FAQ

Anyone producing or testing video or animated content should care. This includes video creators, editors, web and game developers, and accessibility specialists. For example, web developers can use it to test animated banners or game scenes, and video producers can check their film or ads for safety. WCAG explicitly notes that all content on a webpage must meet seizure-safety criteria w3.org. Our video analysis tool serves the same audience: if your website or video might have flashing content, it’s wise to check it.

Yes! video-audit.com is a completely free, browser-based testing tool. You do not need to download or install any native desktop software to check your clips. Simply drag and drop your `MP4`, `WebM`, or `MOV` file into our analyzer to instantly test for photosensitive epilepsy risks directly in your web browser.

Yes, our analyzer is published on the official W3C Web Accessibility Initiative (WAI) Evaluation Tools List. It is designed to test specifically for WCAG Success Criterion 2.3.1 regarding flashing content.

The Harding FPA (Flash and Pattern Analyzer) is the broadcast industry’s gold standard software, mandated by UK television (Ofcom) to protect viewers from seizure-inducing material. It is a highly sophisticated, technical piece of paid software designed primarily for professional TV production. While our tool uses similar underlying mathematical concepts (analyzing luminance/red transitions) to detect flashing, we are a free, simplified, web-based tool focused squarely on WCAG 2.3.1 compliance for digital web creators. We are not officially affiliated with the Harding Test.

You can test any video file, including screen recordings of websites or apps. Simply record the content (e.g. using screen-capture software) and upload that video to our tool. The system will analyze it frame by frame.

The output shows two main charts: relative luminance (brightness) and red ratio. Spikes in the luminance chart (usually a white line) indicate bright flashes or transitions; spikes in the red-ratio chart indicate frames where the scene is very red. Above each spike, the tool flags whether it constitutes a WCAG “general flash” or “red flash”. Flashes that occur more than three times per second are considered WCAG violations and listed in warning boxes below the charts.

Photosensitive epilepsy is a form of epilepsy where seizures are triggered by visual stimuli – especially flashing or flickering lights and high-contrast patterns. In other words, rapid light/dark changes can induce seizures in susceptible people (epilepsy.org.uk, developer.mozilla.org).

Flashing content in videos (or animations on a webpage) can induce seizures or other symptoms (dizziness, nausea, migraines) in photosensitive viewers. Studies show that flashes in the range of about 5–30 times per second are most likely to provoke seizures (developer.mozilla.org). To protect users, the WCAG guidelines specifically require that video or animated content limit flashes.

The WCAG 2.0 and later standards have specific criteria to prevent seizure triggers. Success Criterion 2.3.1 (Three Flashes or Below Threshold, Level A) states that pages must not flash more than 3 times in any one-second period unless each flash is below defined brightness/size limits (w3.org, silktide.com). In other words, either limit yourself to 3 or fewer flashes per second, or ensure any faster flashes meet safety thresholds.

To meet WCAG Success Criterion 2.3.1 (Three Flashes or Below Threshold), you must ensure your video or animation does not contain anything that flashes more than three times in any one second period. If a sequence does flash rapidly, the flashes must remain below the General Flash and Red Flash Thresholds. You can use our analyzer to visualize these exact thresholds. If the analyzer detects a violation, you must edit your source video to slow down the frame rate of the flashing effect, lower the contrast of the bright flashes, or reduce the physical surface area of the flashing element on screen.