browser code

gistfile1.txt

1. Deploy to Cloudflare workers
2. Proxy ytdl-core thru the proxy

main.ts

import { FFmpeg } from '@ffmpeg/ffmpeg'
import { fetchFile, toBlobURL } from '@ffmpeg/util'
import ytdl from 'ytdl-core'
import './style.css'

// https://github.com/darenliang/darenliang.com/blob/3debad5aaeadf6581dfab36f32e5166c01b7739b/misc/ytdl-ffmpeg-demo/main.js
// https://github.com/ffmpegwasm/ffmpeg.wasm/blob/main/apps/vue-vite-app/src/components/FFmpegDemo.vue

const baseURL = 'https://unpkg.com/@ffmpeg/core-mt@0.12.6/dist/esm'
const ffmpeg = new FFmpeg()

// REPLACE this!
const WORKER_URL = `https://MY_WORKER.workers.dev`

const cleanMemory = () => {
  console.log('[info] unlinking old data')
  try {
    ffmpeg.FS('unlink', 'output.mp3')
  } catch {}
  try {
    ffmpeg.FS('unlink', 'output.mp4')
  } catch {}
}

const ytdlOptions = {
  requestOptions: {
    maxRetries: 2,
    backoff: { inc: 200, max: 500 },
    transform: (parsed) => {
      const originURL = parsed.protocol + '//' + parsed.hostname + parsed.path
      parsed.host = WORKER_URL.split('https://')[1]
      parsed.hostname = WORKER_URL.split('https://')[1]
      parsed.path = '/?url=' + encodeURIComponent(originURL)
      parsed.protocol = 'https:'
      return parsed
    },
  },
}

const proxy = (url) => {
  return `${WORKER_URL}/?url=` + encodeURIComponent(url)
}

const getAudioBuffer = async (audioInfo) => {
  cleanMemory()

  console.log('[info] fetching data')
  await ffmpeg.writeFile('test.m4a', await fetchFile(proxy(audioInfo.url)))
  await ffmpeg.exec(['-i', 'test.m4a', 'output.mp3'])

  const data = await ffmpeg.readFile('output.mp3')

  document.getElementById('track').src = URL.createObjectURL(
    new Blob([(data as Uint8Array).buffer], { type: 'video/mp4' }),
  )
  await document.getElementById('track')?.play()
}

const getBestAudioBuffer = async (url) => {
  const info = await getInfo(url)

  console.log('[info] choosing format')
  const audioInfo = ytdl.chooseFormat(info.formats, {
    quality: 'highestaudio',
    filter: 'audioonly',
  })

  return await getAudioBuffer(audioInfo)
}

const getInfo = async (url) => {
  console.log('[info] getting info')
  return await ytdl.getInfo(url, ytdlOptions)
}

;(async () => {
  ffmpeg.on('log', ({ message }) => {
    console.log(message)
  })
  ffmpeg.on('progress', ({ progress, time }) => {
    console.log(progress)
  })
  await ffmpeg.load({
    coreURL: await toBlobURL(`${baseURL}/ffmpeg-core.js`, 'text/javascript'),
    wasmURL: await toBlobURL(`${baseURL}/ffmpeg-core.wasm`, 'application/wasm'),
    workerURL: await toBlobURL(
      `${baseURL}/ffmpeg-core.worker.js`,
      'text/javascript',
    ),
  })
  getBestAudioBuffer('https://www.youtube.com/watch?v=ui77nVbJZDw').then(
    (i) => {
      console.log(i)
    },
  )
})()

worker.ts

export default {
	async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
		const url = new URL(request.url);
		const params = new URLSearchParams(url.search);
		if (!params.has('url')) {
			return new Response('400 Bad Request', { status: 400 });
		}

		const response = await fetch(decodeURIComponent(params.get('url')), {
			headers: request.headers,
			redirect: 'follow',
		});

		const { readable, writable } = new TransformStream();
		response.body?.pipeTo(writable);

		const newResponse = new Response(readable, response);
		newResponse.headers.append('Access-Control-Allow-Origin', 'http://localhost:5173');
		newResponse.headers.append('Access-Control-Allow-Headers', '*');
		newResponse.headers.append('Access-Control-Allow-Methods', '*');

		return newResponse;
	},
};