[Asterisk-video] MP4Play async Audio / Video

[Thomas Z.]

Hello Ramin,
hello Thomas.

I think both ways are possible. But I don't know if it easy to implement.
Sergio, what do you think about it?

Is this also a problem if we stream the audi/video via rtsp?

Regrads
Thomas


Ramtin Amin schrieb:
> hello
>  
> The way I solved this problem was by sending a H223SkewIndication
> message to the other terminal
> Acutally, You will have to ask Sergio to add a H245 indication message
> of type h223SkewIndication and when playing the video with mp4play, he
> will have to see the difference of timing between Video and Audio and
> then send this value to the remote terminal so the lip sync would work...
>  
>  
>  
> **
>
> *2.3 Multipoint Lip Synchronization*
>
> In a multipoint VC, each terminal may transmit different
>
> //
>
> /H223SkewIndication /message for associated video and
>
> audio channels in H.223 protocol. To enable lip
>
> synchronization at receiving terminals, MCUs will
>
> transmit accurate /H223SkewIndication /messages. MCUs
>
> may accomplish this by adding delay to equalize the
>
> audio/video skew for all transmitting terminals. When
>
> switching between broadcasting terminals, H.223 may
>
> transmit a new /H223SkewIndication /message reflecting the
>
> audio/video skew of the current broadcaster.
>  
>
> -- 
> Ramtin Amin
>
>
>
>  
> ------------------------------------------------------------------------
>
> > From: thomas.frieling at viif.de
> > To: asterisk-video at lists.digium.com
> > Date: Mon, 24 Sep 2007 11:48:12 +0200
> > Subject: Re: [Asterisk-video] MP4Play async Audio / Video
> >
> > Hi Thomas Z!
> >
> > I think this problem is due to the bitrate restriction on 3G calls. The
> > audio stream is always sent immediately while the video stream has to
> > use what is left of the bandwidth. This is why videos become synchrous
> > again when the video bitrate is pretty low for a while in the video...
> >
> > Take a look at this discussion:
> >
> http://lists.digium.com/pipermail/asterisk-video/2007-September/001257.html
> >
> > One solution is to reencode every video with a low bitrate and use a
> > fixed bitrate encoder (ffmpeg is dynamic bitrate for example). I had the
> > impression though that this still doesn't always work, especially when
> > the UMTS connection is not too good...
> >
> > My idea is that we check each time before sending a keyframe if there is
> > already a new keyframe in the queue. If this is the case, we jump to the
> > most recent keyframe and just drop the data before that.
> >
> > What do you think about this? How hard to implement?
> >
> > Regards,
> > Thomas F
> >
> >
> >
> > Am Montag, den 24.09.2007, 11:15 +0200 schrieb Thomas Z.:
> > > Hello,
> > >
> > > We have the problem, that a converted mp4 file is asynchronous via 3g
> > > network.
> > > If we play the file on a pc, everything is synchron.
> > > We tried already to reduce the quality and framerate of the video. But
> > > nothing helps.
> > >
> > > Is it a problem with mp4play or with the video?
> > >
> > > What can we do to get the audio and video synchronized via 3g network?
> > >
> > > Thank you,
> > > best regards
> > > Thomas
> > >
> > >
> > >
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> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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> > Thomas Frieling - IT Development
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