[FFmpeg-trac] #1876(avcodec:new): vc1dec.c multi-threading decode crash issue

FFmpeg trac at avcodec.org
Wed Oct 31 20:15:59 CET 2012

#1876: vc1dec.c multi-threading decode crash issue
             Reporter:  DonMoir  |                     Type:  defect
               Status:  new      |                 Priority:  critical
            Component:  avcodec  |                  Version:  unspecified
             Keywords:           |               Blocked By:
             Blocking:           |  Reproduced by developer:  0
Analyzed by developer:  0        |
 In vc1_decode_frame there is:

 if (ff_msmpeg4_decode_init(avctx) < 0 ||
   ff_vc1_decode_init_alloc_tables(v) < 0)

 If this entire statement is not locked down in a multi-threaded multi-
 video environment, then crash and burn.

 No way I know of to reproduce crash using ffmpeg command line tools.

 The way I produce crash is to pump more than one WMV3 files at ffmpeg
 simultaneously. Multiple instances of a file are using for playback,
 thumbnails, and other things. Then when calling avcodec_decode_video2 you
 will get spurious crashes depending on the current state of things.

 All other file formats I have tested seem to be ok. Just any format that
 makes use of vc1_decode_frame is suspect.

 The file I used for testing is located here: (283 MB)


Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1876>
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