CELT LCA

Position:

This talk introduces CELT, a new open source audio codec from Xiph.Org designed for high-quality communication with very low delay. CELT bridges the gap between Speex and Vorbis by providing very high quality speech and music with less than 10 ms delay. This allows new applications, such as "CD-quality" video-conferencing, and even makes it possible for musicians to play together remotely over a cable or DSL connection. We will explain why latency is a very important issue for audio compression and how CELT solves the difficulty of having good quality with low delay. The CELT API will be presented, along with guidelines for writing low-delay audio applications.

The effort is led by the developer of Speex, with the help of both Vorbis and Theora developers. Although the codec is still in development, we will also show how CELT can already provide both higher quality at a given bitrate and lower delay than the current generation of proprietary low-delay audio codecs. A live demonstration of CELT will be included.

• We want very high quality VoIP/videoconference/...
• Speex doesn't reach a high enough quality level and Vorbis has too much latency.
• For once, open-source is ahead of the proprietary codecs.

Possible contents:

• Explaining why latency is an issue
• How CELT works
• API and writing for low latency
• Comparison, samples
• Low-delay demo (e.g. vs Skype or Ekiga)