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The MP3 audio coding format
3
===========================
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Much has already been said about MP3 and the huge patent portfolio of
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the MPEG members, especially the Fraunhofer institute. Eric Scheirer's
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MPEG, Patents, and Audio Coding FAQ [1.1] is an attempt to "inject
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some sanity in what is becoming an increasingly heated discussion
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about patent rights surrounding MPEG technology, especially for audio
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compression". It also has a few words about other patented products
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covered in this document.
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[1.1] http://web.media.mit.edu/~eds/mpeg-patents-faq
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The AAC audio coding format
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===========================
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Dolby's AAC (Advanced Audio Coding) is covered by patents owned by
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Dolby Laboratories, AT&T Laboratories, Fraunhofer Institute and Sony
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The FAAC project was threatened by the AAC license consortium. Press
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report about how "an opensource project was closed down due to pressures
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from the AAC license consortium which requires a lumpsum payment of
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10,000 USD plus a per-copy payment of 1.35 USD, thus effectively banning
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free software implementations. The policies surrounding AAC also harm
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interoperability [2.2]." This was related by Heise [2.3] and FFII has
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a page about the Dolby threat [2.1] as well as additional information
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about MPEG-related patents [2.4].
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The author stopped distributing the FAAC binaries, but still provides
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full source code and CVS access. To my knowledge he has not been
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threatened again. I also read on a web forum [2.5] that Cisco's lawyers
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claim that their LGPL distribution of AAC software in MPEG4IP is
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completely legal and that Dolby cannot forbid such distribution.
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[2.1] http://swpat.ffii.org/patents/effects/dolby/index.en.html
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[2.2] http://www.xiph.org/archives/vorbis-dev/200011/0286.html
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[2.3] http://www.heise.de/newsticker/data/vza-20.11.00-000/
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[2.4] http://swpat.ffii.org/patents/effects/mpeg/index.en.html
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[2.5] http://www.hydrogenaudio.org/index.php?showtopic=310&
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The ASF file encapsulation format
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=================================
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Microsoft obtained a patent on the ASF (Active Stream Format) audio
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file format on March 21, 2000:
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| United States Patent 6,041,345 Levi , et al. March 21, 2000
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| Active stream format for holding multiple media streams
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| Abstract An active stream format is defined and adopted for a
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| logical structure that encapsulates multiple data streams. The data
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| streams may be of different media. The data of the data streams
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| is partitioned into packets that are suitable for transmission
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| over a transport medium. The packets may include error correcting
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| information. The packets may also include clock licenses for
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| dictating the advancement of a clock when the data streams are
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| rendered. The format of ASF facilitates flexibility and choice
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| of packet size and in specifying maximum bit rate at which data
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| may be rendered. Error concealment strategies may be employed in
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| the packetization of data to distribute portions of samples to
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| multiple packets. Property information may be replicated and stored
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| in separate packets to enhance its error tolerance. The format
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| facilitates dynamic definition of media types and the packetization
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| of data in such dynamically defined data types within the format.
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This patent is rumoured to have been enforced at least once, though
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only through what I'd call non-hostile intimidation. Avery Lee, the
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VirtualDub author, removed ASF support from his software after a phone
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call from a Microsoft employee that he relates in his 5/12/2000 news
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However I could not find evidence of an official threat: all I could
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find on the web seemed to be interpretations of the VirtualDub author's
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article, for instance on Advogato [3.2], CPT [3.3] or FFII [3.4]. Avery
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Lee states that the phone call was from a programmer, not from the
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legal department. There does not seem to be an official statement from
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[3.1] http://web.archive.org/web/20000817222620/http://www.geocities.com/virtualdub/virtualdub_news.html
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[3.2] http://www.advogato.com/article/101.html
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[3.3] http://www.cptech.org/ip/business/software/audio.html
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[3.4] http://swpat.ffii.org/patents/effects/asf/index.en.html
added
removed
debian/patents.txt
