You should use caps on media stream. Filesrc well give you raw file bytes. For mp4 use qtdemux. ... filesrc ... ! qtdemux name=demux demux.audio_00 ! capsfilter ... ! ...sink Some thing like this. <div class="gmail_quote">29-11-2012 07:00, "deepthips" <<a href="mailto:deepthips@tataelxsi.co.in">deepthips@tataelxsi.co.in</a>> napisał(a): <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> Hi , I am really confused about the use of capsfilter in a pipeline. I understand it is for setting some properties. gst-launch filesrc location=sample.ac3 ! ac3parse ! myaudio ---> will work. gst-launch filesrc location=sample.mp4! ac3parse ! myaudio ---> will give error saying "Failed to parse stream" gst-launch filesrc location=sample.mp4! capsfilter caps="audio/x-ac3" ! ac3parse ! myaudio ---> (Using caps filter) will give me same error itself Anyways the pipeline wont allow us to set unmatched properties to next element right.? Then what is the specific use of capsfilter? -- View this message in context: <a href="http://gstreamer-devel.966125.n4.nabble.com/Use-of-capsfilter-tp4657112.html" target="_blank">http://gstreamer-devel.966125.n4.nabble.com/Use-of-capsfilter-tp4657112.html</a> Sent from the GStreamer-devel mailing list archive at Nabble.com. _______________________________________________ gstreamer-devel mailing list <a href="mailto:gstreamer-devel@lists.freedesktop.org">gstreamer-devel@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel" target="_blank">http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel</a> </blockquote></div>