Vidlora guide
How to trim a video without losing quality
Trimming doesn't have to mean re-encoding. A "stream copy" trim cuts the file at the container level, copying the existing video/audio data directly instead of decoding and re-encoding it.
4 minute read
Why stream-copy trimming is lossless
Since the underlying video and audio data is copied byte-for-byte rather than regenerated, the kept portion is identical in quality, resolution, and bitrate to the original — there's nothing to lose.
The one limitation: keyframes
A stream-copy cut has to start at a keyframe (a complete, standalone frame) rather than an arbitrary point, so the actual cut point can land up to a fraction of a second away from exactly where you asked. For most uses this is imperceptible.
When you do need to re-encode
If you need a cut at an exact frame regardless of keyframes, or you're also changing something else (resolution, format), re-encoding becomes necessary — trading a small quality/time cost for that precision.
Try the free video downloader