Video Trimmer

How the Video Trimmer works

Most raw footage carries dead air. There are seconds of fumbling before a screen recording starts, a phone video that runs on after the moment has passed, or a Zoom export that opens with three minutes of people saying "can you hear me?". Trimming those ends is the most common edit there is, and it rarely deserves a full editing suite.

How the video trimmer works

The browser decodes your file with its own video engine, the same one that plays it in a tab. The trimmer seeks to the start time, plays the clip forward, draws each frame onto a canvas and records that canvas with the MediaRecorder API until it reaches the end time. If you keep the sound, the audio track is routed into the same recording, so picture and sound stay in sync.

Because MediaRecorder writes frames as they arrive, the render runs in real time. A 40-second clip takes about 40 seconds. Keep the tab in front while it works, because browsers slow down background tabs and that shows up as dropped frames.

Choosing the start and end

Scrub the preview player above the options to find your cut points. The player's clock shows minutes and seconds, so convert before typing: 1:25.5 is 85.5 seconds. Leave the end blank to keep everything after the start. Cuts are frame-accurate to within one frame, about 33 ms at 30 fps.

What comes out

The trimmed clip is re-encoded, not copied. Chrome, Edge and Firefox write WebM with the VP9 or VP8 codec, and Safari writes MP4. Resolution matches the source. Quality is set by a 6 Mbit/s bitrate, which is plenty for 1080p talking heads and screen recordings but softer than the original on fast-moving 4K footage.

WebM plays in every modern browser, VLC, YouTube, Discord and most social upload forms. If a platform insists on MP4, open this page in Safari, or run the result through a desktop converter such as HandBrake.

Where a quick trim helps

• Screen recordings: cut the moment you clicked Stop Sharing.
• Uploads with length limits: X allows 140 seconds on free accounts, Instagram Reels 3 minutes and LinkedIn mobile uploads 10 minutes. Trim to fit before you post.
• Bug reports: send the 12 seconds that show the bug, not the 4-minute session around it.
• Clips from lectures and meetings: pull one answer out for a colleague.

Tips and pitfalls

Variable frame rate phone footage can drift slightly in the output. The cut points are right, but the length may differ from your typed span by a frame or two.

Very long sources are fine, because the browser streams them from disk, but the render still takes as long as the part you keep. Trim a 2-hour recording to a 5-minute highlight and you wait 5 minutes, not 2 hours.

No audio after trimming? Some files have their sound in a codec the browser cannot decode, such as AC-3 surround in an MKV. The picture still comes through. Extract the audio separately if you need it.

How to read the result

The stats show the span you kept, the clip length and the file size. Press play on the result before downloading to check the first and last frames are the ones you wanted, then Download.

To cut one video into several parts at once, use the video splitter.

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