Ogg Vorbis is a fully Open, non-proprietary, patent-and-royalty-free, general-purpose compressed audio format for high quality (44.1-48.0kHz, 16+ bit, polyphonic) audio and music at fixed and variable bitrates from 16 to 128 kbps/channel. This places Vorbis in the same class as audio representations including MP3, MPEG-4 audio (AAC and TwinVQ), and PAC.
The encoders, decoders, plugins, and tools at www.vorbis.com are under the GPL (GNU Public License) and the libraries are under the business-friendly LGPL (Lesser/Library GNU Public License).
The encoder will create Ogg Vorbis files (.ogg) out of wave format audio (.wav) or MP3 (.mp3) audio files. The encoders are command line tools and aren't yet fully featured.
To encode .wav files:
ogglame input.wav output.ogg
To transcode .mp3 files:
ogglame input.mp3 output.ogg