[vlc-devel] Re: lip sych problem

[Viktor Kompaneyets]

serkan bozkurt wrote:

> Hi to all,
> 
> I have a RTP streamer(liveMedia) that streams DVD's.
> I am using VLC for playing RTP streams.
> But I see that there is a nearly 1 second shift
> between audio and video.
> Is there a way for VLC for compansating this time
> swift?
> Is this a problem of liveMedia or VLC?

I've encountered the same problem using Live.com-only (test*) application.
Lost of sync - is common problem while working with high-bitrate MPEG
streams.

Probably, VLC and your application may be built with different versions of
LiveMedia libraries. Try the latest (or the same) source of them.

> 
> In fact at first 2 second syncronization is okey but
> after 2 second I see
> 
> " audio output is starving (400915), playing silence"

Maybe - buffers are too small or packet size - too large.
Even network jitter can produce out-of-sync problems.

If You're using DotQ environment - check, if packets with audio/video
payloads have the same (high) priority.

> 
> prints from VLC debug and then synchronization
> corrupts ..
> 
> Can we say that is the RTCP synchronization problem of
> SR's.
> 
> I mean NTP and RTP timestamp values are not correct in
> SR's.

Error resilence algo's in both Live & VLC are far from ideal. Some (partial)
success I've had with re-multiplexing source VOD with replex _before_
putting it to streamer.

Try asking this question in Live555 mailing list, or look in the archive -
this is mostly FAQ :(
 
> 
> Please write a few comments on this issue.

There can be a lot of things, that can produce the same result.

-- 
Viktor Kompaneyets
Wnet project manager

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