About Edge Code
Both film and video record frames and produce large numbers of frames over time.
Editors and editing machines need to find frames efficiently and reliably, so film and
video both have ways to uniquely count and identify frames. Film uses edge code, which
can be KeyKode (developed by Kodak and also known as keycode) or ink numbers
printed on the edge of the film. Video uses timecode, stored in a timecode track.
Both edge code and timecode are based on simple frame counters: each time a frame
advances, the frame counter increases by one. But the similarity ends there. Edge code
equates frames with film length, so a certain number of frames equals a foot (thus the
origin of the word footage). Timecode equates frames with time—for example, in PAL
video, 25 frames equals 1 second.
Edge code looks like this:
KJ 29 1234 5678+02
The first eight characters (KJ 29 1234) identify the film manufacturer and include an
identification number for the film roll. The final six numbers (5678+02) actually identify
specific frame numbers. The first four numbers (5678) are the footage count (the
number of feet of film), with the last two numbers (+02) counting the frames for that
foot of film (16 frames with 4-perf 35mm, the most common film format).
Timecode looks like this:
Timecode numbers represent hours, minutes, seconds, and frames, respectively.
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