Convert MP4 to Transparent WebM

Drag your MP4 files here

Or

Want a transparent WebM from an MP4? Rewwwrap keeps any alpha channel it finds — but most MP4s do not have one. Here's how to get a transparent result either way.

How to convert MP4 to Transparent WebM

  1. Add your MP4 filesDrag them onto the drop zone above, or click to browse. Add as many as you like — they stay on your computer.
  2. Tune the settingsSet quality, frame rate and scale. Leave Transparency on to keep any alpha channel.
  3. Convert and downloadClick Convert. Each finished transparent WebM file gets its own download button, or grab everything with Download all.

Can an MP4 be transparent?

Almost all MP4s use H.264, which has no alpha channel — the background is baked into the pixels. Converting such a file cannot recover transparency that was never stored.

For a genuinely transparent WebM, go back to the source and export a MOV with alpha (ProRes 4444) or a WebM directly, then convert that. If you only have a green-screen MP4, key it in your editor first.

Frequently asked questions

Why is my WebM not transparent?

Your MP4 almost certainly has no alpha channel. Export a ProRes 4444 MOV with alpha instead and use MOV to Transparent WebM.

Do any MP4s have transparency?

Apple's HEVC with alpha can, but it is rare and mostly produced by Apple apps.

Is it still worth converting MP4 to WebM?

Yes — even without transparency, WebM is usually smaller for the web.

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