I think it would be very difficult to 'build' a .vpm file from scratch using your own .wav files, but you could replace individual .wav files by de-compiling an existing non-TTS vpm file and replacing the individual files with your custom wav files then re-compile using [Only registered and activated users can see links. ]. I did experiment for another member who wanted to make a custom spanish voice, it should work but is very time consuming because of the need to get the phrases right with correct space before and after them. The basics are here: [Only registered and activated users can see links. ].
Bookmarks