tape crease
Also called: creased tape, tape fold, wrinkled tape
A tape crease is a physical fold in videotape that causes a skewed, noisy band across the picture. Learn how it forms and how to simulate it in After Effects.
WHAT CAUSES IT
A tape crease is a permanent fold or wrinkle in the magnetic tape, usually made when the tape is caught in the transport, stretched around a capstan, or wound under uneven tension. Where the tape is creased, a section of the tape surface lifts away from the head drum. The head loses contact for part of its sweep, so the recorded FM signal is read weakly or not at all, and the horizontal sync pulses go missing. The crease also changes the local length of the track, because the path through the fold is longer or shorter than the track recorded on flat tape. Lines read just before and after the crease are therefore displaced in time, and the monitor shows them shifted sideways while its horizontal oscillator tries to keep lock. A crease runs across the tape width, and since each head traces a slanted track, the damaged part shows up as a band that repeats at about the same position every frame while the tape plays.
WHAT IT LOOKS LIKE
A fixed horizontal band, a few lines to a fifth of the frame high, across the picture, containing noise and snow. At the edges of the band the picture is bent sideways in an S shape or skewed so vertical lines lean. Color usually drops out inside the band, and the lines just below may carry a lighter gray tone. Because the crease repeats on every pass, the band returns at the same height and shape every time the tape rewinds, making it look like a permanent scar rather than a passing glitch. It can move slowly up or down as the tape slips, but stays recognizable.
WHERE YOU SEE IT
Tapes that were eaten and rescued from a VCR, camcorder tapes that jammed, old rental tapes with a history, and archive tapes salvaged after jamming. In film it tells the audience that the tape has been damaged, a favorite detail in found-footage horror and analog horror where the tape itself is the artifact. A crease is also a typical reason a transfer shows one persistent artifact throughout a single scene.
RECREATE IT
TERMINAL FADE
CONTROLS TRACKING COLLAPSE, DROPOUT, CHROMA DEATH
TRACKING COLLAPSE builds the band and its noise. Raise CHROMA DEATH moderately to drop color inside the damaged area, and add a little DROPOUT around it. Keep the band at a stable height because a crease does not wander as a tracking fault does. Do not push everything to maximum, or it reads as total tape failure.
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STATIC DRIFT
CONTROLS STATIC BREAK, DRIFT
Use STATIC BREAK to create the sideways skew at the edges of the band. Keep DRIFT low and constant so the skew looks like a fixed physical fold. Animating it quickly makes it look like electronic instability rather than a crease.
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HOW TO MAKE IT IN AFTER EFFECTS
1. Pre-compose the footage. 2. Apply TERMINAL FADE and raise TRACKING COLLAPSE until one band of noise appears at the height you want, with its color drained by raising CHROMA DEATH. 3. Apply STATIC DRIFT above it, and raise STATIC BREAK a little so the lines at the band edges skew sideways. 4. Keep DRIFT low. 5. To keep the crease in the same place, leave the controls static rather than keyframing them wildly, and make only slow changes to simulate the tape slipping a few lines up or down. 6. If the crease should appear mid-shot, cut the layer and apply the effect to the second half, or keyframe TRACKING COLLAPSE from a minimum to your target over two or three frames, since a physical fold arrives suddenly. 7. Add a small amount of DROPOUT for specks near the band. 8. Compare to a still of a real crease if you can, because the S bend at the edges is what makes it read as physical damage.
QUESTIONS
- What causes a crease in videotape?
- Usually the tape gets caught or pinched in a transport, jams in a camcorder, or is wound under uneven tension. The magnetic tape folds, and the fold stays. Playing a creased tape can harm the heads, so the tape should be cleaned and carefully transferred.
- Can a creased tape be repaired?
- Sometimes the tape can be flattened and transferred on a careful deck, but the crease rarely disappears completely. Archive services will usually try a slow, low-tension playback, and the damaged lines stay noisy in the capture. The fold is baked into the magnetic layer and the base film, so the best result is a slow transfer, then cleanup of the leftover noise in post.
- How is a tape crease different from a tracking error?
- A crease is a fixed physical defect that returns at the same position each time. A tracking error is a head alignment problem that changes when the tracking control moves and affects the whole tape. If you play the tape back on another deck and the band stays in the same place, it is a crease. If it moves with the knob, it is tracking.
- Does a crease affect the audio?
- It can. The linear audio track runs along the edge of the tape, so a crease that reaches the edge causes dropouts or a short loss in the soundtrack, while hi-fi audio recorded with the video heads is damaged by the same noise as the picture.