The Compendium of Image Errors in Analogue Video describes this as “Color Smearing After an Editing Cut.”1
This artifact describes the abrupt start to a recorded program that was created on a previously recorded segment of tape without the use of flying erase heads or advanced insert edit technology. Between two shots in sequence, a band of semi-opaque color moves at a constant rate from top-to-bottom in the video image. After it rolls out of the image, the artifact does not reappear. There may be a small bit of accompanying audio from the first image heard just before or after the second image is displayed.
This is a common artifact in recordings made using consumer grade video recorders because the erase heads on these machines are fixed in a stationary position in the tape path, just before the video drum scanner. As the tape moves past the erase head and comes into contact with the video record heads, an image is recorded. However, there is a small bit of tape that lies between the stationary erase head and the video record head, and if there is content already recorded on a tape and an edit is made without significant pre-roll to account for the dead space in the record path, old video will be left at the edit point. This leftover video displays as color smearing.
Gfeller et al. offer further explanation: “The image error moves down the screen because the head gap on the erase head is oriented vertically; as the tape comes into contact with the erase head, adjacent helical tracks (fields) are erased at a slightly different height on each track, causing the transition from the affected to the unaffected picture areas to move down the screen field by field.”2
VTRs used for professional and non-linear editing employ heads that can be perfectly timed or synchronized to an incoming video signal, so that the edit point is field accurate and clean.
Can it be fixed?
No, this artifact is part of the video signal and there is no way to eliminate or correct it.
1. Johannes Gfeller, Agathe Jarczyk, and Joanna Phillips, “Color Smearing After An Editing Cut” in Compendium of Image Errors in Analogue Video (edited by Swiss Institute for Art Research, Zürich: Scheidegger & Spiess, 2012), p.64, video 12. ↩
2. Gfeller et al., “Color Smearing After An Editing Cut.” ↩