License, see the file COPYING.GPL for details. Their compilation and use
in FFmpeg is optional.
+* The file libavcodec/x86/idct_mmx.c is distributed under the GNU General
+ Public License. It is strictly an optimization and its use is optional.
+
+* The file libavcodec/ac3dec.c is distributed under the GNU General Public
+ License. In order for (E-)AC-3 decoding to work you need to enable GPL
+ components.
+
+* The file libavdevice/x11grab.c is distributed under the GNU General
+ Public License. X11 grabbing is optional.
+
* The files libavcodec/jfdctfst.c, libavcodec/jfdctint.c, libavcodec/jrevdct.c
are taken from libjpeg, see the top of the files for licensing details.