I run the command: GST_DEBUG="rmdemux:4,real*:4" gst-launch playbin uri=file:///home/ruanwen<div id="1elw" class="ArwC7c ckChnd">/Desktop/media/04.rmvb There are too many debug logs and the last  is as the following: <........skip..................> 0:00:27.307954884  4669 0x90cb5a0 DEBUG              rmdemux rmdemux.c:2194:gst_rmdemux_parse_video_packet:<rmdemux0> fragment size 813 0:00:27.307970317  4669 0x90cb5a0 DEBUG              rmdemux rmdemux.c:2222:gst_rmdemux_parse_video_packet:<rmdemux0> stored fragment in adapter 1641/1641 0:00:27.307987285  4669 0x90cb5a0 DEBUG              rmdemux rmdemux.c:2245:gst_rmdemux_parse_video_packet:<rmdemux0> fragmented completed. count 2, header_size 17 0:00:27.308042102  4669 0x90cb5a0 DEBUG              rmdemux rmdemux.c:2274:gst_rmdemux_parse_video_packet:<rmdemux0> 0 bytes left 0:00:27.308079741  4669 0x90cb5a0 DEBUG              rmdemux rmdemux.c:2397:gst_rmdemux_parse_packet:<rmdemux0> flags 2, Keyframe 1 0:00:27.308092660  4669 0xb7201890 DEBUG         realvideodec gstrealvideodec.c:409:open_library:<realvideodec0> Attempting to open shared library for real video version 4 0:00:27.308104950  4669 0x90cb5a0 DEBUG              rmdemux rmdemux.c:877:gst_rmdemux_loop:<rmdemux0> Chain flow failed at offset 0x0000120c 0:00:27.308133092  4669 0x90cb5a0 WARN               rmdemux rmdemux.c:943:gst_rmdemux_loop:<rmdemux0> error: stream stopped, reason not-negotiated ERROR: from element /playbin0/decodebin0/rmdemux0: GStreamer encountered a general stream error. Additional debug info: rmdemux.c(943): gst_rmdemux_loop (): /playbin0/decodebin0/rmdemux0: stream stopped, reason not-negotiated ERROR: pipeline doesn't want to preroll. Setting pipeline to NULL ... 0:00:27.308673092  4669 0x90cb5a0 DEBUG              rmdemux rmdemux.c:1256:gst_rmdemux_send_event:<rmdemux0> Pushing eos event on pad audio_00 0:00:27.308738663  4669 0x90cb5a0 DEBUG              rmdemux rmdemux.c:1256:gst_rmdemux_send_event:<rmdemux0> Pushing eos event on pad video_00 0:00:27.378002892  4669 0xb7201890 DEBUG         realvideodec gstrealvideodec.c:115:gst_real_video_dec_chain:<realvideodec0> got buffer of size 1658, timestamp 0:00:00.000000000 0:00:27.378119230  4669 0xb7201890 DEBUG         realvideodec gstrealvideodec.c:217:gst_real_video_dec_chain:<realvideodec0> buffer alloc failed: wrong-state 0:00:27.378505463  4669 0x8fe7050 DEBUG              rmdemux rmdemux.c:804:gst_rmdemux_sink_activate_pull:<rmdemux0> activate_pull FREEING pipeline ...  From the log, i can't determine which cause the playing failure. And how to diagnose the problem from the log? </div> <div class="gmail_quote">2008/5/13 Edward Hervey <<a href="mailto:bilboed@gmail.com">bilboed@gmail.com</a>>: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">On Mon, 2008-05-12 at 22:10 +0300, Stefan Kost wrote: [...] <div class="Ih2E3d">> GST_DEBUG="rademux:4,real*:4" gst-launch playbin > uri=file:///home/ruanwen/Desktop/media/04.rmvb </div>   Stefan meant: "rmdemux:4,real*:4" (and not rAdemux) > > Stefan > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2008. > <a href="http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/" target="_blank">http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/</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>