This is a very simple SWIG based JNI interface to the C based espeak text-to-speech synthesizer. Note the emphasis on simple. I am not a java programmer and wrote this code for a very simple purpose - to provide an interface to esepak which I could use from within some Clojure code.

This interface library does not provide full espeak API integration. I’ve only added what I needed. However, it should provide a good starting point for anyone who may be interested in developing a more extensive API that will allow Java or Clojure to access the espeak synthesizer.

Espeak is a good quality, open source and fast text-to-speech software synthesizer which runs on many different platforms and supports a number of languages. It can be found at http://espeak.sf.net. Most distributions have a package for the synthesizer, which includes a command line utility for synthesizing text from files or the command line into speech.

I am using this library to write a simple speech server for emacspeak in Clojure, which uses espeak as the back-end synthesizer. There is already a TCL based espeak speech server for emacspeak. My version is really just an experiment which I’m using to both learn Clojure and to understand and hopefully document the architecture and API used by emacspeak. Once it has reached a stable stage, I will release clj-espeak in another git repository for anyone who may be interested in trying it out or developing it further. One possibility may be to use this as a basis for a speech server for emacspeak that will run on Windows platforms. While I personally have little interest in Windows, the existance of a Clojure/Java server may be useful as a starting point for anyone who wants to have a go.

I used SWIG to generate the necessary C and Java interface files as well as the shared native library. Using SWIG makes this process almost trivial and so far, quite adequate for my requirements. The necessary interface definitions are in the javaSpeak.i file.

To build the library and Main.class test program, you need the following software installed. I built on a Ubuntu 10.10 machine with the following packages installed

• gcc
• swig
• openJdk
• espeak

Run Make to build all the necessary files and libraries. If successful, you should have a libjavaSpeak.so shared library and a number of java class files, including Main.class, which is a very simple test program. The javaSpeak.c file can be used in conjunction with the javaspeak.i file to identify the various API calls available and their arguments. The Main.java file should give you the basic idea of how to use the library.

NOTE: The libjavaSpeak.so library must be located where Java can find it. I copied the library to

/usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libjavaSpeak.so

on my system. However, you should be able to achieve similar results using

java -Djava.library.path=. Main "Hello World"

If you have any feedback, suggestions or criticisms, please don’t hesitate to let me know. This is mainly a learning exercise for me, so I’m always keen to get feedback or suggestions.