ViewtronEvent

Overview

ViewtronEvent is a factory function that parses the raw XML from a camera HTTP POST and returns a typed event object. It automatically detects whether the source is an IPC (v1.x) or NVR (v2.0) and returns the appropriate class.

Usage

from viewtron import ViewtronEvent

event = ViewtronEvent(xml_string)
if event is None:
    # Keepalive, alarm status, or unrecognized — skip
    return

print(event.category)           # "lpr", "intrusion", "face", etc.
print(event.get_alarm_type())   # Raw smartType code
print(event.get_alarm_description())  # Human-readable name

Usually you don't call ViewtronEvent directly — ViewtronServer calls it internally and passes the result to your on_event callback. But you can use it standalone if you're building your own HTTP server.

Return Values

Camera sends...	Returns	Category
License plate detection (IPC)	LPR	"lpr"
License plate detection (NVR)	VehicleLPR	"lpr"
Face detection (IPC)	FaceDetection	"face"
Face detection (NVR)	FaceDetectionV2	"face"
Perimeter intrusion (IPC)	IntrusionDetection	"intrusion"
Zone entry (IPC)	IntrusionEntry	"intrusion"
Zone exit (IPC)	IntrusionExit	"intrusion"
Loitering (IPC)	LoiteringDetection	"intrusion"
Illegal parking (IPC)	IllegalParking	"intrusion"
Region intrusion (NVR)	RegionIntrusion	"intrusion"
Line crossing (NVR)	LineCrossing	"intrusion"
Pass line count (IPC)	IntrusionDetection	"counting"
Intrusion target count (IPC)	IntrusionDetection	"counting"
Counting by line (NVR)	TargetCountingByLine	"counting"
Counting by area (NVR)	TargetCountingByArea	"counting"
Video metadata (IPC)	VideoMetadata	"metadata"
Video metadata (NVR)	VideoMetadataV2	"metadata"
Smart tracking	Traject	"traject"
Keepalive heartbeat	None	—
Alarm status	None	—
Unrecognized	None	—

Common Properties

All event objects (except Traject) share these properties and methods.

Properties

Property	Type	Description
category	str	Event category: "lpr", "face", "intrusion", "counting", "metadata", "traject"
alarm_type	str	Raw smartType code (e.g., "VEHICE", "vehicle", "PEA", "regionIntrusion")
alarm_description	str	Human-readable description (e.g., "License Plate Recognition")
ip_cam	str	Camera/device name

Methods

Method	Returns	Description
get_alarm_type()	str	Raw smartType code
get_alarm_description()	str	Human-readable event description
get_ip_cam()	str	Camera device name
get_time_stamp()	str	Unix timestamp as string
get_time_stamp_formatted()	str	Formatted timestamp (e.g., "2026-04-09 15:30:45")
get_plate_number()	str	Plate text, or "\<NO PLATE EXISTS>" for non-LPR events
get_ip_address()	str	Camera IP address (if set)
set_ip_address(ip)	int	Set the camera IP (called by server automatically)
source_image_exists()	bool	Whether a source (overview) image is attached
target_image_exists()	bool	Whether a target (cropped) image is attached
images_exist()	bool	Whether any images are attached
get_source_image()	str or None	Base64-encoded source image
get_target_image()	str or None	Base64-encoded target image
get_source_image_bytes()	bytes or None	Decoded JPEG bytes for source image
get_target_image_bytes()	bytes or None	Decoded JPEG bytes for target image
dump_xml()	None	Print raw XML to stdout (debugging)
dump_json()	None	Print parsed data as JSON to stdout (debugging)

NVR-only Methods

Method	Returns	Description
get_channel_id()	str	NVR channel number

Category Routing

The recommended pattern for handling events by type:

def handle_event(event, client_ip):
    if event.category == "lpr":
        plate = event.get_plate_number()
        group = event.get_plate_group()
        print(f"Plate {plate} ({group})")

    elif event.category == "intrusion":
        print(f"Intrusion: {event.get_alarm_description()}")

    elif event.category == "face":
        # NVR v2.0 only — check class
        if hasattr(event, 'get_face_age'):
            print(f"Face: age {event.get_face_age()}, sex {event.get_face_sex()}")

    elif event.category == "counting":
        print(f"Count event: {event.get_alarm_type()}")

IPC vs NVR Detection

ViewtronEvent automatically detects the source format by checking the XML API version:

• Version starts with "1" (or no version) -- IPC v1.x classes (LPR, FaceDetection, IntrusionDetection, etc.)
• Version starts with "2" -- NVR v2.0 classes (VehicleLPR, FaceDetectionV2, RegionIntrusion, etc.)

Your code doesn't need to worry about this -- use event.category for routing and the appropriate getter methods.

Related Pages

• LPR Events -- get_plate_number(), get_plate_group(), vehicle attributes, IPC vs NVR differences
• Intrusion Events -- perimeter, line crossing, zone entry/exit, loitering
• Face Detection Events -- age, sex, glasses, mask (NVR v2.0 only)
• Counting Events -- line counting, area counting
• Images -- working with event images
• ViewtronServer -- the server that produces these events