Sync Checker

Play a test clip with 1-frame white flashes and 1-frame 1kHz pops, one pair per second. Point the camera at the flash and the mic at the speaker. The camera's own capture rate limits video timing precision to roughly ±16–33ms even though audio timing is much tighter — this tool is built to catch frame-level and half-frame drift reliably, not to match dedicated photosensor hardware at sub-millisecond precision. If your rig has a consistent fixed offset, play a known-good reference once and tap "Zero" to calibrate it out.