-* The files libavcodec/jfdctfst.c, libavcodec/jfdctint.c, libavcodec/jrevdct.c
- are taken from libjpeg, see the top of the files for licensing details.
+* The files libavcodec/jfdctfst.c, libavcodec/jfdctint_template.c and
+ libavcodec/jrevdct.c are taken from libjpeg, see the top of the files for
+ licensing details. Specifically note that you must credit the IJG in the
+ documentation accompanying your program if you only distribute executables.
+ You must also indicate any changes including additions and deletions to
+ those three files in the documentation.
+
+
+external libraries
+==================
+
+Libav can be combined with a number of external libraries, which sometimes
+affect the licensing of binaries resulting from the combination.
+
+compatible libraries
+--------------------
+
+The libcdio, libx264, libx265, libxavs and libxvid libraries are under GPL. When
+combining them with Libav, Libav needs to be licensed as GPL as well by
+passing --enable-gpl to configure.
+
+The OpenCORE and VisualOn libraries are under the Apache License 2.0. That
+license is incompatible with the LGPL v2.1 and the GPL v2, but not with
+version 3 of those licenses. So to combine these libraries with Libav, the
+license version needs to be upgraded by passing --enable-version3 to configure.
+
+incompatible libraries
+----------------------