lip sync by daylight noise

The slip

It hears the picture's lines (a phrase after a gap, or every cut on the clock) and cuts each one in where SLIP says.

SLIP, the big knob: how late the dub is: dead in sync fully left, 6 ms just above (a tight double), 87 ms at noon (a slap), a second and a half at full (a canon). The meter round it shows how far out the dub is now, early to the left, late to the right.

SLIP, the jack: its CV, added to the knob. Below zero the dub comes early: the picture is held back for the line to let it, so it plays that much behind the rest of the rack.

WANDER: how the slip moves. Fully left it holds still. Turned up it drifts like a loose tape, its pitch wowing. Further, lines start being cut in somewhere new, early or late; at full, every one.

LEFT, RIGHT: the picture in. The dub is made from the two together.

The other actor

VOICE: who says it again. At noon the same voice; to the left heavier and lower, to the right thinner and higher. The formants move most and the pitch only a little, so it's another person, not a harmoniser.

ROOM: where they said it. At noon the picture's own room; to the left a dead booth, close and boxy, every tail cut short; to the right a big hall the picture was never in, four seconds of tail.

REPLACE: how much of the picture the dub replaces. Fully left a double alongside it; turned up the picture goes down, and each line of the dub comes in at its own level, jumping where it was cut in. At full only the dub is left.

The clap and the cut

SLATE, a lit button and its gate: the clap. The dub snaps dead in sync and the round window at the top of the meter flashes; then it wanders off until the next line. The cap glows while it's in sync.

CUT: a clock, the editor's cuts. Every pulse starts a line: the dub is put back where SLIP says and drifts off before the next. SLIP counts in its steps: past half a step the slip is a whole number of them, so at full the dub is whole beats or bars behind.

The streamer: before each late line a sweep runs in from both ends of the meter to the round window, which flashes as the dub's line comes in.

What comes out

LEFT, RIGHT: the picture and the dub together, the dub in the middle and its hall in stereo.

DUB: the dub alone, in its voice and its room.

SYNC: how far out of sync it is, either way: 0 V in sync, 0.8 V more for every doubling, 8 V at two seconds.

CUE: three beeps spread over the gap before each late line, which comes in on the silent fourth.

With SLIP, WANDER and REPLACE fully left and VOICE and ROOM at noon, DUB is the two ins together, exactly.

Inside

One board sits 10 mm behind the panel with everything on its front: the jacks, the knobs, SLATE, the meter's 39 white LEDs and the whole circuit, the USB-C in a notch in its left edge. Each window of the meter has its own cell in a black printed baffle, two LEDs under each tick and three under the round one. An RP2350 runs it on both its cores, one making the other actor's voice while the other follows the lines and the slip; the two tapes are in 8 MB of memory beside it.

The LIP SYNC panel out of sync: the needle lit on the late side of the meter, a line's sweep running in to the round window, its knobs, jacks and SLATE on.

Drag it or use the arrow keys to turn it; click it to take it apart.

Specs

Format

Width: 20 HP
Depth: 20.8 mm behind the panel
+12 V: about 70 mA dark, 155 mA out of sync, 175 mA at the most, its lights at their cap (estimated)
−12 V: about 6 mA (estimated)
+5 V: not used
Controls: a big knob, 4 knobs, a lit button

I/O

LEFT, RIGHT: audio in, ±5 V with room to ±9 V; RIGHT takes LEFT when it's empty
CUT, SLATE: gates, high past about 1 V; safe to ±12 V
SLIP: CV, added to the knob, 5 V the whole way; below zero early; safe to ±12 V
LEFT, RIGHT: audio out, the picture and the dub, soft past 8 V, never past 10 V
DUB: audio out, the dub alone, mono, the same ceiling
SYNC: CV, 0 V in sync, 0.8 V more a doubling, 8 V from 2 s
CUE: trigger, 5 V, 5 ms

Engine

Brain: RP2350, both cores, at 46.875 kHz, 32-bit float
Slip: dead in sync to 1.5 s late, early by its CV; 1,000 steps a second
Tapes: 11 s each of the picture and the dub, 16-bit, in 8 MB of PSRAM (this page's: 5.5 s)
Light: 39 white LEDs, 183 frames a second
Power cycle: it wakes in sync with empty tapes; only the calibration is kept