Signaling valid entry points in a video stream

• US 20050105883A1
• Filed: 06/30/2004
• Published: 05/19/2005
• Est. Priority Date: 11/13/2003
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Crinon, Regis J., Srinivasan, Sridhar, Regunathan, Shankar, Holcomb, Thomas W., Onders, Timothy E.
• Granted Patent: US 7,839,930 B2
• Time in Patent Office: Days
• US Class Current: 386/241
• CPC Class Codes: H04N 21/23424 involving splicing one content stream with another content stream, e.g. for inserting or substituting an advertisement
• CPC Class Codes: H04N 21/44016 involving splicing one content stream with another content stream, e.g. for substituting a video clip
• CPC Class Codes: H04N 21/8455 involving pointers to the content, e.g. pointers to the I-frames of the video stream

Abstract

Techniques and tools for coding/decoding of digital video, and in particular, for determining, signaling and detecting entry points in video streams are described. Techniques and tools described herein are used to embed entry point indicator information in the bitstream that receivers, editing systems, insertion systems, and other systems can use to detect valid entry points in compressed video.

Claims

1. A method comprising:

determining one or more entry points for a sequence comprising plural video frames based at least in part on an entry point policy; and

inserting in a bitstream an entry point indicator that indicates a first frame of the plural frames is one of the one or more entry points, wherein the first frame has a type selected from a set of types comprising field interlaced P/I frame.

2. The method of claim 1 wherein the set of types further comprises:

frame interlaced I-frame, field interlaced I/P-frame, field interlaced I/I-frame, and progressive I-frame.

3. The method of claim 1 wherein the one or more entry points comprises plural entry points positioned at different intervals.

4. The method of claim 1 wherein the entry point indicator comprises an entry point header.

5. The method of claim 4 wherein the entry point header includes buffer fullness information.

6. The method of claim 1 wherein the entry point indicator comprises an entry point start code.

7. The method of claim 6 wherein the entry point start code is an abbreviated start code sufficient to distinguish the entry point start code from other start codes in the bitstream.

8. The method of claim 1 wherein the bitstream has plural syntax levels, and wherein the entry point indicator is included at a syntax level below sequence level.

9. The method of claim 1 wherein the syntax level below sequence level is entry point level.

10. The method of claim 1 wherein the entry point indicator immediately follows a sequence header in the bitstream.

11. The method of claim 1 wherein the entry point indicator indicates a commercial insertion point to facilitate video splicing.

12. A computer readable medium storing computer executable instructions for causing the computer system to perform the method of claim 1 during video encoding.

13. A method comprising:

receiving a bitstream for a sequence comprising plural video frames;

detecting an entry point indicator in the bitstream, wherein the entry point indicator marks a first frame of the plural frames as an entry point for decoding and is positioned in the bitstream according to an entry point policy; and

decoding at least a portion of the bitstream based at least in part on the entry point indicator;

wherein the entry point policy comprises one or more conditions for entry point indicator positioning, the one or more conditions comprising restriction of the first frame to a type selected from a set of types comprising field interlaced P/I-frame.

14. The method of claim 13 wherein the set of types further comprises frame interlaced I-frame, field interlaced I/P-frame, field interlaced I/I-frame, and progressive I-frame.

15. The method of claim 13 wherein the bitstream comprises plural syntax levels, and wherein the entry point indicator is at a syntax level below sequence level.

16. The method of claim 15 wherein the syntax level below sequence level is entry point level.

17. The method of claim 13 wherein the entry point indicator comprises an entry point start code and an entry point header.

18. The method of claim 13 wherein the first frame is a frame interlaced I-frame, the one or more conditions further comprising no other restrictions.

19. The method of claim 13 wherein the first frame is a progressive I-frame, the one or more conditions further comprising no other restrictions.

20. The method of claim 13 wherein the first frame is a field interlaced I/I-frame, the conditions further comprising no other restrictions.

21. The method of claim 13 wherein the first frame is a field interlaced I/P-frame, wherein the field interlaced I/P-frame contains an interlaced I-field followed by an interlaced P-field, the one or more conditions further comprising:

the interlaced P-field is only predicted from the interlaced I-field.

22. The method of claim 21 wherein a numref field in a field header for the interlaced P-field is set to 0, and wherein a reffield field in the field header for the interlaced P-field is set to 0.

23. The method of claim 13 wherein the first frame is a field interlaced P/I-frame, and wherein the field interlaced P/I-frame contains an interlaced P-field followed by an interlaced I-field, the one or more conditions further comprising:

a P-field of a field interlaced P/P-frame following the field interlaced P/I-frame is not predicted from the interlaced P-field of the field interlaced P/I frame.

24. The method of claim 13 wherein the first frame is a field interlaced P/I-frame, and wherein the field interlaced P/I frame contains an interlaced P-field followed by an interlaced I-field, the one or more conditions further comprising:

a B-field of a field interlaced B/B-frame following the field interlaced P/I frame is not predicted from the interlaced P-field of the field interlaced P/I frame.

25. The method of claim 13 wherein the first frame is a field interlaced P/I-frame, and wherein the field interlaced P/I-frame contains an interlaced P-field followed by an interlaced I-field, the one or more conditions further comprising:

a frame interlaced B-frame following the field interlaced P/I-frame is not predicted from the field interlaced P/I-frame.

26. The method of claim 13 wherein the first frame is a field interlaced P/I-frame, and wherein the field interlaced P/I frame contains an interlaced P-field followed by an interlaced I-field, the one or more conditions further comprising:

a frame interlaced P-frame following the field interlaced P/I-frame is not predicted from the field interlaced P/I-frame.

27. The method of claim 13 wherein the first frame is a field interlaced P/I-frame, wherein the field interlaced P/I-frame contains an interlaced P-field followed by an interlaced I-field, and wherein a frame following the field interlaced P/I-frame is a frame selected from the set comprising:

frame interlaced I-frame, field interlaced I/P-frame, field interlaced I/I-frame, progressive I-frame and field interlaced P/I-frame.

28. The method of claim 13 wherein a frame following the first frame is a frame selected from the set comprising:

frame interlaced I-frame, field interlaced I/P-frame, field interlaced I/I-frame, progressive I-frame and field interlaced P/I-frame.

29. The method of claim 13 further comprising producing a summarized version of the sequence based at least in part on the entry point.

30. The method of claim 29 wherein the producing a summarized version is performed via a video editing application.

31. The method of claim 13 wherein the decoding is performed in a trick mode.

32. The method of claim 31 wherein the trick mode is fast rewind mode.

33. The method of claim 31 wherein the trick mode is fast forward mode.

34. A method comprising:

receiving a bitstream for a sequence comprising plural video frames;

detecting an entry point for decoding, wherein the entry point is a field interlaced P/I frame; and

decoding at least a portion of the bitstream based at least in part on the entry point indicator.

35. The method of claim 34 wherein the detecting the entry point comprises detecting an entry point start code.

36. The method of claim 34 wherein the detecting the entry point comprises detecting an entry point indicator comprising an entry point start code and an entry point header.

37. The method of claim 36 wherein the entry point header comprises buffer fullness information.

38. A method comprising:

receiving a bitstream for a sequence comprising plural video frames; and

decoding starting from an entry point signaled by an entry point indicator in the bitstream, wherein the entry point is a field interlaced frame of the plural video frames, and wherein after the entry point indicator the bitstream includes the following elements for the entry point;

frame header, first field header, first field data, second field header, and second field data.

39. The method of claim 38 wherein the bitstream further includes a frame start code immediately before the frame header and a field start code immediately before the second field header.

40. The method of claim 38 wherein the entry point indicator includes an entry point start code and an entry point header.

41. The method of claim 38 wherein the first field data is for an I-field and the second field data is for a P-field.

42. The method of claim 38 wherein the first field data is for an I-field and the second field data is for an I-field.

43. The method of claim 38 wherein the first field data is for a P-field and the second field data is for an I-field.

44. A method comprising:

receiving a bitstream for a sequence comprising plural video frames;

detecting an entry point for decoding, wherein the entry point is a field interlaced I/P frame, and wherein the I-field of the field interlaced I/P frame is signaled in the bitstream to be the single reference field for the P-field of the field interlaced I/P frame; and

decoding at least a portion of the bitstream based at least in part on the entry point indicator.

45. The method of claim 44 wherein the detecting the entry point comprises detecting an entry point start code.

46. The method of claim 44 wherein the detecting the entry point comprises detecting an entry point indicator comprising an entry point start code and an entry point header.

47. The method of claim 44 wherein a numref field in a field header for the P-field is set to 0, and wherein a reffield field in the field header for the P-field is set to 0.