Load both videos, then either set START/END on each manually, or mark one common sync frame in each and press "Compute from sync frames".
Click a deck, then ←/→ = 1 frame, Shift+←/→ = 10 frames, Space = play/pause, s = mark sync frame. After computing, go to Tab 2 to preview and export.
00:00.000/ 00:00.000
Clips arrive here automatically from "Compute from sync frames" — playing only the trimmed, synced section of each original. Both stay locked together; drift is auto-corrected. ←/→ step both, Space plays both.
Export synced clips
Angle A
Angle B
Lossless: instant stream-copy via ffmpeg.wasm, keeps original quality & codec (first use downloads ~10 MB once). Re-encode: real-time WebM, always works in any browser — tab must stay visible.