extra byte and are not compliant with ISO 14496-12.  This causes some strict
demuxers (notably the MPEG-4 ALS reference software) to fail.  It has been
confirmed that not writing the extra byte will still allow the generated MP4
files to work with QuickTime/iTunes/iPod.

Originally committed as revision 20571 to svn://svn.ffmpeg.org/ffmpeg/trunk