About Video Trimmer
AntiUpload's Video Trimmer lets you cut a clip out of a longer video — useful for stripping a 30-second highlight from an hour-long recording, removing dead time at the start and end before sharing, or extracting a specific moment to embed elsewhere. The tool runs in two modes that match the two real-world trimming needs: fast lossless trim (the default) and frame-accurate re-encode (for precision cuts). Most online trimmers offer one or the other; we expose both and let you pick per-cut.
**Fast mode** uses FFmpeg's stream-copy (`-c copy`) which doesn't decode or re-encode the video — it copies byte ranges from the source to the output. This means: zero quality loss, near-instant processing (a 5-minute trim on a 1-hour source takes 2-3 seconds), and the output's video stream is bit-identical to the source's. The catch: the cut snaps to the nearest keyframe before the requested timestamp. On a typical 30 fps source with 2-second keyframe intervals, the actual cut can land up to 150 ms earlier than you asked for. For most use cases ("trim the first 10 seconds of nothing", "clip 45 seconds out of the middle") this is invisible.
**Frame-accurate mode** re-encodes the trimmed segment with libx264 — the cut lands exactly on the requested timestamp instead of snapping to a keyframe. Use this when you need precise frame-level control (for an edit suite hand-off, for example). The trade-off is re-encode time (~real-time on hardware-accelerated paths, slower on Firefox / older browsers) and some compression generation loss. The fade-in / fade-out option (0.25s / 0.5s / 1s) automatically enables frame-accurate mode because fades require re-encoding to apply the gradient.
How it works
- Drop your videoAccepts MP4, MOV, WebM, MKV, AVI, M4V, FLV. No file-size limit from us — multi-hour recordings work fine, the limit is your device RAM.
- Set start and end times in secondsDecimal seconds (e.g. 12.5 for 12.5 s). Use 90 for 1:30. The trimmed segment is the range [start, end]; everything outside is dropped.
- Optionally pick a fade-in and fade-outNone / 0.25 / 0.5 / 1 second presets. Fades use FFmpeg's fade filter for video and afade for audio, anchored at the segment boundaries. Setting either fade automatically forces frame-accurate mode (fades can't be applied with stream-copy).
- Optionally enable frame-accurate cutDefault is fast stream-copy (lossless, keyframe-snapped). Toggle frame-accurate when you need the cut to land exactly on the requested timestamp — slower but precise. Auto-enabled when fades are set.
- Click Trim videoOutput is MP4 in either mode. Fast mode finishes in a few seconds regardless of clip length. Re-encode mode takes proportional to the trimmed segment's length.