transform-videos-to-frames.js

const fs = require('fs')
const ffmpeg = require('fluent-ffmpeg')
const path = require('path')


const FRAMES_PER_SECOND = 30
const framesFolder = path.resolve('myfolder', 'videos', 'frames')

function getAllFilesFromFolder(folderPath, extension) {
  return new Promise((resolve, reject) => {
    fs.readdir(folderPath, (err, files) => {
      if(err) {
        reject(err)
      } else {
        resolve(files.map(f => {
           return {
             name: f.split('.').slice(0, -1).join('.'),
             fullPath: path.join(folderPath, f),
             extension: f.split('.').pop()
           }
        }).filter( f => f.extension === extension))
      }
    })
  })
}

function generateFrames(input, output) {
    const cmd = ffmpeg(input)
      .outputOptions('-r ' + FRAMES_PER_SECOND)
      .on('start', (cmd) => console.log({ cmd }))

    return new Promise((resolve, reject) => {
      cmd
        .on('end', () => resolve(output))
        .on('error', (err) => {
          console.log('failing for ', input, output) 
          reject(err)
        })
        .output(output)
        .run()
    })
}


function createFoldersForFiles(files) {
  files.forEach(f => {
    const filePath = path.resolve(framesFolder, f.name)
    if (fs.existsSync(filePath)) {
      console.log('folder already exist... removing')
      fs.rmdirSync(filePath, { recursive: true })
    }
    fs.mkdirSync(filePath)
  })
}

function generateFramesForFiles(files) {
  return Promise.all(files.map( f => {
    const outputPath = path.resolve(framesFolder, f.name, '%0d.jpg')
    return generateFrames(f.fullPath, outputPath)
  }))
}

function execute() {
  const filePath = path.resolve('videosFolder')
  console.log('Get all mp4 files')

  getAllFilesFromFolder(filePath, 'mp4')
  .then(files => {
    if (files.length === 0) {
      console.log('Oops.. we found 0 files')
      return
    }

    console.log('creating folders...')
    createFoldersForFiles(files)

    console.log('generating frames for files')
    generateFramesForFiles(files)
      .then(() => {
        console.log('frames generated')
      })
  })
  .catch(err => {
    console.log(err)
  })
}

execute()