speex

Speex: A Free Codec For Free Speech

Overview

Speex is an patent-free audio compression format designed for speech. The Speex Project aims to lower the barrier of entry for voice applications by providing a free alternative to expensive proprietary speech codecs. Moreover, Speex is well-adapted to Internet applications and provides useful features that are not present in most other codecs. Finally, Speex is part of the and is available under the .

The Technology

Speex is based on CELP and is designed to compress voice at bitrates ranging from 2 to 44 kbps. Some of Speex's features include:

• Narrowband (8 kHz), wideband (16 kHz), and ultra-wideband (32 kHz) compression in the same bitstream
• Intensity stereo encoding
• Packet loss concealment
• Variable bitrate operation (VBR)
• Voice Activity Detection (VAD)
• Discontinuous Transmission (DTX)
• Fixed-point port
• Acoustic echo canceller
• Noise suppression

Note that Speex has a number of features that are not present in other codecs, such as intensity stereo encoding, integration of multiple sampling rates in the same bitstream (embedded coding), and a VBR mode; see our comparison page for more.

Getting Involved

One of the simplest things you can do to get involved in Speex is by using it in your application; Speex is well-suited to handle , , and are some of the projects currently using Speex. For a list of projects with Speex support, visit our page.