Vorbis is a free and open-source software project headed by the Xiph.Org Foundation. The project produces an audio coding format and software reference encoder/decoder (codec) for lossy audio compression. Vorbis is most commonly used in conjunction with the Ogg container format and it is therefore often referred to as Ogg Vorbis. ~ en.wikipedia.org/wiki/Vorbis
Ogg Vorbis is a completely open, patent-free, professional audio encoding and streaming technology with all the benefits of Open Source.
VorbisGain is a utility that uses a psychoacoustic method to correct the volume of an Ogg Vorbis file to a predefined standardized loudness.