[vlc-devel] Re: lip sych problem
serkanboz80 at yahoo.com
Thu Nov 24 15:17:01 CET 2005
Thanks for your replay Viktor,
I have some questions ,
First; you are saying that network jitter may cause
lip synch problem.
Jitter means the timestamp frequency difference
between 2 adjacent
rtp packets in the receiver side.
if network goes down then timestamp difference between
adjacent rtp packets will be bigger than the previous
This may cause starvation on the receiver side buffers
because datas are late!
But after network is okey from the RTCP SR
timestamps(they are sent periodically), lip synch must
be ok isn't it?
Second problem:Why bid rtp packets may result in
on the reiver side can you please explain.
Third one :
For the time being live55.com is inactive but I know 2
days ago it was okey.
Do you have any idea about this.
--- Viktor Kompaneyets <vato at wnet.ua> wrote:
> serkan bozkurt wrote:
> > Hi to all,
> > I have a RTP streamer(liveMedia) that streams
> > 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
> 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
> > after 2 second I see
> > " audio output is starving (400915), playing
> Maybe - buffers are too small or packet size - too
> Even network jitter can produce out-of-sync
> 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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