Frame-accurate SMPTE math: add and subtract HH:MM:SS:FF timecodes at 24 or 30 fps with correct frame carry.
Timecode arithmetic is base-60 math with a frame twist: the last field rolls over at the frame rate, not at 60. Adding 12 frames at 24 fps is half a second — get the carry wrong and your edit is off by frames.
TCalc parses SMPTE timecodes natively. Write them as HH:MM:SS:FF with the frame rate suffix (f24, f30), mix them with plain durations, and read the result back as frame-accurate timecode.
Add a clip length to a start timecode.
Carry across seconds, minutes, and the hour boundary.
Subtraction with frame borrow at 30 fps.
Add field by field from the right, carrying frames at the frame rate and seconds/minutes at 60. At 24 fps, 00:59:30:00 + 00:01:15:12 = 01:00:45:12. In TCalc you type both timecodes with an f24 suffix and get the frame-accurate sum.
The output formats include 24 fps and 30 fps timecode, plus a configurable default frame rate. Input accepts an explicit suffix per value, e.g. 01:00:00:00f24 or 00:00:05:15f30.
Yes — a timecode is a duration under the hood, so you can add plain time to it (e.g. a 90m runtime) and format the result back as timecode at your frame rate.