I have managed to read the function doorbell button (or in VMS video call).
First you have to know that the VD1 sends a GET request when the doorbell button is pressed. So I installed webhook (https://github.com/adnanh/webhook) and looked what happens here and saw how the data looks like in wireshark.
The integration itself I have integrated via httplistener binding (https://community.openhab.org/t/webhook-new-very-simple-binding-for-listening-incomming-http-requests/123597) the configuration in the http listeren binding looks like this.
UID: httplistener:HttpListener:doorbell
label: Doorbell HttpListener
thingTypeUID: httplistener:HttpListener
configuration:
jsonConfig: |-
{
"channels": [
{
"key":"motion_detection",
"kind": "STATE",
"state": "req.parameters.motion_detection[0]"
},
{
"key": "sound_detection",
"kind": "STATE",
"state": "req.parameters.sound_detection[0]"
},
{
"key": "video_call",
"kind": "STATE",
"state": "req.parameters.video_call[0]"
},
{
"key": "face_detection",
"kind": "STATE",
"state": "req.parameters.face_detection[0]"
}
]
}
With the channel video_call I have linked an item with which I can e.g. trigger a bell or a speaker or simply send a notification.