CLOCK COMPENSATION TECHNIQUES FOR AUDIO DECODING

• US 20080008281A1
• Filed: 03/27/2007
• Published: 01/10/2008
• Est. Priority Date: 07/06/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Verrall, Stephen, Abrol, Nischal, Veerepalli, Sivaramakrishna, Singhai, Sandeep
• Granted Patent: US 9,420,332 B2
• Time in Patent Office: Days
• US Class Current: 375/359
• CPC Class Codes: G10L 21/01 Correction of time axis
• CPC Class Codes: H04J 3/0632 Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES] queuing arrangements in packet switching elements H04L49/90; synchronising systems for the synchronous transmission of a pulse code modulated video signal with one or more other pulse code modulated signals H04N7/56
• 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 21/439 Processing of audio elementary streams
• CPC Class Codes: H04N 21/4398 involving reformatting operations of audio signals details of audio signal transcoding G10L19/173

Abstract

This disclosure describes audio decoding techniques for decoding audio information that needs to be properly clocked. In accordance with this disclosure, the number of audio samples in decoded audio output can be adjusted to compensate for an estimated error the in decoder clock. That is to say, rather than adjust the decoder clock to synchronize the decoder clock to the encoder clock, this disclosure proposes adding or removing audio samples from the decoded audio output in order to ensure that the decoded audio output is properly timed. In this way, the techniques of this disclosure can eliminate the need for an adjustable or controllable clock at the decoding device, which can save cost and/or allow legacy devices that do not include an adjustable or controllable clock to decode and output audio information that needs to be properly clocked.

Claims

1. A method comprising:

receiving audio information that includes first timing information associated with an encoder clock;

generating second timing information for the audio information based on a decoder clock;

estimating error in the decoder clock relative to the encoder clock based on a difference between the first timing information and the second timing information;

decoding the audio information to generate audio samples; and

adjusting a number of the audio samples in decoded audio output to compensate for the estimated error in the decoder clock.

2. The method of claim 1, wherein adjusting the number of audio samples comprises inserting additional audio samples into the decoded output to compensate for the decoder clock being slower than the encoder clock.

3. The method of claim 2, wherein inserting the additional audio samples comprises inserting silent audio samples.

4. The method of claim 3, wherein inserting the additional audio samples comprises:

estimating times of substantial silence in the decoded audio output; and

inserting the silent audio samples in the times of substantial silence.

5. The method of claim 2, wherein inserting the additional audio samples comprises inserting interpolated audio samples.

6. The method of claim 1, wherein adjusting the number of audio samples comprises removing one or more of the audio samples from the decoded output to compensate for the decoder clock being faster than the encoder clock.

7. The method of claim 6, wherein removing one or more of the audio samples comprises removing substantially silent audio samples.

8. The method of claim 7, wherein removing one or more of the audio samples comprises:

estimating times of substantial silence in the decoded output; and

removing the silent audio samples from the times of substantial silence.

9. The method of claim 1, wherein the audio information comprises encoded audio information within audio packets.

10. The method of claim 9, wherein the audio packets comply with a motion pictures expert group 2 (MPEG-2) Transport Stream (TS) protocol.

11. The method of claim 1, further comprising:

synchronizing video decoding to the decoded audio output that includes the adjusted number of audio samples.

22. The device of claim 1, further comprising:

a video decoder unit that synchronizes video decoding to the decoded audio output that includes the adjusted number of audio samples.

44. The device of claim 1, further comprising:

means for synchronizing video decoding to the decoded audio output that includes the adjusted number of audio samples.

12. A device comprising:

a receiver that receives audio information including first timing information associated with an encoder clock;

a decoder clock that generates second timing information for the audio information;

a timing adjustment unit that estimates error in the decoder clock relative to the encoder clock based on a difference between the first timing information and the second timing information; and

a decoder unit that decodes the audio information to generate audio samples, wherein the decoder unit adjusts a number of the audio samples in decoded audio output to compensate for the estimated error in the decoder clock.

13. The device of claim 12, wherein the decoder unit inserts additional audio samples into the decoded output to compensate for the decoder clock being slower than the encoder clock.

14. The device of claim 13, wherein the decoder unit inserts silent audio samples into the decoded output.

15. The device of claim 14, wherein the decoder unit:

estimates times of substantial silence in the decoded audio output; and

inserts the silent audio samples in the times of substantial silence.

16. The device of claim 13, wherein the decoder unit inserts interpolated audio samples into the decoded output.

17. The device of claim 12, wherein the decoder unit removes one or more of the audio samples from the decoded output to compensate for the decoder clock being faster than the encoder clock.

18. The device of claim 17, wherein the decoder unit removes substantially silent audio samples from the decoded output.

19. The device of claim 18, wherein the decoder unit:

estimates times of substantial silence in the decoded output; and

removes the silent audio samples from the times of substantial silence.

20. The device of claim 12, wherein the audio information comprises encoded audio information within audio packets.

21. The device of claim 20, wherein the audio packets comply with a motion pictures expert group 2 (MPEG-2) Transport Stream (TS) protocol.

23. A computer readable medium comprising instructions that upon execution in a device cause the device to:

receive audio information that includes first timing information associated with an encoder clock;

generate second timing information for the audio information based on a decoder clock;

estimate error in the decoder clock relative to the encoder clock based on a difference between the first timing information and the second timing information;

decode the audio information to generate audio samples; and

adjust a number of the audio samples in decoded audio output to compensate for the estimated error in the decoder clock.

24. The computer readable medium of claim 23, wherein the instructions cause the device to insert additional audio samples into the decoded output to compensate for the decoder clock being slower than the encoder clock.

25. The computer readable medium of claim 24, wherein the instructions cause the device to insert silent audio samples into the decoded output.

26. The computer readable medium of claim 25, wherein the instructions cause the device to:

estimate times of substantial silence in the decoded audio output; and

insert the silent audio samples in the times of substantial silence.

27. The computer readable medium of claim 23, wherein the instructions cause the device to insert interpolated audio samples into the decoded output.

28. The computer readable medium of claim 23, wherein the instructions cause the device to remove one or more of the audio samples from the decoded output to compensate for the decoder clock being faster than the encoder clock.

29. The computer readable medium of claim 28, wherein the instructions cause the device to remove substantially silent audio samples from the decoded output.

30. The computer readable medium of claim 29, wherein the instructions cause the device to:

estimate times of substantial silence in the decoded output; and

remove the silent audio samples from the times of substantial silence.

31. The computer readable medium of claim 23, wherein the audio information comprises encoded audio information within audio packets.

32. The computer readable medium of claim 31, wherein the audio packets comply with a motion pictures expert group 2 (MPEG-2) Transport Stream (TS) protocol.

33. The computer readable medium of claim 23, wherein the instructions cause the device to synchronize video decoding to the decoded audio output that includes the adjusted number of audio samples.

34. A device comprising:

means for receiving audio information that includes first timing information associated with an encoder clock;

means for generating second timing information for the audio information based on a decoder clock;

means for estimating error in the decoder clock relative to the encoder clock based on a difference between the first timing information and the second timing information;

means for decoding the audio information to generate audio samples; and

means for adjusting a number of the audio samples in decoded audio output to compensate for the estimated error in the decoder clock.

35. The device of claim 34, wherein the means for adjusting the number of audio samples inserts additional audio samples into the decoded output to compensate for the decoder clock being slower than the encoder clock.

36. The device of claim 35, wherein the means for adjusting the number of audio samples inserts silent audio samples into the decoded audio output.

37. The device of claim 36, wherein the means for adjusting the number of audio samples:

estimates times of substantial silence in the decoded audio output; and

inserts the silent audio samples in the times of substantial silence.

38. The device of claim 35, wherein the means for adjusting the number of audio samples inserts interpolated audio samples into the decoded audio output.

39. The device of claim 34, wherein the means for adjusting the number of audio samples removes one or more of the audio samples from the decoded output to compensate for the decoder clock being faster than the encoder clock.

40. The device of claim 39, wherein the means for adjusting the number of audio samples removes substantially silent audio samples from the decoded audio output.

41. The device of claim 40, wherein the means for adjusting the number of audio samples:

estimates times of substantial silence in the decoded output; and

removes the silent audio samples from the times of substantial silence.

42. The device of claim 34, wherein the audio information comprises encoded audio information within audio packets.

43. The device of claim 42, wherein the audio packets comply with a motion pictures expert group 2 (MPEG-2) Transport Stream (TS) protocol.