MIDI, OSC, keys and triggers

Run your show from a MIDI controller, a tablet with TouchOSC, QLab or Ableton, or the keyboard. Faders and knobs move settings; pads, keys, beats and drum hits fire triggers: GO, a scene, a flash, a blackout, a new colour. Everything here lives in Design ▸ Live control.

1Controls and triggers

• A control (a knob, a fader, the velocity of a key, an OSC fader) sets a setting directly: the fader's bottom is the setting's lowest value, its top the highest. Unlike automation, it doesn't add to the value: it is the value.
• A trigger is something that happens: a pad or key pressed, an OSC button, a key on the keyboard, the Tap button, every beat or bar, a kick or snare hit. It runs an action: GO, a scene or cue, flash, blackout, or a setting (set it, step it, flip it, a random colour).

2MIDI

1. Plug the controller in, then open Live control ▸ MIDI.
2. Click Turn on MIDI and allow MIDI when the browser asks, next to the address bar. MIDI works in Chrome and Edge.
3. MIDI is on: choose the controller under Listen to, or keep All devices. Move something: Last message shows what arrives, for example CC 16 = 85 · ch 1, so you know it's connected.
4. Pads and keys: under Buttons and pads, click Learn a button and press the pad. It becomes a trigger that starts as GO (next cue); change its Do as in Triggers.
5. Knobs and faders: under Knobs and faders, click Learn a knob or fader and move it. Choose what it Moves: Projector brightness or a surface, then its Layer and Setting.

• Notes fire their trigger, and their velocity can drive a control. CCs drive controls, and fire a trigger when they cross the middle (64) upwards, which is what buttons that send 127 and 0 do. Program changes fire triggers. Pitch bend is a control.
• The browser remembers that MIDI was on and which device you chose; next time it reconnects without asking. Your controls and triggers are saved with the project.
• MIDI clock: to follow a DAW's tempo, choose MIDI clock as the tempo source in Live control ▸ Audio ▸ Beat settings. See Beat settings.

3Learn from a setting

The quickest way to link a knob to a setting is from the setting itself.

1. Right-click the setting in the look panel or the inspector ▸ MIDI / OSC learn.
2. A message waits: “Move a MIDI knob, fader or pad, or send OSC, for speed…”. Turn the knob.
3. It confirms: “Speed now follows MIDI CC 17 · ch 1.” Its range is the setting's whole range, and its kind (hue, on/off…) suits the setting.

Learning the same knob again for the setting replaces its old link; a different knob adds a second control. Learn gives up by itself after 20 seconds.

4A control's range and response

Every control has the same Response block as automation (see Automation): the part of the knob that counts, a curve, and where the setting goes at the bottom and the top. Drag the ends past each other, or press Invert, to turn it round. Attack and Release make a jump glide. Open it from the control's Response line in the MIDI and OSC tabs, from the setting's wave button, or with right-click ▸ Controller range….

A line under each control shows the value now, for example Speed now: 1.65. Locked surfaces are left alone.

5OSC

OSC is a network protocol many show apps speak: TouchOSC on a tablet, QLab, Ableton, Resolume. The prism server listens for it on UDP port 8000 and passes each message to the studio.

1. Open Live control ▸ OSC. Send OSC to shows where to send: an address and port such as 127.0.0.1:8000 UDP (copy it with the button beside it). 127.0.0.1 means “this computer”, so apps on the same PC can reach it.
2. Keep Accept OSC in this window on.
3. Point your app at that address and send something: Last message shows it.
4. Use prism's own addresses (next section), or learn your controller's: under Your controller, Learn a button (it starts as GO) or Learn a fader (then pick what it moves).

6OSC addresses

A button acts on a press: no value, a number above 0, true, or a word. The 0 a button sends when released is ignored.

• Surfaces by number (the OSC tab lists them under Surface numbers; hand-drawn surfaces start at 64), by name (capitals, spaces and _ don't matter) or * for all. Layers by number from the bottom (1 is the bottom layer) or *. Settings by their name; @opacity and @speed are the layer's opacity and playback speed.
• You don't need to work them out: right-click a setting ▸ OSC ▸ Copy the address or Copy the fader address (0..1), or use the copy buttons in its wave-button popover.

7Show keys

Live control ▸ Keys lists the keyboard keys that run the show. They are saved with the project.

1. Click Change beside the action, then press the new key (Esc cancels). Taking a key from another action moves it.
2. ✕ leaves the action without a key; Defaults puts every key back.

Esc, Tab, Enter, 1–9, + and ? stay free, and so do combinations with Ctrl, Alt or ⌘. Show mode also has 1–9 (the triggers Key 1–9) and Esc (back to Design). In Show, the GO key always means GO, even with a button focused; Enter still presses buttons.

8Triggers

Live control ▸ Triggers lists every trigger as a card: When an input fires ▸ Do an action.

1. Add trigger adds a card for the first free input, set to Flash white.
2. Pick When (or Learn a MIDI or OSC button), then Do; for setting actions pick On (a surface or All surfaces), the Setting and its value.
3. Try runs just this trigger now. The bin removes it.

New projects start with Tap → Flash white, Key 1 → Next scene, Key 2 → Flash white and Key 3 → Randomize. Defaults… puts that list back: it asks first, because it replaces every trigger, including learned MIDI and OSC buttons (Ctrl + Z undoes it).

From a setting, or a tile

• Right-click a setting ▸ Trigger ▸ Set to … on (a switch: Turn on with or Turn off with), Next option on (a choice) or Flip with (a switch), or Random colour on (a colour) ▸ Tap, Key 1–Key 9, Every beat, Every bar (4 beats), Audio onset, or Learn a MIDI / OSC button….
• A scene's or cue's options have Triggers and keys: Learn MIDI / OSC and Add a key or trigger, so one pad fires that exact tile.

9Hints and tips

• Learn from the setting. Right-click ▸ MIDI / OSC learn is faster than picking surface, layer and setting in the MIDI tab.
• One pad per scene. In a scene's options, Learn MIDI / OSC: that pad fires that scene, whatever the GO order.
• Beat triggers for strobes. Every beat → Flash white keeps flashes on the beat (and on time on wireless projectors).
• Test with Try. Key triggers only fire in Show; Try runs a trigger anywhere.
• Label your controller. Last message shows exactly what each knob sends; note CC numbers down for your next show.
• Randomize needs something random. The default Key 3 trigger re-rolls random sources; add a Random per surface source (Automation) for it to do something.

10When something looks wrong

11Mouse and keyboard

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