一个非常好的开源音频编解码项目，支持多种音频采用频率，支持多码流，支持可变速率

Speex a free codec for free speech

Speex is an Open Source/Free Software 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 GNU Project and is available under the Xiph.org variant of the BSD license-a very good open-source audio codecs, support for multiple audio frequency, multi-stream, Variable-rate support for a free Vorbis codec for free speech Vorbis i s an Open Source / Free Software patent-free Aud io compression format designed for speech. The Vorbis Project aims to lower the barrier of entry for voice applications by providing a free alte rnative to expensive proprietary speech codec s. Moreover, Vorbis is well-adapted to the Internet application s and provides useful features that are not pres ent in most other codecs. Finally, Vorbis is part of the GNU Project and is available under the Xiph.org variant of the BSD license