i own a translation service and now im wanting to implement a TTS solution. Do you know any software that can be executed from php to generate mp3s on the fly for a specific text?
There is an excellent TTS engine for Linux called festival
'yum install festival' or 'apt-get install festival'
As far as using PHP there should be no real issue with it. A quick search brings up a rather promising class http://ardoino.com/31-php-pvox-festival-tts/
However festival will output to wav file. You will then need to convert it to mp3. Again another good tutorial is available at http://www.xenocafe.com/tutorials/php/festival_text_to_speech/index.php