Hector Martin

What is GoP? And doesn’t MSE allow for low-latency streaming?

group of pictures; the span between two keyframes MSE requires you to pass the browser an entire MP4 segment at once; theoretically those are allowed to start on non-keyframes, but in practice browsers flip a shit if they don't

that gets you around it in theory, but it's not ubiquitous in browsers yet (especially mobile), doesn't work on all networks, and adds a large amount of server-side complexity

WebRTC works in practice, but is very heavy server-side. We use it for audio (<70ms latency end to end) but it's a lost cause for video with our infra.

Why is it heavy? Is it an issue with the server software or something more fundamental?

It's basically mandatory DTLS, which requires negotiating a 1:1 stream with each client, so multicast doesn't work. The server-side software stacks are a lot less mature than the HTTP ecosystem. It's possible but not nice.

ah. of course, for Internet streaming where multicast isn’t possible and the alternative is HLS over regular TLS, that should make less difference…