showstack / glossary / drop-frame
Drop frame 丟幀時碼
A timecode counting scheme that skips frame numbers 00 and 01 at the start of every minute except every tenth minute, so the count stays in step with the wall clock at 29.97 fps. It drops numbers, not frames — no picture is lost. 108 labels an hour, which is very close to the 107.89 frames a 30 fps counter gains over real 29.97 time.
中文
一種時碼計數方式：每分鐘開頭跳過 00 與 01 兩個幀號，但每第十分鐘不跳，使計數在 29.97 fps 下與牆上的時鐘同步。它丟的是編號而不是畫格，沒有任何影像遺失。每小時跳過 108 個編號，與 30 fps 計數器相對真實 29.97 時間所多算的 107.89 格非常接近。
Regional usage
| Where | Term | Note |
|---|---|---|
| UK / US | Drop frame / DF, against non-drop / NDF | |
| HK / TW | 丟幀 / 掉幀時碼 |
Easy to get wrong
The name is the problem; no picture is dropped. And 00:01:00:00 is not a valid drop-frame time at all, so a system that accepts it is not validating.
Next to this
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Where it shows up on the wire
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Sources
- SMPTE ST 12-1 Time and Control Code — SMPTE primary
Understand the mechanism
Something wrong, or missing?
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