MIDI, OSC and MQTT

Normally, Strudel is used to pattern sound, using its own ‘web audio’-based synthesiser called SuperDough.

It is also possible to pattern other things with Strudel, such as software and hardware synthesisers with MIDI, other software using Open Sound Control/OSC (including the SuperDirt synthesiser commonly used with Strudel’s sibling TidalCycles), or the MQTT ‘internet of things’ protocol.

MIDI

Strudel supports MIDI without any additional software (thanks to webmidi), just by adding methods to your pattern:

midiin(inputName?)

let cc = await midin('IAC Driver Bus 1')
note("c a f e").lpf(cc(0).range(0, 1000)).lpq(cc(1).range(0, 10)).sound("sawtooth")

midi(outputName?,options?)

Either connect a midi device or use the IAC Driver (Mac) or Midi Through Port (Linux) for internal midi messages. If no outputName is given, it uses the first midi output it finds.

$: chord("<C^7 A7 Dm7 G7>").voicing().midi('IAC Driver')

In the console, you will see a log of the available MIDI devices as soon as you run the code, e.g.

 `Midi connected! Using "Midi Through Port-0".`

The .midi() function accepts an options object with the following properties:

$: note("d e c a f").midi('IAC Driver', { isController: true, midimap: 'default'})

midiport(outputName)

Selects the MIDI output device to use, pattern can be used to switch between devices.

$: midiport('IAC Driver');
$: note('c a f e').midiport('<0 1 2 3>').midi();

note("c a f e").midiport("<0 1 2 3>").midi()

midichan(number)

Selects the MIDI channel to use. If not used, .midi will use channel 1 by default.

midicmd(command)

midicmd sends MIDI system real-time messages to control timing and transport on MIDI devices.

It supports the following commands:

• clock/midiClock - Sends MIDI timing clock messages
• start - Sends MIDI start message
• stop - Sends MIDI stop message
• continue - Sends MIDI continue message

// You can control the clock with a pattern and ensure it starts in sync when the repl begins. // Note: It might act unexpectedly if MIDI isn’t set up initially.

$:stack(
midicmd("clock*48,<start stop>/2").midi('IAC Driver')
)

control, ccn && ccv

• control sends MIDI control change messages to your MIDI device.
• ccn sets the cc number. Depends on your synths midi mapping
• ccv sets the cc value. normalized from 0 to 1.

note("c a f e").control([74, sine.slow(4)]).midi()

note("c a f e").ccn(74).ccv(sine.slow(4)).midi()

In the above snippet, ccn is set to 74, which is the filter cutoff for many synths. ccv is controlled by a saw pattern. Having everything in one pattern, the ccv pattern will be aligned to the note pattern, because the structure comes from the left by default. But you can also control cc messages separately like this:

$: note("c a f e").midi()
$: ccv(sine.segment(16).slow(4)).ccn(74).midi()

Instead of setting ccn and ccv directly, you can also create mappings with midimaps:

midimaps

midimaps({ mymap: { lpf: 74 } })
$: note("c a f e")
.lpf(sine.slow(4))
.midimap('mymap')
.midi()

midimaps({ mymap: {
  lpf: { ccn: 74, min: 0, max: 20000, exp: 0.5 }
}})
$: note("c a f e")
.lpf(sine.slow(2).range(400,2000))
.midimap('mymap')
.midi()

defaultmidimap

defaultmidimap({ lpf: 74 })
$: note("c a f e").midi();
$: lpf(sine.slow(4).segment(16)).midi();

progNum (Program Change)

progNum sends MIDI program change messages to switch between different presets/patches on your MIDI device. Program change values should be numbers between 0 and 127.

// Switch between programs 0 and 1 every cycle
progNum("<0 1>").midi()

// Play notes while changing programs
note("c3 e3 g3").progNum("<0 1 2>").midi()

Program change messages are useful for switching between different instrument sounds or presets during a performance. The exact sound that each program number maps to depends on your MIDI device’s configuration.

sysex, sysexid && sysexdata (System Exclusive Message)

sysex sends MIDI System Exclusive (SysEx) messages to your MIDI device. ysEx messages are device-specific commands that allow deeper control over synthesizer parameters. The value should be an array of numbers between 0-255 representing the SysEx data bytes.

// Send a simple SysEx message
let id = 0x43; //Yamaha
//let id = "0x00:0x20:0x32"; //Behringer ID can be an array of numbers
let data = "0x79:0x09:0x11:0x0A:0x00:0x00"; // Set NSX-39 voice to say "Aa"
$: note("c a f e").sysex(id, data).midi();
$: note("c a f e").sysexid(id).sysexdata(data).midi();

The exact format of SysEx messages depends on your MIDI device’s specification. Consult your device’s MIDI implementation guide for details on supported SysEx messages.

midibend && miditouch

midibend sets MIDI pitch bend (-1 - 1) miditouch sets MIDI key after touch (0-1)

note("c a f e").midibend(sine.slow(4).range(-0.4,0.4)).midi()

note("c a f e").miditouch(sine.slow(4).range(0,1)).midi()

OSC/SuperDirt/StrudelDirt

In TidalCycles, sound is usually generated using SuperDirt, which runs inside SuperCollider. Strudel also supports using SuperDirt, although it requires installing some additional software.

There is also StrudelDirt which is SuperDirt with some optimisations for working with Strudel. (A longer term aim is to merge these optimisations back into mainline SuperDirt)

Prequisites

To get SuperDirt to work with Strudel, you need to

1. install SuperCollider + sc3 plugins, see Tidal Docs (Install Tidal) for more info.
2. install SuperDirt, or the StrudelDirt fork which is optimised for use with Strudel
3. install node.js
4. download Strudel Repo (or git clone, if you have git installed)
5. run pnpm i in the strudel directory
6. run pnpm run osc to start the osc server, which forwards OSC messages from Strudel REPL to SuperCollider

Now you’re all set!

Usage

1. Start SuperCollider, either using SuperCollider IDE or by running sclang in a terminal
2. Open the Strudel REPL

…or test it here:

If you now hear sound, congratulations! If not, you can get help on the #strudel channel in the TidalCycles discord.

Note: if you have the ‘Audio Engine Target’ in settings set to ‘OSC’, you do not need to add .osc() to the end of your pattern.

Pattern.osc

SuperDirt Params

Please refer to Tidal Docs for more info.

But can we use Strudel offline?

MQTT

MQTT is a lightweight network protocol, designed for ‘internet of things’ devices. For use with strudel, you will need access to an MQTT server known as a ‘broker’ configured to accept secure ‘websocket’ connections. You could run one yourself (e.g. by running mosquitto), although getting an SSL certificate that your web browser will trust might be a bit tricky for those without systems administration experience. Alternatively, you can use a public broker.

Strudel does not yet support receiving messages over MQTT, only sending them.

Usage

The following example shows how to send a pattern to an MQTT broker:

Other software can then receive the messages. For example using the mosquitto commandline client tools:

> mosquitto_sub -h mqtt.eclipseprojects.io -p 1883 -t "/strudel-pattern"
> hello
> world
> hello
> world
> ...

Control patterns will be encoded as JSON, for example:

Will send messages like the following:

{"s":"sax","speed":2}
{"s":"sax","speed":2}
{"s":"sax","speed":3}
{"s":"sax","speed":2}
...

Libraries for receiving MQTT are available for many programming languages.