Encode video directory into mp4 and webm

videos.js

/**
 * Generate web videos mp4 + webm from given folder
 * You can pass options by file in videos.json
 * Options are crop size
 * NODE and FFMEPG is required. On mac brew install node && brew install ffmpeg
 * FFMPEG command are inspired by https://gist.github.com/Vestride/278e13915894821e1d6f
 * eg: node videos.js --input=../inputDir --output=../dir/outputDir --prefix=compressed --r-audio
 * if missing outputDir, inputDir will be use
 */

const path = require('path')
const fs = require('fs')
const util = require('util')
const {spawnSync} = require('child_process')

const args = process.argv

let videoFileOptions = false
let videosInputFolder = false
let videosOutputFolder = false
let prefixOutFilename = '_'
let removeAudio = false

args.forEach(arg => {
  if (arg.startsWith('--input=')) {
    videosInputFolder = arg.replace('--input=', '')
    return
  }

  if (arg.startsWith('--output=')) {
    videosOutputFolder = arg.replace('--output=', '')
    return
  }

  if (arg.startsWith('--prefix=')) {
    prefixOutFilename = arg.replace('--prefix=', '')
  }

  if (arg.startsWith('--r-audio')) {
    removeAudio = true
  }
})

if (!videosInputFolder) {
  console.log('A folder directory must be specified')
  return
}

const videosDir = path.join(__dirname, videosInputFolder)

videosOutputFolder = videosOutputFolder ? path.join(__dirname, videosOutputFolder) : videosDir

// List videos to encode and get videos json config file if exists
const videosFiles = fs.readdirSync(videosDir).map((file) => {
  return path.join(videosDir, file)
}).filter(function (file) {
  if (path.basename(file) === 'videos.json') {
    videoFileOptions = file
    return false
  }
  return fs.statSync(file).isFile()
})

// Read video file options if exist
if (videoFileOptions) {
  videoFileOptions = JSON.parse(fs.readFileSync(videoFileOptions))
}

// Encode videos
videosFiles.forEach((file) => {
  const filename = path.basename(file)
  const ext = path.extname(file)
  const fileNameWExt = path.basename(file, ext)
  const fileOpts = videoFileOptions.find(f => f.filename === filename)
  // ffmpeg -an -i input.mov -vcodec libx264 -pix_fmt yuv420p -profile:v baseline -level 3 output.mp4

  /**
   * ffmpeg -i <source> -c:v libvpx-vp9 -pass 1 -b:v 1000K -threads 1 -speed 4 \
   -tile-columns 0 -frame-parallel 0 -auto-alt-ref 1 -lag-in-frames 25 \
   -g 9999 -aq-mode 0 -an -f webm /dev/null

   ffmpeg -i <source> -c:v libvpx-vp9 -pass 2 -b:v 1000K -threads 1 -speed 0 \
   -tile-columns 0 -frame-parallel 0 -auto-alt-ref 1 -lag-in-frames 25 \
   -g 9999 -aq-mode 0 -c:a libopus -b:a 64k -f webm out.webm
   */

  let mp4Exec = `ffmpeg -i ${file} -vcodec libx264 -profile:v baseline -level 3`
  let audio = removeAudio

  if (fileOpts) {
    // remove audio track
    if ('audio' in fileOpts) {
      audio = fileOpts.audio
    }

    if ('crop' in fileOpts) {
      mp4Exec += ` -vf "crop=${fileOpts.crop.w}:${fileOpts.crop.h}:${fileOpts.crop.x}:${fileOpts.crop.y}"`
    }
  }

  if (audio) {
    mp4Exec += ' -an'
  }

  const outMp4Filename = prefixOutFilename + fileNameWExt + '.mp4'
  const outMp4path = path.join(videosOutputFolder, outMp4Filename)
  const outWebmFilename = prefixOutFilename + fileNameWExt + '.webm'

  mp4Exec += ` -y ${outMp4path}`
  const webmExecPass1 = `ffmpeg -i ${outMp4path} -c:v libvpx-vp9 -pass 1 -b:v 1000K -threads 1 -speed 4 \\
   -tile-columns 0 -frame-parallel 0 -auto-alt-ref 1 -lag-in-frames 25 \\
   -g 9999 -aq-mode 0 -an -y -f webm /dev/null`

  const webmExecPass2 = `ffmpeg -i ${outMp4path} -c:v libvpx-vp9 -pass 2 -b:v 1000K -threads 1 -speed 0 \\
   -tile-columns 0 -frame-parallel 0 -auto-alt-ref 1 -lag-in-frames 25 \\
   -g 9999 -aq-mode 0 -c:a libopus -b:a 64k -y -f webm ${path.join(videosOutputFolder, outWebmFilename)}`

  console.log(`***********************`)
  console.log(`processing file ${outMp4Filename}`)
  console.log(`***********************`)
  encodeVideo(mp4Exec)
  console.log(`***********************`)
  console.log(`end of processing file ${outMp4Filename}`)
  console.log(`***********************`)

  console.log(`***********************`)
  console.log(`processing file ${outWebmFilename} pass 1`)
  console.log(`***********************`)
  encodeVideo(webmExecPass1)
  console.log(`***********************`)
  console.log(`end of processing file ${outWebmFilename} pass 1`)
  console.log(`***********************`)

  console.log(`***********************`)
  console.log(`processing file ${outWebmFilename} pass 2`)
  console.log(`***********************`)
  encodeVideo(webmExecPass2)
  console.log(`***********************`)
  console.log(`end of processing file ${outWebmFilename} pass 2`)
  console.log(`***********************`)
})

function encodeVideo (cmd) {
  spawnSync(cmd, {stdio: 'inherit', shell: true})
}

videos.json

[
  {
    "filename": "filename.ext",
    "audio": false,
    "crop": {
      "x": "292",
      "y": "0",
      "w": "375",
      "h": "500"
    }
  }
]