Synchronization of signals

• US 20060053455A1
• Filed: 11/26/2003
• Published: 03/09/2006
• Est. Priority Date: 12/04/2002
• Status: Active Grant

• Current Assignee: MaxLinear Communications, LLC (f/k/a Entropic Communications, LLC) (Maxlinear Incorporated)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Shen, Richard Chi-Te, Mani, Murali, Cavallerano, Alan P.
• Granted Patent: US 7,552,352 B2
• Time in Patent Office: Days
• US Class Current: 725/87
• CPC Class Codes: G11B 27/10 Indexing; Addressing; Timing or synchronising; Measuring tape travel
• CPC Class Codes: H04N 21/23614 Multiplexing of additional data and video streams arrangements for simultaneous broadcast of plural pieces of information H04H20/28
• CPC Class Codes: H04N 21/2368 Multiplexing of audio and video streams
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• 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 21/4348 Demultiplexing of additional data and video streams
• CPC Class Codes: H04N 21/435 Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream
• CPC Class Codes: H04N 21/439 Processing of audio elementary streams
• CPC Class Codes: H04N 21/8126 involving additional data, e.g. news, sports, stocks, weather forecasts
• CPC Class Codes: H04N 21/8547 involving timestamps for synchronizing content
• CPC Class Codes: H04N 5/04 Synchronising for television systems using pulse code modulation H04N7/56

Abstract

A method and system for synchronizing signals. First and second signals are sent (compressed or uncompressed) from a source to a receiving apparatus of a receiving system. The first signal has content of a first modality (e.g., audio) and the second signal has content of a second modality (e.g., video). The first and second signals are to be displayed on a display apparatus of the receiving system. The first and second signals have been time-synchronized at the source. If the first and second signals are not synchronized in time when received at the receiving apparatus, then the first and second signals may be time-synchronized at the receiving apparatus either manually or through timestamping of both signals at the source, in conjunction with use of a real-time clock at the receiving apparatus.

Claims

1. A method for synchronizing signals, comprising:

receiving, from a source, a first signal and a second signal by a receiving apparatus of a receiving system, the first and second signals to be displayed on a display apparatus of the receiving system, the first and second signals having been time-synchronized at the source, the first signal having content of a first modality, the second signal having content of a second modality;

displaying on the display apparatus the first and second signals, said displayed first and second signals being accessible to a user; and

manually reducing, by the user, the time rate of displaying one of the first signal and the second signal, said manually reducing being directed to time-synchronizing said displaying of the first and second signals on the display apparatus.

2. The method of claim 1, wherein said manually reducing comprises:

manually directing a delay compensation circuit of the receiving apparatus to electronically reduce said time rate of displaying; and

electronically reducing, by the delay compensation circuit, said time rate.

3. The method of claim 1, wherein said manually reducing comprises introducing a time delay gap in the displaying of said one of the first signal and the second signal.

4. The method of claim 1, wherein said manually reducing does not comprise introducing a time delay gap in the displaying of said one of the first signal and the second signal.

5. The method of claim 1, wherein said manually reducing comprises manually manipulating a control.

6. The method of claim 5, wherein said control is on the display apparatus.

7. The method of claim 5, wherein said control is on a wireless device.

8. The method of claim 1, wherein the first modality differs from the second modality.

9. The method of claim 8, wherein the first modality is a video modality, and wherein the second modality is an audio modality.

10. The method of claim 8, wherein the first modality is a video modality, and wherein the second modality is an text modality.

11. The method of claim 8, wherein the first modality is an audio modality, and wherein the second modality is a text modality.

12. The method of claim 1, wherein said receiving the first signal and the second signal comprises receiving the first signal and the second signal on separate channels.

13. The method of claim 1, wherein said receiving the first signal and the second signal comprises receiving the first signal and the second signal as not multiplexed with each other.

14. The method of claim 1, wherein said receiving the first signal and the second signal comprises receiving the first signal and the second signal as multiplexed but not time-synchronized with each other.

15. A system for synchronizing signals, comprising:

receiving means for receiving, from a source, a first signal and a second signal by a receiving apparatus of a receiving system, the first and second signals to be displayed on a display apparatus of the receiving system, the first and second signals having been time-synchronized at the source, the first signal having content of a first modality, the second signal having content of a second modality;

display means for displaying on the display apparatus the first and second signals, said displayed first and second signals being accessible to a user; and

manual reducing means for manually reducing, by the user, the time rate of displaying one of the first signal and the second signal, said manually reducing being directed to time-synchronizing said displaying of the first and second signals on the display apparatus.

16. The system of claim 15, wherein said manually reducing comprises:

directing means for manually directing a delay compensation circuit of the receiving apparatus to electronically reduce said time rate of displaying; and

electronic reducing means for electronically reducing, by the delay compensation circuit, said time rate.

17. The system of claim 15, wherein said manually reducing comprises introducing a time delay gap in the displaying of said one of the first signal and the second signal.

18. The system of claim 15, wherein said manually reducing does not comprise introducing a time delay gap in the displaying of said one of the first signal and the second signal.

19. The system of claim 15, wherein said manual reducing means comprises a control.

20. The system of claim 19, wherein said control is on the display apparatus.

21. The system of claim 19, wherein said control is on a wireless device.

22. The system of claim 15, wherein the first modality differs from the second modality.

23. The system of claim 22, wherein the first modality is a video modality, and wherein the second modality is an audio modality.

24. The system of claim 22, wherein the first modality is a video modality, and wherein the second modality is an text modality.

25. The system of claim 22, wherein the first modality is an audio modality, and wherein the second modality is a text modality.

26. The system of claim 15, wherein said receiving means comprises means for receiving the first signal and the second signal on separate channels.

27. The system of claim 15, wherein said receiving means comprises means for receiving the first signal and the second signal as not multiplexed with each other.

28. The system of claim 15, wherein said receiving means comprises means for receiving the first signal and the second signal as multiplexed but not time-synchronized with each other.

29. A method for synchronizing signals, comprising:

receiving, from a source, a first signal and a second signal by a receiving apparatus of a receiving system, the first and second signals to be synchronously displayed on a display apparatus of the receiving system, the first and second signals having been time-synchronize at the source, the first signal having content of a first modality and a first plurality of time stamps originating from the source, the second signal having content of a second modality and a second plurality of time stamps originating from the source, the second plurality of time stamps being synchronized with the first plurality of time stamps;

determining at a plurality of times on a real-time clock C_R at the receiving system whether the first and second signals are time-synchronized relative to the clock C_R, said determining being based on analyzing the first and second plurality of time stamps in relation to the clock C_R; and

reducing the time rate of displaying one of the first signal and the second signal when said determining determines that the first and second signals are not time-synchronized relative to the clock C_R such that the one is time advanced relative to the remaining other of the first signal and the second signal, said reducing being directed to time-synchronizing said displaying of the first and second signals on the display apparatus.

30. The method of claim 29,

wherein the first signal is in an uncompressed format as received by the receiving apparatus, wherein each timestamp of the first plurality of timestamps includes a time corresponding to a location in the first signal at which said timestamp of the first plurality of timestamps is positioned,

wherein the second signal is in an uncompressed format as received by the receiving apparatus, and wherein each timestamp of the second plurality of timestamps includes a time corresponding to a location in the second signal at which said timestamp of the second plurality of timestamps is positioned.

31. The method of claim 29,

wherein the first signal is in a compressed format as received by the receiving apparatus, wherein each timestamp of the first plurality of timestamps includes a time corresponding to a location in a first uncompressed signal which was compressed at the source to form the first signal, wherein said timestamp of the first plurality of timestamps further includes an identification of said location in the first uncompressed signal,

wherein the second signal is in a compressed format as received by the receiving apparatus, wherein each timestamp of the second plurality of timestamps includes a corresponding to a location in a second uncompressed signal which was compressed at the source to form the second signal, and wherein said timestamp of the second plurality of timestamps further includes an identification of said location in the second uncompressed signal.

32. The method of claim 29,

wherein the first signal is in an uncompressed format as received by the receiving apparatus, wherein each timestamp of the first plurality of timestamps includes corresponding to a location in the first signal at which said timestamp of the first plurality of timestamps is positioned,

wherein the second signal is in a compressed format as received by the receiving apparatus, wherein each timestamp of the second plurality of timestamps includes a time corresponding to a location in an uncompressed signal which was compressed at the source to form the second signal, and wherein said timestamp of the second plurality of timestamps further includes an identification of said location in the uncompressed signal.

33. The method of claim 29, wherein said reducing is effectuated by a delay compensation controller of the receiving apparatus.

34. The method of claim 29, wherein said reducing comprises introducing a time delay gap in the displaying of said one of the first signal and the second signal.

35. The method of claim 29, wherein said reducing does not comprise introducing a time delay gap in the displaying of said one of the first signal and the second signal.

36. The method of claim 29, wherein the first modality differs from the second modality.

37. The method of claim 36, wherein the first modality is a video modality, and wherein the second modality is an audio modality.

38. The method of claim 36, wherein the first modality is a video modality, and wherein the second modality is an text modality.

39. The method of claim 36, wherein the first modality is a text modality, and wherein the second modality is an audio modality.

40. The method of claim 29, wherein said receiving the first signal and the second signal comprises receiving the first signal and the second signal on separate channels.

41. The method of claim 29, wherein said receiving the first signal and the second signal comprises receiving the first signal and the second signal as not multiplexed with each other.

42. The method of claim 29, wherein said receiving the first signal and the second signal comprises receiving the first signal and the second signal as multiplexed but not time-synchronized with each other.

43. A system for synchronizing signals, comprising:

receiving means for receiving, from a source, a first signal and a second signal by a receiving apparatus of a receiving system, the first and second signals to be synchronously displayed on a display apparatus of the receiving system, the first and second signals having been time-synchronized at the source, the first signal having content of a first modality and a first plurality of timestamps originating from the source, the second signal having content of a second modality and a second plurality of timestamps originating from the source, the second plurality of time stamps being synchronized with the first plurality of time stamps;

determining means for determining at a plurality of times on a real-time clock C_R at the receiving system whether the first and second signals are time-synchronized relative to the clock C_R, said determining being based on analyzing the first and second plurality of timestamps in relation to the clock C_R; and

reducing means for reducing the time rate of displaying one of the first signal and the second signal when said determining determines that the first and second signals are not time-synchronized relative to the clock C_R such that the one is time advanced relative to the remaining other of the first signal and the second signal, said reducing being directed to time-synchronizing said displaying of the first and second signals on the display apparatus.

44. The system of claim 43,

wherein the first signal is in an uncompressed format as received by the receiving apparatus, wherein each timestamp of the first plurality of timestamps includes a time corresponding to a location in the first signal at which said timestamp of the first plurality of timestamps is positioned,

wherein the second signal is in an uncompressed format as received by the receiving apparatus, and wherein each timestamp of the second plurality of timestamps includes a time corresponding to a location in the second signal at which said timestamp of the second plurality of timestamps is positioned.

45. The system of claim 43,

wherein the first signal is in an uncompressed format as received by the receiving apparatus, wherein each timestamp of the first plurality of timestamps includes a time corresponding to a location in a first uncompressed signal which was compressed at the source to form the first signal, wherein said timestamp of the first plurality of timestamps further includes an identification of said location in the first uncompressed signal,

wherein the second signal is in an uncompressed format as received by the receiving apparatus, wherein each timestamp of the second plurality of timestamps includes a time corresponding to a location in a second uncompressed signal which was compressed at the source to form the second signal, and wherein said timestamp of the second plurality of timestamps further includes an identification of said location in the second uncompressed signal.

46. The system of claim 43,

wherein the first signal is in an uncompressed format as received by the receiving apparatus, wherein each timestamp of the first plurality of timestamps includes a time corresponding to a location in the first signal at which said timestamp of the first plurality of timestamps is positioned,

wherein the second signal is in an uncompressed format as received by the receiving apparatus, wherein each timestamp of the second plurality of timestamps includes a time corresponding to a location in a second uncompressed signal which was compressed at the source to form the second signal, and wherein said timestamp of the second plurality of timestamps further includes an identification of said location in the second uncompressed signal.

47. The system of claim 43, wherein said reducing is effectuated by a delay compensation controller of the receiving apparatus.

48. The system of claim 43, wherein said reducing comprises introducing a time delay gap in the displaying of said one of the first signal and the second signal.

49. The system of claim 43, wherein said reducing does not comprise introducing a time delay gap in the displaying of said one of the first signal and the second signal.

50. The system of claim 43, wherein the first modality differs from the second modality.

51. The system of claim 50, wherein the first modality is a video modality, and wherein the second modality is an audio modality.

52. The system of claim 50, wherein the first modality is a video modality, and wherein the second modality is an text modality.

53. The system of claim 50, wherein the first modality is a text modality, and wherein the second modality is an audio modality.

54. The system of claim 43, wherein said receiving means comprises means for receiving the first signal and the second signal on separate channels.

55. The system of claim 43, wherein said receiving means comprises means for receiving the first signal and the second signal as not multiplexed with each other.

56. The system of claim 43, wherein said receiving means comprises means for receiving the first signal and the second signal as multiplexed but not time-synchronized with each other.