How the Boomerang Tool Works
AnyTool builds a boomerang in the browser with a self-hosted ffmpeg engine (no CDN). A single filter_complex pass splits the stream, reverses one copy with the reverse filter, then concats forward + reversed (n grows with the loop count) so the clip plays forward and back seamlessly; dimensions are snapped to even values and the result is encoded H.264 + AAC and read back as an MP4 blob. Doing it in one pass avoids the fragile concat-demuxer route. Audio is muted by default because reversed audio sounds jarring. Single-threaded is deliberate: the multi-threaded core needs SharedArrayBuffer + cross-origin isolation (COOP/COEP), which would block cross-origin ad iframes.
- Runs client-side — the clip is never uploaded
- Self-hosted ffmpeg core — no CDN
- Single filter_complex pass: split, reverse one copy, concat forward+reversed
- concat n scales with the loop count; even-dimension snap
- Audio muted by default (reversed audio is jarring)
- Avoids the fragile concat-demuxer; no backend, no cap
