MEDIA_SERVER_PREFERRED: A recommended choice is done for you,
based on the media server that is currently in use.
This is the default setting, and is equivalent to these values:
- For *mediasoup*, `NONE` is selected.
- For *Kurento*, `VP8` is selected.
Simulcast is a per-Publisher configuration that allows to enable
Simulcast senders on the client's PeerConnection of each sender.
Simulcast is a WebRTC feature that sends multiple simultaneous streams
with different video qualities, in order to let the media server decide
which quality is best for which Subscriber on the receiving side.
Enabled by default.