Video Trimmer

No. The trimmer loads FFmpeg via WebAssembly and processes the file locally in your browser tab. Nothing is transmitted to any server — you can watch the network tab to confirm.

MP4 output is re-encoded with H.264 at CRF 23 (visually near-lossless), which guarantees an accurate cut on a non-keyframe boundary without a black first frame. WebM uses VP9 at CRF 30. Audio is re-encoded to AAC 128 kbps for MP4 and Opus 128 kbps for WebM. If you want an exact bit-for-bit slice with no re-encode, use a desktop tool — browser FFmpeg always re-encodes for accuracy.

WebM (VP9 + Opus) requires FFmpeg's multi-threaded core, which only loads when your browser has SharedArrayBuffer support available. That requires specific HTTP headers (COOP/COEP) that this tool page sets. On very old browsers the WebM option may be disabled — MP4 will still work everywhere.

Yes. Pick the MP3 output format and the trimmer drops the video track and encodes the audio with LAME at VBR quality 2 (≈190 kbps). WAV is also available if you need a lossless PCM file for editing.

Up to 10 clip ranges per upload. Each clip is processed in sequence and downloaded individually, so you can cut a long recording into several named pieces in one pass without re-uploading.