Beat-Synced Slideshows Explained: Timing and Real Browser Limits

Quick answer

Sync to beat advances an image on each metronome beat. Fixed timer changes images every 1–10 seconds independently of BPM, so you can keep images slower than the sound.

The actual timing choices

The fixed timer slider permits half-second steps from 1 to 10 seconds. BeatSlide does not currently include an every-two-beats or every-four-beats control. For more viewing time, use the fixed timer rather than looking for those options.

Calculate beat-synced duration

Seconds per beat equals 60 divided by BPM. At 40 BPM an image lasts approximately 1.5 seconds; at 60 BPM, 1 second; at 180 BPM, about a third of a second. The slideshow advances in its current order and loops to the beginning after the last image.

The current image uses a short 0.4-second fade-in transition. At fast BPM, a new change may arrive before that duration completes. This is different from promising an instantaneous change or a measured perfect audiovisual crossfade.

What random BPM changes

Random mode affects image pace only when Sync to beat is selected. A faster tempo produces more image changes per second. Fixed timer retains its own interval, regardless of the selected random state.

Automatic pauses display a countdown overlay. With beat sync, no new beats means no beat-driven image advancement. With fixed timing, the image timer currently continues behind the overlay, so the image visible afterward may differ. Holding an image suppresses advancement in either timing mode but leaves audio playing.

How accurate is synchronization?

The app generates pulses using Web Audio and advances slides through browser state updates. Its metronome ticks use browser timers, not a published sample-accurate audiovisual scheduling benchmark. Screen refresh, image loading, main-thread workload and output hardware can all affect perceived alignment.

The design connects image advancement to beat events; that does not establish microsecond accuracy or prove the result is more precise than another metronome. Keeping images loaded and the page visible reduces some avoidable interruptions.

Choose for the material

If you want to inspect detailed photography, a fixed timer gives a stable viewing interval. If the visual changes themselves should mark the rhythm, choose beat sync. A single image will simply recur; several images make order and timing easier to observe.

Avoid rapid high-contrast changes if uncomfortable. Stop or slow image timing instead of interpreting discomfort as a difficulty target. No choice has been validated here as improving focus, stamina or immersion for every reader.

Related guides

• BPM settings and timing examples
• How random BPM works
• Choosing a timing mode with worked examples