[gstreamer-bugs] [Bug 373003] New: debug traces prevent segmentation fault when playing RTSP/RTP

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gst-plugins-good | Ver: HEAD CVS

           Summary: debug traces prevent segmentation fault when playing
                    RTSP/RTP
           Product: GStreamer
           Version: HEAD CVS
          Platform: Other
        OS/Version: All
            Status: UNCONFIRMED
          Severity: critical
          Priority: Normal
         Component: gst-plugins-good
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: gstdbg at yahoo.com
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


Steps to reproduce:
1. Run vlc as an RTSP server for an MP3 file:
  1.1 cp /path/to/xxx.mp3 .
  1.1 vlc --ttl 12 -vvv --color -I telnet --telnet-password toto --rtsp-host
0.0.0.0:5555
  1.2 telnet localhost 4212
        > new tst vod enabled
        > setup tst input xxx.mp3

2. Run gstreamer with debug traces:
  $ gst-launch --gst-debug=3 rtspsrc location=rtsp://myserver:5555/tst !
rtpmpadepay ! fakesink
=> it does not crash

3. Run gstreamer without debug traces:
  $ gst-launch rtspsrc location=rtsp://myserver:5555/tst ! rtpmpadepay !
fakesink
=> it crashes (segmentation fault), probably on reception of the first RTP
packet

4. Run gstreamer without debug traces and without an RTP depayloaded:
  $ gst-launch rtspsrc location=rtsp://myserver:5555/tst ! fakesink
=> it does not crash!

Conclusion: the problem is probably in the RTP depayloader



Stack trace:
N/A (enabling debug traces prevent the crash to occur).

Other information:
The MP3 file is 256kbps, 32kHz, stereo
The machine running gstreamer is a quad proc, AMD Opteron 270, 2GHz, 4Gb RAM
(this last bit is just pendantic!)

Personally, I think that this kind of problem is symptomatic of a shared
resource accessed by 2 threads without proper mutexing. When debug is off, a
thread is pre-empted by the other in the middle of writing something to this
shared memory (variable/buffer/etc.)

IMPORTANT: when using RTP interleaved in RTSP (using fenice server, as vlc does
not support interleaved mode), the crash does not occur!!


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