- How does it find the beats?
- It listens to the video's own sound in your browser: it measures where the music hits hardest, works out the tempo in BPM, and places a beat on each strong hit that keeps that tempo. Nothing uploads for this step. If the tempo comes out at half or double the real one, the Half and Double buttons fix it, or type the BPM yourself.
- Can I choose which beats get an effect?
- Yes. Pick every beat, every 2nd or every 4th, and which beat of each group starts it. Tap the timeline to add a hit anywhere, or tap a hit to remove it. Your edits stay when you change the other settings.
- My video has no music yet. Can I still use it?
- Add the song first with the add audio tool, then bring that video here so the hits follow the music. If you know the tempo, you can also type the BPM and the hits land on a steady beat from the start of the clip, or play the video and press Add hit here on each beat.
- Will the flashes land exactly on the beat?
- Each hit peaks on the frame closest to the beat, so it is never more than one frame away: about 33 ms at 30 fps. That is tighter than people can notice between sound and picture.
- Does it change my audio or the video size?
- No. The soundtrack is copied over unchanged, and the video keeps its size, shape and frame rate.
- How is this different from Overlay Effects and Auto Zoom?
- Overlay Effects lays one clip over your video, like a light leak, film grain or a single flash at a time you pick. Auto Zoom adds punch-ins to talking videos on a fixed rhythm. Beat Sync Effects follows the music: every hit lands on a beat of the song.
- Is there a limit on length?
- One render places up to 1,000 hits, which covers almost 8 minutes of a 128 BPM song with a hit on every beat. For longer videos, pick every 2nd or every 4th beat.