Vorbis

Introduction

Ogg Vorbis (www.vorbis.com) is a fully open, non-proprietary, patent-free (subject to speculation), and royalty-free, general-purpose compressed audio format for mid to high quality (8khz-48.0kHz, 16+ bit, polyphonic) audio and music at fixed and variable bitrates from 16 to >256 kbps/channel. This places vorbis in the same competitive class as audio representations such as MPEG-4 (AAC), and similar to, but higher performance MP3, twinvq (VQF), WMA and PAC.

Vorbis is the first of a planned family of Ogg multimedia coding formats being developed as part of Xiph.org's ogg multimedia project.

Informal listening test suggests Vorbis to be comparable to MPEG-4 AAC at most bitrates and MPC at 128 kbps. Transparency is generally reached at about 150-170 kbps (-q 5) (with some exceptions). The encoder is reasonably young and unoptimized, so further improvements can be expected.

Unfortunately, Xiph.org has failed to improve Vorbis at a steady rate since its initial 1.0 release in July 2002 (due to other developement projects and time constraints). Since then development has been lead by other coders such as Garf and Aoyumi. Aoyumi's AoTuV series of encoders was incorporated into the September 2004 release of 1.1, which brought about the first quality improvements across the board for 2 years.

Pros

• Free (as in speech), Open Source and claimed to be patent free
• Good all-round performance (>48 kbps - a leading codec at 128 kbps)
• Well written specs
• Several portable hardware players
• Suitable for internet-streaming (via Icecast)
• Fully gapless playback

Cons

• Limited official development
• Current implementations are more computationally intensive to encode and decode than MP3 (Vorbis 2.0 seeks to overcome this limitations by slimlining the decoder)
• Quality at low bitrates could benefit from further tuning

Technologies used in compression

• Advanced psymodel (based upon ATH model)
• Coupled stereo modes (point/phase stereo and lossless)
• Huffman coding
• Vector quantization
• Modified discrete cosine transform (MDCT)
• Multiple block sizes for window switching

Software

Encoders

• oggenc

Decoders

• ogg123 for Unix systems (GPL), a very simple to use command-line player.
• QuickTime Component (Allows playback in QuickTime/iTunes)
• CoreVorbis (DirectShow)
• illiminable Ogg Directshow Filters (Also plays Speex, Theora and FLAC)

Hardware

The following list contains some players that support Vorbis playback.

• iRiver H-Series
• Rio Karma
• IAudio M3
• Neuros

External links

The following links contain information surrounding the Ogg Vorbis codec that can be found on Hydrogenaudio and elsewhere throughtout the web.

• Ogg (Container)
• Ogg Vorbis at Wikipedia.
• Ogg Vorbis at AudioCoding
• Ogg Vorbis binaries at Rarewares.
• Discussion of Vorbis' legal status
• Recommended settings thread for encoding with Vorbis.
• Aoyumi homepage tuned versions of Vorbis 1.1 encoder and current beta binaries.
• Archer homepage optimized versions of AoTuV Beta 3 Vorbis encoder and SSE optmizations.
• Xiph.org Foundation
• Xiph.org Vorbis bounties