How MP4 to WAV Conversion Works
AnyTool extracts WAV audio from an MP4 entirely in the browser using a self-hosted single-threaded ffmpeg.wasm engine — the core (ffmpeg-core.js + the 32 MB wasm) is bundled from npm and served as a same-origin asset, so nothing is fetched from a CDN. The video track is dropped with -vn, the AAC audio is decoded, and ffmpeg writes it out with -c:a pcm_s16le, producing uncompressed 16-bit PCM in a WAV container — a lossless, editor-friendly audio file. Single-threaded is deliberate: the multi-threaded core needs SharedArrayBuffer + cross-origin isolation (COOP/COEP), which would block cross-origin ad iframes, so it is avoided.
- Runs client-side — the video is never uploaded
- Self-hosted ffmpeg core (bundled) — no CDN
- -vn drops video; -c:a pcm_s16le decodes audio to PCM
- Lossless uncompressed WAV output
- Single-threaded (keeps ads working); no backend, no cap
- Works offline after first load
