Difference between revisions of "Vorbis"
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Revision as of 20:36, 21 October 2004
Ogg Vorbis (http://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 xiphophorus's ogg multimedia project.
Informal listening test suggest Vorbis to be comparable to mpeg-4 AAC at most bitrates and MPC at 128kbs. Transparency is generally reached at about 150-170kbps (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. Since then development has been lead by other coders such as Garf and Aoyumi, who have improved the quality particularly at high bitrates. Aoyumi's AoTuV series of encoders was incorporated into the August 2004 (??) release of 1.1, which bought about the first quality improvements across the board for 2 years.
- Open Source and claimed to be patent free
- Good all-round performance (>48kbs - a leading codec at 128kbs)
- Well written specs
- Several portable hardware players
- Suitable for internet-streaming (via Icecast)
- Fully gapless playback
- Limited official development
- More computationally intensive to encode and decode than MP3
- Quality at high bitrates could benefit from further tuning
Features of compression
- Advanced psymodel
- Coupled stereo modes (lossy and lossless)
- Huffman coding
- Vector quantization
- Modified discrete cosine transform (MDCT)
- Multiple block sizes for block switching
The following player support playback of Ogg Vorbis.