barnowl-axis converts AXIS Object Analytics messages from network cameras into standard developer-friendly JSON that is vendor/technology/application-agnostic.
barnowl-axis is a lightweight Node.js package that can run on resource-constrained edge devices as well as on powerful cloud servers and anything in between. It is included in reelyActive's Pareto Anywhere open source middleware suite, and can just as easily be run standalone behind a barnowl instance, as detailed in the code examples below.
Clone this repository, install package dependencies with npm install, and then from the root folder run at any time:
npm start
barnowl-axis will attempt to connect to a local MQTT server localhost (mqtt://localhost) and subscribe to the Object Analytics topic, outputting processed messages as JSON to the console.
Developing an application directly from barnowl-axis? Start by pasting the code below into a file called server.js:
const Barnowl = require('barnowl');
const BarnowlAxis = require('barnowl-axis');
let barnowl = new Barnowl({ enableMixing: true });
barnowl.addListener(BarnowlAxis, {}, BarnowlAxis.MqttListener,
{ url: "mqtt://localhost" });
barnowl.on('infrastructureMessage', (infrastructureMessage) => {
console.log(infrastructureMessage);
// Trigger your application logic here
});From the same folder as the server.js file, install package dependencies with the commands npm install barnowl-axis and npm install barnowl. Then run the code with the command node server.js and observe infrastructureMessage objects output to the console:
{
deviceId: "b8a44f941234",
deviceIdType: 2,
isMotionDetected: [ true ],
timestamp: 1645568542222
}See the Supported Listener Interfaces below to adapt the code to listen for your network camera(s).
The following listener interfaces are supported by barnowl-axis. Extend the Hello barnowl-axis! example above by pasting in any of the code snippets below.
Connect to a MQTT server and subscribe to the Object Analytics topic to receive messages:
let options = { url: "mqtt://localhost", clientOptions: { username: "user",
password: "pass" } };
barnowl.addListener(BarnowlAxis, {}, BarnowlAxis.MqttListener, options);Provides periodic AXIS Object Analytics messages for testing purposes.
barnowl.addListener(BarnowlAxis, {}, BarnowlAxis.TestListener, {});The following AXIS Object Analytics scenarios are supported:
| Scenario | Decoded property | Required scenario name |
|---|---|---|
| Object in area | isMotionDetected | n/a |
| Line crossing | isMotionDetected | n/a |
| Time in area | isMotionDetected | n/a |
| Crossline counting | passageCounts | Crossline |
| Occupancy in area | numberOfOccupants | Occupancy |
See the advlib Standard Properties for details of each decoded property.
Note that the Crossline counting scenario must be named Crossline and the Occupancy in area scenario named Occupancy in order for the corresponding messages to be decoded into passageCounts and numberOfOccupants properties, respectively. The AXIS Object Analytics MQTT messages do not include a property to distinguish scenario type, and hence the user-defined name (included in the message as "scenario" property) is observed by barnowl-axis to make this distinction.
The other scenarios require no naming constraints. The messages for the other scenarios simply include an "active" property which is interpreted by barnowl-axis as isMotionDetected. It is therefore possible for two such scenarios to simultaneously produce contradictory isMotionDetected outputs.
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MIT License
Copyright (c) 2024 reelyActive
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