Convert timecode to frames and real time, add or subtract two timecodes, or find the duration between them. Handles drop-frame and non-drop-frame at every common broadcast frame rate.
Type digits with or without separators (01020304 works). Drop-frame timecode uses a semicolon before the frames.
Timecode counts frames in whole numbers: 30 frames a second makes a second, 60 seconds a minute. But NTSC-derived video does not run at exactly 30 frames a second. It runs at 30000/1001, about 29.97. Count that picture at "30 per second" and the timecode slowly falls behind the wall clock: 3.6 seconds every hour.
Drop-frame fixes the numbers, not the pictures. No video frame is ever discarded. Instead, the timecode skips frame numbers 00 and 01 at the start of every minute, except every tenth minute. That is 18 numbers skipped every 10 minutes, which cancels out the drift, so one hour of drop-frame timecode matches one hour on the clock. The same idea at 59.94 fps skips four numbers (00 to 03) per minute.
Non-drop-frame is written with colons, 01:00:00:00, and drop-frame with a semicolon before the frames, 01:00:00;00. The two are not interchangeable: one hour of non-drop at 29.97 is 108,000 frames and about 1 hour 3.6 seconds on the clock, while one hour of drop-frame is 107,892 frames and 1 hour on the clock.
Impossible timecodes are rejected with an explanation. In drop-frame, for example, 00:01:00;00 does not exist, because that frame number was skipped.
Drop-frame rule: skip frame numbers 00 and 01 (00–03 at 59.94) at the start of each minute except every tenth minute. Verified against the standard reference values, such as 107,892 frames in one drop-frame hour at 29.97 fps.
Because 29.97 fps is slightly slower than 30. Counting frames as if they ran at 30 per second makes timecode drift from the clock by about 3.6 seconds an hour. Drop-frame skips certain frame numbers, never frames, so that timecode stays in step with real time.
Drop-frame is only defined for the NTSC-derived rates, 29.97 and 59.94 fps. Rates such as 24, 25 and 50 fps have no drop-frame version, and 23.976 is normally used non-drop.
At 29.97 fps, 108 frame numbers are skipped per hour (two a minute, except every tenth minute). At 59.94 fps it is 216. That is exactly the difference between 108,000 and 107,892 frames in an hour at 29.97.
Use the Duration tab: enter the start and end timecode and the frame rate. For a drop-frame source the tool counts the skipped numbers correctly, and for one that crosses midnight it also shows the length across midnight.
No. Everything is calculated in your browser.
Yes: a free full-screen gallery clock with time of day and a countdown to air. And CGRoll, our broadcast graphics playout app, includes clocks, tickers and countdowns for on-air graphics.
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