[gst-devel] A/V sync issues

Zaheer Merali zaheermerali at gmail.com
Mon Dec 11 21:55:47 CET 2006

On 12/11/06, Pavan Kumar Patale <pavanpatale at hotmail.com> wrote:
> Hi,
> How does the setting sync property of sink elements effect the
> recording/playback ?
> This query came up when i built the below pipeline and observed that there
> is huge different in the playback.
> When the below pipeline is exectued  the observations are:-
> i. Playback was not smooth
> ii. Video frames are getting dropped and A/V sync was happening only at few
> places.
> gst-launch-0.10 avimux name=mux ! queue ! avidemux name=demux demux.video_00
> ! queue ! video_decoder ! ffmpegcolorspace ! xvimagesink demux.audio_00 !
> queue ! audio_decoder ! audio_sink v4l2src ! ffmpegcolorspace !
> video/x-raw-yuv, width=176, height=144, framerate=15 ! videorate !
> video_encoder ! mux. audio_source ! queue ! audio_encoder ! mux.

Firstly, you have a live source at the end going to a synchronised
sink.  This will produce exactly what you mentioned, ie. not smooth
playback and frames being dropped.

Also remember framerate is a fraction, so better to specify framerate as 15/1.

You are better off recording to a file, and then trying to playback
the file.  The file is not a live source and you'll be able to tell
better the a/v sync and the quality of the recording and resulting
playback than by capturing, encoding, muxing, demuxing, decoding and
playing back in the same pipeline.


More information about the gstreamer-devel mailing list