See the old issue entry from aug-2010
It seems that in the meantime there is at least one alternative to resolve this, using Pure Java MP3 Encoder.
This is a burning issue for HTML5 enabled applications, since Internet Explorer's tag only accepts mp3, see here
Problems are of two kinds here:
Basically as I understand it, for patent legal issues we cannot ship MARY TTS with mp3 encoding software. What I have no problem with, legally speaking, to add is a generic audio compression mechanism "hook", into which a user who believes they have the right license plugs in the compressor of their choice.
But this brings me to problem 1: a proper and generic solution takes time that I don't have.
So once again, this must wait until a volunteer can be found to implement it. Sorry.
Just a comment on the "pure java mp3 encoder": from what I can tell, jump3r depends on jma-api-1.0.1.jar to wrap LAME or something, and I can't find sources or license info on that. If anyone has more info, feel free to contribute!
I know this is an old issue, but probably still important to many people. We had some trouble to get wav sound working in Safari on iPad (speech file shipped via servlet and played in html5 audio tag). Finally we searched a solutin for converting to mp3.
Jave was the winner. It's a wrapper for ffmpeg (no seperate installation required) and works under windows and linux. I guess Mac doesn't work without modifications, but our servers are anyway running on windows/linux.