Lossless Video Trimmer
Most video editors re-encode your video when you trim it, degrading quality with each edit. JustTrimVideo uses "stream copy" mode - it extracts the exact bytes you want without touching the video data. The output is bit-for-bit identical quality to the input.
What is Stream Copy?
Stream copy (also called "remuxing") copies the video and audio data directly without decoding or re-encoding. It's like cutting a piece of tape rather than copying it to a new tape. The result: zero quality loss and instant speed.
Lossless vs Lossy Trimming
| Aspect | Lossless (Stream Copy) | Lossy (Re-encode) |
|---|---|---|
| Quality | Identical to original | Degraded (generation loss) |
| Speed | Instant (seconds) | Slow (minutes to hours) |
| File Size | Proportional to length | Depends on settings |
| CPU Usage | Minimal | Heavy |
| Format Change | Same format out | Can convert formats |
Why Quality Loss Matters
Every time a video is re-encoded, it loses quality - this is called "generation loss." Consider:
- Original video: Crisp 4K footage from your camera
- After 1 re-encode: Slight softness, minor compression artifacts
- After 2-3 re-encodes: Visible blockiness, color banding
- After many re-encodes: Severely degraded, "YouTube reupload" quality
With lossless trimming, you can edit the same file 100 times and it stays identical to the original.
The Keyframe Tradeoff
Why cuts might be slightly off
Lossless cutting can only happen at "keyframes" (I-frames) - typically every 1-10 seconds in most videos. This means your cut point might be up to a few seconds off from where you specified.
The tradeoff: Slightly imprecise cuts vs. perfect quality and instant speed. For most users, this is a worthwhile tradeoff. If you need frame-perfect cuts, you'll need a tool that re-encodes (with quality loss).
Technical Details
Under the hood, JustTrimVideo runs FFmpeg with the -c copy flag:
ffmpeg -i input.mp4 -ss 00:01:00 -t 30 -c copy output.mp4This tells FFmpeg to copy (-c copy) both video and audio streams without re-encoding. The same command that professional editors use for quick cuts.
Best Use Cases for Lossless Trimming
Archival Footage
Preserve original quality for family videos, historical footage, or master copies.
Raw Camera Files
Trim before importing to your editor to save storage without quality loss.
Iterative Editing
Make multiple cuts over time without cumulative quality degradation.
Quick Rough Cuts
Instant results when you just need to remove the beginning or end.
Ready for lossless trimming?
Go to the Video Trimmer →