Variable bit rate

The term variable bit rate (VBR) is a term in telecommunications Quality of Service. Compare with constant bit rate.

When referring to audio codecs, variable bit rate encoding varies the compression in each time segment (usually one second), based on the complexity of the sounds to be compressed. The goal being to get the best balance between sound quality and compression possible at any given moment.

Formats such as Ogg Vorbis are inherently VBR. MP3s can optionally be encoded in this way.