Can ONVIF Profile S send ANPR metadata?
Answered by ANPR AI·Sourced
Short answer
No. There is a universal misunderstanding across the industry that ONVIF Profile S supports metadata. Profile S only standardizes the transmission of RTSP video pixels and simple binary motion alarms. It cannot transmit license plate text or structured XML metadata.
Explanation
When an installer connects an edge-processing ANPR camera to an NVR using the ONVIF protocol, they frequently expect the license plate numbers to populate the NVR's database. When they only see a video feed, they assume the integration is broken. The reality is that ONVIF Profile S (the standard used by almost all legacy CCTV systems) was designed purely for video streaming and basic contact closures.
It fundamentally lacks the capability to transmit highly structured data like bounding boxes, OCR confidence scores, or string text.
To transmit this advanced data natively via standard protocols, both the edge camera and the receiving software must support the modern ONVIF Profile M. Profile M was specifically developed to serialize object detections as Scene Description XML or MQTT JSON payloads, allowing real metadata integration. If either the camera or the NVR lacks Profile M support, the system will silently fall back to Profile S, resulting in a video-only connection.
Things to check
- Audit the manufacturer's Declaration of Conformance (DoC) for both the camera and the receiving VMS/NVR to verify official ONVIF Profile M support.
- Check the firmware versions; ONVIF conformance is granted to specific firmware builds, and upgrading or downgrading can break compliance.
What to do
If your hardware fully supports ONVIF Profile M, configure the camera's metadata stream to push Scene Description XML or route MQTT JSON payloads to an IoT broker. If Profile M is unavailable on your legacy NVR, you must abandon ONVIF entirely for metadata transport. Instead, rely on proprietary vendor APIs (like Hikvision ISAPI or Dahua CGI) to push HTTP webhooks directly to a third-party listener, completely bypassing the ONVIF protocol for the text data.
ANPR Edge
Skip the dedicated ANPR camera. Read plates from the cameras you already have.
ANPR Edge is plate-recognition software that runs on a PC at your site and works with ordinary IP cameras, so plate reads no longer depend on one vendor's camera, NVR or firmware.
- Works with standard IP cameras over RTSP
- One license per location covers every camera
- Runs on a Windows PC or Mac you own