Expose PlayerStats to subscribers

[improbable-andreaskrugersen]

While still on the UE4.27 branch, I implemented a divergence to expose WebRTC stats to the UMillicastSubscriber component which we used to track metrics about incoming bandwidth.

Now that we've upgraded to the dev branch, I was excited to see that stats support was already present. Unfortunately, it's opinionated in that it only renders stats to the screen. We need to be able to extract that information to send it off to a metrics server. I could keep a divergence again but I'd much rather use the plugin as-is and find a solution that works for us both.

I don't know what your future plans for this are, so I'll just write down what we'd need on our side:

• Currently, the engine stat hook drives WebRTC stats polling. I'd like to change that so that stats can be polled independently of the consumer. They also just need to be polled once per frame. So if both the engine stats display and our metrics are turned on, we'd still only poll once but process the stats object in two different places
• PlayerStats.h is currently private. This would need to be made public to expose the FPlayerStatsCollector type
• There must be a way to access the PeerConnection's stats collector from game code. In my divergence I routed this through the MillicastSubscriberComponent as a protected OnStatsReceived function. We could do that differently of course.

Would that direction be in line with your own plans? If so, would you want to do that change or are you happy to accept a PR?

[rweber89]

Thank you @improbable-andreaskrugersen I am working on a Simulcast issue right now but I`ll get on making this more accessible. As you can see we are making architectural improvements, this would be one of them.

I can get back to you on this with further details next week.

[improbable-andreaskrugersen]

@rweber89 Sounds great, thanks! I think we can live without these stats for a short while. I'm very happy that we're currently divergence-free though, so great work on the architectural changes so far 😃

[rweber89]

Divergence-free is what I like to aim for, because otherwise you miss out on changes&fixes and need to manually main. You should only need to update 🙏

[rweber89]

Addressed in 1bc22c57dd40b44e6d281927d08f8208b7f2f115 on the dev branch