WebM to MP4 Converter
Convert WebM files with VP8, VP9 or AV1 video into MP4 that older devices, editors and televisions can actually play.
Convert with this tool
or choose a file from your device — it is processed in this tab and never uploaded
Accepted: WebM with VP8, VP9 or AV1 video and Vorbis or Opus audio
Files stay on your device. There is no upload, no queue and no watermark, so a conversion works even with the network switched off after the page has loaded.
Supported formats & processing
| Accepted input | WebM with VP8, VP9 or AV1 video and Vorbis or Opus audio |
|---|---|
| Produced output | MP4 with H.264 video and AAC audio |
| Processing | FFmpeg.wasm (video engine, downloaded on first use) |
| Upload required | No — the file is read locally and never transmitted |
How to use this tool
- Add the .webm fileScreen recordings from browser tools work well here.
- Choose the qualityVP9 sources are efficient, so CRF 22–24 usually looks excellent.
- Set the audio bitrateOpus at 96 kbps converts well to AAC at 128 kbps.
- ConvertShort screen recordings finish in under a minute.
- Preview and downloadCheck that the audio came through cleanly in the player.
About this tool
WebM is an open container built for the web, usually carrying VP8, VP9 or AV1 video with Vorbis or Opus audio. Browsers love it; plenty of other software does not, including many video editors, older televisions and presentation tools.
This converter decodes the VP8, VP9 or AV1 stream and re-encodes it as H.264 inside an MP4, converting the audio to AAC at the same time. If your WebM came from a browser screen recording, the audio may be Opus, which MP4 does not accept — the conversion handles that translation as part of the same pass.
Features
- Decodes VP8, VP9 and AV1 video streams
- Converts Opus and Vorbis audio to AAC for MP4 compatibility
- Frame-accurate re-encoding rather than a container rename
- Quality and resolution control in the same pass
- Works with browser screen recordings and downloaded web video you own
- No upload, so confidential screen recordings stay local
Frequently asked questions
Why will my editor not open WebM?
Most non-linear editors do not support VP8 or VP9 decoding, and some refuse the WebM container outright. Converting to H.264 in an MP4 makes the file editable in Premiere, Final Cut, DaVinci Resolve and others.
Does converting VP9 to H.264 lose quality?
At a comparable CRF there is a small loss, and the file will usually be larger because H.264 is less efficient than VP9. It is a compatibility trade, not a quality upgrade.
Can I keep VP9 and just change the container?
MP4 can technically carry VP9, but support is inconsistent and it defeats the purpose of the conversion. H.264 is the point.
What about AV1 sources?
AV1 decoding is handled by the FFmpeg engine and re-encoded to H.264. It is slower than VP9 because AV1 is more complex to decode.