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Chippy

Chippy is a module for creating simple "chiptune" style audio waveforms

Chippy is a pure Python 3 module for creating various types of basic waveforms, such as Sine, Triangle, Saw, Square/Pulse, etc. It also does simple FM synthesis. Under the hood are Python generators for each of these waveforms, which can give you an endless stream of signed integers representing the wave data. There are also methods that will return a specific length of PCM data, with or without a standard RIFF header. Use it directly in your application, or save the waveforms to disk.

Chippy is not, however, an audio player. It simply creates the waveforms.

API documentation is hosted at ReadTheDocs: https://chippy.readthedocs.io/

Inspired by Zach Denton's Wavebender: http://github.com/zacharydenton/wavebender

What's New

0.1.0 - First release! Everything should work fine, but bug reports or improvement suggestions are most welcome. There isn't any documentation yet, but the code should be pretty easy to understand.

1. Compatibility

Chippy is developed for Python 3. It will also work on Pypy3 and, being written in pure Python, should work on any compliant interpreter. Please let me know if you encounter any issues.

2. Installation

No installation is necessary. Chippy is a tiny library with no dependencies. Simply copy the chippy directory into the top level of your project folder, and import chippy.

If you prefer, Chippy is also available on PyPI for easy installation via pip.

3. Usage

Several types of waveforms are supported: sine, saw, triange, square, and FM. If you just want to make a byte string of raw PCM data, you can use the _pcm(length=1) methods. There is another set of methods for producing standard RIFF format wave data, ready to play: _riff(length=1). You can save this data to disk with the following methods: save_wave(pcm_data, filename) and save_raw_pcm(pcm_data, filename). Here is a quick example of usage below.

First, import chippy and create an instance of chippy.Synthesizer::

import chippy
synth = chippy.Synthesizer(framerate=44100)

Create a some waveforms, and then save them to disk. Whether you have raw pcm, or a RIFF wave, the synth.save_wave and synth.save_raw_pcm methods will add or remove the RIFF wave header as appropriate.::

sine_wave = synth.sine_pcm(length=2, frequency=220, amplitude=0.8)
saw_wave = synth.saw_riff(length=1, frequency=440)
synth.save_wave(sine_wave, "wavefile.wav")
synth.save_raw_pcm(saw_wave, "sawpcm.raw")

The Square and FM waveforms have a few more options. The FM waveform has carrier and modulator values instead of just frequency, as you would expect. You can also adjust the modulator amplitude. The Square/Pulse wave has a duty cycle parameter, which is set as a percentage of 0-100::

fm_pcm = synth.fm_riff(length=2, carrier=440, modulator=122, amplitude=0.9, mod_amplitude=1.0)
square_pcm = synth.pulse_riff(length=3, frequency=183, duty_cycle=25)

In addition to the methods above which return bytes of wave data, there are also generators available that will return infinite streams of wave representation data on a scale of -1.0 to 1.0. This can be useful if you want to generate wave data in your own application. Simply create an instance of the generator and pull from it::

sine_generator = synth.sine_generator(frequency=220, amplitude=0.3)
next(sine_generator)
...