Health warning

WARNING — Photosensitive seizure warning: This visualizer produces strong contrast, rapid flashes, and flickering patterns synchronized to audio. Certain combinations of light, color and flashing can have adverse effects on your health. A very small percentage of people may experience seizures, blackouts, or other symptoms when exposed to such visual stimuli, even with no prior history of epilepsy. Stop using the visualizer immediately if you feel any discomfort, and consult a doctor if you experience dizziness, altered vision, eye or muscle twitches, loss of awareness, disorientation, or any involuntary movement or convulsion. Use in a well-lit room and sit a comfortable distance from the screen.

Showing it to others

The warning applies to everyone who can see the screen, not only to the person operating Spiroshader. On a TV, a second screen or at a party or event, tell your audience before the visuals start.

Flicker metric and filters

Spiroshader can rate presets by how much they flicker and filter the playlist by that rating. The rating is an estimate, not a safety guarantee: a preset can flicker more with your music, or later in its run, than during its brief measurement; an authored value is only as reliable as its author’s judgment; and unmeasured presets pass the filters unless you exclude them. If you or your audience are sensitive to flashing light, do not rely on the metric or the filters alone.

Flash protection and blackout

Settings → Safety offers Flash Protection, which dims the picture while repeated flashes cover a large part of the screen. It is on at Standard by default; Strict steps in sooner and for smaller areas, slows every transition to at least one second, turns off beat cuts and skips flickering presets. Skip Flickering Presets keeps auto-advance away from presets with a high flicker rating and from presets not measured yet. The blackout key (b by default) turns the picture black at once.

These tools are best effort and not a safety guarantee. Flash protection can miss flashes, the first flashes always pass, and content it lets through can still be uncomfortable or harmful for some viewers. They do not offset this warning: everything above still applies, with or without them. Keep the blackout at hand and stop at the first sign of discomfort.