Libav.org has removed this while moving the code around

For reference, the code was originally added in:
commit 9aeeeb63
Author: Fabrice Bellard <fabrice@bellard.org>
Date:   Wed Dec 20 00:02:47 2000 +0000

    Initial revision

    Originally committed as revision 2 to svn://svn.ffmpeg.org/ffmpeg/trunk
--
The function name originates from:
commit 94988531
Author: Fabrice Bellard <fabrice@bellard.org>
Date:   Thu Jul 25 16:01:46 2002 +0000

    more consistent naming

    Originally committed as revision 802 to svn://svn.ffmpeg.org/ffmpeg/trunkSigned-off-by: Michael Niedermayer <michaelni@gmx.at>