[gst-devel] add latency to audio in gstrtpbin
Wim Taymans
wim.taymans at gmail.com
Thu Sep 4 18:54:36 CEST 2008
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:
> http://chris.pirillo.com/2007/07/11/audio-video-capture/
> 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?
>
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
> -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 <tristan at sat.qc.ca <mailto:tristan at sat.qc.ca>>
> >
> > 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:
> > http://gstreamer.freedesktop.org/data/doc/gstreamer/stable/gstreamer/html/gstreamer-GstEvent.html#gst-event-new-latency
> >
> > 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: tristan at sat.qc.ca <mailto:tristan at sat.qc.ca>
> > web: http://www.music.mcgill.ca/~tmatthews
> > <http://www.music.mcgill.ca/%7Etmatthews>
> >
> >
> > -------------------------------------------------------------------------
> > 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
> > http://moblin-contest.org/redirect.php?banner_id=100&url=/
> > <http://moblin-contest.org/redirect.php?banner_id=100&url=/>
> > _______________________________________________
> > gstreamer-devel mailing list
> > gstreamer-devel at lists.sourceforge.net
> > <mailto:gstreamer-devel at lists.sourceforge.net>
> > https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
> >
> >
> > ------------------------------------------------------------------------
> >
> > -------------------------------------------------------------------------
> > 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
> > http://moblin-contest.org/redirect.php?banner_id=100&url=/
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > gstreamer-devel mailing list
> > gstreamer-devel at lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
> >
>
>
More information about the gstreamer-devel
mailing list