mpv is a fork of mplayer2, which is a fork of MPlayer.

mpv as a whole is licensed under the GNU General Public License GPL version 2
or later (called GPLv2+ in this document, see LICENSE.GPL for full license
text) by default, or the GNU Lesser General Public License LGPL version 2 or
later (LGPLv2.1+ in this document, see LICENSE.LGPL for full license text) if
built with the --enable-lgpl configure switch.

Most source files are LGPLv2.1+ or GPLv2+, but some files are available under
more liberal licenses, such as BSD, MIT, ISC, and possibly others. Look at the
copyright header of each source file, and grep the sources for "Copyright" if
you need to know details. C source files without Copyright notice are usually
licensed as LGPLv2.1+. Also see the list of files with specific licenses below
(not all files can have a standard license header).

All new contributions must be LGPLv2.1+ licensed. Using a more liberal license
compatible to LGPLv2.1+ is also ok.

If changes are done on GPL code, must come with the implicit agreement that the
project can relicense the changes to LGPLv2.1+ at a later point without asking
the contributor. This is a safeguard for making potential relicensing of
remaining GPL code to LGPLv2.1+ easier.

For information about authors and contributors, consult the git log, which
contains the complete SVN and CVS history as well.

"v2.1+" in this context means "version 2.1 or later".

Some libraries are GPLv2+ or GPLv3+ only. Building mpv with Samba support makes
it GPLv3+.

mpv can be built as LGPLv2.1+ with the --enable-lgpl configure option. To add
a LGPL mode to mpv, MPlayer code had to be relicensed from GPLv2+ to LGPLv2.1+
by asking the MPlayer authors for permission. Since permission could not be
obtained from everyone, LGPL mode disables the following features, some of
them quite central:
- no audio filtering, which breaks: --af, pitch correction, fine control over
  downmix/upmix/resampling behavior
- Linux X11 video output
- BSD audio output via OSS
- NVIDIA/Linux hardware decoding (vdpau, although nvdec usually works)
- Linux TV input
- minor features: jack, DVD, CDDA, SMB, CACA, legacy direct3d VO
Some of these will be fixed in the future. The intended use for LGPL mode is
with libmpv, and currently it's not recommended to build mpv CLI in LGPL mode
at all.

The following files are still GPL only (--enable-lgpl disables them):

    audio/filter/*                  will be replaced with new filter chain
    audio/filter/af_format.c        mostly LGPL (except af glue code)
    audio/filter/af_lavc3enc.c          as above
    audio/filter/af_lavfi.c             as above
    audio/filter/af_scaletempo.c        as above
    audio/filter/af_rubberband.c        as above
    audio/out/ao_jack.c             will stay GPL
    audio/out/ao_oss.c              will stay GPL
    audio/audio.*                   needed by af code only
    demux/demux_tv.c                will stay GPL
    stream/ai_*                     will stay GPL (TV code)
    stream/audio_in.*               will stay GPL (TV code)
    stream/dvb*                     must stay GPL
    stream/frequencies.*            must stay GPL
    stream/stream_cdda.c            unknown
    stream/stream_dvb.*             must stay GPL
    stream/stream_dvd.c             unknown
    stream/stream_dvd_common.*      unknown
    stream/stream_dvdnav.c          unknown
    stream/stream_smb.c             will stay GPLv3
    stream/stream_tv.c              will stay GPL
    stream/tv*                      will stay GPL
    video/out/opengl/hwdec_vaglx.c  GPL
    video/out/vo_caca.c             unknown
    video/out/vo_direct3d.c         unknown
    video/out/vo_vaapi.c            probably impossible (some company's code)
    video/out/vo_vdpau.c            probably impossible (nVidia's code)
    video/out/vo_x11.c              probably impossible
    video/out/vo_xv.c               probably impossible
    video/out/x11_common.*          probably impossible
    video/vdpau.c                   hard (GPL-only parts must be ifdefed)
    video/vdpau.h                   unknown
    video/vdpau_mixer.*             actual code must be rewritten
    DOCS/man/                       GPLv2+
    bootstrap.py                    unknown license, probably GPLv2+ or LGPLv2+
    etc/mplayer-input.conf          unknown license, probably GPLv2+
    mpv.desktop                     unknown license, probably GPLv2+
    etc/restore-old-bindings.conf   unknown license, probably GPLv2+

The following files contain some optional GPL code (--enable-lgpl disables it):

    options/parse_commandline.c     dvd:// expansion
    player/audio.c                  libaf glue code

None of the exceptions listed above affect the final binary if it's built as
LGPL. Linked libraries still can affect the final license (for example if
FFmpeg was built as GPL).