Method and Apparatus for Audio and Video Synchronization Timestamp Rollover Correction

• US 20090295992A1
• Filed: 10/10/2006
• Published: 12/03/2009
• Est. Priority Date: 10/21/2005
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Richardson, John William, Cahnbley, Jens
• Granted Patent: US 8,994,879 B2
• Time in Patent Office: Days
• US Class Current: 348/515
• CPC Class Codes: H04N 21/2368 Multiplexing of audio and video streams
• CPC Class Codes: H04N 21/242 Synchronization processes, e.g. processing of PCR [Program Clock References] arrangements for synchronising broadcast or distribution via plural systems in broadcast distribution systems H04H20/18
• CPC Class Codes: H04N 21/4302 Content synchronisation processes, e.g. decoder synchronisation
• CPC Class Codes: H04N 21/43072 of multiple content streams on the same device
• CPC Class Codes: H04N 21/4341 Demultiplexing of audio and video streams
• CPC Class Codes: H04N 21/6437 Real-time Transport Protocol [RTP]
• CPC Class Codes: H04N 21/8547 involving timestamps for synchronizing content

Abstract

There are provided methods and apparatus for audio and video synchronization timestamp rollover correction. A synchronization apparatus includes a synchronizer for providing synchronization information for synchronizing a video stream with an audio stream during any point in a broadcast thereof irrespective of whether the video stream and the audio stream have different rollover points for their respective timestamps. The synchronization information is encoded for an out of band transmission with respect to the broadcast of the audio and video streams.

Claims

1. An apparatus comprising:

a synchronizer for providing synchronization information for synchronizing a video stream with an audio stream during any point in a broadcast thereof irrespective of whether the video stream and the audio stream have different rollover points for their respective timestamps, the synchronization information encoded for an out of band transmission with respect to the broadcast of the audio and video streams.

2. The apparatus of claim 1, further comprising a transmitter for transmitting the synchronization information to a receiving device in the out of band transmission.

3. The apparatus of claim 2, wherein said synchronizer further provides an expiration time for the timestamps such that any given timestamp for either of the streams is only valid once within the expiration time, and said transmitter transmits the expiration time in the out of band transmission.

4. The apparatus of claim 1, wherein the different rollover points relate to different clocks or different clock multipliers.

5. The apparatus of claim 1, wherein the synchronization information enables the video stream to be synchronized with the audio stream any time before and after a first timestamp rollover relating to any of the streams.

6. The apparatus of claim 1, wherein the synchronization information specifies a timing relationship between at least one audio time stamp and at least one video timestamp corresponding to the audio stream and the video stream, respectively.

7. The apparatus of claim 1, wherein the synchronization information is provided in a data structure that signals at least one of the audio stream and the video stream.

8. The synchronization apparatus of claim 1, wherein the synchronization information is specified in metadata.

9. The apparatus of claim 1, wherein the synchronization information is specified using Session Description Protocol.

12. The method of claim 1, further comprising:

providing an expiration time for the timestamps such that any given timestamp for either of the streams is only valid once within the expiration time; and

transmitting the expiration time to the receiving device in the out of band transmission.

10. A synchronization method, comprising:

providing synchronization information for synchronizing a video stream with an audio stream during any point in a broadcast thereof irrespective of whether the video stream and the audio stream have different rollover points for their respective timestamps, the synchronization information encoded for an out of band transmission with respect to the broadcast of the audio and video streams.

11. The method of claim 10, further comprising transmitting the synchronization information to a receiving device in the out of band transmission.

13. The method of claim 10, wherein the different rollover points relate to different clocks or different clock multipliers.

14. The method of claim 10, wherein the synchronization information enables the video stream to be synchronized with the audio stream any time before and after a first timestamp rollover relating to any of the streams.

15. The method of claim 10, wherein the synchronization information specifies a timing relationship between at least one audio time stamp and at least one video timestamp corresponding to the audio stream and the video stream, respectively.

16. The method of claim 10, wherein the synchronization information is provided in a data structure that signals at least one of the audio stream and the video stream.

17. The method of claim 10, wherein the synchronization information is specified in metadata.

18. The method of claim 10, wherein the synchronization information is specified using Session Description Protocol.

19. An apparatus, comprising:

a synchronizer for synchronizing a video stream and an audio stream using synchronization information received in an out of band transmission with respect to a broadcast of the video stream and the audio stream, wherein the synchronization information is adapted to synchronize the video stream and the audio stream during any point in the broadcast irrespective of whether the video stream and the audio stream have different rollover points for their respective timestamps.

20. The apparatus of claim 19, further comprising a receiver for receiving the synchronization information from a sending device in the out of band transmission.

21. The apparatus of claim 20, wherein said receiver receives an expiration time from the sending device in the out of band transmission, and said synchronizer applies the expiration time to the timestamps of the streams such that any given timestamp for either of the streams is only valid once within the expiration time.

22. The apparatus of claim 19, wherein the different rollover points relate to different clocks or different clock multipliers.

23. The apparatus of claim 19, wherein the synchronization information enables the video stream to be synchronized with the audio stream any time before and after a first timestamp rollover relating to any of the streams.

24. The apparatus of claim 19, wherein the synchronization information specifies a timing relationship between at least one audio time stamp and at least one video timestamp corresponding to the audio stream and the video stream, respectively.

25. The apparatus of claim 19, wherein the synchronization information is provided in a data structure that signals at least one of the audio stream and the video stream.

26. The apparatus of claim 19, wherein the synchronization information is specified in metadata.

27. The apparatus of claim 19, wherein the synchronization information is specified using Session Description Protocol.

28. A synchronization method, comprising:

synchronizing a video stream and an audio stream using synchronization information received in an out of band transmission with respect to a broadcast of the video stream and the audio stream, wherein the synchronization information is adapted to synchronize the video stream and the audio stream during any point in the broadcast irrespective of whether the video stream and the audio stream have different rollover points for their respective timestamps.

29. The method of claim 28, further comprising receiving the synchronization information from a sending device in the out of band transmission.

30. The method of claim 29, further comprising:

receiving an expiration time from the sending device in the out of band transmission, the expiration time for applying to the timestamps of the streams such that any given timestamp for either of the streams is only valid once within the expiration time.

31. The method of claim 28, wherein the different rollover points relate to different clocks or different clock multipliers.

32. The method of claim 28, wherein the synchronization information enables the video stream to be synchronized with the audio stream any time before and after a first timestamp rollover relating to any of the streams.

33. The method of claim 28, wherein the synchronization information specifies a timing relationship between at least one audio time stamp and at least one video timestamp corresponding to the audio stream and the video stream, respectively.

34. The method of claim 28, wherein the synchronization information is provided in a data structure that signals at least one of the audio stream and the video stream.

35. The method of claim 28, wherein the synchronization information is specified in metadata.

36. The method of claim 28, wherein the synchronization information is specified using Session Description Protocol.

37. A video signal structure for stream synchronization, comprising:

synchronization information for synchronizing a video stream with an audio stream during any point in a broadcast thereof irrespective of whether the video stream and the audio stream have different rollover points for their respective timestamps, the synchronization information encoded for an out of band transmission with respect to the broadcast of the audio and video streams.

38. A storage media having information stored thereon, comprising:

synchronization information for synchronizing a video stream with an audio stream during any point in a broadcast thereof irrespective of whether the video stream and the audio stream have different rollover points for their respective timestamps, the synchronization information encoded for an out of band transmission with respect to the broadcast of the audio and video streams.