Move licensing information into a separate file called LICENSE and

rewrite it for greater clarity in the process.

Originally committed as revision 18185 to svn://svn.ffmpeg.org/ffmpeg/trunk

LICENSE

+Most files in FFmpeg are under the GNU Lesser General Public License version 2.1
+or later (LGPL v2.1+). Read the file COPYING.LGPL for details. Some other files
+have a MIT/X11/BSD-style license. In combination the LGPL v2.1+ applies to
+FFmpeg.
+
+Some optional parts of FFmpeg are licensed under the GNU General Public License
+version 2 or later (GPL v2+). See the file COPYING.GPL for details. None of
+these parts are used by default, you have to explicitly pass --enable-gpl to
+configure to activate them. In this case, FFmpeg's license changes to GPL v2+.
+
+Specifically, the GPL parts of FFmpeg are
+
+- libpostproc
+- some x86 and AltiVec optimizations in libswscale
+- optional x86 optimizations in the files
+  libavcodec/x86/h264_deblock_sse2.asm
+  libavcodec/x86/h264_idct_sse2.asm
+  libavcodec/x86/idct_mmx.c
+- the AC-3 decoder in libavcodec/ac3dec.c
+- the X11 grabber in libavdevice/x11grab.c
+
+Some external libraries, e.g. libx264, are under GPL and can be used in
+conjunction with FFmpeg. They require --enable-gpl to be passed to configure
+as well.
+
+The nonfree external libraries libamrnb and libamrwb can be hooked up in FFmpeg.
+You need to pass --enable-nonfree to configure to enable them. Employ this
+option with care as FFmpeg then beomes nonfree and unredistributable.
+
+There are a handful of files under other licensing terms, namely:
+
+* The files libavcodec/jfdctfst.c, libavcodec/jfdctint.c, libavcodec/jrevdct.c
+  are taken from libjpeg, see the top of the files for licensing details.
+
+* The file libavcodec/fdctref.c is copyrighted by the MPEG Software Simulation
+  Group with all rights reserved. It is only used to create a DCT test program
+  and not compiled into libavcodec.

README

@@ -9,35 +9,4 @@ FFmpeg README
 2) Licensing
 ------------
 
-* Read the file COPYING.LGPL. FFmpeg and the associated libraries EXCEPT
-  for libpostproc are licensed under the GNU Lesser General Public License
-  version 2.1 or later.
-
-* libpostproc is distributed under the GNU General Public License version 2
-  or later, see the file COPYING.GPL for details. Its compilation and use in
-  FFmpeg is optional.
-
-* libswscale contains some optional processor-specific optimizations that are
-  distributed under the GNU General Public License version 2 or later.
-
-* The files libavcodec/x86/idct_mmx.c, libavcodec/x86/h264_deblock_sse2.asm
-  and libavcodec/x86/h264_idct_sse2.asm are distributed under the GNU General
-  Public License version 2 or later. They are strictly optimizations and
-  their use is optional.
-
-* The file libavcodec/ac3dec.c is distributed under the GNU General Public
-  License version 2 or later. In order for (E-)AC-3 decoding to work you
-  need to enable GPL components.
-
-* The file libavdevice/x11grab.c is distributed under the GNU General
-  Public License version 2 or later. X11 grabbing is optional.
-
-* The files libavcodec/jfdctfst.c, libavcodec/jfdctint.c, libavcodec/jrevdct.c
-  are taken from libjpeg, see the top of the files for licensing details.
-
-* The file libavcodec/fdctref.c is copyrighted by the MPEG Software Simulation
-  Group with all rights reserved. It is only used to create a DCT test program
-  and not compiled into libavcodec.
-
-* Some external libraries are under GPL. If you wish to use them with FFmpeg,
-  you have to configure FFmpeg as GPL as well.
+* See the LICENSE file.