Hello Phausto
Lesson 1 The minimal Phausto program. A sine wave oscillator at 440 Hz (A4), wrapped in a DSP object and started.
In Phausto, every sound is built from Unit Generators (UGens). To hear a UGen, you must wrap it in a DSP object, initialise it, and start it. Evaluate these lines one at a time in a Playground:
"Create a new SineWave Oscillator — default frequency is 440 Hz (A4)"
sine := SineOsc new.
"Wrap it in a DSP object"
dsp := sine asDsp.
"Initialise the DSP (compiles the FAUST code to native audio)"
dsp init.
"Start playback — you should now hear the tone"
dsp start.
"Stop the sound"
dsp stop.The DSP Lifecycle
Every Phausto patch follows the same four-step lifecycle:
asDsp to get a DSP object.dsp init compiles the FAUST DSP to native code and allocates audio buffers.dsp start begins audio output. The DSP runs on a separate audio thread.dsp stop halts audio. Call dsp destroy to free native resources when done.| Message | Effect |
|---|---|
| asDsp | Wrap UGen chain in a DSP object (mono) |
| stereo asDsp | Wrap with stereo output |
| dsp init | Compile and allocate |
| dsp start | Begin audio playback |
| dsp stop | Halt audio output |
| dsp destroy | Free native resources |
Hello Stereo
Lesson 2 Most instruments need a stereo output. Add stereo before asDsp to duplicate the signal to both channels.
"Create a Sawtooth oscillator"
saw := SawOsc new.
"Create a STEREO DSP — notice 'stereo' before 'asDsp'"
dsp := saw stereo asDsp.
dsp init.
dsp start.
dsp stop.stereo for instruments you plan to run through effects chains. Effects like GreyHole and Freeverb expect stereo input.
Unit Generators 101
Lesson 3 Unit Generators are the atoms of synthesis in Phausto — oscillators, noise generators, envelopes, filters, effects, physical models. All UGens share a common interface.
"White noise is the simplest signal source"
noise := Noise new.
dsp := noise stereo asDsp.
dsp init.
dsp start.
"All UGens have a 'uLevel' parameter — linear volume control"
"Open its UI to see the knob"
dsp displayUI.
dsp stop.UGen categories
| Category | Examples |
|---|---|
| Oscillators | SineOsc, SawOsc, TriOsc, SquareOsc, PulseOsc |
| Noise | Noise |
| Envelopes | ADSREnv |
| Filters | MoogVcf, PhSvfLp, PhModeFilter |
| Effects | GreyHole, Freeverb |
| Physical Models | Djembe, Marimba, ElecGuitar |
| LFOs | LFOTriPos, LFORandomPos |
| Pulse generators | Pulse, Pulsen |
| FM operators | Dx7Op |
uLevel: setter for linear amplitude. Human loudness perception is logarithmic, so small uLevel changes sound more dramatic at lower values.
At the Controls
Lesson 4 Change UGen parameters in real time with setValue:parameter:, or inspect what parameters are available with traceAllParams.
"PulseOsc is a square oscillator with a variable duty cycle"
pulse := PulseOsc new.
dsp := pulse asDsp.
dsp init.
dsp start.
"Change the duty cycle while running"
dsp setValue: 0.2 parameter: 'PulseOscDuty'.
"Change the frequency"
dsp setValue: 120 parameter: 'PulseOscFreq'.
"See all available parameters for this DSP"
dsp traceAllParams.
dsp stop."Set a named DSP parameter in real time.
aNumber — the new value.
aString — exact FAUST parameter label (check traceAllParams or class comments)."
dsp setValue: 440 parameter: 'SineOscFreq'."Print all parameter labels and current values to the Transcript."
dsp traceAllParams.dsp traceAllParams after init.
Display the UI
Lesson 5 FAUST generates a UI automatically from the slider and button definitions in each module. Call displayUI to open it as a Pharo window.
"Djembe — a physical model of the West African goblet drum"
perc := Djembe new.
dsp := perc asDsp.
dsp init.
dsp start.
"Open the auto-generated UI — press DjembeTrigger to trigger the drum"
dsp displayUI.
"Try substituting Djembe with Marimba for a different timbral character"
dsp stop.UI parameter types
| FAUST element | Phausto class | Use |
|---|---|---|
| hslider | PhHSlider | Horizontal slider (range + step) |
| nentry | PhNumEntry | Numerical entry (integer or float) |
| button | auto-generated | Trigger (pulse on click) |
| knob | auto-generated | Rotary control |