# Trim MP4 Without Re-encoding

> Trim an MP4 locally in your browser with stream copy, preserving the original quality and keeping the video on your device.

Canonical URL: https://soulnio.com/trim-mp4-without-re-encoding

## How it works

Choose an MP4, set the start and end times, and trim it with stream copy. Compatible video and audio streams are copied rather than re-encoded.

## Result

A shorter MP4 that preserves the original encoded video and audio quality.

## Limitations

Lossless trimming follows nearby keyframes, so the first frame can differ slightly from the exact start time you requested.

## Privacy

Selected media is processed locally in your browser and is not uploaded to Soulnio.

## Frequently asked questions

### Is the MP4 uploaded?

No. Trimming runs locally in your browser and the selected MP4 is never sent to Soulnio.

### Does trimming reduce quality?

No. Compatible streams are copied directly without a full video re-encode.

### Why can the start time shift slightly?

Compressed video can begin cleanly only at keyframes when stream-copy trimming is used.