BBB Screenshare extractor CLI

extractor.js

'use strict';

/* generate mp4's of the screenshare + audio from a BBB hosted recording

  $   node   this-file.js   meeting-id   name-of-output-file   keep

  - meeting-id (required) a big blue button meeting id, you can find this in the URL for recorded sessions.
    the script will exit early if this is not provided
  - name-of-output-file (optional) the output file name should not include an extension, just the name.
    defaults to class-recording.mp4
  - keep (optional) can be anything, the script just checks for a 4th cli arg
    if present, the original videos will not be removed

  test it out with this short video:

  - video link: https://meet.openknowledge.be/playback/presentation/2.0/playback.html?meetingId=05594ce10542676cd7f00b5d118cb2f367054196-1606646031832
  - cli input: $ node this-file.js 05594ce10542676cd7f00b5d118cb2f367054196-1606646031832 test-download

  heads-up: you will need https://www.ffmpeg.org/ installed on your computer for this to work

  possible improvement: do everything in memory without writing temp files?

  credits: adapted from https://github.com/bermarte/HYF-small-video-utility

*/

const fs = require('fs');
const path = require('path');
const util = require('util');

const writeFilePromise = util.promisify(fs.writeFile);
const unlinkPromise = util.promisify(fs.unlink);

const ffmpeg = require('fluent-ffmpeg');
const fetch = require('node-fetch');

// exit early if there is no meeting id
const meetingId = process.argv[2];
if (!meetingId) {
  console.log('no meeting id provided');
  process.exit(0);
}

// configurations
const mediaExtension = '.mp4';
const domain = 'https://meet.openknowledge.be/';
const uniquifier = Math.random()
  .toString(16)
  .substr(2, 12);

// read in the file name and generate a temporary output path
const outputFileName = `${process.argv[3] ||
  `class-recording-${uniquifier}`}${mediaExtension}`;
const outputPath = path.join(__dirname, outputFileName);

// did the user ask to keep the temp files?
const keepTemps = process.argv[4];

// generate fetch URL and temporary output path for the silent screenshare video
const deskshareUrl = `${domain}presentation/${meetingId}/deskshare/deskshare${mediaExtension}`;
const deskshareFileName = 'temp-deskshare-' + uniquifier;
const desksharePath = path.join(
  __dirname,
  `${deskshareFileName}${mediaExtension}`
);

// generate fetch URL and temporary output path for the webcams with audio
const webcamsUrl = `${domain}presentation/${meetingId}/video/webcams${mediaExtension}`;
const webcamsFileName = 'temp-webcams-' + uniquifier;
const webcamsPath = path.join(__dirname, `${webcamsFileName}${mediaExtension}`);

// generate temporary audio output path
const audioFileName = `temp-audio-${uniquifier}.aac`;
const audioPath = path.join(__dirname, audioFileName);

// main script
(async () => {
  try {
    console.log('--- downloading videos ---');
    await Promise.all([
      // downloadVideo is hoisted from the bottom of the file
      downloadVideo(deskshareUrl, desksharePath),
      downloadVideo(webcamsUrl, webcamsPath),
    ]);

    console.log('--- extracting audio from webcams ---');
    await new Promise((res, rej) => {
      ffmpeg(webcamsPath)
        .outputOptions(['-vn', '-acodec copy'])
        .save(audioPath)
        .on('end', () => (console.log('mixing done'), res()))
        .on('error', err => (console.error(err), rej()));
    });

    console.log('--- combining audio with deskshare video ---');
    await new Promise((res, rej) => {
      ffmpeg()
        .input(audioPath)
        .input(desksharePath)
        .output(outputPath)
        // .outputOptions('-c', 'copy')
        .on('end', () => (console.log('mixing done'), res()))
        .on('error', err => (console.error(err), rej()))
        .run();
    });

    if (!keepTemps) {
      console.log('--- clearing temporary files ---');
      await Promise.all([
        unlinkPromise(desksharePath),
        unlinkPromise(webcamsPath),
        unlinkPromise(audioPath),
      ]);
    }

    console.log('all done');
  } catch (err) {
    console.error(err);
  }
})();

async function downloadVideo(url, filePath) {
  try {
    console.log(`... fetching ${url}`);
    const response = await fetch(url);

    console.log(`... buffering ${url}`);
    const buffer = await response.buffer();

    console.log(`... writing ${url}`);
    await writeFilePromise(filePath, buffer);

    console.log(`finished downloading ${url}`);
  } catch (err) {
    console.error(err);
  }
}

package.json

{
  "description": "A little  script used to convert the lesson of HYF available on [openknowledge.be](https://meet.openknowledge.be/playback/presentation/2.0/playback.html?meetingId=48966e92bc14f80c53d450f9e59dc77e812b2f8b-1605437686426)",
  "dependencies": {
    "ffmpeg-extract-audio": "^1.0.2",
    "fluent-ffmpeg": "^2.1.2",
    "node-fetch": "^2.6.1"
  }
}