The Text-to-speech (TTS) applications vary in their quality, complexity, and price. One thing most high-end TTS engines have in common, though, is a command line interface for generating audio from text. FreeSWITCH's
mod_tts_commandline module is designed to take advantage of this. While it is completely possible to create a separate module for each engine—and indeed this is the case for
mod_flite—it is convenient to utilize a more generic interface that is somewhat agnostic to the exact TTS engine being used.
In this recipe we will install
mod_tts_commandline and then download a free TTS engine that has a command line interface to use with it. We will also show command line examples of using some commercial TTS engines.