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List:       gstreamer-bugs
Subject:    [gstreamer-bugs] [Bug 576997] floating point stack corruption :
From:       "GStreamer (bugzilla.gnome.org)" <bugzilla-daemon () bugzilla ! gnome ! org>
Date:       2009-03-30 21:57:56
Message-ID: 20090330215756.B996223F519 () label ! gnome ! org
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  http://bugzilla.gnome.org/show_bug.cgi?id=576997

  GStreamer | gst-ffmpeg | Ver: 0.10.5




------- Comment #2 from Yves Lefebvre  2009-03-30 21:58 UTC -------
Here is a quick test to confirm this issue : 

gdb --args gst-launch-0.10 videotestsrc num-buffers=2 ! ffdeinterlace !
fakesink

and put a break point in avpicture_deinterlace

b avpicture_deinterlace

run it.

Once it break, check the value of the mm_flags. Without the patch, it is 0.
After applying the patch and redoing this test, it should be different than 0
if running on a pc with mmx.

if the mm_flags is not properly set, the emms_c macro defined in
gst-libs/ext/ffmpeg/libavcodec/dsputil.h will not call emms();

#define emms_c() \
{\
    if (mm_flags & MM_MMX)\
        emms();\
}

This will leave the floating point stack potentially corrupted after the
deinterlace mmx function.


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