[dmm]

Pull-based streaming can work with webrtc. I implemented it for my custom ip camera nvr solution. I just open N streams on the client and when one is deactivated (typically by scrolling it out of the viewport), the client sends an unsubscribe message over a separate control channel and the server just stops sending video until they resubscribe.

I'm currently switching to a quic-based solution for other reasons, mainly that webrtc is a giant blackbox which provides very limited control[1], yet requires deep understanding of its implementation[2] and I'm tired[3].

I looked at moq-lite but decided against it for some reason. I think because I have <5 clients and don't need the fanout. The auth strategy is very different than what I currently use too.

[1] Why is firefox now picking that (wrong) ice candidate?

[2] rtp, ice, sdp, etc

[3] webrtc isn't bad for the video conferencing use-case but anything else is a pain

[scottlamb]

I've also looked at switching my open source IP camera NVR to WebCodecs and WebTransport (maybe MoQ). Two things giving me pause:

* Firefox support for WebCodecs is poor—none at all on Android [1], H.265 is behind a feature flag. [2]

* Mobile Safari doesn't support WebTransport. Or didn't...I just looked it up again and see it does in 26.4 TP. Progress! [3]

[1] https://searchfox.org/firefox-main/rev/da2bfb8bf7dc476186dfe...

[2] https://searchfox.org/firefox-main/rev/da2bfb8bf7dc476186dfe...

[3] https://caniuse.com/webtransport

[kixelated]

Yeah for Safari support I'm using polyfills; it sucks.

- libav.js for AudioEncoder/AudioDecoder. - QMux over WebSockets for WebTransport.

Both are NPM packages if you want to use them. @kixelated/libavjs-webcodecs-polyfill and @moq/qmux

26.4 removes the need for both so there's hope!

[scottlamb]

Thanks!

Any idea what Firefox is waiting for? To me those lines I quoted seem entirely arbitrary, and a skim through bugzilla didn't help.

[Sean-Der]

That's exciting! When you were evaluating it everything about the protocol/APIs fits your needs?

Just features/software need to be implemented?

[scottlamb]

I wouldn't say I'm done evaluating it, and as a spare-time project, my NVR's needs are pretty simple at present.

But WebCodecs is just really straightforward. It's hard to find anything to complain about.

If you have an IP camera sitting around, you can run a quick WebSocket+WebCodecs example I threw together: <https://github.com/scottlamb/retina> (try `cargo run --package client webcodecs ...`). For one of my cameras, it gives me <160ms glass-to-glass latency, [1] with most of that being the IP camera's encoder. Because WebCodecs doesn't supply a particular jitter buffer implementation, you can just not have one at all if you want to prioritize liveness, and that's what my example does. A welcome change from using MSE.

Skipping the jitter buffer also made me realize with one of my cameras, I had a weird pattern where up to six frames would pile up in the decode queue until a key frame and then start over, which without a jitter buffer is hard to miss at 10 fps. It turns out that even though this camera's H.264 encoder never reorders frames, they hadn't bothered to say that in their VUI bitstream restrictions, so the decoder had to introduce additional latency just in case. I added some logic to "fix" the VUI and now its live stream is more responsive too. So the problem I had wasn't MSE's fault exactly, but MSE made it hard to understand because all the buffering was a black box.

[1] https://pasteboard.co/Jfda3nqOQtyV.png

[Sean-Der]

What was the WebRTC bug, would love to help! I saw at work that FireFox doesn't properly implement [0] I wanted to go fix after FFmpeg + WHEP.

If you are still struggling with WebRTC problems would love to help. Pion has a Discord and https://webrtcforthecurious.com helps a bit to understand the underlying stuff, makes it easier to debug.

[0] https://datatracker.ietf.org/doc/html/rfc8445#section-7.2.5....

[kixelated]

Absolutely agree.

You can convert any push-based protocol into a pull-based one with a custom protocol to toggle sources on/off. But it's a non-standard solution, and soon enough you have to control the entire stack.

The goal of MoQ is to split WebRTC into 3-4 standard layers for reusability. You can use QUIC for networking, moq-lite/moq-transport for pub/sub, hang/msf for media, etc. Or don't! The composability depends on your use case.

And yeah lemme know if you want some help/advice on your QUIC-based solution. Join the discord and DM @kixelated.

[mzs]

1. is? https://bugzilla.mozilla.org/show_bug.cgi?id=1659672