Need help understanding Data Rate on ATEM Mini Pro

Hey everyone,

I’m somewhat new to streaming, but I consider myself pretty good when it comes to tech. I’ve been building a mobile rig, but when it comes to Data Rates, I’m still trying to wrap my head around what that means.

For example, I just did a test. When I output video from my BMPC4K, the Data Rate hovers around 4-6 mb/s and YouTube says my connection is excellent. When I cut to a still from my Media Library, the Data Rate drops to 1.1 and YouTube warns me about my bitrate (screenshot attached).

Am I doing something wrong? I’m using the GL iNet Travel Router (AR750S) and have my ATEM and Computer hardwired to the internet. I did an internet speed test on my computer and I’m getting 200 down / 20 up.

I assume Data Rate means the amount of data the ATEM is pumping to YouTube. But it worries me seeing that error on YouTube when I switch to something other than a camera feed. Am I over thinking this? Thanks for your help!

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Hi Rob, this is surely due to the high compression possible for the still image? Personally, I would not worry. Others here have much more experience though.

Yeah this is fine. The ATEM Mini uses variable bitrate encoding, so when the picture doesn’t change much (e.g. static graphics) then it can send the image at a much lower bitrate. Youtube doesn’t expect a variable bitrate, and also expects people will be mainly streaming camera video, so it throws up a warning that the bitrate is too low. It’s safe to ignore it though!

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Awesome. Thanks, @aaronpk and @tim_hughes!

Tnaks for explaining this. But some of the streaming platforms don’t like VBR in low data rate mode. For example Castr starts dropping signal, when I show stills :confused: Data rate is to low for signal. With FaceBook I hade this problem too, but not so bad as it was with Castr. The only solution - stream at high profile if your ISP provides good internet speed. Then stills are streming with a little bit higer data rate. I guess that the problem not in the endcoders (ATEM or vMix etc.), but in streaming services - they just don’t appropriately accept low data rate. Maybe there is some kind of solution, to get biger data rate for stills and photos? ATEM endcoder / software could restrict lowes acceptible data rate? Any solution for now?

So, the problem here is, networks like constant data rate, because it makes buffering and latency more stable (and less likely to get dropped packages than when instantly increasing rates when picture changes) but, H264 doesn’t have cbr, it has preferred rate (and maximum limit), it’s made for high compression, so simple images are highly compressed and there’s not enough data to keep the rate constant. Some streaming devices/software counter that by padding data or increasing quality dynamically, but it is also not a standard way to do it and could cause other problems.

ok, I found that low data rate problem is depending of streaming services . Some of them dropping signal, but most of all will handl this.

So what happens if you’re streaming to Castr and the data rate drops? The stream completely disconnects? Also have you contacted Castr about this issue?

It’s seems a pretty big oversight if a service like Castr won’t work probably with a product like Atem Mini Pro.

I’ve now tested Castr with the AMP, and I can see that the issue is there. And results in the embeddable player buffing when it really shouldn’t.

I reached out to Castr’s support, but they seem unaware of the issue. It’s a shame as it’s a service I’d like to be able to utilise.

Janis, streaming services are you aware of that can handle this?

I stoped to use Castr for that reason. The problem with droped signal was even with vMix… Interesting, that in 2020 there was no problem with Castr. Probably that they change something.