See INSTALL file for instruction on how to install Speex.

The Speex is a patent-free, Open Source/Free Software voice codec. Unlike other codecs like MP3 and Ogg Vorbis, Speex is designed to compress voice at bitrates in the 2-45 kbps range. Possible applications include VoIP, internet audio streaming, archiving of speech data (e.g. voice mail), and audio books. In some sense, it is meant to be complementary to the Ogg Vorbis codec.

To use the Speex command line tools:

% speexenc [options] input_file.wav compressed_file.spx

% speexdec [options] compressed_file.spx output_file.wav

Name: speex
URL: http://downloads.xiph.org/releases/speex/speex-1.2rc1.tar.gz
Version: 1.2.rc1
License: BSD
Security Critical: yes

Description:
This contains a copy of speex-1.2.rc1

This library is required for the browser to compress and encode recorded audio
before sending to Google servers for speech recognition. This is a straight dump
of speex-1.2rc1 with all the unused files removed with the following changes:

1. Added include/speex/speex_config_types.h generated by the configure script
   on Linux.