Problem 1) I am trying to stream MPEG-4 video (MP4V-ES) using RTP. On the sender side I give: gst-launch videotestsrc ! ffenc_mpeg4 ! rtpmp4vpay ! udpsink port = 1234 This is producing packets as can be seen from Ethereal packet capture. On decoding the packet as RTP, I can see the payload typ as 96. On the sender side I type: gst-launch udpsrc port=1234 ! application/x-rtp,clock-rate=90000,pt=96 ! rtpmp4vdepay ! ffdec_mpeg4 ! xvimagesink This does not work. The output I get is: Setting pipeline to PAUSED ... Pipeline is live and does not need PREROLL ... Setting pipeline to PLAYING ... New clock: GstSystemClock ERROR: from element /pipeline0/ffdec_mpeg40: Internal GStreamer error: negotiation problem.  Please file a bug at <a href="http://bugzilla.gnome.org/enter_bug.cgi?product=GStreamer">http://bugzilla.gnome.org/enter_bug.cgi?product=GStreamer</a>. Additional debug info: gstffmpegdec.c(1276): gst_ffmpegdec_chain (): /pipeline0/ffdec_mpeg40: ffdec_mpeg4: input format was not set before data start Execution ended after 129952000 ns. Setting pipeline to PAUSED ... Setting pipeline to READY ... Setting pipeline to NULL ... FREEING pipeline ... ----------------------- Problem 2) Instead of using the videotestsrc, I am trying to use an existing MPEG-4 video elementary stream. Here I get a problem on the sender side itself. My command is: gst-launch filesrc location= test.m4v ! rtpmp4vpay ! application/x-rtp,clock-rate=90000 ! udpsink port = 1234 Setting pipeline to PAUSED ... Pipeline is PREROLLING ... ERROR: from element /pipeline0/rtpmp4vpay0: Element doesn't implement handling of this stream. Please file a bug. Additional debug info: gstbasertppayload.c(420): gst_basertppayload_push (): /pipeline0/rtpmp4vpay0: subclass did not specify clock_rate ERROR: pipeline doesn't want to preroll. Setting pipeline to NULL ... FREEING pipeline ... Can you please help me out? Thanks, Deeptendu.