Speex is an audio codec that is part of the OGG container format. Speex is optimized for voice recording and transmission. It makes for very small file sizes for voice recording. If you have a video, or audio for the olpc that just consists of speaking, you should strongly consider encoding it in Speex.
Audiobooks should be encoded (or transcoded into) speex for size reasons, and mpeg issues.
GStreamer plays speex and works in the current build.
Several people are working on encoding Audiobooks in speex from existing formats.
 Making Speex files
There are a few tools and programs that can output to speex. We would like our speex audio to be 16000 Hz mono quality five. This reduces file sizes from raw .wav files manyfold. If you would like to encode this via command line use the following commands:
- speexenc -w --quality 5 --vbr --comp 10 FileA.wav FileA.spx
First you should make sure that your audio is 16 kHz mono before you take it to speex
- sox FileA.wav -r 16000 -c 1 FileB.wav
 Playing Speex files back
Speex files will play back when launched from the Journal through Etoys. They should play back through "Watch & Listen" too, but don't seem to for some reason...