What is video trimming?

Trimming a video means keeping one continuous part of it and throwing away the rest, such as cutting the silence before a talk starts, removing the end of a screen recording, or saving the one minute of a long clip you want to share. Unlike full video editing, nothing is added or rearranged. The clip simply gets a new start and end.

Tool description

This tool trims a video in your browser. Choose a video, drag the handles on its timeline or type where the clip should start and end, and download the result. The timeline shows thumbnails of the video and the waveform of its sound, so you can find the right moments, and the length of the clip is shown as you go. Nothing is uploaded: the video is processed on your device with FFmpeg compiled to WebAssembly.

Features

  • Drag the start and end handles on a timeline with thumbnails and an audio waveform, and zoom in for precise cuts
  • Set the start and end as seconds, mm:ss, or hh:mm:ss, with fractions of a second
  • Leave Start or End empty to keep the beginning or the end of the video
  • Move the playhead where the clip should start or end and set Start or End to it with one click
  • Play only the selection in the preview to check the cut before trimming
  • Fast mode copies the video and audio without re-encoding, so there is no quality loss and the file keeps its format
  • Precise mode re-encodes the clip to MP4 (H.264 and AAC) so it starts on the exact frame
  • Shows the clip length, output file size, and a preview before you download
  • Works with MP4, WebM, MOV, and other videos your browser can play

How it works

The tool reads the length of the video in the browser, then runs FFmpeg on your device. In fast mode FFmpeg seeks to the start and copies the streams into a new file of the same type. A video can only begin on a keyframe, the full picture that the following frames are based on, so a fast cut starts at the keyframe nearest to Start, which can be a second or two away. Precise mode decodes the video and encodes it again from the exact start frame, which takes longer and produces an MP4.

Tips

  • Use fast mode first. If the clip starts a little early or late, turn on Cut on the exact frame.
  • Processing happens in your browser's memory, so very large videos can be slow or fail. Close other heavy tabs if that happens.
  • The first run downloads FFmpeg, about 30 MB. Later runs on the same page start right away.