ONVIF IP Cameras for ANPR Parking Systems

ONVIF (Open Network Video Interface Forum) is an open industry standard for IP-based security products, founded in 2008 by Axis, Bosch and Sony. It defines a common API based on Web Services (SOAP/XML) for discovery, configuration, streaming, recording and event handling. For ANPR (Automatic Number Plate Recognition), ONVIF matters because it removes vendor lock-in: any ONVIF-compliant camera that exposes an RTSP stream can feed our plate recognition software without custom drivers. The camera streams video over RTSP (Real-Time Streaming Protocol) and the ANPR software pulls frames for plate detection. In our September 2026 tests we used ordinary ONVIF/RTSP cameras, Tapo and Hikvision at 1080p and 20 fps, not dedicated ANPR hardware.

ONVIF defines several profiles for different use cases. PROFILE S (2011): real-time streaming (RTSP, H.264), PTZ control, audio and video configuration. It is the baseline an ANPR engine needs, because all it requires is a real-time stream. PROFILE T (2018): advanced video streaming with H.265 (HEVC) and bidirectional audio, metadata streaming and imaging settings. Use T when you want H.265 to lower bandwidth on high-resolution cameras. PROFILE G (2014): video storage and retrieval on the device (edge SD card) or on an NVR. Use G when you need local event recording as evidence. For ANPR, Profile S is the profile we rely on; Profile T and Profile G are optional depending on your bandwidth and evidence requirements.

What matters is not the brand but the stream and what the camera can see. Our recognition needs an ONVIF/RTSP camera that delivers a stable stream; we tested ordinary 1080p cameras at 20 fps (Tapo and Hikvision). The decisive factor is how the plate is framed. In our setup plates about 30 px high in the frame were read reliably, and at 31-32 px the reads were certain; below that the reads break down. Camera position and frame matter more than zoom. This is why we do not publish a fixed list of recommended camera models: a well-placed camera that meets the framing requirement is what makes recognition work.

No. Any camera that exposes an ONVIF/RTSP stream can feed software-based recognition. A dedicated ANPR camera performs plate detection on the camera itself and sends only plate strings, which lowers network load, but it is not required for a working system. In our September 2026 two-camera test a standard ONVIF/RTSP setup at 1080p and 20 fps confirmed 24 of 24 plates with zero false reads; the median time to confirmation was 0.6 s.

Often yes, if the stream is available and the plate is large enough in the frame. Check that: (1) the camera exposes an ONVIF/RTSP stream you can open in VLC; (2) the plate is at least about 30 px high in the frame where you want to read it; (3) the camera keeps a stable stream (our software detects a stall after 15 s without progress and reconnects); (4) the camera covers the lane at night and in rain (we confirmed reads in rain and at night); (5) it can run at 1080p and around 20 fps. If the plate is too small, reposition the camera or change the lens rather than assuming you need a new camera.

RTSP URL format varies by manufacturer even within the ONVIF standard (ONVIF auto-discovery gets the URL automatically, but manual entry requires knowing it). COMMON FORMATS: Hikvision - rtsp://user:pass@IP:554/Streaming/Channels/101 (101 = channel 1 main stream, 102 = sub stream). Dahua - rtsp://user:pass@IP:554/cam/realmonitor?channel=1&subtype=0 (subtype=0 main, subtype=1 sub). Axis - rtsp://user:pass@IP/axis-media/media.amp. Bosch - rtsp://user:pass@IP:554/rtsp_tunnel?h26x=4&stream=mp&line=1&audio=1. Reolink - rtsp://user:pass@IP:554/h264Preview_01_main. Uniview - rtsp://user:pass@IP:554/media/video1. TP-Link VIGI - rtsp://user:pass@IP:554/stream1. Hanwha/Samsung - rtsp://user:pass@IP:554/profile2/media.smp. Generic ONVIF fallback: use ONVIF Device Manager to discover the actual URL exposed by the camera. Most ANPR software (GMWEB included) has built-in templates for common brands, so manual RTSP entry is rarely needed.

Common ONVIF connection issues and fixes: (1) ONVIF DISABLED ON CAMERA - log in to the camera web UI, open Network then ONVIF and enable it. Some Hikvision and Dahua cameras ship with ONVIF disabled. (2) PORT 80 BLOCKED - ONVIF discovery uses port 80/8080 HTTP and some firewalls block it. Check firewall rules and keep the camera and ANPR server on the same VLAN. (3) AUTHENTICATION FAILURE - the ONVIF user must have the correct role (Admin/Operator); create a dedicated ONVIF user with the Operator role. (4) RTSP URL WRONG - test in VLC first; if VLC cannot connect, ANPR software will not either. (5) SUB STREAM VS MAIN STREAM - for ANPR use the MAIN stream (higher resolution); some configurations default to the sub stream. (6) MULTICAST BLOCKED - some routers block the multicast used by ONVIF discovery, so use unicast. (7) NTP/TIME SYNC - cameras with a wrong clock can fail token-based ONVIF authentication, so keep the camera time synced with the ANPR server within a few minutes.

Reliable recognition depends less on a spec sheet than on framing and the stream. From our measurements: run the camera at 1080p and around 20 fps, keep the plate at roughly 30 px or more of height in the frame (at 31-32 px reads were certain), and make sure the ONVIF/RTSP stream is stable. Our detection step took 38-57 ms per frame (256 px model, 4 threads) and OCR took 15-20 ms per plate crop on the Android device we used as the analysis unit. We confirmed plates at night and in rain. We do not require dedicated ANPR cameras, and we do not publish an accuracy percentage; the number we publish is the test result: 24 of 24 plates with zero false reads.