How powerful is the server for videoconferencing?

Question

Data transfer

Let's say you need to ensure the simultaneous transmission of 100 video chats.
Is it done through the server at all? Or is peer-to-peer used exclusively for such purposes? Are there often times when peer-to-peer transfer is not possible?
Is it only the width of the bridge (server) channel that matters here? Or are there other requirements?
Is it reasonable to use HTTP Live Streaming for this or are there more lightweight options?
You need to make clients for Android and iOS, and for iOS, it seems that HTTP Live Streaming is the only option, otherwise they will not be accepted in the AppStore...
MPEG-4 video will be transmitted with an extension of 640x480, what compression ratio will be sufficient for videos taken from mobile cameras .. .

Answer 1

Is it done through the server at all?

And so and so. It all depends on the chosen technology.
What does "often" mean? It happens.
Modern servers have the following main (conditionally) components that affect their performance:
1. Processor
2. Memory
3. Disk
4. Network
These components have parameters - frequencies, speeds, volumes. They will be needed for your task. Which one is impossible to say. Something will be needed for sure =) Maybe the latency of the Internet will affect, maybe the size of the RAM or the frequency of the processor.
I can't say anything about the rest.
UPD. Completely forgot " power "!