Praat-Py: Extended Praat for Python Scripting

By Joshua Tauberer http://razor.occams.info

Originally developed in 2009. Only vaguely being currently maintained.

Introduction

Praat-Py is a custom build of Praat, the computer program used by linguists for doing phonetic analysis on sound files, to allow for scripts to be written in the Python programming language, rather than in Praat's built-in language.

The motivation for this is to remove the need for Praat script writers to learn an entirely new programming language if they already know Python. Additionally, Python is a more complete programming language and so scripts of any complexity should be more easily written in Python. The goal isn't to make all scripts easier or shorter to write, but to make it possible to do some complex tasks more easily.

All of the functionality of Praat's scripting language is retained when using Python, except forms. Likewise, because the Python interpreter is used, all Python functionality is possible, such as using all Python modules that you happen to have installed.

Praat-Py is a replacement for the Praat executable file you download from the Praat website. Because this project is no longer well maintained, there is no ready-to-go replacement file available. Praat-Py must be compiled from source files. Instructions for compiling Praat-Py are given later.

This project is released under the same terms as Praat itself, the GPL v2 or later.

Example

The following is an example script for Praat written in Python, and after is the corresponding script in Praat's script language. The script converts all .aif files in a directory into .wav format, resamping them in the process. The Praat script on the right is based on the script [here](http://www.helsinki.fi/~lennes/praat- scripts/public/convert_aiff_files_to_16kHz_wav.praat) by Mietta Lennes.

Praat script using Praat-Py:

#lang=python
from glob import glob

aiffdir = "/home/tauberer/"
delete_AIFF_files_after_conversion = False

for file in glob(aiffdir + "*.aiff") :
   print "Converting file", file, "..."
	
   aiff = go("Read from file...", file)
   resampled = go("Resample...", 16000, 50)
   soundtype, soundname = aiff
	
   go("Write to WAV file...", aiffdir + soundname + ".wav")
   if delete_AIFF_files_after_conversion :
      go("filedelete", file)
		
   remove(aiff)
   remove(resampled)

The original Praat script, which can be run either in Praat or in Praat-Py.

Create Strings as file list... aifffiles 'aiffdir$'*.aif
numberOfFiles = Get number of strings

for file to numberOfFiles
   select Strings aifffiles
   file$ = Get string... file
   Read from file... 'aiffdir$''file$'
   soundname$ = selected$ ("Sound", 1)
   Rename... temp
   printline Converting file 'file$'...
   Resample... 16000 50
   Rename... 'soundname$'
   select Sound temp
   Remove
   select Sound 'soundname$'
   Write to WAV file... 'aiffdir$''soundname$'.wav
   if delete_AIFF_files_after_conversion = 1
      filedelete 'aiffdir$''file$'
   endif
   Remove
endfor

Using Python in Praat-Py

Starting a Praat-Py Script

Once you have Praat-Py, you can write scripts in either Praat's built-in scripting language or in Python. You should be roughly familiar with Praat scripting before reading on (see this page), as well as Python. To script with Python, all you have to do is begin your script code with this:

#lang=python

That is, the very first line of your script must be a hash (#) followed immediately by "lang=python" in lowercase letters. This instructs Praat to interpret the remainder of your script as Python code. Without this special line, the script is run as a normal Praat script.

"Print" and "Go" Functions

There are several ways your Python script can make Praat do things. The first way is via the print Python command, which will output a string to the Praat Info window:

#lang=python
print 11500 * 20

The next way is to have Praat do one of its commands on a menu or the main window buttons. You do this with the go(_command_, _arguments..._) function.

#lang=python
go("To Spectrogram...", .005, maxfreq, .002, 20, "Gaussian")
go("View")

The first argument to the go function is the name of a command on a Praat menu to run. The remaning arguments are any options that that command takes, in the order that they show up in Praat. You'll notice that as compared to Praat Script, they way you put the arguments together is significantly more straight-forward. To use variables, for instance, you just use them (no strange quotes). In Praat Script, you never quote the final argument. Here, you quote all arguments uniformly: strings are quoted, and nothing else, as in Python normally.

go(...) returns the selected object after the command completes, or None if nothing is selected. This is particularly useful for commands that create new objects in the Praat list. See selected() below. Here's an example:

#lang=python
wav = go("Read from file...", "myfile.wav")
spec = go("To Spectrogram...", .005, maxfreq, .002, 20, "Gaussian")
select(wav)
part = go("Extract part...", 0.0, 1.0, True)
remove(wav)
remove(spec)
remove(part)

The third way is to have Praat do something but to capture the result of what it does. You can capture numeric results with getNum(_command_, _arguments..._):

#lang=python
print "The end time is: ", getNum("Get end time")*1000, " (ms)"

As in regular Praat scripts, this works by capturing the first number the command would normally print to Praat's Info window. As with go, you can provide any number of arguments to getNum. getNum returns a Python float value.

There is also a function getString which works like getNum but it returns the entire output line sent to the Info window by the command as a Python string value.

#lang=python
print "The end time is: ", getString("Get end time")

Selection Functions

Some additional commands are provided to make it easier to work with Praat's selected objects. select(_object name1_, [_object name2_, ...]) selects one or more objects by their names. It's just a convenience; you can also use go("select", _objectname_). The argument(s) to select can be either Python strings that have the name of the object, or a tuple of the object type and name separately: select( (_type1_, _name1_) [, ...]) . Here are some examples:

#lang=python
select("Sound mysound") # selects just a sound
select("Sound mysound", "TextGrid mysound") # selects these two together (and unselects everything else)
select( ("Sound", "mysound") ) # same as above, might be useful in some cases, note the double parens!
select( ("Sound", "mysound"), ("TextGrid", "mysound") ) # same as above

To add or remove objects from the selection, use plus and minus as in Praat scripting. They work just the same as select:

#lang=python
select("Sound mysound") # selects just a sound
plus("TextGrid mysound") # selects additionally the TextGrid
minus("Sound mysound", "TextGrid mysound") # deselects them
minus( ("Sound", "mysound"), ("TextGrid", "mysound") ) # deselects them using the tuple form

selected() is a function that returns the selected object. It returns a tuple containing the type and name of the object separately. If nothing is currently selected, None is returned.

#lang=python
select("Sound mysound")
(type, name) = selected() # returns ('Sound', 'MySound')

s = selected()
print s # prints "('Sound', 'MySound')"
print s[0] # prints the type of the object, "Sound"
print s[1] # prints the name of the object, "MySound"
minus(s) # deselects the currently selected object

Other Shortcuts

Because removing objects from the Praat objects list is such a common task in scripts that batch-process files, there is a shortcut for selecting and then removing objects using remove(object):

#lang=python
wav = go("Read from file...", "myfile.wav")
...
remove(wav)
   or
remove('Sound myfile')

Running the Script from the Command Line

As with Praat Scripts normally, you can run a script from the command-line directly (and never see Praat itself), besides running it from a script window. Say "myscript.praatpy" is a Praat-Py script, i.e. a Python program beginning with "#lang=python". You can then run it as:

praat-py myscript.praatpy

You can also pass command-line parameters to the script:

praat-py myscript.praatpy arg1 arg2

...and access them with argv similar to the usual Python sys.argv list. The first element in this list is the name of the script itself.

#lang=python
print argv     # this prints [u'myscript.praatpy', u'arg1', u'arg2']  (they're Unicode strings, assumed UTF-8 on command line)

Building Praat-Py from Sources

You can build Praat-Py on any Unix platform... at least in principle. I build it on Ubuntu. YMMV elsewhere. I've also been able to compile it with mingw32 (running on Linux) so that it can be run on Windows.

1. You will need to have Python 2.5 or 2.6 installed and the "python-dev" package (or equivalent) for your distribution, or an install from sources.

2. Get the Praat sources and follow the instructions to build Praat on your platform. (You don't really need to build Praat now, but it would be a really good idea to make sure it builds and runs before going forward.)

For instance, on Linux, with the latest version of Praat at the time of writing:

wget http://www.fon.hum.uva.nl/praat/praat5332_sources.tar.gz
tar -zxf praat5332_sources.tar.gz
cd sources_5332
ln -s makefiles/makefile.defs.linux ./makefile.defs
make
./praat

3. Clone this git repository into a directory called scripting inside the Praat sources directory:

   assuming you are still in the sources directory

   git clone git://github.com/tauberer/praat-py.git scripting

4. The Praat sources must be patched to build Praat-Py and to invoke the Python interpreter instead of the Praat script interpreter when the script begins with the magic string "#lang=python". Do this to patch your Praat source files:

   assuming you are still in the sources directory

   patch -p1 < scripting/praat-py.patch

5. Build Praat (now Praat-Py).

   make ./praat-py # it runs!

The praat-py executable in the current directory will now support Python scripts.