---
title: Csound
layout: ../../layouts/MainLayout.astro
---

import { MiniRepl } from '../../docs/MiniRepl';
import { JsDoc } from '../../docs/JsDoc';
import Colors from '../../docs/Colors.jsx';

# Using CSound with Strudel

🧪 Strudel has experimental support for csound, using [@csound/browser](https://www.npmjs.com/package/@csound/browser).

## Importing .orc files

To use existing csound instruments, you can load and use an orc file from an URL like this:

<MiniRepl
  client:only="react"
  tune={`// livecode.orc by Steven Yi
await loadOrc('github:kunstmusik/csound-live-code/master/livecode.orc')
note("c a f e").csound('FM1')
`}
/>

Note that the above url uses the `github:` shortcut, which resolves to the raw file on github, but you can use any URL you like.

The awesome [`livecode.orc by Steven Yi`](https://github.com/kunstmusik/csound-live-code) comes packed with many sounds ready for use:

<MiniRepl
  client:only="react"
  tune={`// livecode.orc by Steven Yi
await loadOrc('github:kunstmusik/csound-live-code/master/livecode.orc')
note("c a f e").csound(cat(
"Sub1", // 	Substractive Synth, 3osc
"Sub2", // 	Subtractive Synth, two saws, fifth freq apart
"Sub3", // 	Subtractive Synth, three detuned saws, swells in
"Sub4", // 	Subtractive Synth, detuned square/saw, stabby. Nice as a lead in octave 2, nicely grungy in octave -2, -1
"Sub5", // 	Subtractive Synth, detuned square/triangle
"Sub6", // 	Subtractive Synth, saw, K35 filters
"Sub7", // 	Subtractive Synth, saw + tri, K35 filters
"Sub8", // 	Subtractive Synth, square + saw + tri, diode ladder filter
"SynBrass", // 	SynthBrass subtractive synth
"SynHarp", // 	Synth Harp subtracitve Synth
"SSaw", // 	SuperSaw sound using 9 bandlimited saws (3 sets of detuned saws at octaves)
"Mode1", // 	Modal Synthesis Instrument: Percussive/organ-y sound
"Plk", // 	Pluck sound using impulses, noise, and waveguides
"Organ1", // 	Wavetable Organ sound using additive synthesis
"Organ2", // 	Organ sound based on M1 Organ 2 patch
"Organ3", // 	Wavetable Organ using Flute 8' and Flute 4', wavetable based on Claribel Flute http://www.pykett.org.uk/the\_tonal\_structure\_of\_organ\_flutes.htm
"Bass", // 	Subtractive Bass sound
"ms20_bass", // 	MS20-style Bass Sound
"VoxHumana", // 	VoxHumana Patch
"FM1", // 	FM 3:1 C:M ratio, 2->0.025 index, nice for bass
"Noi", // 	Filtered noise, exponential envelope
"Wobble", // 	Wobble patched based on Jacob Joaquin's "Tempo-Synced Wobble Bass"
"Sine", // 	Simple Sine-wave instrument with exponential envelope
"Square", // 	Simple Square-wave instrument with exponential envelope
"Saw", // 	Simple Sawtooth-wave instrument with exponential envelope
"Squine1", // 	Squinewave Synth, 2 osc
"Form1", // 	Formant Synth, buzz source, soprano ah formants
"Mono", // 	Monophone synth using sawtooth wave and 4pole lpf. Use "start("Mono") to run the monosynth, then use MonoNote instrument to play the instrument.
"MonoNote", // 	Note playing instrument for Mono synth. Be careful to use this and not try to create multiple Mono instruments!
"Click", // 	Bandpass-filtered impulse glitchy click sound. p4 = center frequency (e.g., 3000, 6000)
"NoiSaw", // 	Highpass-filtered noise+saw sound. Use NoiSaw.cut channel to adjust cutoff.
"Clap", // 	Modified clap instrument by Istvan Varga (clap1.orc)
"BD", // 	Bass Drum - From Iain McCurdy's TR-808.csd
"SD", // 	Snare Drum - From Iain McCurdy's TR-808.csd
"OHH", // 	Open High Hat - From Iain McCurdy's TR-808.csd
"CHH", // 	Closed High Hat - From Iain McCurdy's TR-808.csd
"HiTom", // 	High Tom - From Iain McCurdy's TR-808.csd
"MidTom", // 	Mid Tom - From Iain McCurdy's TR-808.csd
"LowTom", // 	Low Tom - From Iain McCurdy's TR-808.csd
"Cymbal", // 	Cymbal - From Iain McCurdy's TR-808.csd
"Rimshot", // 	Rimshot - From Iain McCurdy's TR-808.csd
"Claves", // 	Claves - From Iain McCurdy's TR-808.csd
"Cowbell", // 	Cowbell - From Iain McCurdy's TR-808.csd
"Maraca", // 	Maraca - from Iain McCurdy's TR-808.csd
"HiConga", // 	High Conga - From Iain McCurdy's TR-808.csd
"MidConga", // 	Mid Conga - From Iain McCurdy's TR-808.csd
"LowConga", // 	Low Conga - From Iain McCurdy's TR-808.csd
))`}
/>

## Writing your own instruments

You can define your own instrument(s) with `loadCsound` like this:

<MiniRepl
  client:only="react"
tune={`await loadCsound\`
instr CoolSynth
    iduration = p3
    ifreq = p4
    igain = p5
    ioct = octcps(ifreq)

    kpwm = oscili(.05, 8)
    asig = vco2(igain, ifreq, 4, .5 + kpwm)
    asig += vco2(igain, ifreq * 2)

    idepth = 2
    acut = transegr:a(0, .005, 0, idepth, .06, -4.2, 0.001, .01, -4.2, 0) ; filter envelope
    asig = zdf_2pole(asig, cpsoct(ioct + acut + 2), 0.5)

    iattack = .01
    isustain = .5
    idecay = .1
    irelease = .1
    asig *= linsegr:a(0, iattack, 1, idecay, isustain, iduration, isustain, irelease, 0)

    out(asig, asig)

endin\`

"<0 2 [4 6](3,4,2) 3\*2>"
.off(1/4, add(2))
.off(1/2, add(6))
.scale('D minor')
.note()
.csound('CoolSynth')`}
/>

## Parameters

The `.csound` function sends the following p values:

|     |                                  |
| --- | -------------------------------- |
| p1  | instrument name e.g. `CoolSynth` |
| p2  | time offset, when it should play |
| p3  | the duration of the event / hap  |
| p4  | frequency in Hertz               |
| p5  | normalized `gain`, 0-1           |

There is an alternative `.csoundm` function with a different flavor:

|     |                                   |
| --- | --------------------------------- |
| p4  | midi key number, unrounded, 0-127 |
| p5  | midi velocity, 0-127              |

In both cases, p4 is derived from the value of `freq` or `note`.

## Limitations / Future Plans

Apart from the above listed p values, no other parameter can be patterned so far.
This also means that [audio effects](./learn/effects) will not work.
In the future, the integration could be improved by passing all patterned control parameters to the csound instrument.
This could work by a unique [channel](https://kunstmusik.github.io/icsc2022-csound-web/tutorial2-interacting-with-csound/#step-4---writing-continuous-data-channels)
for each value. Channels could be read [like this](https://github.com/csound/csound/blob/master/Android/CsoundForAndroid/CsoundAndroidExamples/src/main/res/raw/multitouch_xy.csd).
Also, it might make sense to have a standard library of csound instruments for strudel's effects.
