Festival offers a general framework for building speech synthesis systems as well as including examples of various modules. As a whole it offers full text to speech through a number APIs: from shell level, though a Scheme command interpreter, as a C++ library, from Java, and an Emacs interface. Festival is multi-lingual (currently English (British and American), and Spanish) though English is the most advanced. Other groups release new languages for the system. And full tools and documentation for build new voices are available through Carnegie Mellon's FestVox project.
The system is written in C++ and uses the Edinburgh Speech Tools Library for low level architecture and has a Scheme (SIOD) based command interpreter for control. Documentation is given in the FSF texinfo format which can generate, a printed manual, info files and HTML.
Festival is free software. Festival and the speech tools are distributed under an X11-type licence allowing unrestricted commercial and non-commercial use alike.
English (British and American), Spanish and Welsh text to speech
Externally configurable language independent modules:phonesets
part of speech tagging
intonation and duration
Waveform synthesizers:Multisyn unit selection engine
HTS parametric synthesis engine
Clustergen parametric synthesis engine
Clunits unit selection engine
diphone based: residual excited LPC (and PSOLA not for distribution)