Univerter/downloader.js

const expressManager = require("./express.js"),
    path = require("path"),
    fs = require("fs"),
    ytdl = require("@distube/ytdl-core"),
    ffmpeg = require("ffmpeg-static"),
    cp = require("child_process")

var qualityLabels = [
    "144",
    "240",
    "360",
    "480",
    "720",
    "1080",
    "1440",
    "2160"
]

var audioFormats = [
    "mp3"
]

expressManager.app.get("/download", async (req, res) => {
    var url = req.query.url,
        quality = req.query.quality,
        format = req.query.format,
        trimAudio = req.query.trimAudio && audioFormats.includes(format) || false

    if (ytdl.validateURL(url) && qualityLabels.includes(quality)) {
        var needsVideo = !audioFormats.includes(format)

        var info = await ytdl.getInfo(url)

        res.setHeader("Content-Disposition", `attachment; filename="${info.videoDetails.title.replace(/[^a-z0-9 ]/gi, '')}.${format}"`)

        var audioFormat = ytdl.chooseFormat(info.formats, { filter: (format) => {
            return format.hasAudio && !format.hasVideo
        } })

        var videoFormat = undefined

        var qualityLabel = quality
        while (videoFormat == undefined) {
            for (let i = 0; i < info.formats.length; i++) {
                const format = info.formats[i];
                if (format.hasVideo && !format.hasAudio && format.height && format.height.toString() == qualityLabel.toString() && (format.videoCodec.includes("avc1") || format.codecs.includes("avc1"))) {
                    // console.log(format.videoCodec)
                    videoFormat = format
                    continue
                }
            }

            if (qualityLabels.indexOf(qualityLabel) - 1 < 0) {
                break
            }
            qualityLabel = qualityLabels[qualityLabels.indexOf(qualityLabel) - 1]
        }

        if (!videoFormat) {
            videoFormat = ytdl.chooseFormat(info.formats, { filter: "videoonly" })
        }

        var baseArgs = [
            // Remove ffmpeg's console spamming
            '-loglevel', 'error',
            // // Set inputs
            // '-i', 'pipe:4',
            // '-i', 'pipe:5',
            // Map audio & video from streams
            // '-map', '0:a',
            // '-map', '1:v',
            // Keep encoding
            '-c:v', 'copy',
            '-movflags','frag_keyframe+empty_moov',        
            '-f', format,
            // Define output file
            '-',
        ]
        
        var inputArgs = [
            '-i', 'pipe:4'
        ]

        var mapArgs = [
            '-map', '0:a'
        ]

        var bonusArgs = []

        if (needsVideo) {
           inputArgs = inputArgs.concat(['-i', 'pipe:5'])
           mapArgs = mapArgs.concat(['-map', '1:v']) 
        }

        if (trimAudio) {
            bonusArgs = bonusArgs.concat(['-af', 'silenceremove=1:0:-50dB'])
        }

        var args = inputArgs.concat(mapArgs).concat(bonusArgs).concat(baseArgs)

        const ffmpegProcess = cp.spawn(ffmpeg, args, {
            windowsHide: true,
            stdio: [
                /* Standard: stdin, stdout, stderr */
                'pipe', 'pipe', 'pipe',
                /* Custom: pipe:3, pipe:4, pipe:5 */
                'pipe', 'pipe', 'pipe',
            ],
        });
        
        ffmpegProcess.stdio[1].pipe(res)

        var audio = ytdl(url, { format: audioFormat || "audioonly" })
        audio.pipe(ffmpegProcess.stdio[4])
        
        if (needsVideo) {
            var video = ytdl(url, { format: videoFormat || "videoonly" })
            video.pipe(ffmpegProcess.stdio[5])
        }

    } else {
        res.send("Invalid URL!")
    }
})