Video Trim & Cut

Video Trim & Cut removes the parts of a video you do not need — the waiting-room screen before a webinar starts, the dead air after a recording ends, or everything except one specific moment you want to isolate. It runs entirely in your browser using FFmpeg compiled to WebAssembly, which means your video is never uploaded to any server. Marketers trimming a 90-minute webinar down to the 73 minutes that actually matter before posting to YouTube, developers extracting a focused product demo from a longer screen recording, and podcast producers cutting a 60-second social clip from a full interview episode all use this for the same workflow: set a start point, set an end point, export.

Lossless export vs. re-encode

The quality of the exported file depends on where the trim points fall relative to keyframes in the video stream. H.264 and H.265 video encodes use keyframes (I-frames) as anchor points — self-contained frames that can be decoded without reference to surrounding frames. All frames between keyframes are delta-encoded relative to the nearest keyframe. Most exported H.264 files place keyframes every 2–5 seconds, though the exact interval depends on the encoder settings used when the original was created.

When both the start and end trim points land exactly on keyframes, the tool uses FFmpeg's -c copy mode: the audio and video streams are copied without re-encoding. The export takes seconds regardless of file size, and the output is bit-for-bit identical to the source at the selected range — no generational loss.

When either trim point falls between keyframes, the affected segment is re-encoded. The tool re-encodes only the short portion between the trim point and the nearest keyframe, then switches back to stream copy for the remainder. This "smart trim" approach touches the minimum number of frames. The re-encode uses H.264 at a quality level that matches the source bitrate closely — the visual difference is not detectable on standard content. The status bar shows whether the export used stream copy or re-encode so you always know which path was taken.

Audio and format handling

Audio streams are processed independently from the video. When video uses stream copy, audio is copied directly. When re-encoding is required, audio is transcoded to AAC at the same bitrate as the source. Input formats supported: MP4, MOV, WebM, and MKV. Output format matches the input — MP4 in, MP4 out. For format conversion, use a separate conversion tool after trimming.

Browser processing and file size

Because processing runs locally in your browser, there is no upload and no file size limit imposed by a server. The practical limit is your device's available memory. Files up to 500 MB work reliably on a modern desktop browser with 8 GB or more of RAM. Performance varies by browser and operating system — Chrome and Firefox on desktop handle large files most consistently. Mobile browsers manage smaller files; for large files on mobile, a desktop browser is more reliable.