AC3Filter
   DirectShow AC3 filter.
   http://ac3filter.sourceforge.net/

ATRAC: Adaptive Transform Acoustic Coding for MiniDisc
   ATRAC is an audio format based on psychoacoustic principles originally used for Sony MiniDisc players.
   http://www.minidisc.org/aes_atrac.html

Free Lossless Audio Coder
   FLAC is an open source lossless audio codec, supports streaming, seeking and archival.
   http://flac.sourceforge.net/

GSM 06.10 Lossy Speech Compression Format
   Details about the format and example source code.
   http://kbs.cs.tu-berlin.de/~jutta/toast.html

Lossless compression vs. speed
   Comparisons of most popular lossless audio formats.
   http://web.inter.nl.net/users/hvdh/lossless/main.htm

MPE Secure Media
   Secure streaming media format giving authors, songwriters and publishers complete control over products distributed through the internet.
   http://www.destinympe.com/

Musepack
   Open audio compression format also known as MPC or MPEGPlus/MP+. Based on MPEG1 Layer-2/MP2 algorithms.
   http://www.musepack.net/

OptimFROG
   Loseless audio compression supporting IEEE Float audio data.
   http://losslessaudiocompression.com/

Rob Nowiks Audio Resource
   Site contains discussion of audio formats, related audio algorithms and general audio production techniques.
   http://rnowik.com

Speex
   Open audio codec designed for speech, part of the Xiph.org Foundation.
   http://www.speex.org/

Study on Audio Compression
   Detailed comparison of various audio compression algorithms including ASF, RealAudio, MP3, Ogg Vorbis, MOV, and VQF.
   http://ekei.com/audio/

The Void: PC Audio Resource
   Information about computer audio formats and sound cards.
   http://www.voidaudio.net/

True Audio
   Open lossless audio codec developed with the main requirements of reasonable compression level and high operation speed.
   http://www.true-audio.com/

Vianix Corporation
   Developed MASC technology (Managed Audio Sound Compression) memory-efficient audio compression algorithm providing voice emulation.
   http://www.vianix.com/

WavPack
   Open audio codec facilitating both loseless compression and a unique hybrid compression mode.
   http://www.wavpack.com/