Video Trimmer

How to use Filesvo

1. Select or drop a video and preview it to find your in and out points.
2. Enter start and end times (like 0:12 and 1:30) and pick a trim mode.
3. Click Trim Video and download the clip.

Exact cut vs. fast copy

Video is stored as occasional full frames (keyframes) with the frames between them describing only changes. A lossless cut can therefore only begin at a keyframe — often a few seconds apart. Fast copy mode uses this: it's nearly instant and touches no pixels, but your clip may start up to a few seconds before the time you asked for.

Exact mode decodes and re-encodes the clip instead, so it starts on the precise frame you chose. The cost is encoding time and a generation of H.264 re-compression at high quality (CRF 23). The tool explains both modes up front instead of quietly picking one.

The FFmpeg command this runs

This tool is FFmpeg itself, compiled to WebAssembly and running in your browser. Below is the command it builds with the options set as they arrive — generated from the same code that performs the conversion, not written out by hand, so it cannot drift out of date. Paste it into a terminal with FFmpeg installed and it does the same job there.

ffmpeg -y -ss 5.000 -i input.mp4 -t 10.000 -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" -c:v libx264 -preset veryfast -crf 23 -pix_fmt yuv420p -c:a aac -b:a 128k -movflags +faststart output.mp4

The 5-second start and 10-second duration stand in for whatever you set on the sliders; every other flag is fixed.

What each option on the tool changes in that command:

Cut accuracy

Frame-accurate — re-encodes — -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" -c:v libx264 -preset veryfast -crf 23 -pix_fmt yuv420p -c:a aac -b:a 128k -movflags +faststart

Keyframe cut — copies the streams — -c copy

The input and output names are placeholders. Your own filenames are used inside the browser, and neither file leaves your device.

Private by design

Your files are processed directly in your browser using the open-source FFmpeg engine compiled to WebAssembly and are not uploaded to Filesvo. Nothing is stored on our servers, because nothing ever reaches them.

The engine is a static file your browser downloads once and then caches — the only network request this tool makes. It is used exactly as its authors published it; see the engines and their licences.

Frequently asked questions

Which mode should I use?

Use Fast copy when 'roughly there' is fine or the file is long — it finishes in seconds with zero quality loss. Use Exact when the cut point matters, like removing the first 3.5 seconds of a take.

Why does my fast-copy clip start earlier than I asked?

Because lossless cutting can only start at a keyframe, the tool includes the footage from the previous keyframe so nothing you asked for is missing. Use Exact mode if you need the precise start time.

Are my files uploaded?

No. The first time you use an audio/video tool, your browser downloads the open-source FFmpeg engine — a 32 MB file, roughly 10 MB once your connection compresses it — as a static file, and that is the only network traffic. Your media files are then processed entirely on your device and never reach a Filesvo server.

Does this work on phones?

Yes on recent devices, with limits: the engine is a 32 MB file (roughly 10 MB compressed in transit), and phones have less memory available to the browser, so large videos can fail on mobile. If a file fails on your phone, try a smaller file or a desktop browser. The 100 MB per-file limit applies everywhere.