How do I fix transparent video alpha in Playwright?

Double-render on black and white, extract with Porter-Duff math via Sharp.

What is premultiplied alpha and why does it break video editors?

RGB pre-scaled by alpha; browsers use it internally but export poorly, corrupting low-opacity edges in NLEs.

Yes — recovers soft edges perfectly, no more solid blobs.

🛠️ Developer Tools

Playwright's transparency? A joke. Grab 1970s math to fix it.

theAIcatchup Apr 11, 2026 3 min read

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Community-driven. Code-first.

#FFmpeg #Sharp.js #alpha compositing #playwright #porter-duff #porter-duff compositing #transparent alpha #transparent video #transparent video alpha #video compositing

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Originally reported by Dev.to