Switching Sphinx to Julius

Ah.. Its been long time since I updated this blog. I was really busy trying to use Julius.
Yes. right. I had to ditch Sphinx4 and move to Julius.

Following are the reasons that made me shift from Sphinx to Julius:

• First and Foremost, Poor Recognition. I really could not get even 80% accuracy from this ASR. Me and one of my American friend tested it many times. Still no success.
• Sphinx4 is based on Java. Hence its 'obviously' slow and hogs lot of memory.
• It doesn't recognize words properly. However Digits are pretty accurately recognized.
• No backward compatibility. Sphinx4 is re-written in Java. Whereas all previous versions are written in C/C++.

Reasons I will miss Sphinx:

• Good documentation
• Great helper demo examples
• Active Forums and help by their developers
• I kind of feel comfortable using Java. Hence using Eclipse for Sphinx4 really helped me in learning about Sphinx4 easy.

From next article onwards I will switch to Julius. I really couldn't get hang of Sphinx to make it work for my task. Sometime later, I shall work again on this and find out where I did wrong or has sphinx indeed become better recognizer :)

Getting Started with Sphinx4 and Eclipse

I started reading the Getting Started page of Sphinx4. After downloading both source code and binaries it was time to set our environment. I have always used and enjoyed working on Eclipse. So went for setting up Eclipse environment.

Pre-requisites: Eclipse (Callisto, Europa or Ganymede). JRE 1.4+
Follow these steps to setup your development environement for Eclipse IDE:

1. Extract Sphinx4 source and binaries in folder. I have /Speech/Sphinx/sphinx4-1.0beta2.
   
2. Create a Empty Java Project titled 'sphinx' or any name you wish to.
   
3. In the Package Explorer, right click on Project and select 'Build Path -> Link Source'
4. A Dialog Box will appear asking you to enter the source folder from your filesystem. navigate your path to /Speech/Sphinx/sphinx4-1.0beta2/src/sphinx4.
   
5. Eclipse parses entire folder structure recursively and also names your source folder.
   
6. Click Next and Finish. A new source folder is now linked with your project.
7. It will contain lot of errors as libraries are not been added yet.
   
8. Add /lib/js.jar, lib/tags.jar and lib/jsapi.jar to your project classpath by right-clicking project and selecting 'Build Path -> Configure Build Path -> Libraries'.
   
9. Eclipse then refreshes the workspace and all errors are nullified.

Sphinx4 also provides you with a handful of sample programs. I found every sample program very useful and it covered most of the details needed to learn Sphinx4.

To Setup the environment for using the samples and viewing the source code, you can follow these steps.

1. Create another new project and title it as 'sphinx-demos'
2. Right click and Link this Source folder: /Speech/Sphinx/sphinx4-1.0beta2/src/apps
3. Add the missing Libraries: /lib/js.jar, lib/tags.jar and lib/jsapi.jar and lib/sphinx4.jar to your project classpath
4. Every demo is a simple Java file. To test any demo, just right-click select Run -> Run as Java Application File.
   

There you go. You are now ready to learn Sphinx4 with proper development environment setup.

Sphinx Project gives you access to entire source code of Sphinx.
Sphinx-demo Project gives you access to all the demo apps for Sphinx.

Now where to start?

Initially I had no idea what to look into and where to look into to find a good speech recognition software. I kind of 'specialize' in Java. So narrowed down my search by searching any SR based on Java.

I came across Java Speech API. The Java Speech API was developed by Sun Microsystems, Inc. in collaboration with leading speech technology companies: Apple Computer, Inc., AT&T, Dragon Systems, Inc., IBM Corporation, Novell, Inc., Philips Speech Processing, and Texas Instruments Incorporated. Now the moment I saw this, I felt It's SUPER COOL. Sun has done some brilliant work in every field. BUT then after reading few more stuffs I realized that these are just APIs.

The Java Speech API defines a standard, easy-to-use, cross-platform software interface to state-of-the-art speech technology. JS API defines two technologies: Speech Synthesis and Speech Recognition.

Speech Synthesis is basically Text To Speech.
Speech Recognition is Speech to Text.


These APIs lead me to SPHINX, IBM's Via Voice, Microsoft Speech API, Julius, and others.
I couldn't get IBM Via Voice or MS Speech API for my use. Hence I started off with Sphinx.

Sphinx was the first-of-its-kind continuous speech recognizer. It has only recognition part of JS API. Sphinx was developed at Carnegie Mellon University by Kai-Fu Lee. Sphinx is currently in 4th version. Sphinx 4 is a complete re-write of the Sphinx engine with the goal of providing a more flexible framework for research in speech recognition. It is written entirely in the Java programming language leveraging the Java Speech API Standard.

Sphinx4 currently is one of the best speech recognizer used. It is also available for devices called 'pocket-sphinx'. If you need a Speech Recognizer then I suggest you to start with this.
Sphinx has very good Documentation and an active Forum too. I really enjoyed exploring it. In following article I will write more detailed scripts for using Sphinx.

One thing that struck me was that Sphinx was developed by an Non-American (Kai-Fu Lee). Kai-Fu Lee is said to be man behind Microsoft Speech *WRECKecognition* Initiative. This video shows all. :)

Why this Blog?

Speech Recognition (SR) is budding technology. Big market players like Microsoft, IBM, Philips, etc are eyeing a pie in this field. Still as per my study past few months on SR Software, I think this technology needs lot of improvements. I found a few Open Source SR tools which do fairly good task of recognition.

I don't have big bucks to pay for SR software from above mentioned vendors. So I do not have idea on how these work. Based on reviews from various sites I found they are kind of OKAY. Not great !!

This blog will basically talk on my experience and trouble I faced using Open Source SR tools (cos' only they were in my reach). I have done a study on Sphinx4 and Julius. Used HMM Toolkit (HTK) to develop acoustic models and did lot of weird stuffs playing with these tools.
There are lot of resources on net. But I came across few problems which were not anywhere or information was distorted. So I will try and compile as much info I can.

PS: If you have any questions or any good links related to SR, please post a comment here. Thanks

ciao,
/A