Gate
A film projector, claw and all, for Resolume
What it does
An FFGL effect for Resolume Arena and Avenue. A projector pulls the film down one frame at a time with a claw, holds it in the gate, and only lets the lamp through while a shutter blade is out of the way. The print going through it is a physical strip with grit, dust and splices on it, and dyes that fade. Gate models that machine, and the look comes out of it.
The clip is held at the projector's rate (16, 18, 24 or 25 frames a second) and only changes at pull-downs, which happen in the dark. The light the blades let through (one, two or three blades, each open for 45 to 315 degrees of its cycle) is integrated over each frame your display shows. So a 24 fps projector on a 60 Hz display beats at 12 Hz, by an amount only the shutter decides, and a display frame that spans a pull-down shows both film frames in proportion to the light each one got.
Each frame lands in the gate slightly off, correlated with the last one because the same perforations carried it, and a shrunk print weaves more. Grit in the gate cuts scratches that stay put on screen while the picture weaves underneath, dark on the base side and green, yellow or clear on the emulsion side. Dust rides the print for a frame or a few, a hair trembles at the edge of the aperture, splices jump and flash, and Cue Dots fires the reel-change marks. Age fades the cyan dye first and the magenta last, so an old print goes pink and its blacks go red.
Lamp picks a carbon arc, xenon or tungsten colour, Framing slides the frame line into view, Vignette sets the lens's cos to the fourth falloff, and Mix fades back to the clip. The projection paints the whole frame, so at full mix the output is opaque whatever the clip's alpha.
There's also an OpenFX plugin for DaVinci Resolve, Vegas Pro, Nuke and Natron with the same projector model, fetching the held pictures from the clip itself. There, Cue Dots becomes a toggle you keyframe.
- The clip held at the projector's rate, 16, 18, 24 or 25 fps, changing only at pull-downs
- One, two or three shutter blades at 45 to 315 degrees, integrated over each display frame: flicker at the beat of the two rates
- Frames spanning a pull-down blend both frames in the shutter's proportions
- Correlated gate weave, more of it on a shrunk print, and Framing onto the frame line
- Scratches fixed in the gate, dust on the print, a hair, splices and reel-change cue dots
- Dyes that fade at their own rates, cyan first, so an old print goes magenta
- Carbon arc, xenon and tungsten lamps, and the lens's cos to the fourth falloff
- Universal macOS bundle and a Windows x64 DLL
Where it stands
v0.2.1, and early days. v0.2.0 added the OpenFX build, which has been checked in DaVinci Resolve Studio 21.1 on macOS; Vegas, Nuke and Natron are untried. The FFGL plugin hasn't been loaded into Resolume on macOS yet. On Windows it has: a build loads, registers and renders in Resolume Arena 7.27.1 on software rendering (no GPU), with every parameter as declared, and it passed all 9 of the fleet's checks. Nine controls showed as moving the picture there and six (FPS, Shutter Angle, Scratches, Dust, Hair and Splices) were inconclusive, because the projection itself never stands still. Everything else is measured by an offline harness driving the real plugin and reading every property back out of the picture: a flat grey's brightness at 60 Hz has, bin for bin, the spectrum the shutter's Fourier series predicts; the picture only changes at pull-downs, and every pull-down happens in the dark; a scratch holds still while the picture weaves under it; the weave has the stated deviation and correlation; each dye keeps its stated density and a grey goes magenta; and a resize leaves the print and the previous frame alone. It catches eight models broken on purpose, and all 15 controls change the picture. The default shutter is 3 blades at 270 degrees, not the classic 2 at 180, because at a 60 Hz output the classic shutter pulses the whole frame at 12 Hz by about 25 to 29 percent, inside the band broadcast flash guidelines restrict. The default keeps it to 7 to 9 percent. The checks prove the stated model, not a real projector: the weave, the dirt rates and the fading rates are numbers I chose, the lamps are black bodies, the double image at a pull-down is always on, and there's no Stock control, only Age. The macOS build is signed and notarised. There's a user guide and a browser demo, but no presets. Try it in your own rig before you trust it in a show.
Watch it running
Nothing loads from YouTube until you press play.Watch it there instead