synopsis-video/createVideoFromMergedFrames.js

Create Video Synopsis from provided videos. Frames are extracted from each video provided and backgrounds are subtracted around moving elements and merged into a single video for quick review.

const {
    mainDirectory,
    mergedFramesDirectory,
    stripNameJpg,
    splitForFfmpeg,
} = require('./utils.js');
const fs = require('fs');
const spawn = require('child_process').spawn;

const createVideoFromJpegImages = (frameDirectory,frames,framesPerSecond,videoOutputLocation) => {
    return new Promise((resolve,reject) => {
        framesPerSecond = parseInt(framesPerSecond)
        if(!framesPerSecond || isNaN(framesPerSecond))framesPerSecond = 2
        var concatFiles = []
        const stripName = (name) => {
            return parseInt(name.replace('.jpg',''))
        }
        frames.forEach(function(filename){
            var n = stripName(filename)
            concatFiles[n] = frameDirectory + filename
        })
        if(concatFiles.length > framesPerSecond){
            videoOutputLocation = videoOutputLocation ? videoOutputLocation : mainDirectory + 'videoOutput.mp4'
            var commandTempLocation = `concatImagesAndMakeVideo.sh`
            var currentFile = 0
            var commandString = `ffmpeg -y -pattern_type glob -f image2pipe -vcodec mjpeg -r ${framesPerSecond} -analyzeduration 10 -i - -q:v 1 -c:v libx264 -r ${framesPerSecond} "${videoOutputLocation}"`
            fs.writeFileSync(commandTempLocation,commandString)
            var videoBuildProcess = spawn('sh',[commandTempLocation])
            var isKilling = false
            var killTimeout
            const exitBuilding = () => {
                setTimeout(()=>{
                    resolve({
                        ok: true,
                        fileLocation: videoOutputLocation,
                        msg: 'Done Building'
                    })
                },5000)
            }
            videoBuildProcess.stderr.on('data',function(data){
                console.log(data.toString())
                clearTimeout(killTimeout)
                killTimeout = setTimeout(()=>{
                    if(isKilling)return;
                    isKilling = true
                    videoBuildProcess.kill('SIGTERM')
                },4000)
            })
            videoBuildProcess.on('exit',function(data){
                exitBuilding()
            })
            var readFile = function(){
                var filePath = concatFiles[currentFile]
                fs.readFile(filePath,function(err,buffer){
                    if(!err)videoBuildProcess.stdin.write(buffer)
                    if(currentFile === concatFiles.length - 1){
                        //is last
                    }else{
                        setTimeout(function(){
                            ++currentFile
                            readFile()
                        },1/framesPerSecond)
                    }
                })
            }
            readFile()
        }else{
            resolve({
                ok: false,
                msg: 'More Frames or Lower FPS'
            })
        }
    })
}

exports.createVideoFromJpegImages = createVideoFromJpegImages