Comment by kixelated

16 hours ago

Horizontal black lines? Dunno what that could be about, we render to a <canvas> element which is resized to match the source video and then resized again to match the window with CSS.

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kixelated

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chrismorgan  10 hours ago

What’s that like for performance and power usage? I understand normal videos can generally be entirely hardware-accelerated so that the video doesn’t even touch the CPU, and are passed straight through to the compositor. I’m guessing with this you’re stuck with only accelerating individual frames, and there’ll be more back and forth so that resource usage will probably be a fair bit higher?

An interesting and unpleasant side-effect of rendering to canvas: it bypasses video autoplay blocking.

  • kixelated  9 hours ago

    It's all hardware accelerated, assuming the VideoDecoder has hardware support for the codec. VideoFrame is available in WebGL and WebGPU as a texture or gpu-buffer. We're only rendering after a`requestAnimationFrame` callback so decoded frames may get automatically skipped based on the display frame rate.

    I don't think the performance would be any worse than the <video> tag. The only exception would be browser bugs. It definitely sounds like the black bars are a browser rendering bug given it's fine when recorded.

    • DaleCurtis  7 hours ago

      Unfortunately canvas (rgb'ish) can't overlay as efficiently as <video> (yuv'ish), so there is some power cost relative to the lowest power video overlays.

      It really only matters in long form content where nothing else on the page is changing though.

Numerlor  13 hours ago

Doesn't show up on screen capture, but there's random rolling quickly flickering lines on my phone, kinda like from analog distortion on old tvs