Discworld and Member Articles
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Written by terrypratchettbooks.org
Tuesday, 02 August 2005 |
BY LOKE KAR SENG
XIPH, Ogg Vorbis, Speex, Theora sounds like some foreign language. But actually they are projects under the Xiph.Org Foundation.
Xiph comes from Xiphophorus helleri, which is a small aquarium fish (the common swordtail). The name was chosen for no particular reason, perhaps other than it satisfies the requirement of having at least one letter 'X' required for a technology-related organisation. The fact that it's almost impossible to pronounce is an added bonus.
But seriously, Xiph.Org is all about providing the foundation for all Internet audio and video standards to be open-source. It is also a response to the Fraunhofer IIS MP3 licensing scheme.
The genesis
MPEG Audio Layer 3, or more commonly known as MP3, is reportedly the second most popular keyword search. But few know that it was invented in Germany by one of the country's most prestigious semi-public research institute, the Fraunhofer Institute. Karlheinz Brandenburg is credited as the inventor of the MP3 format.
The goal of MP3 is to have high-level audio compression while still sounding like a faithful reproduction of the original uncompressed audio to most listeners.
It works by discarding “lossy” sounds, which are not perceptible by the human ear. For example, it is often difficult to hear one sound when a much louder sound is present, i.e. a loud car stereo could mask the car engine noise.
Sometimes a signal can be masked by a sound preceding it, called forward masking, or even by a sound following it, called backward masking.
The objective of the lossy compression is to discard those masked sounds and reduce the file size. MP3 provides a compression ratio of approximately 11:1, with a bit rate of 128Kbps (kilobits per seconds). Many listeners accept this bit rate as near enough to compact disc quality.
It has become so popular that it is now the de facto format for sharing music over the Internet.
In 1998, Fraunhofer IIS sent a notice letter of infringement to several small commercial and open-source MPEG Audio Layer 3 development projects.
Currently the royalty rate for a software MP3 decoder is 75 cents (RM2.85) per unit or US$50,000 to US$60,000 (RM190,000 to 228,000) as a one-time fee.
For games, it is US$2,500 (RM9,500) per title while the rate for electronic music distribution, broadcasting and streaming is 2% of related revenue.
For many, especially free and open-source projects, this is a hefty sum. Many also see it as an attempt to control technology standards and infrastructure, as well as to squeeze the consumer by limiting choices.
Soon after this, Xiph.Org founder Christopher “Monty” Montgomery began work on “correcting the imbalance” by making it impossible for big players to dominate audio-compression standards entirely.
As Xiph.Org puts it: “Our goal is to protect the essential tenets of Internet multimedia from corporate hostage-taking. Free software and open-source are the Net's greatest tools to keep everyone honest.”
Ogg, Vorbis and Theora
Xiph.Org is currently developing four audio-related compression projects, plus one container specification, Ogg.
The Ogg is a patent-free, fully-open multimedia bitstream container format designed for efficient streaming and file compression storage that can be used for audio and video.
The name Ogg was derived from the name of the kamikaze strategy used in the real-time multiplayer arcade/strategy game Netrek.
Ogg was later generalised to mean doing something forcefully, possibly without consideration on the drain of future resources. (At the time the Ogg project was conceived, it was probably thought to be very ambitious, given the PC hardware capabilities then.)
Ogg Vorbis is claimed to be a patent-clear, fully-open general purpose audio encoding format standard that rivals or surpasses the “upcoming” generation of proprietary coders (AAC and TwinVQ, also known as VQF).
Questions pertaining to the legal patent-clear claims can only settled in a court of law, but increasing support for Ogg Vorbis from hardware manufacturers such as Samsung, Rio and iRiver is encouraging its development.
RealNetworks has also awarded the Xiph.Org foundation one of its Helix Grants to support continued development of Ogg.
Vorbis is named after High Priest Vorbis, a character in Terry Pratchett's Discworld: Small Gods novel.
Theora is the video codec part of Xiph.Org. The codec was derived from On2 Technologies' VP3 code. Although the code is patented, On2 has given a royalty-free, irrevocable licence of the VP3 patents to everyone.
In the Ogg multimedia container framework, Theora provides the video layer, while Vorbis acts as the audio layer, thus creating a completely open-source, patent-free multimedia format.
Theora is targeted to compete with MPEG4 (e.g. XviD and DivX), RealVideo, Windows Media Video, and similar lower-bitrate video compression schemes.
Theora is named after Theora Jones, a fictional character on the Max Headroom television programme.
FLAC and Speex
FLAC (Free Lossless Audio Codec) maintains a lossless audio compression codec, unlike lossy formats like Vorbis or MP3.
FLAC is suitable for preserving audio without sacrificing any audio quality because the compression does not discard any information (hence lossless).
The FLAC project joined Xiph.org in January 2003.
Speex is a patent-free audio compression format designed for Voice over Internet Protocol (VoIP) usage and file compression.
Speex features a variable bit rate compression, and is robust enough to handle lost packets in VoIP use.
Speex is also well suited to handle Internet audio streaming, data archival (like voice mail), and audio books.
Currently, Asterisk (an open-source software PBX with VoIP), LinPhone (open-source VoIP phone for Linux), and GnomeMeeting (open-source H.323 video-conferencing program on Linux) are some of the projects currently using Speex.
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