Between 2 vMix hosts yes
From a mobile or a computer using a browser no

Guillaume

Nope. Not strange at all. It helps to have some appreciation for the origins of WebRTC, the foundation of vMix Call.

WebRTC was developed to enable streaming audio & video in browsers. That was to eliminate the need for installed communication clients like Skype, Bria, etc.

The browser makes no presumption about the I/O devices available to it. Most laptops have a built-in webcam that's only capable of 720p30.

Until very recently, access to anything beyond 720p30 required the use of an external webcam that was UVC 1.5 compliant and the app had to be smart enough to set the webcam to send MJPEG or H264 encoded video.

This because the webcam was connected by a USB 2.0 interface. USB 2.0 can only deliver 720p30 unless the stream is in some way compressed.

A generic WebRTC app makes no presumption about the webcam, so it's limited to 720p30. To get beyond that requires a whole lot more effort in the WebRTC app. It has to test the camera for it's reported capabilities.

But the whole point of WebRTC was making handling media easier for web devs. So testing for advanced capabilities is left to the specialists.

It gets worse when USB 3.0 webcams started to show up in 2017. These can deliver 1080p30 uncompressed over USB 3.0, but could just as easily be connected via USB 2.0.

4K webcams, which are still few, add more complexity. Undelivered promise.

WebRTC is evolving and can deliver 4K streams, but literally no-one has implemented that in a commercial service as yet.

No-one makes dime on things like vMix Call, so don't expect niche applications to be a high priority for anyone. If you want tons of control, you can revert to the kind of processes that were used before vMix Call.

VMix Call was supposed to make things easier. And it succeeds in that regard very nicely.