Buffer expansion and contraction over successive intervals for network devices

1. A method implemented by a downstream network device, comprising:

receiving from the network device a multiplex of a compressed video stream and a compressed audio stream, the multiplex comprising a succession of intervals corresponding to a video program corresponding to a first playout rate; and

at the start of each interval, replacing the compressed audio stream with a compressed, pitch-preserving audio stream corresponding to a second playout rate different than the first.

2. The method of claim 1 , wherein a segment of the pitch-preserving audio stream at the end of each interval is not played out, and time stamp values for the compressed audio and the pitch-preserving audio are equal only at the commencement of each succession of the intervals.

3. The method of claim 1 , further comprising adjusting a video decoding rate corresponding to the received video stream at a time corresponding to the start of each of the intervals, the adjusted video decoding rate equal to the second playout rate.

4. The method of claim 1 , wherein a video stream corresponding to the second playout rate comprises a presentation time value equal to a presentation timestamp value of the pitch-preserving audio stream during the succession of intervals.

5. The method of claim 1 , wherein the second playout rate is less than the first playout rate, and further comprising increasing buffering during the succession of intervals.

6. The method of claim 5 , further comprising processing forward error correction packets or processing retransmission of packets during the succession of intervals.

7. The method of claim 1 , wherein the second playout rate is greater than the first playout rate, and further comprising decreasing buffering during the succession of intervals.

8. The method of claim 1 , wherein replacing further comprises receiving the pitch-preserving audio stream in the multiplex or as a stream that is separate from the multiplex.

9. The method of claim 1 , wherein replacing further comprises receiving the pitch-preserving audio stream in the multiplex, wherein receiving the pitch-preserving audio stream in the multiplex comprises receiving the pitch-preserving audio stream as part of an elementary stream alternative to the audio stream.

10. The method of claim 1 , wherein replacing further comprises receiving the pitch-preserving audio stream in the stream that is separate from the multiplex, wherein receiving the pitch-preserving audio stream in the stream that is separate from the multiplex comprises receiving the stream as part of a unicast transmission or a multicast transmission.

11. The method of claim 1 , wherein replacing further comprises receiving, wherein receiving further comprises receiving auxiliary data, wherein the replacing is directly responsive to the auxiliary data.

12. The method of claim 1 , further comprising requesting transmission of the pitch-preserving audio stream, wherein the request for transmission is responsive to a determination by the network device of a need for either buffer expansion or buffer contraction.

13. The method of claim 1 , wherein replacing further comprises generating the pitch-preserving audio stream locally.

14. The method of claim 1 , further comprising presenting a decoded version the video stream and pitch-preserving audio stream during the succession of intervals, the decoded version played-out at the second playout rate, and resuming presentation beyond the succession of intervals of the video stream and audio stream corresponding to the video program at the first playout rate.

15. A method implemented by an upstream network device, comprising:

providing by the network device a multiplex of a compressed video stream and a compressed audio stream, the multiplex comprising a succession of intervals corresponding to a video program corresponding to a first playout rate; and

providing a compressed, pitch-preserving audio stream for each interval of the succession of intervals, each of the pitch-preserving audio streams corresponding to a second playout rate different than the first, the pitch-preserving audio stream synchronous to the video stream when the video stream is played out at the second playout rate.

16. The method of claim 15 , wherein providing the pitch-preserving audio stream comprises providing in the multiplex or as a stream separate from the multiplex, the separate stream corresponding to either a unicast or a multicast session.

17. The method of claim 15 , wherein providing the pitch-preserving audio stream comprises providing in response to a request from a downstream network device.

18. The method of claim 15 , further comprising either generating the pitch-preserving audio stream or receiving the pitch-preserving audio stream.

19. The method of claim 15 , wherein providing the pitch-preserving audio stream further comprises providing auxiliary data, the auxiliary data instructing a downstream network device when to effect a replacement between the audio stream and the pitch-preserving audio stream.

20. A downstream network device, comprising:

a memory encoded with logic; and

a processor configured with the logic to:

receive a multiplex of a compressed video stream and a compressed audio stream, the multiplex comprising a succession of intervals corresponding to a video program corresponding to a first playout rate; and

at the start of each interval, replace the compressed audio stream with a compressed, pitch-preserving audio stream corresponding to a second playout rate different than the first.