chroma-rot
chroma-rot · runs in vfpga-runnerModel
A composite-era circuit-bent VFPGA that corrupts the colour subsystem — the chroma demodulator and colour-burst phase. It separates the picture into luma + a YIQ chroma vector then mis-phases the chroma: a burst-phase offset spins the hue globally (rainbowing), a chroma-gain overdrive bleeds oversaturation, an I/Q swap mangles the colour axes, and a dot-crawl term shimmers chroma per scanline (comb-filter defeat). Because composite splits Y from C, it doubles as an S-video Y/C tool: patch a CHROMA SOURCE to IIN2 and p5 (cxfer) transplants that clip’s colours onto IIN1’s luma (clip A’s shapes in clip B’s colours) — cxfer=0 or an unpatched IIN2 leaves the original single-source bend untouched. vout2 outputs the separated luma (Y) plane. CIN1 adds a continuous hue spin onto the burst phase; CIN2 adds onto the transplant; GIN1 is a HELD gate that toggles the I/Q swap.
I/O
- Video in: 2 (vin1…vin2)
- Video out: 2 (vout1 + vout2)
Controls (param knobs)
| Slot | Knob | Range | Default | What it does |
|---|---|---|---|---|
p1 | phase | 0 … 1 | 0.15 | Burst-phase offset → rotates chroma (global hue spin, 0..1 wheel). |
p2 | gain | 0 … 3 | 1.6 | Chroma amplitude (>1 = oversaturation bleed overdrive). |
p3 | i/q-mix | 0 … 1 | 0 | Static I/Q swap amount (the GIN1 gate adds a held swap on top). |
p4 | dot-crawl | 0 … 1 | 0.4 | Per-line/time chroma shimmer (comb-filter defeat). |
p5 | cxfer | 0 … 1 | 0 | Y/C transplant — blend IIN2’s chroma onto IIN1’s luma (0 = own chroma). |
CV roles
| Input | Role | What it modulates |
|---|---|---|
cv1 | SPIN | Adds a continuous hue spin onto the burst phase (patch an LFO/ramp). |
cv2 | CXFER | Adds onto the Y/C transplant amount (modulate how much of IIN2’s chroma lands on the luma). |
Each CV input has a bipolar SCALE attenuverter + OFFSET on the card, and an always-on scope.
Gate roles
| Input | Role | What it triggers |
|---|---|---|
g1 | I/Q | A HELD gate: while high, the I/Q chroma axes are swapped. |
Gate inputs raw-pass into the host's synthetic gN_evt params; the factory hysteresis edge-detects rising edges (rise > 0.6 / fall < 0.4).
Usage
Add a vfpga-runner, pick chroma-rot from the card's load preset… menu, and patch the
active outputs into OUTPUT / a video mixer / a downstream effect.