By default, the "join" events contain the whole userdata as received
from the "auth" response. This might include a "displayname" field
containing the display name of the associated user.
For privacy reasons in certain scenarios, some attendees should not
be able to know which other users are connected to a room, therefore
the "displayname" should be hidden for them. By default, no filtering
occurrs.
Clients with permission "publish-media" can publish any audio/video. Other
clients need to have "publish-audio" and/or "publish-video" to publish the
corresponding media types. For this the SDP in the offer is parsed to check
what will be sent.