cypress/packages/server/lib/video_capture.js

const _ = require('lodash')
const utils = require('fluent-ffmpeg/lib/utils')
const debug = require('debug')('cypress:server:video')
const ffmpeg = require('fluent-ffmpeg')
const stream = require('stream')
const Promise = require('bluebird')
const ffmpegPath = require('@ffmpeg-installer/ffmpeg').path
const BlackHoleStream = require('black-hole-stream')
const fs = require('./util/fs')

// extra verbose logs for logging individual frames
const debugFrames = require('debug')('cypress-verbose:server:video:frames')

debug('using ffmpeg from %s', ffmpegPath)

ffmpeg.setFfmpegPath(ffmpegPath)

const deferredPromise = function () {
  let reject
  let resolve = (reject = null)
  const promise = new Promise((_resolve, _reject) => {
    resolve = _resolve
    reject = _reject
  })

  return { promise, resolve, reject }
}

module.exports = {
  getMsFromDuration (duration) {
    return utils.timemarkToSeconds(duration) * 1000
  },

  getCodecData (src) {
    return new Promise((resolve, reject) => {
      return ffmpeg()
      .on('stderr', (stderr) => {
        return debug('get codecData stderr log %o', { message: stderr })
      }).on('codecData', resolve)
      .input(src)
      .format('null')
      .output(new BlackHoleStream())
      .run()
    }).tap((data) => {
      return debug('codecData %o', {
        src,
        data,
      })
    }).tapCatch((err) => {
      return debug('getting codecData failed', { err })
    })
  },

  copy (src, dest) {
    debug('copying from %s to %s', src, dest)

    return fs
    .copyAsync(src, dest, { overwrite: true })
    .catch({ code: 'ENOENT' }, () => {})
  },
  // dont yell about ENOENT errors

  start (name, options = {}) {
    const pt = stream.PassThrough()
    const ended = deferredPromise()
    let done = false
    let written = false
    let logErrors = true
    let wantsWrite = true
    let skipped = 0

    _.defaults(options, {
      onError () {},
    })

    const endVideoCapture = function () {
      done = true

      if (!written) {
        // when no data has been written this will
        // result in an 'pipe:0: End of file' error
        // for so we need to account for that
        // and not log errors to the console
        logErrors = false
      }

      pt.end()

      // return the ended promise which will eventually
      // get resolve or rejected
      return ended.promise
    }

    const lengths = {}

    const writeVideoFrame = function (data) {
      // make sure we haven't ended
      // our stream yet because paint
      // events can linger beyond
      // finishing the actual video
      if (done) {
        return
      }

      // we have written at least 1 byte
      written = true

      debugFrames('writing video frame')

      if (lengths[data.length]) {
        return
      }

      lengths[data.length] = true

      if (wantsWrite) {
        if (!(wantsWrite = pt.write(data))) {
          return pt.once('drain', () => {
            debugFrames('video stream drained')

            wantsWrite = true
          })
        }
      } else {
        skipped += 1

        return debugFrames('skipping video frame %o', { skipped })
      }
    }

    const startCapturing = () => {
      return new Promise((resolve) => {
        const cmd = ffmpeg({
          source: pt,
          priority: 20,
        })
        .videoCodec('libx264')
        .outputOptions('-preset ultrafast')
        .on('start', (command) => {
          debug('capture started %o', { command })

          return resolve({
            cmd,
            startedVideoCapture: new Date,
          })
        }).on('codecData', (data) => {
          return debug('capture codec data: %o', data)
        }).on('stderr', (stderr) => {
          return debug('capture stderr log %o', { message: stderr })
        }).on('error', (err, stdout, stderr) => {
          debug('capture errored: %o', { error: err.message, stdout, stderr })

          // if we're supposed log errors then
          // bubble them up
          if (logErrors) {
            options.onError(err, stdout, stderr)
          }

          // reject the ended promise
          return ended.reject(err)
        }).on('end', () => {
          debug('capture ended')

          return ended.resolve()
        })

        if (options.webmInput) {
          cmd
          .inputFormat('webm')

          // assume 18 fps. This number comes from manual measurement of avg fps coming from firefox.
          // TODO: replace this with the 'vfr' option below when dropped frames issue is fixed.
          .inputFPS(18)

          // 'vsync vfr' (variable framerate) works perfectly but fails on top page navigation
          // since video timestamp resets to 0, timestamps already written will be dropped
          // .outputOption('-vsync vfr')

          // this is to prevent the error "invalid data input" error
          // when input frames have an odd resolution
          .videoFilters(`crop='floor(in_w/2)*2:floor(in_h/2)*2'`)

          // same as above but scales instead of crops
          // .videoFilters("scale=trunc(iw/2)*2:trunc(ih/2)*2")
        } else {
          cmd
          .inputFormat('image2pipe')
          .inputOptions('-use_wallclock_as_timestamps 1')
        }

        return cmd.save(name)
      })
    }

    return startCapturing()
    .then(({ cmd, startedVideoCapture }) => {
      return {
        cmd,
        endVideoCapture,
        writeVideoFrame,
        startedVideoCapture,
      }
    })
  },

  process (name, cname, videoCompression, onProgress = function () {}) {
    let total = null

    return new Promise((resolve, reject) => {
      debug('processing video from %s to %s video compression %o',
        name, cname, videoCompression)

      ffmpeg()
      .input(name)
      .videoCodec('libx264')
      .outputOptions([
        '-preset fast',
        `-crf ${videoCompression}`,
      ])
      // .videoFilters("crop='floor(in_w/2)*2:floor(in_h/2)*2'")
      .on('start', (command) => {
        return debug('compression started %o', { command })
      }).on('codecData', (data) => {
        debug('compression codec data: %o', data)

        total = utils.timemarkToSeconds(data.duration)
      }).on('stderr', (stderr) => {
        return debug('compression stderr log %o', { message: stderr })
      }).on('progress', (progress) => {
        // bail if we dont have total yet
        if (!total) {
          return
        }

        debug('compression progress: %o', progress)

        const progressed = utils.timemarkToSeconds(progress.timemark)

        const percent = progressed / total

        if (percent < 1) {
          return onProgress(percent)
        }
      }).on('error', (err, stdout, stderr) => {
        debug('compression errored: %o', { error: err.message, stdout, stderr })

        return reject(err)
      }).on('end', () => {
        debug('compression ended')

        // we are done progressing
        onProgress(1)

        // rename and obliterate the original
        return fs.moveAsync(cname, name, {
          overwrite: true,
        })
        .then(() => {
          return resolve()
        })
      }).save(cname)
    })
  },

}