Browser FFmpeg recipe
Convert WebM to MP4 Online with FFmpeg
Create an MP4 version of a WebM video for broader compatibility.
Command
Run this FFmpeg command
ffmpeg -i input.webm -c:v libx264 -crf 23 -preset fast -c:a aac -b:a 128k output.mp4When to use it
- screen recordings
- browser captures
- platform uploads
How it works
- Upload the WebM file.
- Run the H.264 and AAC conversion command.
- Download the MP4 output.
Option reference
| Option | What it does |
|---|---|
-c:v libx264 | Converts VP8 or VP9 video to H.264. |
-c:a aac | Converts audio to AAC for MP4 compatibility. |
-preset fast | Keeps encoding practical in the browser. |
Practical notes
- Some WebM files have no audio; FFmpeg will simply output video-only MP4.
- For smaller output, increase CRF to 26 or 28.
FAQ
Why convert WebM to MP4?
MP4 is accepted by more editing apps, devices, and upload platforms.
Can I keep the WebM quality?
Use a lower CRF value such as 18 or 20, but the output will be larger.