严格排序
BSD < LGPL < GPL
如果一个项目中即有BSD的库，也有LGPL的库，那么这个项目整体的限制是LGPL的。
如果一个项目中既有LGPL的库，也有GPL的库，那么这个项目整体的限制是GPL的。
也就是说，整体是以最严格的License来定的。
说明
拿opencv来举例，opencv是BSD的。但是opencv有使用到ffmpeg,ffmpeg是LGPL的。ffmpeg库中有用到X264，X264是GPL的。如果在opencv中有用到X264的功能，那么这个opencv就是用GPL。
实例
opencv license
By downloading, copying, installing or using the software you agree to this license.If you do not agree to this license, do not download, install,copy or use the software.License AgreementFor Open Source Computer Vision Library(3-clause BSD License)Copyright (C) 2000-, Intel Corporation, all rights reserved.Copyright (C) -, Willow Garage Inc., all rights reserved.Copyright (C) -, NVIDIA Corporation, all rights reserved.Copyright (C) -, Advanced Micro Devices, Inc., all rights reserved.Copyright (C) -, OpenCV Foundation, all rights reserved.Copyright (C) -, Itseez Inc., all rights reserved.Third party copyrights are property of their respective owners.Redistribution and use in source and binary forms, with or without modification,are permitted provided that the following conditions are met:* Redistributions of source code must retain the above copyright notice,this list of conditions and the following disclaimer.* Redistributions in binary form must reproduce the above copyright notice,this list of conditions and the following disclaimer in the documentationand/or other materials provided with the distribution.* Neither the names of the copyright holders nor the names of the contributorsmay be used to endorse or promote products derived from this softwarewithout specific prior written permission.This software is provided by the copyright holders and contributors "as is" andany express or implied warranties, including, but not limited to, the impliedwarranties of merchantability and fitness for a particular purpose are disclaimed.In no event shall copyright holders or contributors be liable for any direct,indirect, incidental, special, exemplary, or consequential damages(including, but not limited to, procurement of substitute goods or services;loss of use, data, or profits; or business interruption) however causedand on any theory of liability, whether in contract, strict liability,or tort (including negligence or otherwise) arising in any way out ofthe use of this software, even if advised of the possibility of such damage.* On Linux and other Unix flavors OpenCV uses default or user-built ffmpeg/libav libraries.If user builds ffmpeg/libav from source and wants OpenCV to stay BSD library, not GPL/LGPL,he/she should use --enabled-shared configure flag and make sure that no GPL components areenabled (some notable examples are x264 (H264 encoder) and libac3 (Dolby AC3 audio codec)).See /legal.html for details.If you want to play very safe and do not want to use FFMPEG at all, regardless of whether it's installed onyour system or not, configure and build OpenCV using CMake with WITH_FFMPEG=OFF flag. OpenCV will then useAVFoundation (OSX), GStreamer (Linux) or other available backends supported by opencv_videoio module.There is also our self-contained motion jpeg codec, which you can use without any worries.It handles CV_FOURCC('M', 'J', 'P', 'G') streams within an AVI container (".avi").* On Windows OpenCV uses pre-built ffmpeg binaries, built with proper flags (without GPL components) andwrapped with simple, stable OpenCV-compatible API.The binaries are opencv_ffmpeg.dll (version for 32-bit Windows) andopencv_ffmpeg_64.dll (version for 64-bit Windows).See build_win32.txt for the build instructions, if you want to rebuild opencv_ffmpeg*.dll from scratch.The pre-built opencv_ffmpeg*.dll is:* LGPL library, not BSD libraries.* Loaded at runtime by opencv_videoio module.If it succeeds, ffmpeg can be used to decode/encode videos;otherwise, other API is used.FFMPEG build contains H264 encoder based on the OpenH264 library, that should be installed separatelly.OpenH264 Video Codec provided by Cisco Systems, Inc.See /cisco/openh264/releases for details and OpenH264 license.Downloaded binary file can be placed into global system path (System32 or SysWOW64) or near application binaries.You can also specify location of binary file via OPENH264_LIBRARY_PATH environment variable.If LGPL/GPL software can not be supplied with your OpenCV-based product, simply excludeopencv_ffmpeg*.dll from your distribution; OpenCV will stay fully functional except for the ability todecode/encode videos using FFMPEG (though, it may still be able to do that using other API,such as Video for Windows, Windows Media Foundation or our self-contained motion jpeg codec).See license.txt for the FFMPEG copyright notice and the licensing terms.
ffmpeg license
Most files in FFmpeg are under the GNU Lesser General Public License version 2.1or later (LGPL v2.1+). Read the file `COPYING.LGPLv2.1` for details. Some otherfiles have MIT/X11/BSD-style licenses. In combination the LGPL v2.1+ applies toFFmpeg.Some optional parts of FFmpeg are licensed under the GNU General Public Licenseversion 2 or later (GPL v2+). See the file `COPYING.GPLv2` for details. None ofthese parts are used by default, you have to explicitly pass `--enable-gpl` toconfigure to activate them. In this case, FFmpeg's license changes to GPL v2+.Specifically, the GPL parts of FFmpeg are:- libpostproc- optional x86 optimizations in the files- `libavcodec/x86/flac_dsp_gpl.asm`- `libavcodec/x86/idct_mmx.c`- `libavfilter/x86/vf_removegrain.asm`- libutvideo encoding/decoding wrappers in`libavcodec/libutvideo*.cpp`- the X11 grabber in `libavdevice/x11grab.c`- the swresample test app in`libswresample/swresample-test.c`- the `texi2pod.pl` tool- the following filters in libavfilter:- `f_ebur128.c`- `vf_blackframe.c`- `vf_boxblur.c`- `vf_colormatrix.c`- `vf_cover_rect.c`- `vf_cropdetect.c`- `vf_delogo.c`- `vf_eq.c`- `vf_find_rect.c`- `vf_fspp.c`- `vf_geq.c`- `vf_histeq.c`- `vf_hqdn3d.c`- `vf_interlace.c`- `vf_kerndeint.c`- `vf_mcdeint.c`- `vf_mpdecimate.c`- `vf_owdenoise.c`- `vf_perspective.c`- `vf_phase.c`- `vf_pp.c`- `vf_pp7.c`- `vf_pullup.c`- `vf_sab.c`- `vf_smartblur.c`- `vf_repeatfields.c`- `vf_spp.c`- `vf_repeatfields.c`- `vf_spp.c`- `vf_stereo3d.c`- `vf_super2xsai.c`- `vf_tinterlace.c`- `vf_uspp.c`- `vsrc_mptestsrc.c`Should you, for whatever reason, prefer to use version 3 of the (L)GPL, thenthe configure parameter `--enable-version3` will activate this licensing optionfor you. Read the file `COPYING.LGPLv3` or, if you have enabled GPL parts,`COPYING.GPLv3` to learn the exact legal terms that apply in this case.There are a handful of files under other licensing terms, namely:* The files `libavcodec/jfdctfst.c`, `libavcodec/jfdctint_template.c` and`libavcodec/jrevdct.c` are taken from libjpeg, see the top of the files forlicensing details. Specifically note that you must credit the IJG in thedocumentation accompanying your program if you only distribute executables.You must also indicate any changes including additions and deletions tothose three files in the documentation.* `tests/reference.pnm` is under the expat license.external libraries==================FFmpeg can be combined with a number of external libraries, which sometimesaffect the licensing of binaries resulting from the patible libraries--------------------The following libraries are under GPL:- frei0r- libcdio- librubberband- libutvideo- libvidstab- libx264- libx265- libxavs- libxvidWhen combining them with FFmpeg, FFmpeg needs to be licensed as GPL as well bypassing `--enable-gpl` to configure.The OpenCORE and VisualOn libraries are under the Apache License 2.0. Thatlicense is incompatible with the LGPL v2.1 and the GPL v2, but not withversion 3 of those licenses. So to combine these libraries with FFmpeg, thelicense version needs to be upgraded by passing `--enable-version3` to configure./** Copyright (c) Fabrice Bellard** This file is part of FFmpeg.** FFmpeg is free software; you can redistribute it and/or* modify it under the terms of the GNU Lesser General Public* License as published by the Free Software Foundation; either* version 2.1 of the License, or (at your option) any later version.** FFmpeg is distributed in the hope that it will be useful,* but WITHOUT ANY WARRANTY; without even the implied warranty of* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU* Lesser General Public License for more details.** You should have received a copy of the GNU Lesser General Public* License along with FFmpeg; if not, write to the Free Software* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA*//*** @file* simple media player based on the FFmpeg libraries*/
X264 license
/****************************************************************************** me.h: motion estimation****************************************************************************** Copyright (C) - x264 project** Authors: Loren Merritt <lorenm@u.washington.edu>*Laurent Aimar <fenrir@via.ecp.fr>** This program is free software; you can redistribute it and/or modify* it under the terms of the GNU General Public License as published by* the Free Software Foundation; either version 2 of the License, or* (at your option) any later version.** This program is distributed in the hope that it will be useful,* but WITHOUT ANY WARRANTY; without even the implied warranty of* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the* GNU General Public License for more details.** You should have received a copy of the GNU General Public License* along with this program; if not, write to the Free Software* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111, USA.** This program is also available under a commercial proprietary license.* For more information, contact us at licensing@.*****************************************************************************/
