encoder library for Vorbis General Audio Compression Codec

 Ogg Vorbis is a fully open, non-proprietary, patent-and-royalty-free,
 general-purpose compressed audio format for audio and music at fixed
 and variable bitrates from 16 to 128 kbps/channel.
 .
 The Vorbisenc library provides a convenient API for setting up an encoding
 environment using libvorbis.