+Should you, for whatever reason, prefer to use version 3 of the (L)GPL, then
+the configure parameter --enable-version3 will activate this licensing option
+for you. Read the file COPYING.LGPLv3 or, if you have enabled GPL parts,
+COPYING.GPLv3 to learn the exact legal terms that apply in this case.
+
+
+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, 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
+----------------------