shinobi-video-synopsis/mergeFramePairs.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 {
    stripNamePng,
    createBaseFolder,
} = require('./utils.js');
const fs = require('fs');
const gm = require('gm').subClass({imageMagick: true})
const flattenImage = (gmImageBuffer,filename) => {
    return new Promise((resolve,reject) => {
        gmImageBuffer.flatten().write(filename, (err) => {
            resolve(err)
        });
    })
}
exports.mergeFramePairs = (options) => {
    const engine = options.engine
    const videoNames = options.videoNames || []
    const subtractedBackgrounds = options.subtractedBackgroundsDirectory
    const mergedFrames = options.mergedFramesDirectory
    const firstFrameDirectory = options.firstFrameDirectory
    const onFrameComplete = options.onFrameComplete || function(){}
    const response = {
        startedAt: new Date(),
        videoNames: videoNames,
        numberOfVideos: videoNames.length,
        numberOfFrames: 0,
    }
    return new Promise(async (resolve,reject) => {
        var backgroundPath = firstFrameDirectory + fs.readdirSync(firstFrameDirectory)[0]
        var videoImages = {}
        var videoImagePairs = []
        videoNames.forEach((videoName) => {
            const videoFolder = subtractedBackgrounds + videoName + '/'
            videoImages[videoName] = fs.readdirSync(videoFolder)
            videoImages[videoName].forEach((filename) => {
                const n = stripNamePng(filename)
                if(!videoImagePairs[n])videoImagePairs[n] = []
                videoImagePairs[n].push(videoFolder + filename)
            })
        })
        if(videoImagePairs.length > 0){
            for (var i = 0; i < videoImagePairs.length; i++) {
                const pair = videoImagePairs[i]
                var newImage = gm()
                .in('-geometry', '+0+0')
                .in(backgroundPath)
                for (var ii = 0; ii < pair.length; ii++) {
                    const imagePath = pair[ii]
                    newImage.in('-geometry', '+0+0').in(imagePath)
                }
                engine.logStderr(`${mergedFrames}${i}.jpg`)
                const error = await flattenImage(newImage,`${mergedFrames}${i}.jpg`)
                if(error){
                    engine.logStderr(error)
                }
                ++response.numberOfFrames
                engine.logStderr(i === videoImagePairs.length - 1,i, videoImagePairs.length - 1)
                onFrameComplete(i,videoImagePairs.length)
                if(i === videoImagePairs.length - 1 || engine.cancelledProcess){
                    response.endedAt = new Date()
                    response.timeSpent = response.endedAt - response.startedAt
                    resolve(response)
                }
            }
        }else{
            resolve(response)
        }
    })
}