Methods and systems for encoding and decoding video data to enable random access and splicing

• US 7,149,247 B2
• Filed: 01/22/2003
• Issued: 12/12/2006
• Est. Priority Date: 01/22/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Sullivan, Gary J.
• Primary Examiner(s): VO, TUNG T
• Application Number:
  US10/350,145
• Publication Number:
  US 20030156640A1
• Time in Patent Office: 1,420 Days
• Field of Search: 375/240.01, 375/240, 375/240.25, 348/169, 386/52, 382/233
• US Class Current: 375/240.01
• CPC Class Codes: H04N 21/8455 involving pointers to the content, e.g. pointers to the I-frames of the video stream

Abstract

Various embodiments provide approaches that facilitate decoding in the context of video coding standards that allow for complicated dependencies among pictures of an encoded sequence of pictures. In some embodiments, the notion of a random access point or “RAP” is utilized. A random access point is effectively a location within a picture sequence that contains information that facilitates random access of the sequence. In some embodiments, a random access point can contain different types of data. Such data can be defined, in some embodiments, in terms of picture count and/or time. In some embodiments, a random access point'"'"'s data can comprise one or more of an entry point and a recovery point. These points effectively provide measures that a decoder can use to ascertain when its decoding activities will result in accurately and suitably decoded pictures.

Claims

1. A method comprising, at a video encoder:

encoding first information for a first location in a video sequence of pictures, wherein the first location is a random access point location in the video sequence, wherein pictures at or after the random access point location are to be decoded by a video decoder, the encoded first information facilitating random access of the video sequence by the video decoder; and

transmitting the encoded first information;

wherein the encoded first information comprises second information indicating a second location in the video sequence, wherein pictures at or after, but not before, the second location are displayable with an assured level of correctness after random access, the second location being at or after the random access point location.

2. The method of claim 1 wherein the first information further comprises video splicing information.

3. The method of claim 2 wherein the video splicing information comprises a broken link flag.

4. The method of claim 1 wherein the random access point location is at an I-picture.

5. The method of claim 1 wherein the random access point location is at a P-picture.

6. The method claim 1 wherein the random access point location is at a B-picture.

7. The method of claim 1 further comprising:

encoding first information for each of one or more additional random access point locations in the video sequence.

8. A method comprising, at a video decoder:

receiving and decoding first information for a first location in a video sequence of pictures, wherein the first location is a random access point location in the video sequence, wherein the first information comprises second information indicating a second location in the video sequence, wherein pictures at or after, but not before, the second location are displayable with an assured level of correctness after random access, the second location being at or after the random access point location; and

decoding pictures at or after the random access point location, the random access point facilitating random access of the video sequence by the video decoder.

9. The method of claim 8 wherein the first information further comprises video splicing information.

10. The method of claim 9 wherein the video splicing information comprises a broken link flag.

11. The method of claim 8 wherein the random access point location is at an I-picture.

12. The method of claim 8 wherein the random access point location is at a P-picture.

13. The method claim 8 wherein the random access point location is at a B-picture.

14. A computer-readable medium having stored thereon computer-executable instructions for causing a computer to perform a method comprising, at a video encoder:

encoding first information for a first location in a video sequence of pictures, wherein the first location is a random access point location in the video sequence, wherein pictures at or after the random access point location are to be decoded by a video decoder, the encoded first information facilitating random access of the video sequence by the video decoder; and

transmitting the encoded first information;

wherein the encoded first information comprises second information indicating a second location in the video sequence, wherein pictures at or after, but not before, the second location are displayable with an assured level of correctness after random access, the second location being at or after the random access point location.

15. The computer-readable medium of claim 14 wherein the first information further comprises video splicing information.

16. The computer-readable medium of claim 15 wherein the video splicing information comprises a broken link flag.

17. The computer-readable medium of claim 14 wherein the random access point location is at an I-picture.

18. The computer-readable medium of claim 14 wherein the random access point location is at a P-picture.

19. The computer-readable medium of claim 14 wherein the random access point location is at a B-picture.

20. The computer-readable medium of claim 14 further comprising:

encoding first information for each of one or more additional random access point locations in the video sequence.

21. A computer-readable medium having stored thereon computer-executable instructions for causing a computer to perform a method comprising, at a video decoder:

receiving and decoding first information for a first location in a video sequence of pictures, wherein the first location is a random access point location in the video sequence, wherein the first information comprises second information indicating a second location in the video sequence, wherein pictures at or after, but not before, the second location are displayable with an assured level of correctness after random access, the second location being at or after the random access point location; and

decoding pictures at or after the random access point location, the random access point facilitating random access of the video sequence by the video decoder.

22. The computer-readable medium of claim 21 wherein the first information further comprises video splicing information.

23. The computer-readable medium of claim 22 wherein the video splicing information comprises a broken link flag.

24. The computer-readable medium of claim 21 wherein the random access point location is at an I-picture.

25. The computer-readable medium of claim 21 wherein the random access point location is at a P-picture.

26. The computer-readable medium of claim 21 wherein the random access point location is at a B-picture.

27. The computer-readable medium of claim 21 further comprising:

encoding first information for each of one or more additional random access point locations in the video sequence.

28. A method comprising, at a video encoder:

encoding first information for a first location in a video sequence of pictures, wherein the first location is a random access point location in the video sequence, wherein pictures at or after the random access point location are to be decoded by a video decoder, the encoded first information facilitating random access of the video sequence by the video decoder; and

transmitting the encoded first information;

wherein the encoded first information comprises second information indicating a second location in the video sequence, wherein pictures at or after, but not before, the second location are displayable with an assured level of correctness after random access, the second location being at or after the random access point location; and

wherein one or more of the pictures at or after the random access point location have one or more references to pictures not available to the video decoder.

29. The method of claim 28 wherein the one or more references to pictures not available to the video decoder include references to pictures before the random access point location.

30. The method of claim 28 wherein the one or more references to pictures not available to the video decoder include references to pictures before and after the random access point location.

31. The method of claim 28 wherein the one or more references to pictures not available to the video decoder include references to pictures after the random access point location.

32. The method of claim 28 wherein the one or more pictures at or after the random access point location that have one or more references to pictures not available to the video decoder include at least one P-picture.

33. The method of claim 28 wherein the one or more pictures at or after the random access point location that have one or more references to pictures not available to the video decoder include at least one B-picture.

34. The method of claim 28 wherein the one or more references to pictures not available to the video decoder are treated as referring to pictures with predetermined values.

35. The method of claim 34 wherein the predetermined values are mid-level gray values.

36. A computer-readable medium having stored thereon computer-executable instructions for causing a computer to perform a method comprising, at a video encoder:

encoding first information for a first location in a video sequence of pictures, wherein the first location is a random access point location in the video sequence, wherein pictures at or after the random access point location are to be decoded by a video decoder, the encoded first information facilitating random access of the video sequence by the video decoder; and

transmitting the encoded first information;

wherein the encoded first information comprises second information indicating a second location in the video sequence, wherein pictures at or after, but not before, the second location are displayable with an assured level of correctness after random access, the second location being at or after the random access point location; and

wherein one or more of the pictures at or after the random access point location have one or more references to pictures not available to the video decoder.

37. The computer-readable medium of claim 36 wherein the one or more references to pictures not available to the video decoder include references to pictures before the random access point location.

38. The computer-readable medium of claim 36 wherein the one or more references to pictures not available to the video decoder include references to pictures before and after the random access point location.

39. The computer-readable medium of claim 36 wherein the one or more references to pictures not available to the video decoder include references to pictures after the random access point location.

40. The computer-readable medium of claim 36 wherein the one or more pictures at or after the random access point location that have one or more references to pictures not available to the video decoder include at least one P-picture.

41. The computer-readable medium of claim 36 wherein the one or more pictures at or after the random access point location that have one or more references to pictures not available to the video decoder include at least one B-picture.

42. The computer-readable medium of claim 36 wherein the one or more references to pictures not available to the video decoder are treated as referring to pictures with predetermined values.

43. The computer-readable medium of claim 42 wherein the predetermined values are mid-level gray values.

44. A method comprising, at a video decoder:

receiving and decoding first information for a first location in a video sequence of pictures, wherein the first location is a random access point location in the video sequence, wherein the first information comprises second information indicating a second location in the video sequence, wherein pictures at or after, but not before, the second location are displayable with an assured level of correctness after random access, the second location being at or after the random access point location; and

decoding pictures at or after the random access point location, the random access point facilitating random access of the video sequence by the video decoder;

wherein one or more of the pictures at or after the random access point location have one or more references to pictures not available to the video decoder.

45. The method of claim 44 wherein the one or more references to pictures not available to the video decoder include references to pictures before the random access point location.

46. The method of claim 44 wherein the one or more references to pictures not available to the video decoder include references to pictures before and after the random access point location.

47. The method of claim 44 wherein the one or more references to pictures not available to the video decoder include references to pictures after the random access point location.

48. The method of claim 44 wherein the one or more pictures at or after the random access point location that have one or more references to pictures not available to the video decoder include at least one P-picture.

49. The method of claim 44 wherein the one or more pictures at or after the random access point location that have one or more references to pictures not available to the video decoder include at least one B-picture.

50. The method of claim 44 wherein the one or more references to pictures not available to the video decoder are treated as referring to pictures with predetermined values.

51. The method of claim 50 wherein the predetermined values are mid-level gray values.

52. A computer-readable medium having stored thereon computer-executable instructions for causing a computer to perform a method comprising, at a video decoder:

receiving and decoding first information for a first location in a video sequence of pictures, wherein the first location is a random access point location in the video sequence, wherein the first information comprises second information indicating a second location in the video sequence, wherein pictures at or after, but not before, the second location are displayable with an assured level of correctness after random access, the second location being at or after the random access point location; and

decoding pictures at or after the random access point location, the random access point facilitating random access of the video sequence by the video decoder;

wherein one or more of the pictures at or after the random access point location have one or more references to pictures not available to the video decoder.

53. The computer-readable medium of claim 52 wherein the one or more references to pictures not available to the video decoder include references to pictures before the random access point location.

54. The computer-readable medium of claim 52 wherein the one or more references to pictures not available to the video decoder include references to pictures before and after the random access point location.

55. The computer-readable medium of claim 52 wherein the one or more references to pictures not available to the video decoder include references to pictures after the random access point location.

56. The computer-readable medium of claim 52 wherein the one or more pictures at or after the random access point location that have one or more references to pictures not available to the video decoder include at least one P-picture.

57. The computer-readable medium of claim 52 wherein the one or more pictures at or after the random access point location that have one or more references to pictures not available to the video decoder include at least one B-picture.

58. The computer-readable medium of claim 52 wherein the one or more references to pictures not available to the video decoder are treated as referring to pictures with predetermined values.

59. The computer-readable medium of claim 58 wherein the predetermined values are mid-level gray values.