Live Looper

Your own instrument, layered by yourself. Plug in a guitar, a microphone or a keyboard's audio out, and a Looper records four bars of it on the downbeat, plays them back, and lets you play over them, layer on layer. A soft click keeps you in time, and the whole thing goes through tempo-synced echoes and a room.

Load it: choose 📚 Examples → Live Looper in the toolbar. Pick your interface under Input in the toolbar, press ▶ Play, tap Rec on the Looper and play. The patch file is patches/live-looper.json.

The patch as it opens. The Looper's ring is grey dashes: empty, waiting for Rec.

What it teaches

• Building a piece in layers. Record a part, then play the next over it, as a solo looping player does.
• Takes on the beat. The Looper's Clock is once a bar, so takes start on the downbeat and close on a bar line.
• Latency, and taking it back. Live sound reaches the patch late. The Looper writes each layer back by the measured round trip, so layers sit where you played them.
• A click you can switch off. The metronome runs into the Mixer, where two mute buttons silence it once the loop is going.

Modules

How it's built

You, into the Looper

[Audio Input L] ──> [Looper In L]
[Audio Input R] ──> [Looper In R]

The Looper's Out carries what you play now and the loop together. Everything after it, echo and room, treats them as one performance.

The bar clock

[Clock Gate]         ──> [Clock Divider Clock]
[Clock Divider Trig] ──> [Looper Clock]

The Clock ticks quarter notes at 90 BPM. The Divider passes every fourth tick, the downbeat of each bar, to the Looper's Clock. A tap on Rec waits for the next downbeat, then records four Bars and closes the loop by itself: one tap to start, none to stop. A tap that lands up to 50 ms after a downbeat counts as on it.

A bar is 2.67 s at 90 BPM, so four bars are 10.7 s. Change the Clock's BPM before you record, and the loop is four bars at the new tempo.

Layers

Once the loop is playing, tap Rec to overdub (the ring turns amber), play your next part, and tap Rec again when it's done. Each overdub pass lays a thin band inside the ring. Undo takes back the layer you just made, if it didn't work, and a second Undo brings it back. Stop silences the loop and Clear empties it to start over.

Turn FB down before an overdub to let the older layers fade as the new one goes on, so a loop can change gradually rather than only pile up.

Keeping your layers

Your layers are part of the patch. Save it (an example has no file of its own, so Save asks where), and the loop goes into a <patch name> loops folder beside it. Open the patch tomorrow and the loop is there, stopped at the top: tap Rec to hear it and go on overdubbing from where you left off. What's kept is the loop as you hear it, so a layer you've undone stays out. See Keeping the loop.

Latency

The status bar's In figure is the round trip from the input jack to your speakers, typically 20 to 50 ms. You play along with the loop you hear, and what you play arrives that long after the moment you were playing to. Auto latency writes each overdub that much earlier, so a strum on beat one lands on beat one. If layers still feel a hair late (your converters add delay no timestamp reports), trim with Offset.

Click, echo and room

[Clock Gate]         ──> [Drum (Rim) Trig]     ──> [Mixer Ch 1]
[Clock Divider Trig] ──> [Drum (Cowbell) Trig] ──> [Mixer Ch 2]
[Looper Out L/R] ──> [Stereo Delay In L/R] ──> [Reverb In L/R] ──> [Mixer Return L/R]
[Mixer Out L/R]  ──> [Audio Output Left/Right]

The click goes straight to the Mixer, never through the Looper, so it isn't recorded. Mute channels 1 and 2 when you no longer need it. The echo is a dotted eighth, ping-ponging, with tape wobble: it fills the space between a picked guitar's notes.

Things to try

• Learn a footswitch. Right-click Rec on the Looper, choose Learn MIDI CC, and press a MIDI pedal. Now your hands stay on the instrument.
• Octave down. Set Speed to ½× after recording a guitar part: it becomes a bass line, twice as long.
• Free time. Set Bars to Free and unpatch the Looper's Clock: the loop is exactly as long as you held it, for playing out of time.
• Effects on the loop only. Patch Loop L/R through a filter or the Distortion while Out carries you dry.

Rendering it offline

The render tool can play a recording into the Audio Input and press the footswitches from a cue script:

# cues.txt: press Rec before the first downbeat; four bars record by themselves
0.5   param util.looper Pedal Rec 1
0.8   param util.looper Pedal Rec 0
14.0  param util.looper Pedal Rec 1     # overdub
14.3  param util.looper Pedal Rec 0

cargo run --release --bin render -- patches/live-looper.json out.wav --seconds 30 --input take.wav --cue cues.txt

A copy saved with its loop renders that loop too: it opens stopped, so press Rec (or Stop) in the cues to start it.