Clap Slate Audio-Video Sync Offset Calculator
What timeline translation aligns an audio clap sample with its video frame after accounting for sound travel?
Method, formula and assumptions
Video clap time = frame index/FPS; audio clap time = sample index/sample rate. Expected acoustic arrival = video event time + path/speed. Audio translation = expected arrival - observed audio time.
Input definitions and supported units
- Video clap frame index: Whole-number count, from 0 to 1000000000; zero is supported where the stated method permits it.
- Video frame rate (frames/s): Measured or assumed numerical value, from 0.1 to 10000; must be positive.
- Audio clap sample index: Whole-number count, from 0 to 1000000000000; zero is supported where the stated method permits it.
- Audio sample rate (Hz): Whole-number count, from 8000 to 384000; must be positive.
- Slate-to-microphone acoustic path (m): Measured or assumed numerical value, from 0 to 1000; zero is supported where the stated method permits it.
- Assumed sound speed (m/s): Measured or assumed numerical value, from 100 to 500; must be positive.
Worked example with answer
Video frame 240 at 24 fps is 10 seconds. Audio sample 480,480 at 48 kHz is 10.01 seconds. A 3.4 m sound path at 340 m/s adds 10 ms, so required translation is 0 ms or zero samples.
How to use the results
Positive translation moves the audio later; negative moves it earlier. This aligns the physical arrival at the microphone, not an artificially zero-delay clap.
Results retain full precision internally and display up to four decimal places. Very small nonzero results use scientific notation rather than appearing as zero. Check the labels before comparing values across units.
Limitations and references
Video frame choice has sub-frame uncertainty. Clock drift, separate recording starts, rolling shutter and processing latency may require additional calibration.
The method is a self-contained arithmetic, geometric or explicitly stated mathematical model. There are no imported tariffs, empirical presets or equipment specifications; measured values and allowances must come from your own process.
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