概要 動画トリマー
This trimmer cuts videos to the exact start and end point you choose, entirely inside your browser using the WebCodecs API. The video is decoded, trimmed at the timestamps you pick and re-encoded to a clean MP4 (or WebM) — with a quality selector to balance file size against clarity.
Because nothing is uploaded, it is safe for private or confidential footage and there is no file-size ceiling beyond your device's memory. Keep the original audio or remove it entirely, and preview the trimmed result before downloading.
使い方 動画トリマー
- Open your video
Drop an MP4, WebM or MOV file. A preview player appears together with the trim range controls.
- Set start and end
Scrub the preview and press Start here / End here to mark the cut points, or fine-tune with the seek slider. The selected length is shown live.
- Trim and download
Pick format, quality and audio handling, then press Trim video. Preview the result and download it — the original file is never uploaded.
よくある質問
Are my videos uploaded to a server?
No. Decoding, trimming and encoding all happen locally in your browser via WebCodecs. Your footage never leaves the device, so private clips stay private.
Why is the video re-encoded instead of cut losslessly?
Frame-accurate cuts require re-encoding, because lossless cutting can only split at sparse keyframes (often 2-10 seconds apart). Re-encoding lets you cut at any timestamp — use the High quality setting to minimise quality loss.
Which formats are supported?
Anything your browser can decode — MP4 (H.264), WebM and most MOV files. Output is MP4 (H.264/AAC) or WebM (VP9/Opus), chosen automatically based on what your browser can encode.