Sound stopping (pipeline sync issue?)

Tvrtko Ursulin tvrtko.ursulin at
Thu Jun 2 04:45:57 PDT 2011

Hi all,

I have a test pipeline where sound works very unreliable unless sync property 
on alsasink is set to false and I am wondering about why, what is happening 
under the hood and so on.

Pipeline looks like this:

gst-launch-0.10 v4l2src device=/dev/video0 ! video/x-raw-
yuv,width=1920,height=1080,framerate=50/1 ! queue ! deinterlace ! queue ! 
xvimagesink alsasrc device=hw:2,0 provide-clock=false ! audio/x-raw-
int,rate=48000 ! queue ! alsasink

What is happening is that sound stops less than a second after pipeline is 
launched and stays off. Video works fine.

If I add "sync=false" to alsasink then it all works fine. "provide-clock" on 
the alsasrc has no effect there, I added it assuming video clock must be a 
better choice? How

My main question would be is "sync=false" on the audio output sync in any way 
dangerous or not recommended?

How does GStreamer synchronise video and audio with this kind of pipeline and 
how does "sync=false" on audio sink affect that?

Many thanks,


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