Use hardware accelerated FFmpeg to encode tab or screen

[Torbins]

I have pretty powerful PC, but when I stream any Tab or Screen, I see very low quality video, and with low framerate. Please, use FFmpeg with hardware accelerated encoding to produce good quality video for streaming.

[hensm]

I've definitely considered this before and it's on the roadmap, though I can't say when I'll get to it (PRs welcome).

I'm not sure as to whether Firefox supports hardware-accelerated WebRTC (or if it uses OpenH264 everywhere), but the issue with the current screen sharing is on the Chromecast side. If I substitute for another PC or phone it's about as smooth as you'd expect from a WebRTC stream. It'd be nice if this were fixable, since I'd prefer not to reimplement display enumeration and selector UI for each platform if I can avoid it.

There's no reasonable means of capturing tabs (especially background tabs) at all, which is why the current implementation is so terrible.