diff -ruN ffmpeg.orig/doc/patents.txt ffmpeg/doc/patents.txt --- ffmpeg.orig/doc/patents.txt 1970-01-01 03:00:00 +0300 +++ ffmpeg/doc/patents.txt 2005-04-08 00:47:38 +0400 @@ -0,0 +1,88 @@ + +The MP3 audio coding format +=========================== + + Much has already been said about MP3 and the huge patent portfolio of +the MPEG members, especially the Fraunhofer institute. Eric Scheirer's +MPEG, Patents, and Audio Coding FAQ [1.1] is an attempt to "inject +some sanity in what is becoming an increasingly heated discussion +about patent rights surrounding MPEG technology, especially for audio +compression". It also has a few words about other patented products +covered in this document. + +[1.1] http://web.media.mit.edu/~eds/mpeg-patents-faq + + +The AAC audio coding format +=========================== + + Dolby's AAC (Advanced Audio Coding) is covered by patents owned by +Dolby Laboratories, AT&T Laboratories, Fraunhofer Institute and Sony +Corp. + + The FAAC project was threatened by the AAC license consortium. Press +report about how "an opensource project was closed down due to pressures +from the AAC license consortium which requires a lumpsum payment of +10,000 USD plus a per-copy payment of 1.35 USD, thus effectively banning +free software implementations. The policies surrounding AAC also harm +interoperability [2.2]." This was related by Heise [2.3] and FFII has +a page about the Dolby threat [2.1] as well as additional information +about MPEG-related patents [2.4]. + + The author stopped distributing the FAAC binaries, but still provides +full source code and CVS access. To my knowledge he has not been +threatened again. I also read on a web forum [2.5] that Cisco's lawyers +claim that their LGPL distribution of AAC software in MPEG4IP is +completely legal and that Dolby cannot forbid such distribution. + +[2.1] http://swpat.ffii.org/patents/effects/dolby/index.en.html +[2.2] http://www.xiph.org/archives/vorbis-dev/200011/0286.html +[2.3] http://www.heise.de/newsticker/data/vza-20.11.00-000/ +[2.4] http://swpat.ffii.org/patents/effects/mpeg/index.en.html +[2.5] http://www.hydrogenaudio.org/index.php?showtopic=310& + + +The ASF file encapsulation format +================================= + + Microsoft obtained a patent on the ASF (Active Stream Format) audio +file format on March 21, 2000: + + | United States Patent 6,041,345 Levi , et al. March 21, 2000 + | + | Active stream format for holding multiple media streams + | + | Abstract An active stream format is defined and adopted for a + | logical structure that encapsulates multiple data streams. The data + | streams may be of different media. The data of the data streams + | is partitioned into packets that are suitable for transmission + | over a transport medium. The packets may include error correcting + | information. The packets may also include clock licenses for + | dictating the advancement of a clock when the data streams are + | rendered. The format of ASF facilitates flexibility and choice + | of packet size and in specifying maximum bit rate at which data + | may be rendered. Error concealment strategies may be employed in + | the packetization of data to distribute portions of samples to + | multiple packets. Property information may be replicated and stored + | in separate packets to enhance its error tolerance. The format + | facilitates dynamic definition of media types and the packetization + | of data in such dynamically defined data types within the format. + + This patent is rumoured to have been enforced at least once, though +only through what I'd call non-hostile intimidation. Avery Lee, the +VirtualDub author, removed ASF support from his software after a phone +call from a Microsoft employee that he relates in his 5/12/2000 news +[3.1]. + + However I could not find evidence of an official threat: all I could +find on the web seemed to be interpretations of the VirtualDub author's +article, for instance on Advogato [3.2], CPT [3.3] or FFII [3.4]. Avery +Lee states that the phone call was from a programmer, not from the +legal department. There does not seem to be an official statement from +Microsoft. + +[3.1] http://web.archive.org/web/20000817222620/http://www.geocities.com/virtualdub/virtualdub_news.html +[3.2] http://www.advogato.com/article/101.html +[3.3] http://www.cptech.org/ip/business/software/audio.html +[3.4] http://swpat.ffii.org/patents/effects/asf/index.en.html + diff -ruN ffmpeg.orig/doc/README.ALT ffmpeg/doc/README.ALT --- ffmpeg.orig/doc/README.ALT 1970-01-01 03:00:00 +0300 +++ ffmpeg/doc/README.ALT 2005-04-08 00:55:46 +0400 @@ -0,0 +1,42 @@ +Notes for the ALT Linux ffmpeg packages +======================================= +(Copied from Debian package notes) + + The license for the whole work is the GPL, not the LGPL, because GPL-only +parts of ffmpeg were activated. If you need LGPL versions of the libraries, +please contact me. + + +Linking code against ffmpeg +=========================== + + To compile code against the ffmpeg libraries, use `ffmpeg-config --cflags`: + + gcc `ffmpeg-config --cflags` -c code.c -o code.o + + To link it afterwards, use `ffmpeg-config --libs avcodec`: + + gcc code.o -o code `ffmpeg-config --libs avcodec` -lotherlibs + + Accepted arguments for --libs are "avcodec", "avformat" and "postproc". If +you are linking a plugin for an application with one of these libraries, use +the --plugin-libs flag instead of --libs. + + +Summary of the patent issues with ffmpeg +======================================== + + The only patents related to ffmpeg which seem to be enforced against open +source software cover the following codec technologies and file formats: + + * MP3 encoding + * AAC decoding and encoding + * the ASF file format + + I did not activate MP3 encoding (through LAME) in libavcodec, nor AAC +support (through FAAC/FAAD). However, since I have found no real enforcement +of the mysterious ASF file format patents, I did not deactivate ASF support in +libavformat. See more details in the patents.txt file. + + + -- Sam Hocevar Fri, 16 Jul 2004 12:47:27 +0200