[gst-devel] Problem with mpeg2 playback

[Benjamin Otte]

Please make sure to file this as a bug (preferrably reproducable) if you can't 
get anyone to fix it.
Bug reports on this list get lost far too often.

Benjamin


Quoting Mathew Spencer <matthew.spencer at eu.sony.com>:

> Hi all,
> I am currently working on an MXF demuxer that uses gstreamer, but I am 
> running into a problem with this pipeline (using gstreamer version 0.8.0):
> 
>   filesrc location=file.mxf ! mxfdemux ! mpeg2dec ! xvimagesink
> 
> The pipeline segfaults in mpeg2dec.  If I run this pipeline (or 
> something like):
> 
>   filesrc location=file.mxf ! mxfdemux ! fdsink fd=1 | mpeg2dec 
> /proc/self/fd/1
> 
> all goes fine.
> 
> I have been analyzing the problem using valgrind at it seems that on my 
> system (Fedora core 1) the mpeg2dec is overrunning its buffers when 
> decoding.  Valgrinds output from the simple pipeline:
> 
>   filesrc location=file.mpeg2 ! mpeg2dec ! xvimagesink
> 
> if gives me the output:
> Invalid write of size 8
> ==22720==    at 0x4C16D40: mpeg2_idct_copy_mmxext (idct_mmx.c:613)
> ==22720==    by 0x4C068CE: mpeg2_slice (slice.c:954)
> ==22720==    by 0x4C04704: mpeg2_parse (decode.c:188)
> ==22720==    by 0x6501FE: gst_mpeg2dec_chain (gstmpeg2dec.c:478)
> ==22720==    by 0xD9F6A4: gst_pad_push (gstpad.c:3032)
> ==22720==    by 0xE700C2: get_group_schedule_function 
> (gstoptimalscheduler.c:1138)
> ==22720==    by 0xE6FC41: schedule_group (gstoptimalscheduler.c:1007)
> ==22720==    by 0xE6FCF7: gst_opt_scheduler_schedule_run_queue 
> (gstoptimalscheduler.c:1050)
> ==22720==    Address 0x3ACD524 is 0 bytes after a block of size 656640 
> alloc'd
> ==22720==    at 0xE8A68E: malloc (vg_replace_malloc.c:153)
> ==22720==    by 0xAF38C6: g_malloc (in /usr/lib/libglib-2.0.so.0.200.3)
> ==22720==    by 0xD85B9F: gst_buffer_new_and_alloc (gstbuffer.c:224)
> ==22720==    by 0x64FE04: gst_mpeg2dec_alloc_buffer (gstmpeg2dec.c:293)
> ==22720==    by 0x6503CD: gst_mpeg2dec_chain (gstmpeg2dec.c:508)
> ==22720==    by 0xD9F6A4: gst_pad_push (gstpad.c:3032)
> ==22720==    by 0xE700C2: get_group_schedule_function 
> (gstoptimalscheduler.c:1138)
> ==22720==    by 0xE6FC41: schedule_group (gstoptimalscheduler.c:1007)
> 
> informing us that the buffer being read from that was allocated by 
> 'gst_mpeg2dec_alloc_buffer' is being accessed invalidly.
> 
> I checked mpeg2dec command line tool for processing the same file, and I 
> get no such error.
> 
> I have been unable to track down the problem yet (but am still looking), 
> and was wondering if the mpeg2dec plugin maintainer could also have a 
> look at the problem?
> 
> Thanks for your time.
> 
> Mat
> 
> 
> 
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