Last year I learned about music21 and ever since I have been wondering how I can use it to learn more about the Moroccan musical repertoires that I study. Long story short, I ended up building a tool for creating interactive web-based contour visualizations from the command line and I'd like to share it here.
Climbing out of a rabbit hole
I was working through a project and struggling to keep track of things. The paper was an analysis of a genre of Moroccan sung poetry called malhun for the 2016 Analytical Approaches to World Music conference. The performance of each poem can last twenty-ish minutes and contains a number of repetitions of the refrain text. These refrains are short (roughly eight 2/4 measures long) and modulate through repetitive--but different--melodies. I had transcribed over sixty of them in an attempt to understand how they worked, how they changed, and how they were related to each other.
|Malhun Performance in Fez, Morocco|
Over the previous months, I had been teaching myself Python in an effort to learn more about music21 and what it could do. It was time to try and build the tool that I needed instead of wishing I could find it.
For the presentation, I put together a small library that carried out two main tasks. First, it used music21 to parse my transcriptions, normalize the length of each melody, and build a dataset. Using offsets, frequencies, and distances from the final note of each melody, it turned note objects into a JSON of coordinates. At 1,000 different y values (each corresponding with 1/1,000th of the length of the total melody), it measured an x value for the frequency and one for the "distance from the root," the distance in steps above or below the melody's final pitch.
|Malhun Contour Example|
Building a tool
Maybe two weeks ago I decided to try my hand at creating a Python library of my own. I simplified the chart, creating a sort of template, remove the stepwise element of the visualization, and fought my way through learning to upload a project to PyPI. The result is ContourViz... I didn't give much thought to the name, my apologies.
|ContourViz, simple example|
You can install ContourViz using the following in your terminal:
pip install contourviz
It runs from the command line, so creating a visualization of multiple melodies, like the one above, is as easy as:
Working with a directory is similar:
|ContourViz, more complex example|
I'm still toying with the system and it has a number of issues. For example, I would love for it to parse voices as individual melodies if they are present. Instead, it only works with monophonic lines, meaning that each voice has to be in an individual file if you wanted to visualize voice leaning or other contrapuntal patterns. There are smaller issues: I still need to set up the Y axis to render note names properly.
Please feel free to check out the GitHub repo and suggest any other changes or ways in which it could be more helpful. This is my first go around at building a tool of this sort, so I am eager to hear if it is helpful and how it could be improved. And thank you for allowing me to join the community.