Speak Ada! Speak!

Text to speech was a valuable tool in a recent class. It made for great debugging information when no visual interaction was possible, and was a helpful feature in the final application. The text to speech system used there was easy to program dedicated hardware. I may be a hardware junkie, but I'm pretty sure I can get by with a software solution.

After a bit of searching around I found Festival. Festival is available as a package for Linux and seems to be pretty mature. I installed festival and read through a tutorial on it. Some reading needed to be done to understand the parameters in GNAT.OS_Lib. After a bit of examining the code it made sense.

First needed to make a script to translate the way Ada's spawning passes parameters into the way Festival takes input.
(festival_helper.sh)
#! /bin/sh echo $1 | festival --tts
Simple shell script that needs to be saved and be made executable. "./festival_helper.sh "your text goes here"" will call festival.

The Ada part was a bit kludgy with how the parameters were passed, but nothing too bad.
(festival_demo.adb)
with Ada.Text_IO; with GNAT.OS_Lib; procedure Festival_Demo is Success : Boolean; Message : aliased string := """Hello world, text to speech version."""; Arguments : GNAT.OS_Lib.Argument_List (1 .. 1) := (1 => Message'unchecked_access); begin Ada.Text_IO.Put_Line ("Hello world, text to speech version."); GNAT.OS_Lib.Spawn ("festival_helper.sh", Arguments, Success); if Success then Ada.Text_IO.Put_Line ("Success!"); else Ada.Text_IO.Put_Line ("Failure!"); end if; end Festival_Demo;

I'd like to think that is pretty straightforward...

I doubt this is the most efficient way. Some magic with bash scripts could easily be more efficient. Instead of re-spawning Festival with every call another possible approach might be to use Festival's --server and send over the network. I've dabbled with interfacing directly with the Festival C++ API, but my understanding of C++ compiler messages is limited. I had to do some shoehorning to get a gcc on this system, so that might be a problem as well.

It works, its simple, I'm happy.