1# License 2 3Most files in FFmpeg are under the GNU Lesser General Public License version 2.1 4or later (LGPL v2.1+). Read the file `COPYING.LGPLv2.1` for details. Some other 5files have MIT/X11/BSD-style licenses. In combination the LGPL v2.1+ applies to 6FFmpeg. 7 8Some optional parts of FFmpeg are licensed under the GNU General Public License 9version 2 or later (GPL v2+). See the file `COPYING.GPLv2` for details. None of 10these parts are used by default, you have to explicitly pass `--enable-gpl` to 11configure to activate them. In this case, FFmpeg's license changes to GPL v2+. 12 13Specifically, the GPL parts of FFmpeg are: 14 15- libpostproc 16- optional x86 optimization in the files 17 - `libavcodec/x86/flac_dsp_gpl.asm` 18 - `libavcodec/x86/idct_mmx.c` 19 - `libavfilter/x86/vf_removegrain.asm` 20- the following building and testing tools 21 - `compat/solaris/make_sunver.pl` 22 - `doc/t2h.pm` 23 - `doc/texi2pod.pl` 24 - `libswresample/swresample-test.c` 25 - `tests/checkasm/*` 26 - `tests/tiny_ssim.c` 27- the following filters in libavfilter: 28 - `vf_blackframe.c` 29 - `vf_boxblur.c` 30 - `vf_colormatrix.c` 31 - `vf_cover_rect.c` 32 - `vf_cropdetect.c` 33 - `vf_delogo.c` 34 - `vf_eq.c` 35 - `vf_find_rect.c` 36 - `vf_fspp.c` 37 - `vf_geq.c` 38 - `vf_histeq.c` 39 - `vf_hqdn3d.c` 40 - `vf_interlace.c` 41 - `vf_kerndeint.c` 42 - `vf_mcdeint.c` 43 - `vf_mpdecimate.c` 44 - `vf_owdenoise.c` 45 - `vf_perspective.c` 46 - `vf_phase.c` 47 - `vf_pp.c` 48 - `vf_pp7.c` 49 - `vf_pullup.c` 50 - `vf_repeatfields.c` 51 - `vf_sab.c` 52 - `vf_smartblur.c` 53 - `vf_spp.c` 54 - `vf_stereo3d.c` 55 - `vf_super2xsai.c` 56 - `vf_tinterlace.c` 57 - `vf_uspp.c` 58 - `vsrc_mptestsrc.c` 59 60Should you, for whatever reason, prefer to use version 3 of the (L)GPL, then 61the configure parameter `--enable-version3` will activate this licensing option 62for you. Read the file `COPYING.LGPLv3` or, if you have enabled GPL parts, 63`COPYING.GPLv3` to learn the exact legal terms that apply in this case. 64 65There are a handful of files under other licensing terms, namely: 66 67* The files `libavcodec/jfdctfst.c`, `libavcodec/jfdctint_template.c` and 68 `libavcodec/jrevdct.c` are taken from libjpeg, see the top of the files for 69 licensing details. Specifically note that you must credit the IJG in the 70 documentation accompanying your program if you only distribute executables. 71 You must also indicate any changes including additions and deletions to 72 those three files in the documentation. 73* `tests/reference.pnm` is under the expat license. 74 75 76## External libraries 77 78FFmpeg can be combined with a number of external libraries, which sometimes 79affect the licensing of binaries resulting from the combination. 80 81### Compatible libraries 82 83The following libraries are under GPL: 84- frei0r 85- libcdio 86- librubberband 87- libvidstab 88- libx264 89- libx265 90- libxavs 91- libxvid 92 93When combining them with FFmpeg, FFmpeg needs to be licensed as GPL as well by 94passing `--enable-gpl` to configure. 95 96The OpenCORE and VisualOn libraries are under the Apache License 2.0. That 97license is incompatible with the LGPL v2.1 and the GPL v2, but not with 98version 3 of those licenses. So to combine these libraries with FFmpeg, the 99license version needs to be upgraded by passing `--enable-version3` to configure. 100 101### Incompatible libraries 102 103There are certain libraries you can combine with FFmpeg whose licenses are not 104compatible with the GPL and/or the LGPL. If you wish to enable these 105libraries, even in circumstances that their license may be incompatible, pass 106`--enable-nonfree` to configure. But note that if you enable any of these 107libraries the resulting binary will be under a complex license mix that is 108more restrictive than the LGPL and that may result in additional obligations. 109It is possible that these restrictions cause the resulting binary to be 110unredistributable. 111 112The Fraunhofer FDK AAC and OpenSSL libraries are under licenses which are 113incompatible with the GPLv2 and v3. To the best of our knowledge, they are 114compatible with the LGPL. 115 116The NVENC library, while its header file is licensed under the compatible MIT 117license, requires a proprietary binary blob at run time, and is deemed to be 118incompatible with the GPL. We are not certain if it is compatible with the 119LGPL, but we require `--enable-nonfree` even with LGPL configurations in case 120it is not. 121