Trim Video

How it works

Trim Video reads your file's metadata — duration, resolution, and the position of every keyframe — using just a few kilobytes of the file, regardless of its actual size. When you trim, it works out exactly which bytes of the original file cover your selected time range and copies them straight into a new, smaller file. No frame is ever decoded or re-encoded, which is why the operation finishes in a couple of seconds even on a multi-gigabyte source file, and why the output is pixel-for-pixel identical to the original — there's no generation loss, because there's no re-generation at all.

Limitations

The trim's start always snaps to the nearest keyframe at or before your selection — the timeline shows exactly where, so this is never a surprise. Supported containers are MP4, M4V and MOV (including ProRes, since the video itself is never decoded); WebM and Matroska (MKV) use a different container format and aren't supported yet. Audio and any additional tracks are copied through unchanged, trimmed to the same time range as the video.

FAQ

Is this really instant, even for a huge file?

Yes, because nothing gets decoded or re-encoded. The trimmed file is assembled by copying the exact byte range covering your selected time range out of the original — the same 'smart cut' technique professional video editors use for lossless trims. A 2GB file trims in roughly the same time as a 20MB one, because the actual video data is never touched, just referenced.

Why does my cut start slightly before where I dragged the slider?

Because it snaps to the nearest keyframe at or before your selection — see the timeline's tick marks. Most frames in a compressed video only make sense as a difference from the frame before them, so a lossless cut can only start cleanly at a frame that stands on its own. Starting anywhere else would produce a broken, glitchy first second until the next keyframe arrives. Losing a fraction of a second you didn't ask to keep is better than a broken start, so the cut always rounds outward, never in.

Does the end of the clip need to land on a keyframe too?

No — only the start does. Once decoding is underway, it can stop cleanly at any frame, so your out-point is exact to the frame you chose.

Is my video uploaded anywhere?

No. This tool reads only the small metadata region of your file plus the exact byte range you're keeping — using your browser's own file APIs — and nothing ever leaves your device.