Browser FFmpeg recipe
Set CRF Online with FFmpeg
Create an H.264 MP4 using a selected CRF quality value.
Command
Run this FFmpeg command
ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset fast -c:a copy crf-output.mp4When to use it
- quality tuning
- file size control
- H.264 exports
How it works
- Upload the source video.
- Change the CRF value to tune quality and size.
- Run FFmpeg and download the encoded output.
Option reference
| Option | What it does |
|---|---|
-crf 23 | Sets quality for H.264. Lower values improve quality. |
-preset fast | Controls encoding speed and compression efficiency. |
-c:a copy | Keeps original audio. |
Practical notes
- Common H.264 CRF values range from 18 to 30.
- CRF 18 is high quality, while CRF 28 is much smaller.
FAQ
What CRF should I start with?
Start around 23 for H.264 and adjust after checking the result.
Does lower CRF mean smaller files?
No. Lower CRF means higher quality and larger files.