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. The mpv program is licensed 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 without using any GPL only files.
The -Dgpl=false configure switch is provided as a convenience for excluding
the GPL only files listed below from the build process.

However, do note that the build system is provided "as is" and using the
-Dgpl=false configure switch does not in itself create a LGPLv2.1+ license
grant.

Additionally, some non-program parts, such as the documentation and some config
files listed below, are still built and licensed under their respective licenses
even when -Dgpl=false is used. Please consult GPLv2+ and LGPLv2.1+ license texts
for further details on how to distribute these files.

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.

Changes done to GPL code must come with the implicit/explicit 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.

See DOCS/contribute.md for binding rules wrt. licensing for contributions.

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

mpv can be built as LGPLv2.1+ without using any GPL only files. 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:
- Linux X11 video output
- BSD audio output via OSS
- NVIDIA/Linux hardware decoding (vdpau, although nvdec usually works)
- minor features: jack, DVD, CDDA, DVB, 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 (-Dgpl=false disables them):

    audio/out/ao_jack.c             will stay GPL
    audio/out/ao_oss.c              will stay GPL
    stream/dvb*                     must stay GPL
    stream/stream_cdda.c            unknown
    stream/stream_dvb.*             must stay GPL
    stream/stream_dvdnav.c          unknown
    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+
    etc/mplayer-input.conf          unknown license, probably GPLv2+
    etc/mpv.desktop                 unknown license, probably GPLv2+
    etc/restore-old-bindings.conf   unknown license, probably GPLv2+

None of the cases 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).