{ "$ref": "core/room_event.json", "type": "m.call.negotiate", "content": { "version" : "1", "party_id": "67890", "call_id": "12345", "lifetime": 10000, "description": { "type" : "offer", "sdp" : "v=0\r\no=- 6584580628695956864 2 IN IP4 127.0.0.1[...]" }, "sdp_stream_metadata": { "271828182845": { "purpose": "m.screenshare" }, "314159265358": { "purpose": "m.usermedia" } } } }