How to blur a face in an MP4 video
MP4 is a container, not a codec. The video inside still has to play in your browser. FaceBlur accepts MP4 files up to 90 MB and covers each face it finds.
Updated August 20, 2026
Four steps
- Choose the MP4 and wait for face masks to appear.
- Play and scrub the clip. Check every visible face.
- Choose mosaic, blur, or solid cover. Adjust strength and margin.
- Export, then watch the downloaded file.
Why an MP4 might export as WebM
To create an MP4, your browser needs an AVC encoder. If it does not have one, FaceBlur tries VP9 and VP8 in a WebM file. The cover settings stay the same; only the video format changes.
MP4 troubleshooting
| No preview | Your browser may not support the codec inside the MP4. Try current Chrome or Edge, or convert the source to H.264. |
|---|---|
| Export unavailable | Your browser cannot encode AVC, VP9, or VP8. Try current Chrome or Edge on a desktop. |
| Several people covered | This is expected. FaceBlur uses the same settings for every face it finds. |
| Audio identifies someone | Enable Remove audio before export. |
The extension is only a label. Two .mp4 files can contain different codecs. Renaming a file does not convert it.
Try an MP4
Choose a file up to 90 MB. No account or watermark.
Choose an MP4