<!DOCTYPE html >html lang="en" >meta charset="utf-8" >title >Reftest that checks whether WebM video with alpha is rendered with the correct stride</title >style >0 0 0 4 px magenta, inset 0 0 0 4 px magenta;style >div style ="position: relative" ><!-- The video below was created as follows: 1. Run this code on the web console: var c = document.createElement("canvas") c.width = 334; c.height = 334; var ctx = c.getContext("2d") ctx.fillStyle = "white" ctx.fillRect(0, 0, 334, 334) ctx.fillStyle = "red" ctx.fillRect(0, 0, 64, 64) ctx.fillStyle = "blue" ctx.fillRect(64, 0, 64, 64) ctx.fillStyle = "yellow" ctx.fillRect(0, 64, 64, 64) ctx.fillStyle = "lime" ctx.fillRect(64, 64, 64, 64) ctx.fillStyle = "black" ctx.fillRect(196, 0, 16, 334) c.toDataURL() 2. Save the PNG to a file called "frame.png". 3. Convert it to a WebM file using: ffmpeg -framerate 25 -f image2 -i frame.png -c:v libvpx -auto-alt-ref 0 -pix_fmt yuva420p output.webm (The "a" in "yuva420p" gives the video an alpha plane.) 4. Convert the WebM file to a data url. The video size is 334x334. 334 is not divisible by 4. But 336 is divisible by 4 (and by 16). video autoplay src="data:video/webm;base64,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" ></video >div class="edgeCover" style ="left: 0; top: 0; width: 64px; height: 64px;" ></div >div class="edgeCover" style ="left: 64px; top: 0; width: 64px; height: 64px;" ></div >div class="edgeCover" style ="left: 0; top: 64px; width: 64px; height: 64px;" ></div >div class="edgeCover" style ="left: 64px; top: 64px; width: 64px; height: 64px;" ></div >div class="edgeCover" style ="left: 196px; top: 0; width: 16px; height: 334px;" ></div >div >
Messung V0.5 in Prozent C=95 H=98 G=96
¤ Dauer der Verarbeitung: 0.12 Sekunden
(vorverarbeitet am 2026-06-04)
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