stats.js

const logger = require('./utils');

const streamStats = {
    second: Math.floor(new Date().getTime() / 1000),
    totalSeconds: 0,
    framesPerSecond: 0,
    totalFramesForFPS: 0,
    currentFPS: 27, // we will start with an empirical middle ground
    framesDeltaForFPS: 0,
    ffmpegRestartSuggested: false,
    ffmpegRestartSuggestedCounter: 0,
    lastKnownDelta: 0,

    // Smoothing algo vars
    firstFrameTime: 0,
    lastFrameReceivedTime: 0,
    currentElapsedTime: 0,
    idealTotalFrames: 0,
    totalFramesReceived: 0,
    totalFramesAdded: 0,
    ffmpegReady: false
};
exports.getStats = streamStats;

exports.track = function () {
    const now = new Date().getTime();
    streamStats.lastFrameReceivedTime = now;
    const nowInSecond = Math.floor(now / 1000);

    // This will happen only once every
    if (streamStats.second !== nowInSecond) {
        if (streamStats.totalSeconds > 0) {
            streamStats.framesDeltaForFPS = streamStats.framesReceivedPerSecond - streamStats.currentFPS;
            logger.debug("Second: " + streamStats.second + " received " + streamStats.framesReceivedPerSecond + "/" + streamStats.currentFPS + ". Delta: " + streamStats.framesDeltaForFPS + ". Sent to FFMPEG: " + streamStats.totalFramesAddedPerSecond + " .");
            logger.debug("Total Frames Received: " + streamStats.totalFramesReceived + " . Total Time Elapsed: " + streamStats.currentElapsedTime + " . Ideal Total Frames: " + streamStats.idealTotalFrames + " . Current Frames Added: " + streamStats.totalFramesAdded);
        }
        if (streamStats.totalSeconds > 20) {
            if (shouldConsiderRestart() && false) {
                logger.info("We should be considering restarting ffmpeg as this delta is too consistent..");
                streamStats.currentFPS = streamStats.currentFPS + streamStats.framesDeltaForFPS;
                streamStats.ffmpegRestartSuggested = true;
            }
        }
        streamStats.totalSeconds++;
        streamStats.second = nowInSecond;
        streamStats.framesReceivedPerSecond = 0;
        streamStats.totalFramesAddedPerSecond = 0;
    }

    streamStats.framesReceivedPerSecond++;

    //calculate frames to add now only start adding when we know we are read
    if (streamStats.ffmpegReady) {
        //adjust first time
        if (streamStats.firstFrameTime === 0) {
            streamStats.firstFrameTime = now;
        }

        streamStats.totalFramesReceived++;
        streamStats.idealFrameDistance = 1000 / streamStats.currentFPS;
        streamStats.currentElapsedTime = now - streamStats.firstFrameTime;
        streamStats.idealTotalFrames = Math.floor(streamStats.currentElapsedTime / streamStats.idealFrameDistance) + 1;
        streamStats.framesToAddNow = streamStats.idealTotalFrames - streamStats.totalFramesAdded;
    }
}

exports.frameAdded = function () {
    if (streamStats.firstFrameTime === 0) {
        streamStats.firstFrameTime = streamStats.lastFrameReceivedTime;
    }
    streamStats.totalFramesAddedPerSecond++;
    streamStats.totalFramesAdded++;
    streamStats.framesToAddNow--;
}

exports.resetSmoothingAlgoStats = function () {
    streamStats.firstFrameTime = 0;
    streamStats.lastFrameReceivedTime = 0;
    streamStats.currentElapsedTime = 0;
    streamStats.idealTotalFrames = 0;
    streamStats.totalFramesReceived = 0;
    streamStats.totalFramesAdded = 0;
    streamStats.ffmpegReady = false;
}

function shouldConsiderRestart() {
    if (streamStats.framesDeltaForFPS === streamStats.lastKnownDelta && streamStats.lastKnownDelta !== 0) {
        //if(streamStats.framesDeltaForFPS == streamStats.lastKnownDelta ){
        streamStats.ffmpegRestartSuggestedCounter++
    } else {
        streamStats.ffmpegRestartSuggestedCounter = 0;
    }
    streamStats.lastKnownDelta = streamStats.framesDeltaForFPS;

    return streamStats.ffmpegRestartSuggestedCounter > 4;
}