The only definitions from MPlayer code are the CONTROL_* defines (added
in 7a2eec4b as part of libao2 - not part of libao), and MP_NOPTS_VALUE,
which was added in e6338c58. The latter is by "michael", who has agreed
under the condition that the core is LGPL, which has not happened yet,
but considering the macro definition used to be different, has the same
value and similar name to libavformat's AV_NOPTS_VALUE (which existed
first, and as LGPL), and that this almost certainly not copyrightable,
I'm assuming that this is fine.