stats.js

stats.js module contains the functions to check WebRTC statistics parameters and to detect their leaps above a thresholds defined

Analyzing the source code

To analyze the source code take the stats.js module version available here

Parameter leaps detection

1. Parameter initialization

Threshold() code

Where:

• parameter name and a maximum leap threshold value are stored
• Kalman filter is created for the parameter

const threshold = {
    parameter: parameter,
    maxLeap: maxLeap,
    filter: SFU.createFilter(),
    previousValue: -1,
    ...
}

2. Receiving WebRTC statistics data array and checking the parameter value

Threshold.isReached() code

Where:

• current parameter value is passed through the Kalman filter
• if the value exeeds the threshold, parameter leap is detected

isReached: function(stats) {
    let hasLeap = false;
    if (stats && parameter in stats) {
        let value = threshold.filter.filter(stats[parameter]);
        if (threshold.previousValue > -1) {
            if (Math.round(Math.abs(value - threshold.previousValue)) > maxLeap) {
                hasLeap = true;
            }
        }
        threshold.previousValue = value;
    }
    return hasLeap;
}

Parameters list handling

1. Adding parameter to list

Thresholds.add() code

add: function(parameter, maxLeap) {
    if (!thresholds.thresholds[parameter]) {
        thresholds.thresholds[parameter] = new Threshold(parameter, maxLeap);
    }
},

2. Removing parameter from list

Thresholds.remove() code

remove: function(parameter) {
    if (thresholds.thresholds[parameter]) {
        delete thresholds.thresholds[parameter];
    }
},

3. Receiving WebRTC statistics data array and checking the values

Thresholds.isReached() code

isReached: function(stats) {
    let result = false;
    Object.keys(thresholds.thresholds).forEach((key) => {
        result = result || thresholds.thresholds[key].isReached(stats);
    });
    return result;
}