*.OGG

.OGG is a file format for compressed multimedia files, and a popular competitor to .MP3. Unlike .MP3, .OGG uses an open-source, open-standard format and a permissive license, both of which allow it to be incorporated into the FS2_Open source code. Also unlike .MP3, .OGG can contain video in addition to audio data.

Since .OGG, as a compressed format, delivers significantly smaller file sizes than .WAV, while retaining substantially the same level of audio quality, it is becoming more and more frequently used in FSO-targeted mods.

Audacity and Goldwave are two popular programs that allow .WAV files to be converted to .OGG.