How to use Video Calibration Clip Generator

Choose bounded clip dimensions, duration and event interval.
Set flash/beep length, beep frequency and its offset after each flash.
Generate with the page visible and compare the intended-event report with decoded playback.

Example: Video Calibration Clip Generator

Schedule a beep a tenth of a second after each flash.

You add

Duration: 3 seconds; width: 640; height: 360; interval: 1 second; pulse: 0.1 seconds; audio offset: 0.1 seconds; frequency: 1000 Hz.

You get

The intended report places flashes at 1 and 2 seconds and beeps at 1.1 and 2.1 seconds. The WebM report states its measured recording duration.

Options

Duration and dimensions: The clip requests 0.5–10 minutes and must fit the output pixel and side limits. Measured duration is reported separately.
Interval, pulse and audio offset: The interval schedules event starts. Pulse length must be shorter than that interval; a beep offset must keep the complete event inside the clip.
Beep frequency: This chooses the oscillator tone. It changes pitch rather than its scheduled start time.

Supported inputs and limits

Generated duration10 intended minutes

Output frame2,073,600 pixels maximum

Generate up to 10 minutes of WebM, within 128 MiB and 1080p. Native canvas recording and Web Audio support are required. Keep the page visible while it records in real time. Browser scheduling and encoding can shift the flashes and beeps, so this is not a precision measurement source.

Where your input is processed

This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.

The schedule describes the requested events

The event JSON records intended flash and beep times. Browser scheduling, encoder startup and playback can move what is actually decoded. Reopen the output and measure its events before using it to assess a system; the requested offset alone is not a measured synchronization result.

Test the playback path you care about

A browser preview, an external display and another player can have different delays. Keep the clip and intended schedule together and describe the path you tested. The generator does not calibrate speakers, displays or an entire audiovisual chain automatically.

Questions about Video Calibration Clip Generator

Is the generated clip a certified timing reference?

No. Its schedule is explicit, but encoded timing needs independent measurement.

Does the event JSON prove the encoded event times?

No. It records the requested schedule. Reopen and measure the recorded WebM to establish its actual event times.

Is my input uploaded?

Nothing is uploaded.

Project manager: Tony Hines · Content updated 4 October 2026 · Report a problem

Video Calibration Clip Generator

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