Does any one know?

I'm not interested in 'outputs' as that info is already known (4), but what are the limits/requirements for inputs?

Vmix 4K and above.

If anyone can share some clarity it would be appreciated thanks.

@ Podcast Bob

Realistically, most systems should be able to handle 6 or 7 SRT Inputs before you start to encounter performance issues, depending of course on what else you are doing with vMix, the same goes for NDI and/or RTSP IP streams.
As nikosman88 says, you pretty much have to test for yourself what the limits of your system are and/or what you can tolerate quality and performance wise.


Ice

Bob,

the limiting factors are:

- Network performance of your system. People tend to forget that each network connection also uses CPU power in the operating system.

- Your graphics card. Incoming SRT streams are mostly encoded in H.264 or HEVC. These need to be decoded. It depends on the graphics card, how many streams it can support. It seems a bit trick to get accurate numbers for this...

- Depending on your system, decoding uses CPU power and generates heat and fan noise. Your big fan tower gaming PC running a i9 CPU is better here than a sleek i5 office laptop with little howling fans.

- Beware of incoming HEVC streams. It seems that if your Windows installation has no HEVC codec installed, your SRT video input is black. Outgoing streams can use HEVC, since this codec seems to come from within vMix / FFMPEG.

A few numbers:

vMix 27 encoding 1 SRT stream in 1080p50, upstream bandwidth 6 Mbit/s.

Pulling back this signal from my SRT gateway I could receive 5 streams before getting the "GPU Overload" warning. Adding another stream the warnng would be solid.

The Dell laptop system runs a i7-10870H CPU, 16 cores @ 2.2 GHz, RTX 3060 Laptop GPU.

- Overall CPU is at 42%, all cores are moderately busy.
- GPU is solid at 63% load, video decode at 63 %
- Ethernet sends 7 Mbit/s, receives around 50 Mbit/s

Adding 4 more streams would not increase GPU and CPU load much. Fan noise would rise a bit, but the 4 last inputs would consistently drop frames every 5 seconds or so.

This indicates that vMix software can not keep up with the data streams between network, CPU and GPU and shows two things.

- For this setup the overal system throughput has reached its limit.
- The GPU warning in vMix is useful. If it shows up check the statistics and see if the frame drop rate is acceptable or not.

Thanks for reading this long text, maybe it helps a bit.

Christian