mihir0 / sampler

A real-time sampler engine for playing audio files from your keyboard or raspberry pi.

Sampler

This Sampler was initially built to support lego-pi-ano and supports 16-bit .wav files.

• Max number of samples is bound by memory limitiations of the Python execution environment. Currently all testing is done with 36 16 bit samples, each sized at 2.18 MB.
• Debug mode records and visualizes which samples are played. Silent gaps are not recorded.
• KeyListener class which allows you to trigger samples from your computer keyboard.
• Fast, simultaneous playback of the samples. I am using Cython to offload the audio processing into a C-compiled routine which allows for continous playback of over 25 pressed keys without breaking a sweat.

Setting up and building the sampler

Since this module uses Cython to create a C-compiled build for efficient audio playback, you will need to have a C compiler on your system.

1. Run pip install requirements.txt
2. Build the cython module with python setup.py build_ext --inplace. You will need a C compiler for this step.

Using the sampler with your computer keyboard

1. Initialize the sampler in a python file by setting a playback sample rate. You will need to check what your current sound card is running. Most PCs run either 44100Hz or 48000Hz.

    from sampler import Sampler
    sampler = Sampler(sample_rate=48000, record_enabled=False)

2. Load the samples by feeding in a python dictionary of [key: note name, value: file name]. If you want to use the keyboard listener, the key names control which keyboard keys will trigger which file.

    sample_map = {"a":"01.wav", "s":"02.wav", "d": "03.wav", "f": "04.wav", "g": "05.wav", "h": "06.wav", "j": "07.wav", "k": "08.wav", "l": "09.wav", ":": "10.wav", "'":"11.wav", "w":"12.wav", "e":"13.wav", "r":"14.wav", "t":"15.wav", "y":"16.wav", "u":"17.wav", "i":"18.wav", "o":"19.wav", "p":"20.wav", "[": "21.wav", "]":"22.wav"}
    sampler.load(sample_map, "samples/legopiano1/")

3. Start the sampler.

    sampler.start()

4. Initialize and start the key listener. This uses the keyboard python module to detect keypresses.

    listener = KeyListener(sampler)
    listener.start_listening()

5. Once the key listener terminates, close the sampler. If you are running the sampler in debug mode, this is when the recorded audio will display.

    sampler.close()

Future Enhancements

My development is currently focused on supporting the lego-pi-ano project but this module can be used for many more purposes as well. Here are some of the enhancements I have in store:

1. Supporting different file formats and bit-depth
2. Adding a nice ADSR envelope that's fully customizable