[Asterisk-video] MP4Play async Audio / Video

[Ramtin Amin]

RTSP has timestamp... so you can usually know how to sync the audio/video
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...
 



> Date: Mon, 24 Sep 2007 13:48:54 +0200> From: mobilemail at gmx-topmail.de> To: asterisk-video at lists.digium.com> Subject: Re: [Asterisk-video] MP4Play async Audio / Video> > 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> > > >> > > >> > > >> > > > _______________________________________________> > > > --Bandwidth and Colocation Provided by http://www.api-digital.com--> > > >> > > > asterisk-video mailing list> > > > To UNSUBSCRIBE or update options visit:> > > > http://lists.digium.com/mailman/listinfo/asterisk-video> > > --> > > www.ViiF.de - your Mobile Video Community> > >> > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~> > >> > > Thomas Frieling - IT Development> > > ViiF Mobile Video GmbH, Poststr. 21-22, 10178 Berlin> > > Cell: +49 (0) 173 63 62 62 3> > >> > > mailto:thomas at ViiF.de> > >> > > Sitz: Berlin, Amtgericht Berlin-Charlottenburg, HRB: 108350B> > >> > > Geschäftsführer: Daniel Höpfner, Steffen Brünn> > >> > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~> > >> > > _______________________________________________> > > --Bandwidth and Colocation Provided by http://www.api-digital.com--> > >> > > asterisk-video mailing list> > > To UNSUBSCRIBE or update options visit:> > > http://lists.digium.com/mailman/listinfo/asterisk-video> >> >> > ------------------------------------------------------------------------> > Besoin d'un e-mail ? Créez gratuitement un compte Windows Live Hotmail> > et bénéficiez d'un filtre antivirus gratuit ! Windows Live Hotmail> > <http://www.windowslive.fr/hotmail/default.asp>> > ------------------------------------------------------------------------> >> > _______________________________________________> > --Bandwidth and Colocation Provided by http://www.api-digital.com--> >> > asterisk-video mailing list> > To UNSUBSCRIBE or update options visit:> > http://lists.digium.com/mailman/listinfo/asterisk-video> > > _______________________________________________> --Bandwidth and Colocation Provided by http://www.api-digital.com--> > asterisk-video mailing list> To UNSUBSCRIBE or update options visit:> http://lists.digium.com/mailman/listinfo/asterisk-video
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