Ogg Vorbis

An open, patent-free lossy codec tuned by a subjective quality scale.

Pro Audio Converter can convert audio files to and from Ogg Vorbis (.ogg).

Vorbis is a codec, not a container: .ogg files store Vorbis-compressed audio inside an Ogg transport layer.

Ogg Vorbis is roughly comparable to other formats used to store and play digital music, such as MP3, AAC, and other digital audio formats. It is different from these other formats because it is completely free, open, and unpatented.

Ogg is the name of Xiph.org's container format for audio, video, and metadata. Vorbis is the name of a specific audio compression scheme designed to be contained in Ogg. Note that other formats are capable of being embedded in Ogg as well, such as FLAC.

Vorbis Quality, Not Bitrate

Vorbis' audio quality is not best measured in kilobits per second, but on a scale from -1 to 10 called quality. This change in terminology was brought about by a tuning of the variable-bitrate algorithm that produces better sound quality for a given average bitrate but does not adhere as strictly to that average as a target.

This scale is not tied to a quantifiable characteristic of the stream like bitrate, so it's a fairly subjective metric — but it provides a more stable basis of comparison to other codecs and is relatively future-proof. As Segher Boessenkool explained: "If you upgrade to a new vorbis encoder and keep the same quality setting, you will get smaller files which sound the same. If you keep the same nominal bitrate, you get about the same size files, which sound somewhat better." The former behavior is the aim of the quality metric, so encoding to a target bitrate is now officially deprecated for all uses except streaming over bandwidth-critical connections.

For now, quality 0 is roughly equivalent to 64 kbps average, 5 is roughly 160 kbps, and 10 gives about 400 kbps. Most people seeking very-near-CD-quality audio encode at quality 5 or, for lossless stereo coupling, quality 6. The default setting is quality 3, which at approximately 110 kbps gives a smaller filesize and significantly better fidelity than MP3 compression at 128 kbps.

As always, if you need truly CD-quality sound, neither Vorbis nor MP3 (nor any other lossy audio codec) can provide exact reproduction; instead, consider using a lossless audio compression scheme like FLAC.