Changing source without stopping pipeline

Stefan Sauer ensonic at
Wed Nov 2 09:14:51 PDT 2011

On 11/01/2011 01:19 AM, superlou wrote:
>> You might want to use "videotestsrc ! capsfilter" and set the format 
>> that you use on v4l2src to videotestsrc. 
> I had actually over simplified my pipeline down too much.  The actual
> pipeline is a bit more complex ( with the before
> image being the working output of mixing the v4l2src with a videotestsrc and
> the after showing the result of swapping in the second videotestsrc
> (swapping in the bottom left of both images).  I also am swapping the
> ffmpegcolorspace since I heard there might be a bug with it renegotiating
> caps, but that might be a red herring.
> As shown in the after, I had been forgetting to set the new videotestsrc and
> ffmpegcolorspace playing.  Making sure to set both to playing, I see that
> the two new elements seem to negotiate ok (  This
> leads to video that updates every few seconds or so.  I notice I get alot of
> this warning:
> 0:00:19.731523367 17149 0x7fcc00002290 WARN             videomixer2
> videomixer2.c:706:gst_videomixer2_fill_queues:<videomixer22:sink_0> Buffer
> from the past, dropping

Set is-live=true on videotestsrc.

> I'm also seeing a lot of Quality of Service messages:
> Source: ffmpegcsp3, Type: 16777216

Where does this message come from, try to print it with correct details
(Type: 16777216is not helpful).
> Do I need to do something to sync the timestamps on the new source?

Normally you would need to seek on the new source, but not for live-srcs.

> --
> View this message in context:
> Sent from the GStreamer-devel mailing list archive at
> _______________________________________________
> gstreamer-devel mailing list
> gstreamer-devel at

More information about the gstreamer-devel mailing list