Audio Looper

audio-looper.js

const mp3Duration = require('mp3-duration')
const humanInterval = require('human-interval')
const path = require('path')
const fs = require('fs')
const { exec } = require("child_process")

const MYLIST = path.basename("mylist.txt")

var milliseconds, duration, source, destination

if(!process.argv[2] || !process.argv[3] || !process.argv[4]){
    throw new Error("Insuficient arguments error")
}

// Get Interval:
duration = process.argv[2]
milliseconds = humanInterval(duration)
console.log(milliseconds)
// Get Source Filename:
source = process.argv[3]
source = path.basename(source)

// Get Destination Filename:
destination = process.argv[4]
destination = path.basename(destination)

//file exists
if (fs.existsSync(MYLIST)) {
    fs.unlinkSync(MYLIST)
}

const handler = fs.createWriteStream(MYLIST, {
    flags: 'a'
})

mp3Duration(source, function (err, duration) {
    if (err) return console.log(err.message)
    let durationInMilliseconds = duration * 1000;
    let times = Math.ceil(milliseconds / durationInMilliseconds)
    //
    handler.write(`# this is a comment\n`)
    for (let index = 0; index < times; index++) {
        handler.write(`file '${source}'\n`)
    }
    handler.end()
    //
    const command = `ffmpeg -f concat -safe 0 -i ${MYLIST} -c copy ${destination}`;
    
    exec(command, (error, stdout, stderr) => {
        if (error) {
            console.log(`error: ${error.message}`)
            return
        }

        if (stderr) {
            console.log(`stderr: ${stderr}`)
            return
        }

        console.log(`stdout: ${stdout}`)

        console.log(`File generated: ${destination}`)
    })
})

//SOURCE: https://stackoverflow.com/questions/5717093/check-if-a-javascript-string-is-a-url/49849482
// Check Valid URL for new implementations:
function validURL(str) {
    var pattern = new RegExp('^(https?:\\/\\/)?'+ // protocol
      '((([a-z\\d]([a-z\\d-]*[a-z\\d])*)\\.)+[a-z]{2,}|'+ // domain name
      '((\\d{1,3}\\.){3}\\d{1,3}))'+ // OR ip (v4) address
      '(\\:\\d+)?(\\/[-a-z\\d%_.~+]*)*'+ // port and path
      '(\\?[;&a-z\\d%_.~+=-]*)?'+ // query string
      '(\\#[-a-z\\d_]*)?$','i'); // fragment locator
    return !!pattern.test(str);
}

// -> Relies on Youtube-dl and FFMpeg
//youtube-dl --extract-audio --audio-format mp3 https://www.youtube.com/watch?v=DVob1D8WlBM

package.json

{
  "name": "audio-looper",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Daniel Farias",
  "license": "ISC",
  "dependencies": {
    "human-interval": "^1.0.0",
    "mp3-duration": "^1.1.0"
  }
}