jarmitage / resonators

Resonant filter bank synthesis on Bela based on [resonators~] Max/Pd object

Resonators

Resonant filter bank synthesis on Bela based on the [resonators~] Max/Pd object:

#include <Bela.h>
#include "Resonators.h"
#include "Model.h"

ResonatorBank resBank;
ResonatorBankOptions resBankOptions = {};
ModelLoader model;

bool setup(BelaContext *context, void *userData) {
  model.load("models/marimba.json");
  resBankOptions.total = model.getSize();
  resBank.setup(resBankOptions, context->audioSampleRate, context->audioFrames);
  resBank.setBank(model.get());
  resBank.update();
  return true;
}

void render(BelaContext *context, void *userData) { 
  for (unsigned int n = 0; n < context->audioFrames; ++n) {
    float in = audioRead(context, n, 0); // an excitation signal
    float out = resBank.render(in);

    audioWrite(context, n, 0, out);
    audioWrite(context, n, 1, out);
  }
}

The corresponding marimba.json:

{
  "metadata": { 
    "name":        "marimba",
    "fundamental": 800,
    "resonators":  8
  },
  "resonators": [
    { "freq": 800,  "gain": 0.500000, "decay": 0.2 },
    { "freq": 1600, "gain": 0.033333, "decay": 0.4 },
    { "freq": 2400, "gain": 0.016666, "decay": 0.6 },
    { "freq": 3200, "gain": 0.006666, "decay": 0.7 },
    { "freq": 4000, "gain": 0.003333, "decay": 0.8 },
    { "freq": 4800, "gain": 0.001666, "decay": 0.9 },
    { "freq": 5400, "gain": 0.000666, "decay": 1.0 },
    { "freq": 6200, "gain": 0.000333, "decay": 1.0 }
  ]
}

---

Bela examples

1. An individual resonator.
2. A bank of resonators based on a model file.
3. Loading updated models periodically into a bank of resonators via scp.
4. Multiple banks of resonators based on a model file, tranposed up a scale.
5. Combination of examples 3 & 4, plus Bela scope for inputs.

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Resonance models

Collection of ~100 resonance models of mostly percussion instruments, based on aLib resonance models

• Indian percussion instruments (Chakoa, Dhalki, Hand-Dhal, khol, Madal, Manjeera, Mirdangam, Stick-Dhal)
• A set of 12 Ghanaian double-bells, recorded with hard and soft beater
• Guitar strings plucked behind the bridge
• SampleCell Dumbeck, Gong

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p5.js GUI

WIP! Relies on Bela WebSocket server wrapper and integration with Resonator.h.

• BelaWS.js: connects to Bela over a Web Socket
• Resonators.js: real-time bidirectional updating of resonator model, using p5.js

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Jupyter & Python

Some convenience functions, not pretty yet...

• Importing Max/Pd formatted models (see references below)
• Working with models as Pandas dataframes
• Loading/saving/converting to/from .csv .coll & .json
• scp-ing models to Bela for real-time updates

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Max/Pd References

• Max version: https://github.com/CNMAT/CNMAT-Externs/releases/tag/v1.0.4 (resonators~.mxo)
• Pd example patches: https://github.com/batchku/aLib/tree/master/for%20resonators
• Example resonance models: http://alimomeni.net/project/alib-resonance-models

---

Python Bindings

Bindings for Python are available via Swig, meaning Resonators can be used from a Python script or a Jupyter notebook:

model = resonators.ModelLoader()
model.load(args.model_path)
rb_ops = resonators.ResonatorBankOptions()
rb_ops.total = model.getSize()
rb = resonators.ResonatorBank()
rb.setup(rb_ops, 44100.0, 128)
rb.setBank(model.getShiftedToNote("c4"))
rb.update()
out = rb.render(0.5)

• At the top level directory, run cmake ., and then make.
• If this succeeds, run py/test_bindings.py to confirm.
• For now, you can crudely sys.path.append the directory to import the module.

Note: this has been tested with Python 3.6.5 (and should support Python 2.7+), SWIG 4.0.0 and CMake 3.14.3 on OSX 10.14.

---

License

Unless otherwise stated, CC0.

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TODO

Resonators

• More comprehensive comments/documentation
• Add examples for real-time manipulation of model parameters
• Add functions for useful/interesting real-time variation of model parameters

Models

• Real-time functions for simple scaling of gain and decay parameters
• Generate models (offline) based on samples (using HPSS?)

Data analysis/offline exploration

[x] Python bindings for Resonators.cpp for offline synthesis (merged 05c089c)

• Clean up Python utils
• Add Jupyter notebook examples

p5.js

• Refactor the p5.js sketch to work with topic/p5-gui