CELT

CELT
Developed byXiph.Org Foundation
Type of formatAudio
Contained byOgg
Extended toOpus
StandardDocumentation
libcelt
Developer(s)Xiph.org Foundation, Jean-Marc Valin
Preview release
0.11.1 / February 15, 2011; 13 years ago (2011-02-15)
TypeAudio codec, reference implementation
License2-clause BSD
Websiteopus-codec.org

Constrained Energy Lapped Transform (CELT) is an open, royalty-free lossy audio compression format and a free software codec with especially low algorithmic delay for use in low-latency audio communication. The algorithms are openly documented and may be used free of software patent restrictions. Development of the format was maintained by the Xiph.Org Foundation (as part of the Ogg codec family) and later coordinated by the Opus working group of the Internet Engineering Task Force (IETF).

CELT was meant to bridge the gap between Vorbis and Speex for applications where both high quality audio and low delay are desired.[1] It is suitable for both speech and music. It borrows ideas from the CELP algorithm, but avoids some of its limitations by operating in the frequency domain exclusively.[1]

The original stand-alone CELT has been merged into Opus. Therefore, CELT as stand-alone format is now abandoned and obsolete. Development is going on only for its hybridised form as a layer of Opus, integrated with SILK. This article covers the historic, stand-alone format; for the integrated form and its evolution since the integration into Opus see the article on Opus.

  1. ^ a b Cite error: The named reference celt-web was invoked but never defined (see the help page).