PraatJS

** in development **

Server + communication module for audio analysis in JS.

PraatJS is a JS module (PraatServer) + CherryPy server (main.py) for performing audio analysis from Javascript. At a basic level, the code allows you to call Praat scripts from Javascript.

• For testing, you'd host the server locally and use the module in your scripts.

Requirements + dependencies:

jQuery, Praat, HTK (optional). Server runs on Mac. Tested on Mac OS X 10.10.5.

Installation

There are three steps to getting PraatJS up and running:

1. Importing the praat.js script
2. Setting up the server and installing dependencies
3. Running the audio analysis server

Importing praat.js

Copy praat.js into your site directory and add to HTML:

<script src="praat.js"></script>

Make sure you have jQuery imported as well.

Server setup: installing dependencies

• Download the Praat app for Mac. Drop Praat.app into the python-server/praat directory.
• (Optional) Install HTK if you want to use the built-in 'align' function to perform forced alignment.
• • For HTK, you must also install SoX.
• • The Penn Forced Aligner (P2FA) included in this repo has been modified. In line 50 of align.py, 'polyphase' now reads 'rate'.

Running the server

In Terminal, cd into the python-server directory and type:

python main.py

That's it! CherryPy takes care of the rest.

• By default, the server runs locally on port 8080. If you want to change this, correct the HOST constants in main.py and praat.js.

Built-in Functions

PraatJS comes with some specific scripts:

• calcTimestamps: Given WAV file and transcript, performs forced alignment using HTK.
• calcAveragePitch: Given WAV file, returns average 'pitch' (f0) in Hz.
• transferProsody: Given a pair of speech files saying the same thing and their timestamp data, transfers the prosody (here only the pitch contour) of the source speech to the target speech.
• run: See below for details.

Running a generic script

For example, to run the script avg_pitch.praat in the python-server/praat/scripts:

Praat.run('avg_pitch', [wav_url, 10, 75, 500, 11025]).then(function(data) {
    doSomething(data);
});

where wav_url is the URL or blob url to a WAV file. The console output from Praat will be the result of the call. For this example, you'd get something like 135.42104541. This means that to read the results, you must modify your Praat script to output to console.

• However, there is an exception: If the Praat script outputs a filepath to a local file, the server will automatically load that file and send the file itself.
• This 'automatic conversion' also applies when passing URLs: any urls will be identified + their contents passed as data to the server.