This page is dedicated to collect information on audio codecs (=encoding and decoding algorithms).
If you know of related sources of information, let me know.
Hydrogen Audio is a forum based community about 'cross-platform cross-format psychoacoustic audio compression' and focuses around the discussion and testing of current and future audio codecs.
Among its members there are multiple developers of many Open- and closedsource audio codecs, who participate in the discussions and listening tests and share/exchange ideas there. Most of the time the discussions are on a pretty high level.
While most members of the community are runnung Windows-family OSes, there is a fair amount of GNU/Linux users there and most of the discussed tools are available (source and/or binary) for Linux.
MPEG-4 Structured Audio: MP4-SA is a standard for normative algorithmic sound, that combines an audio signal processing language (SAOL) with score languages (SASL, and the legacy MIDI File Format). The website includes an online book about MP4-SA and a multimedia presentation.
See also this article from the archive.
Ogg Vorbis is a new compression method for audio data that is licensed under the GPL/LGPL. Unlike mp3, it is free from patent problems. The XMMS player already has an output plugin for this format. A developer's site is at http://www.xiph.org/ogg/vorbis/index.html.
LAME is a free re-implementation of the ISO standard mp3 encoder. The site has many links to related projects, and there is a mailing list.
Here is a small snippet from Richard W.E. Furse about AmbiSonics, a surround-sound codec.