main.js

console.log("Test");
const osc = require("osc");
const mixerIP = "192.168.1.178";
const decibels = false;
function processMeter1Packet(inBuffer) {
    let thisBuffer = Buffer.from(inBuffer);
    let levels = { //Output structure
        '1':0.0, //channel 1 - prefade
        '2':0.0, //channel 2 - prefade
        '3':0.0, //channel 3 - prefade
        '4':0.0, //channel 4 - prefade
        '5':0.0, //channel 5 - prefade
        '6':0.0, //channel 6 - prefade
        '7':0.0, //channel 7 - prefade
        '8':0.0, //channel 8 - prefade
        '9':0.0, //channel 9 - prefade
        '10':0.0, //channel 10 - prefade
        '11':0.0, //channel 11 - prefade
        '12':0.0, //channel 12 - prefade
        '13':0.0, //channel 13 - prefade
        '14':0.0, //channel 14 - prefade
        '15':0.0, //channel 15 - prefade
        '16':0.0, //channel 16 - prefade
        'auxL':0.0, //aux in channel - prefade (left)
        'auxR':0.0, //aux in channel - prefade (right)
        'fx1PreL':0.0, //Effect prefade
        'fx1PreR':0.0,
        'fx2PreL':0.0,
        'fx2PreR':0.0,
        'fx3PreL':0.0,
        'fx3PreR':0.0,
        'fx4PreL':0.0,
        'fx4PreR':0.0,
        'bus1Pre':0.0, //Bus prefade
        'bus2Pre':0.0,
        'bus3Pre':0.0,
        'bus4Pre':0.0,
        'bus5Pre':0.0,
        'bus6Pre':0.0,
        'fx1SendPre':0.0, //Effect send prefade
        'fx2SendPre':0.0,
        'fx3SendPre':0.0,
        'fx4SendPre':0.0,
        'mainPostL':0.0, //Main mix out postfade (left)
        'mainPostR':0.0, //Main mix out postfade (right)
        'monL':0.0, //Monitor out (left)
        'monR':0.0, //Monitor out (right)
    }
    let i = 4;
    Object.keys(levels).forEach(function(key){
        let value = thisBuffer.readIntLE(i, 2); //Convert the two bytes into a signed int
        value = value/256; //Convert to float as decibels
        if (!decibels) value = dbToPercentage(value);
        levels[key] = value;
        i = i+2; //Increment by two bytes for the next one
    });
    return levels;
}
function dbToPercentage(d) {
    /*
        Function courtesy of Patrick‐Gilles Maillot (see their X32 Documentation)
        “d” represents the dB float data. d:[-90, +10]
        “f” represents OSC float data. f: [0.0, 1.0]
     */
    let f = 0.0;
    if (d <= -90) f = 0.0;
    else if (d < -60) f = (d + 90) / 480;
    else if (d < -30) f = (d + 70) / 160;
    else if (d < -10) f = (d + 50) / 80;
    else if (d <= 10) f = (d + 30) / 40;
    /*
        f is now a fudged linear value between 0.0 and 1.0 for decibel values from -90 to 10.
        0.75 = 0dB, so given our highest values are 0 we want to scale it again slightly to give us a 0.0 to 1.0 value for -90dB to +0 dB
        0.375 should now be 0.5 for example
    */
    return f/0.75;
}

udpPort = new osc.UDPPort({
    localAddress: "0.0.0.0",
    localPort: 57121,
    remotePort: 10024,
    remoteAddress: mixerIP, //Set to your XAirs' IP
});
udpPort.on("ready", function () {
    console.log("UDP Socket open and listening");
});
udpPort.on("message", function (oscMessage) {
    if (oscMessage.address == "/meters/1") {
        //This is a data packet we requested of meter data
        console.log(processMeter1Packet(oscMessage['args'][0]));
    } else {
        //This is another packet, which we'll just print to console
        console.log(oscMessage);
    }
});
udpPort.on("error", function (err) {
    console.log(err);
});
udpPort.open();

setInterval(function () {
    udpPort.send({address:"/meters",args:[{ type: "s", value: "/meters/1"}]}); //Issue subscriber, which lasts 10 seconds before a new subscriber has to have been issued.
}, 9000);