ONVIF Integration

Meridian VMS uses the ONVIF protocol for camera auto-discovery, stream negotiation, event subscriptions, and time synchronisation.

Supported Features

Feature	Description
WS-Discovery	Broadcasts a multicast probe to find all ONVIF-compliant devices on the network
Device Probing	Queries discovered devices for manufacturer, model, firmware, hardware ID, and serial number
RTSP Stream Negotiation	Retrieves main-stream and sub-stream RTSP URIs from the device media service
PullPoint Events	Subscribes to camera-native events for motion detection, tamper, and audio triggers
Time Synchronisation	Compares camera time to server UTC and corrects drift by setting the camera clock
Digest Authentication	Authenticates to cameras using HTTP Digest Auth with the credentials stored in Meridian VMS

Camera Discovery

On-Demand Discovery

From the Settings > Cameras page, use the Discover Cameras button to run a WS-Discovery probe across the network. The system broadcasts a multicast message and collects responses from all ONVIF-compliant devices within the network segment.

Discovered cameras are presented in a list showing:

• IP address and ONVIF port
• Manufacturer and model
• Firmware version
• Whether the camera is already registered in Meridian VMS

Scheduled Discovery

Meridian VMS supports daily scheduled discovery that automatically scans configured IP ranges for new cameras. This is useful for large deployments where cameras may be added to the network between manual discovery sessions.

Scheduled discovery runs once per day and:

1. Scans the configured IP address ranges using WS-Discovery
2. Probes each responding device for its full profile
3. Logs any newly discovered devices that are not yet registered
4. Sends a notification if new cameras are found (when a notification channel is configured)

Network segmentation

WS-Discovery uses multicast, which is typically limited to the local subnet. If your cameras are on a different VLAN from the management server, ensure multicast routing is configured or use the IP range scan feature instead.

ONVIF Events (PullPoint)

Meridian VMS subscribes to ONVIF PullPoint event notifications to receive camera-native events without polling. This is more reliable and bandwidth-efficient than periodic snapshot comparisons.

Supported Event Types

Motion Detection : Triggered when the camera’s built-in motion detection activates. Used as a pre-filter for AI object detection and as a standalone event source.

Tamper Detection : Triggered when the camera detects lens obstruction, defocus, or physical movement of the camera housing.

Audio Detection : Triggered when the camera’s audio analytics detect a sound event above the configured threshold.

Event Flow

Camera (ONVIF PullPoint)
    │
    │  Event subscription
    v
Management Server
    │
    ├── Creates event record
    ├── Evaluates alarm definitions
    └── Triggers notifications (if alarm matched)

PullPoint compatibility

PullPoint subscriptions work reliably across all major camera manufacturers including Hikvision, Dahua, Uniview, Axis, and Hanwha. This approach was chosen over WS-BaseNotification because it works through NAT and does not require the camera to initiate connections back to the server.

Time Synchronisation

Camera clocks drift over time, which causes misalignment between recorded segment timestamps and the actual time of events. Meridian VMS includes automatic time synchronisation to prevent this.

How It Works

1. The management server runs a daily time sync task for all cameras that have ONVIF credentials configured
2. For each camera, it retrieves the current device time via the ONVIF device service
3. It compares the camera time to the server’s UTC clock
4. If the drift exceeds a configurable threshold, it corrects the camera clock
5. The sync result (success, skipped, or failed) is logged for each camera

Configuration

Time synchronisation is enabled by default for all cameras with valid ONVIF credentials. The sync runs as part of the daily maintenance cycle.

NTP conflicts

If a camera is configured to use NTP, Meridian VMS will override this during synchronisation. If you prefer cameras to use an NTP server, disable Meridian time sync and ensure your NTP infrastructure is reliable.

Authentication

ONVIF communication uses HTTP Digest Authentication. When adding a camera — either manually or via discovery — you provide the ONVIF username and password. These credentials are stored securely and used for all subsequent ONVIF operations including discovery probing, event subscriptions, and time synchronisation.

Default credentials

Most cameras ship with a default ONVIF user (commonly admin). For security, change default credentials before deploying cameras in production and update the stored credentials in Meridian VMS accordingly.