<div dir="ltr"> <div class="gmail_quote">On Thu, Sep 4, 2008 at 1:54 PM, Wim Taymans <<a href="mailto:wim.taymans@gmail.com">wim.taymans@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> <div class="Ih2E3d">On Thu, 2008-09-04 at 11:34 -0400, Tristan Matthews wrote: > Thanks for the feedback Eric. I had seen the RFC before but that book > looks pretty useful as well. > My concern isn't that the AV will get out of sync in > gstreamer/gstrtpbin, but rather that it will be out of sync immediately > at the capture stage, i.e. if i have video input from a camera with more > latency than a separate audio source. An example scenario is given here: > <a href="http://chris.pirillo.com/2007/07/11/audio-video-capture/" target="_blank">http://chris.pirillo.com/2007/07/11/audio-video-capture/</a> > where you have video of someone clapping and you have to adjust the > delay to make the sound and image of the clap line up. > I would need to be able to manually adjust the latency to ensure the > video and audio are sync'd. Should I just put the audio through a > Ladspa-delay or is their a better solution in gstreamer? > </div>This situation can not occur in gstreamer when you have a well written source element that generates correct timestamps and reports its latency correctly. You could write an element that applies an offset to all timestamps on the buffers. Wim <div><div></div><div class="Wj3C7c"></div></div></blockquote><div> AFAIK, This element already exists and is called GstShift from gentrans plugins  </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> <div><div class="Wj3C7c"> > -T > > Eric Zhang wrote: > > Hi, Tristan: > > > >     You should not adjust video/audio latency manually because RTP > > provides a mechanism to accomplish this, called `lip-synchronization'. > > Refer to RFC 3550 or book `RTP: Video and Audio for the Internet' for > > more details. These will help you a lot. > > > > Eric Zhang > > > > 2008/9/3 Tristan Matthews <<a href="mailto:tristan@sat.qc.ca">tristan@sat.qc.ca</a> <mailto:<a href="mailto:tristan@sat.qc.ca">tristan@sat.qc.ca</a>>> > > > >     Hi, > > > >     If I have a pipeline using gstrtpbin (similar to the example in the > >     documentation) to send audio and video, what is the best/most reliable > >     way of adding latency to the audio? Would gst_event_new_latency work > >     (and if so, how), or am I missing its intent: > >     <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/stable/gstreamer/html/gstreamer-GstEvent.html#gst-event-new-latency" target="_blank">http://gstreamer.freedesktop.org/data/doc/gstreamer/stable/gstreamer/html/gstreamer-GstEvent.html#gst-event-new-latency</a> > > > >     Basically my concern is that if video capture is too slow, can I > >     manually adjust the audio latency to match. > > > >     Best, > > > >     Tristan > > > >     -- > >     Tristan Matthews > >     Société des arts technologiques [SAT] > >     email: <a href="mailto:tristan@sat.qc.ca">tristan@sat.qc.ca</a> <mailto:<a href="mailto:tristan@sat.qc.ca">tristan@sat.qc.ca</a>> > >     web: <a href="http://www.music.mcgill.ca/%7Etmatthews" target="_blank">http://www.music.mcgill.ca/~tmatthews</a> > >     <<a href="http://www.music.mcgill.ca/%7Etmatthews" target="_blank">http://www.music.mcgill.ca/%7Etmatthews</a>> > > > > > >     ------------------------------------------------------------------------- > >     This SF.Net email is sponsored by the Moblin Your Move Developer's > >     challenge > >     Build the coolest Linux based applications with Moblin SDK & win > >     great prizes > >     Grand prize is a trip for two to an Open Source event anywhere in > >     the world > >     <a href="http://moblin-contest.org/redirect.php?banner_id=100&url=/" target="_blank">http://moblin-contest.org/redirect.php?banner_id=100&url=/</a> > >     <<a href="http://moblin-contest.org/redirect.php?banner_id=100&url=/" target="_blank">http://moblin-contest.org/redirect.php?banner_id=100&url=/</a>> > >     _______________________________________________ > >     gstreamer-devel mailing list > >     <a href="mailto:gstreamer-devel@lists.sourceforge.net">gstreamer-devel@lists.sourceforge.net</a> > >     <mailto:<a href="mailto:gstreamer-devel@lists.sourceforge.net">gstreamer-devel@lists.sourceforge.net</a>> > >     <a href="https://lists.sourceforge.net/lists/listinfo/gstreamer-devel" target="_blank">https://lists.sourceforge.net/lists/listinfo/gstreamer-devel</a> > > > > > > ------------------------------------------------------------------------ > > > > ------------------------------------------------------------------------- > > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > > Build the coolest Linux based applications with Moblin SDK & win great prizes > > Grand prize is a trip for two to an Open Source event anywhere in the world > > <a href="http://moblin-contest.org/redirect.php?banner_id=100&url=/" target="_blank">http://moblin-contest.org/redirect.php?banner_id=100&url=/</a> > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > gstreamer-devel mailing list > > <a href="mailto:gstreamer-devel@lists.sourceforge.net">gstreamer-devel@lists.sourceforge.net</a> > > <a href="https://lists.sourceforge.net/lists/listinfo/gstreamer-devel" target="_blank">https://lists.sourceforge.net/lists/listinfo/gstreamer-devel</a> > > > > ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world <a href="http://moblin-contest.org/redirect.php?banner_id=100&url=/" target="_blank">http://moblin-contest.org/redirect.php?banner_id=100&url=/</a> _______________________________________________ gstreamer-devel mailing list <a href="mailto:gstreamer-devel@lists.sourceforge.net">gstreamer-devel@lists.sourceforge.net</a> <a href="https://lists.sourceforge.net/lists/listinfo/gstreamer-devel" target="_blank">https://lists.sourceforge.net/lists/listinfo/gstreamer-devel</a> </div></div></blockquote></div> -- Thiago Sousa Santos Embedded Systems and Pervasive Computing Lab (Embedded) Center of Electrical Engineering and Informatics (CEEI) Federal University of Campina Grande (UFCG) </div>