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<body class='hmmessage'><BR><BR><BR>RTSP has timestamp... so you can usually know how to sync the audio/video<BR>
But the problem would be more that we'll need to add a Skew Indication concept inside asterisk's core so it could make the message go throught the different channel/application, as it is currently done for VideoFastUpdatePicutre... Which means that currently, if a SIP channel receives a VideoFastUpdatePicture, it is capable of resending it to an other channel...<BR>
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> Date: Mon, 24 Sep 2007 13:48:54 +0200<BR>> From: mobilemail@gmx-topmail.de<BR>> To: asterisk-video@lists.digium.com<BR>> Subject: Re: [Asterisk-video] MP4Play async Audio / Video<BR>> <BR>> Hello Ramin,<BR>> hello Thomas.<BR>> <BR>> I think both ways are possible. But I don't know if it easy to implement.<BR>> Sergio, what do you think about it?<BR>> <BR>> Is this also a problem if we stream the audi/video via rtsp?<BR>> <BR>> Regrads<BR>> Thomas<BR>> <BR>> <BR>> Ramtin Amin schrieb:<BR>> > hello<BR>> > <BR>> > The way I solved this problem was by sending a H223SkewIndication<BR>> > message to the other terminal<BR>> > Acutally, You will have to ask Sergio to add a H245 indication message<BR>> > of type h223SkewIndication and when playing the video with mp4play, he<BR>> > will have to see the difference of timing between Video and Audio and<BR>> > then send this value to the remote terminal so the lip sync would work...<BR>> > <BR>> > <BR>> > <BR>> > **<BR>> ><BR>> > *2.3 Multipoint Lip Synchronization*<BR>> ><BR>> > In a multipoint VC, each terminal may transmit different<BR>> ><BR>> > //<BR>> ><BR>> > /H223SkewIndication /message for associated video and<BR>> ><BR>> > audio channels in H.223 protocol. To enable lip<BR>> ><BR>> > synchronization at receiving terminals, MCUs will<BR>> ><BR>> > transmit accurate /H223SkewIndication /messages. MCUs<BR>> ><BR>> > may accomplish this by adding delay to equalize the<BR>> ><BR>> > audio/video skew for all transmitting terminals. When<BR>> ><BR>> > switching between broadcasting terminals, H.223 may<BR>> ><BR>> > transmit a new /H223SkewIndication /message reflecting the<BR>> ><BR>> > audio/video skew of the current broadcaster.<BR>> > <BR>> ><BR>> > -- <BR>> > Ramtin Amin<BR>> ><BR>> ><BR>> ><BR>> > <BR>> > ------------------------------------------------------------------------<BR>> ><BR>> > > From: thomas.frieling@viif.de<BR>> > > To: asterisk-video@lists.digium.com<BR>> > > Date: Mon, 24 Sep 2007 11:48:12 +0200<BR>> > > Subject: Re: [Asterisk-video] MP4Play async Audio / Video<BR>> > ><BR>> > > Hi Thomas Z!<BR>> > ><BR>> > > I think this problem is due to the bitrate restriction on 3G calls. The<BR>> > > audio stream is always sent immediately while the video stream has to<BR>> > > use what is left of the bandwidth. This is why videos become synchrous<BR>> > > again when the video bitrate is pretty low for a while in the video...<BR>> > ><BR>> > > Take a look at this discussion:<BR>> > ><BR>> > http://lists.digium.com/pipermail/asterisk-video/2007-September/001257.html<BR>> > ><BR>> > > One solution is to reencode every video with a low bitrate and use a<BR>> > > fixed bitrate encoder (ffmpeg is dynamic bitrate for example). I had the<BR>> > > impression though that this still doesn't always work, especially when<BR>> > > the UMTS connection is not too good...<BR>> > ><BR>> > > My idea is that we check each time before sending a keyframe if there is<BR>> > > already a new keyframe in the queue. If this is the case, we jump to the<BR>> > > most recent keyframe and just drop the data before that.<BR>> > ><BR>> > > What do you think about this? How hard to implement?<BR>> > ><BR>> > > Regards,<BR>> > > Thomas F<BR>> > ><BR>> > ><BR>> > ><BR>> > > Am Montag, den 24.09.2007, 11:15 +0200 schrieb Thomas Z.:<BR>> > > > Hello,<BR>> > > ><BR>> > > > We have the problem, that a converted mp4 file is asynchronous via 3g<BR>> > > > network.<BR>> > > > If we play the file on a pc, everything is synchron.<BR>> > > > We tried already to reduce the quality and framerate of the video. But<BR>> > > > nothing helps.<BR>> > > ><BR>> > > > Is it a problem with mp4play or with the video?<BR>> > > ><BR>> > > > What can we do to get the audio and video synchronized via 3g network?<BR>> > > ><BR>> > > > Thank you,<BR>> > > > best regards<BR>> > > > Thomas<BR>> > > ><BR>> > > ><BR>> > > ><BR>> > > > _______________________________________________<BR>> > > > --Bandwidth and Colocation Provided by http://www.api-digital.com--<BR>> > > ><BR>> > > > asterisk-video mailing list<BR>> > > > To UNSUBSCRIBE or update options visit:<BR>> > > > http://lists.digium.com/mailman/listinfo/asterisk-video<BR>> > > --<BR>> > > www.ViiF.de - your Mobile Video Community<BR>> > ><BR>> > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<BR>> > ><BR>> > > Thomas Frieling - IT Development<BR>> > > ViiF Mobile Video GmbH, Poststr. 21-22, 10178 Berlin<BR>> > > Cell: +49 (0) 173 63 62 62 3<BR>> > ><BR>> > > mailto:thomas@ViiF.de<BR>> > ><BR>> > > Sitz: Berlin, Amtgericht Berlin-Charlottenburg, HRB: 108350B<BR>> > ><BR>> > > Geschäftsführer: Daniel Höpfner, Steffen Brünn<BR>> > ><BR>> > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<BR>> > ><BR>> > > _______________________________________________<BR>> > > --Bandwidth and Colocation Provided by http://www.api-digital.com--<BR>> > ><BR>> > > asterisk-video mailing list<BR>> > > To UNSUBSCRIBE or update options visit:<BR>> > > http://lists.digium.com/mailman/listinfo/asterisk-video<BR>> ><BR>> ><BR>> > ------------------------------------------------------------------------<BR>> > Besoin d'un e-mail ? Créez gratuitement un compte Windows Live Hotmail<BR>> > et bénéficiez d'un filtre antivirus gratuit ! Windows Live Hotmail<BR>> > <http://www.windowslive.fr/hotmail/default.asp><BR>> > ------------------------------------------------------------------------<BR>> ><BR>> > _______________________________________________<BR>> > --Bandwidth and Colocation Provided by http://www.api-digital.com--<BR>> ><BR>> > asterisk-video mailing list<BR>> > To UNSUBSCRIBE or update options visit:<BR>> > http://lists.digium.com/mailman/listinfo/asterisk-video<BR>> <BR>> <BR>> _______________________________________________<BR>> --Bandwidth and Colocation Provided by http://www.api-digital.com--<BR>> <BR>> asterisk-video mailing list<BR>> To UNSUBSCRIBE or update options visit:<BR>> http://lists.digium.com/mailman/listinfo/asterisk-video<BR><BR><br /><hr />Besoin d'un e-mail ? 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