Thank you very much Arnout. Using the method you described I am able to record from the webcam every time the user presses a button. As you pointed, also, I am having trouble with timestamps. In my case, since I just need to record one file at time, I would be ok to reset the base time for the v4l2src element. However ,when I try to set the base_time to 0 for this element it stops streaming new images. Since I'd like to stick to the "default" gstreamer packages, is there a way to set the base_time for v4l2src without it being stopped ? Thanks <div class="gmail_quote">2009/1/31 Arnout Vandecappelle <<a href="mailto:arnout@mind.be">arnout@mind.be</a>> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div><div></div><div class="Wj3C7c">On Friday 30 January 2009 20:37:49 Marc wrote: > I am trying to build an application more or less like Cheese > (<a href="http://projects.gnome.org/cheese/" target="_blank">http://projects.gnome.org/cheese/</a>). However I would like to switch from > just showing the webcam to a recording state "smoothly" when the user press > the record button. > > So far I have tried the following approaches without succes: > Changing location property of filesink while playing (from /dev/null to a > real path). This is not possible (filesink tells me so). Open 2 different > pipelines both of them pointing to the same v4l2src (no success since only > one pipeline can access the webcam at once). Since these approaches were > not working I tried to set the pipeline to STATE_NULL, change the location > of the filesink, and then set the pipeline to STATE_PLAYING again. However, > when setting the pipeline to STATE_NULL, no STATE_CHANGE event is thrown. > Is this the expected behavior ? > > Any ideas ? Can the smooth "play-to-record" be accomplished with GStreamer > ? > > Thank you > PD. For the record: I am programming in Python and the pipeline I am trying > to manage is the following: > >  gst-launch-0.10 v4l2src ! tee name=videoout ! queue ! videorate ! > video/x-raw-yuv,fps=15 ! queue ! theoraenc quality=60 ! queue ! muxout. > pulsesrc ! audio/x-raw-int,rate=22000,channels=1,width=16 ! queue ! > audioconvert ! vorbisenc ! queue ! muxout. oggmux name=muxout ! filesink > location=test.ogg videoout. ! queue ! ffmpegcolorspace ! ximagesink </div></div> You can add the videoout tail of the pipeline dynamically.  Start without it, and when the user presses the record button, add it to the pipeline and link it (and set each element to PLAYING individually).  It's not even necessary to pause the pipeline.  It's more difficult to smoothly stop the recording, though.  You'll have to block the queue element behind the tee (see docs/design/part-block.txt in the source tree).  In addition, you have to push an EOS into it to make sure the muxer writes duration and index to the file.  A last caveat is the timestamps.  The buffer timestamps start running as soon as the v4l2src starts playing, which makes it appear in the output file as if it starts with a big hole.  The only way I found to fix that is to add an adapter element that shifts the buffer timestamps (see <a href="http://bugzilla.gnome.org/show_bug.cgi?id=561224" target="_blank">http://bugzilla.gnome.org/show_bug.cgi?id=561224</a> ).  Regard,  Arnout -- Arnout Vandecappelle                               arnout at mind be Senior Embedded Software Architect                 +32-16-286540 Essensium/Mind                                     <a href="http://www.mind.be" target="_blank">http://www.mind.be</a> G.Geenslaan 9, 3001 Leuven, Belgium                BE 872 984 063 RPR Leuven LinkedIn profile: <a href="http://www.linkedin.com/in/arnoutvandecappelle" target="_blank">http://www.linkedin.com/in/arnoutvandecappelle</a> GPG fingerprint:  D206 D44B 5155 DF98 550D  3F2A 2213 88AA A1C7 C933 ------------------------------------------------------------------------------ This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. <a href="http://p.sf.net/sfu/sf-spreadtheword" target="_blank">http://p.sf.net/sfu/sf-spreadtheword</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> </blockquote></div> -- Marc S.