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 always 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. Currently Aoyumi is working on AoTuv Beta 4 and future releases.

Vorbis has had success with many recent video game titles employing Vorbis as opposed to MP3 (with Epic Games' Unreal Tournament 2003 and Unreal Tournament 2004, the PC port of Microsoft's Halo and Uru being notable examples).

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 and other methods)
• Fully gapless playback
• High potential for further tuning

Cons

• Limited official development (third-party developement is always encouraged)
• Current implementations are more computationally intensive to encode and decode than MP3 (Vorbis 2.0 seeks to overcome this limitations by slimlining the encoder)
• Multichannel mappings for 5.1, Ambisonic-G, and other config. have no channel coupling and aren't tuned (expect sub-optimal results until code is imrpoved).

Technologies used in compression

• Advanced psymodel (based upon ATH model)
• Advanced coupled stereo modes (point/phase stereo and lossless)
• Huffman coding
• Vector quantization
• Modified Discrete Cosine Transform (MDCT)
• Multiple block sizes for window switching
• Customly designed window function similiar to the Sine window (good sidelobe rejection).

Software

Encoders

• oggenc (Win32/Posix)
• oggdropXPd Advanced drag-and-drop encoder by John33 (Win32)
• foo_vorbisenc Vorbis encoder library for Foobar2000 (Win32)

Decoders

• ogg123 for Unix systems (GPL), a very simple to use command-line player. (Win32/Posix)
• OggDec for Windows, by John33, a very featureful command line decoder. (Win32)
• QuickTime Component (Allows playback in QuickTime/iTunes) (Win32)
• CoreVorbis (DirectShow) (Win32)
• illiminable Ogg Directshow Filters (Also plays Speex, Theora and FLAC) (Win32)

Supported Digital Audio Players

The following list contains some players that support Vorbis playback.

• iRiver H-Series
• MPIO 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 throughout the web.

• Ogg (Container)
• Ogg Vorbis official website (requires updating)
• Ogg Vorbis at Wikipedia.
• Ogg Vorbis at AudioCoding
• Ogg Vorbis binaries at Rarewares.
• Listening tests comparing Vorbis against MP3, AAC, WMA, etc.
• Recommended settings thread for encoding with Vorbis.
• Configuring EAC and Vorbis as an external command-line encoder
• Aoyumi homepage tuned versions of Vorbis 1.1 encoder and current beta binaries.
• Archer/Lancer homepage optimized versions of AoTuV Beta 3 Vorbis encoder and SSE optmizations.
• Xiph.org Foundation
• Xiph.org Vorbis bounties