame as part of the frame-by-frame backward playback. In some embodiments, the part (i) is performed whether or not it is determined that a decoded version of a particular frame is in the decoded frame cache without part (iv) being performed. Other embodiments are described and claimed.

Claims

1. A method of processing a video stream, comprising:

(a) detecting a request to playback a particular frame; and

(b) determining whether a decoded version of the particular frame is in a decoded frame cache, and if it is not

(i) determining a frame dependency for the particular frame;

(ii) determining which of the frames in the frame dependency are in the decoded frame cache;

(iii) decoding any frame in the frame dependency that is not in the decoded frame cache and placing it in the decoded frame cache; and

(iv) using at least some of the decoded frames in the frame dependency to decode the particular frame to create a decoded version of the particular frame.

2. The method of claim 1, wherein the request to playback a particular frame is part of a request to perform frame-by-frame backward playback and part (b) is performed for successively earlier frames with respect to the particular frame as part of the frame-by-frame backward playback.

3. The method of claim 1, wherein part (i) is performed whether or not it is determined that a decoded version of a particular frame is in the decoded frame cache without part (iv) being performed.

4. The method of claim 1, wherein the particular frame may be an I, P, or B frame of MPEG compressed video.

5. The method of claim 1, wherein the frame dependency is an immediate frame dependency.

6. The method of claim 5, wherein the at least some of the decoded frames referred to in part (a) (iv) are those frames in the immediate dependency.

7. The method of claim 5, wherein part (b) includes recursion where frames in the immediate frame dependency of the frame of interest are not in the decoded frame cache.

8. The method of claim 1, wherein part (b) includes a loop with a terminating condition that all frames on which the particular frame is dependent have been decoded.

9. The method of claim 1, wherein decoded frames are replaced in the decoded frame cache according to a least recently used policy.

10. The method of claim 1, wherein an index is used to represent each frame in the frame dependency.

11. The method of claim 1, wherein the frame dependency is determined through a look-up table.

12. The method of claim 11, wherein the frame dependency is determined through successive uses of a look-up table.

13. The method of claim 1, wherein the decoded frame cache includes a data structure.

14. The method of claim 1, wherein the decoded frame cache includes a section of main memory.

15. An article comprising:

a computer readable medium having instructions thereon which when executed cause a computer to;

(a) detect a request to playback a particular frame; and

(b) determine whether a decoded version of the particular frame is in a decoded frame cache, and if it is not

(i) determine a frame dependency for the particular frame;

(ii) determine which of the frames in the frame dependency are in the decoded frame cache;

(iii) decode any frame in the frame dependency that is not in the decoded frame cache and place it in the decoded frame cache; and

(iv) use at least some of the decoded frames in the frame dependency to decode the particular frame to create a decoded version of the particular frame.

16. The article of claim 15, wherein the request to playback a particular frame is part of a request to perform frame-by-frame backward playback and part (b) is performed for successively earlier frames with respect to the particular frame as part of the frame-by-frame backward playback.

17. The article of claim 15, wherein part (i) is performed whether or not it is determined that a decoded version of a particular frame is in the decoded frame cache without part (iv) being performed.

18. The article of claim 15, wherein the frame dependency is an immediate frame dependency.

19. The article of claim 18, wherein the at least some of the decoded frames referred to in part (a) (iv) are those frames in the immediate dependency.

20. The article of claim 18, wherein part (b) includes recursion where frames in the immediate frame dependency of the frame of interest are not in the decoded frame cache.

21. The article of claim 15, wherein part (b) includes a loop with a terminating condition that all frames on which the particular frame is dependent have been decoded.

22. The article of claim 15, wherein decoded frames are replaced in the decoded frame cache according to a least recently used policy.

23. The article of claim 15, wherein an index is used to represent each frame in the frame dependency.

24. The article of claim 15, wherein the frame dependency is determined through a look-up table.

25. The article of claim 24, wherein the frame dependency is determined through successive uses of a look-up table.