# Audio

> Make music apps in Python with Pyzed — a modular audio engine, FL Studio-style knobs, faders and pads, waveforms, spectrum analyzers, a webcam view and a VCV Rack-style rack with animated cables.

Source: https://albakore.github.io/pyzed/audio/

(Image: A modular rack: modules on rails, cables being plugged, a knob turning the filter)

Pyzed has everything to build a synthesizer, a drum machine, a MIDI controller or a music
visualizer in Python. It comes in two layers that you can use together or apart:

- **The engine** (`pyzed.audio`) makes the sound. You add modules (oscillators, filters,
  envelopes, effects, sequencers, drums), join them with cables and it plays them on your sound
  card with low latency. It needs no window: a script, a test or a server can use it alone.
- **The interface** (`pyzed.ui.audio`, `pyzed.ui.rack`, `pyzed.ui.camera`) shows and controls
  it: knobs, faders, pads, a piano, meters, waveforms, spectrum analyzers and a rack where you
  patch modules with cables you drag, like VCV Rack or Reaktor.

**In plain words:**

The engine is the instrument; the interface is its front panel. You can play the instrument with
code only, or give it a panel the user can touch.

```python
import pyzed as pz
from pyzed import audio, ui

engine = audio.Engine()
osc = engine.add("oscillator", wave="saw", freq=110)
lpf = engine.add("filter", cutoff=800, resonance=0.5)
engine.chain(osc, lpf, engine.add("audio_out"))

class Synth(pz.App):
    def on_start(self):
        engine.start()

    def subscriptions(self):
        return [pz.frames(lambda dt: None)]  # redraw every frame: the meters move

    def view(self):
        return pz.row([
            ui.audio.Knob(value=engine.get(lpf, "cutoff"), min=20, max=20000, curve="log", unit="Hz",
                          caption="Cutoff", variant="fl",
                          on_change=lambda e: engine.set(lpf, "cutoff", e.value)),
            ui.audio.Spectrum(magnitudes=engine.spectrum(), width=360, height=120),
            ui.audio.VuMeter(level=engine.level()),
        ], spacing=16, align="center")

pz.run(Synth)
```

## Where to start

- [The engine](https://albakore.github.io/pyzed/audio/engine/getting-started/): Modules, cables, MIDI and latency: making sound from Python.
- [Components](https://albakore.github.io/pyzed/audio/components/knob/): Knobs, faders, pads, piano, meters, waveforms and analyzers.
- [The rack](https://albakore.github.io/pyzed/audio/rack/rack/): A VCV Rack-style rack with modules you patch with cables.
- [Demos](https://albakore.github.io/pyzed/audio/demos/synth/): A synthesizer, a visualizer, a MIDI controller, a drum machine and more.

## The components

Every component is in the designer's toolbox, in the **Audio** group (the webcam is under
**Media**), and has its own page with an animation:

| Component | What it is |
| --- | --- |
| [`Knob`](https://albakore.github.io/pyzed/audio/components/knob/) | A rotary control: five looks, logarithmic ranges, stepped selectors. |
| [`Fader`](https://albakore.github.io/pyzed/audio/components/fader/) | A slider like a mixing desk's, with an optional level meter. |
| [`Pad`, `LedButton`](https://albakore.github.io/pyzed/audio/components/pads-and-buttons/) | Velocity pads and buttons with a light. |
| [`StepSequencer`](https://albakore.github.io/pyzed/audio/components/step-sequencer/) | A grid of steps like FL Studio's channel rack. |
| [`Piano`](https://albakore.github.io/pyzed/audio/components/piano/) | A keyboard you play with the mouse or the computer keys. |
| [`VuMeter`](https://albakore.github.io/pyzed/audio/components/vu-meter/) | LED, bar and analog needle meters with peak hold. |
| [`Waveform`](https://albakore.github.io/pyzed/audio/components/waveform/) | A recording's shape, with a playhead and a selection. |
| [`Scope`](https://albakore.github.io/pyzed/audio/components/scope/) | An oscilloscope with trigger, XY mode and persistence. |
| [`Spectrum`](https://albakore.github.io/pyzed/audio/components/spectrum/) | A spectrum analyzer: bars, blocks, lines, mirror, radial. |
| [`Spectrogram`](https://albakore.github.io/pyzed/audio/components/spectrogram/) | The spectrum over time, as a scrolling picture. |
| [`Webcam`](https://albakore.github.io/pyzed/audio/components/webcam/) | The live picture of a camera. |
| [`Rack`](https://albakore.github.io/pyzed/audio/rack/rack/) | Modules on rails joined with [animated cables](https://albakore.github.io/pyzed/audio/rack/cables/). |

Colors and palettes are explained in [Colors and palettes](https://albakore.github.io/pyzed/audio/components/colors/).