ffmpeg.js

/**
 * Reencode audio & video without creating files first
 *
 * Requirements: ffmpeg, ether via a manual installation or via ffmpeg-static
 *
 * If you need more complex features like an output-stream you can check the older, more complex example:
 * https://github.com/fent/node-ytdl-core/blob/cc6720f9387088d6253acc71c8a49000544d4d2a/example/ffmpeg.js
 */

// Buildin with nodejs
const cp = require('child_process');
const readline = require('readline');
// External modules
const ytdl = require('../');
const ffmpeg = require('ffmpeg-static');
// Global constants
const ref = 'https://www.youtube.com/watch?v=aqz-KE-bpKQ';
const tracker = {
  start: Date.now(),
  audio: { downloaded: 0, total: Infinity },
  video: { downloaded: 0, total: Infinity },
  merged: { frame: 0, speed: '0x', fps: 0 },
};

// Get audio and video streams
const audio = ytdl(ref, { quality: 'highestaudio' })
  .on('progress', (_, downloaded, total) => {
    tracker.audio = { downloaded, total };
  });
const video = ytdl(ref, { quality: 'highestvideo' })
  .on('progress', (_, downloaded, total) => {
    tracker.video = { downloaded, total };
  });

// Prepare the progress bar
let progressbarHandle = null;
const progressbarInterval = 1000;
const showProgress = () => {
  readline.cursorTo(process.stdout, 0);
  const toMB = i => (i / 1024 / 1024).toFixed(2);

  process.stdout.write(`Audio  | ${(tracker.audio.downloaded / tracker.audio.total * 100).toFixed(2)}% processed `);
  process.stdout.write(`(${toMB(tracker.audio.downloaded)}MB of ${toMB(tracker.audio.total)}MB).${' '.repeat(10)}\n`);

  process.stdout.write(`Video  | ${(tracker.video.downloaded / tracker.video.total * 100).toFixed(2)}% processed `);
  process.stdout.write(`(${toMB(tracker.video.downloaded)}MB of ${toMB(tracker.video.total)}MB).${' '.repeat(10)}\n`);

  process.stdout.write(`Merged | processing frame ${tracker.merged.frame} `);
  process.stdout.write(`(at ${tracker.merged.fps} fps => ${tracker.merged.speed}).${' '.repeat(10)}\n`);

  process.stdout.write(`running for: ${((Date.now() - tracker.start) / 1000 / 60).toFixed(2)} Minutes.`);
  readline.moveCursor(process.stdout, 0, -3);
};

// Start the ffmpeg child process
const ffmpegProcess = cp.spawn(ffmpeg, [
  // Remove ffmpeg's console spamming
  '-loglevel', '8', '-hide_banner',
  // Redirect/Enable progress messages
  '-progress', 'pipe:3',
  // Set inputs
  '-i', 'pipe:4',
  '-i', 'pipe:5',
  // Map audio & video from streams
  '-map', '0:a',
  '-map', '1:v',
  // Keep encoding
  '-c:v', 'copy',
  // Define output file
  'out.mkv',
], {
  windowsHide: true,
  stdio: [
    /* Standard: stdin, stdout, stderr */
    'inherit', 'inherit', 'inherit',
    /* Custom: pipe:3, pipe:4, pipe:5 */
    'pipe', 'pipe', 'pipe',
  ],
});
ffmpegProcess.on('close', () => {
  console.log('done');
  // Cleanup
  process.stdout.write('\n\n\n\n');
  clearInterval(progressbarHandle);
});

// Link streams
// FFmpeg creates the transformer streams and we just have to insert / read data
ffmpegProcess.stdio[3].on('data', chunk => {
  // Start the progress bar
  if (!progressbarHandle) progressbarHandle = setInterval(showProgress, progressbarInterval);
  // Parse the param=value list returned by ffmpeg
  const lines = chunk.toString().trim().split('\n');
  const args = {};
  for (const l of lines) {
    const [key, value] = l.split('=');
    args[key.trim()] = value.trim();
  }
  tracker.merged = args;
});
audio.pipe(ffmpegProcess.stdio[4]);
video.pipe(ffmpegProcess.stdio[5]);