indiWiz.com

Festival is an interesting OpenSource project for converting text-to-speech in Linux environment. It has a commandline tool text2wave which converts, guess what, text to voice in wave format. Simple usage:

$ echo "Hello World" | text2wave > a.wav

Wave files are uncompressed, and occupy lot of space. To encode to Ogg Vorbis format:

$ oggenc a.wav

This will create a.ogg in the current directory.