FFMPEG Splice Ads Into Audio File

index.js

const ffmpeg = require('fluent-ffmpeg');
const fs = require('fs');
const _ = require('lodash');

const INPUT_FILE = "./data/input.mp3";
const OUTPUT_FILE = "./output.mp3";

function splice(fileName, startTime, duration, outputFile) {
  var command = ffmpeg(fileName);
  command.seekInput(startTime);
  if (duration) {
    command.duration(duration + 0.1); // AHAHAHAHAHAHA
  }
  command.save(outputFile);
}

function concat(files, outputFile) {
  var command = ffmpeg();
  files.forEach((file) => { command = command.input(file); });
  return command.mergeToFile(outputFile, './tmp');
}

function makeSplices(inputFile, adTimes, outputDir) {
  var files = [];
  var cursor = 0;

  adTimes.forEach((adTime, index) => {
    var outputFile = './tmp/splice-' + index + '.mp3';
    var duration = (index == adTimes.length-1) ? null : (adTime - cursor);
    splice(inputFile, cursor, duration, outputFile);
    cursor = adTime;
    files.push(outputFile);
  });

  return files;
}

function getAds(numberOfAds, cb) {
  fs.readdir("./ads", (err, files) => {
      var betterFiles = _.map(files, (file) => "./ads/" + file);
      var ads = _.sampleSize(betterFiles, numberOfAds);
      cb(ads);
  })
}

function interperseAds(splices, cb) {
  var numberOfAds = splices.length - 1;

  var ads = getAds(numberOfAds, function (ads) {
    console.log(ads);

    var zipped = _.zip(splices, ads);
    console.log(zipped);

    var files = _.flatten(zipped);
    console.log(files);

    return files;
  });
}

function doStuff(originalFile, adTimes, outputFile) {
  var splices = makeSplices(originalFile, adTimes, outputFile);
  setTimeout(function () {
    interperseAds(splices, function (files) {
      concat(files, outputFile);
    });
  }, 1000);
}

// splice(INPUT_FILE, START_TIME, END_TIME, OUTPUT_FILE);
// concat(FILES, OUTPUT_FILE);
// makeSplices(INPUT_FILE, [15, 30, 90, 120], OUTPUT_FILE)
doStuff(INPUT_FILE, [10, 30], OUTPUT_FILE)