mpv is a fork of mplayer2, which is a fork of MPlayer. mpv as a whole is licensed as GPL version 2 or later (see LICENSE). Most source files are GPLv2+, but some files are available under a more liberal license, such as LGPLv2.1+, 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 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 code 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: --volume, --af, replaygain, pitch correction, fine control about downmix/upmix/resampling behavior - Linux X11 video output - Linux audio output via ALSA (PulseAudio works) - BSD audio output via OSS - NVIDIA/Linux hardware decoding (vdpau, although CUDA usually works) - many builtin video filters (use libavfilter instead) - automatic rotation and stereoscopic video handling - Linux TV input - the --frames option - the add/cycle and sub-add/audio-add/sub-remove/audio-remove commands - video format conversion (if not supported by the VO) - minor features: jack, DVD, CDDA, SMB, CACA, legacy direct3d VO Some of these will be fixed in the future. The lack of the add/cycle commands makes this particularly useless for CLI mode, and most of the appeal of LGPL is for libmpv anyway. Thus 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_alsa.c chaotic history, one later author did not decide 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/filter/vf_crop.c will be deleted video/filter/vf_dsize.c will be deleted video/filter/vf_expand.c will be deleted video/filter/vf_flip.c will be deleted video/filter/vf_format.c will be deleted video/filter/vf_gradfun.c will be deleted video/filter/vf_mirror.c will be deleted video/filter/vf_noformat.c will be deleted video/filter/vf_pullup.c will be deleted video/filter/vf_rotate.c will be deleted video/filter/vf_scale.c will be deleted video/filter/vf_stereo3d.c will be deleted video/filter/vf_sub.c will be deleted video/filter/vf_yadif.c will be deleted 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 unkniwn license, probably GPLv2+ The following files contain some optional GPL code (--enable-lgpl disables it): input/cmd_list.c potentially some commands demux/demux_mkv.c some verbose message options/options.c --frames option options/parse_commandline.c dvd:// expansion player/audio.c libaf glue code player/loadfile.c --frames option (minor but probably fatal) player/osd.c OSD level 3 player/command.c add/cycle command, possibly sub-add command 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).