audiobookshelf/server/utils/ffmpegHelpers.js

const axios = require('axios')
const Ffmpeg = require('../libs/fluentFfmpeg')
const fs = require('../libs/fsExtra')
const Path = require('path')
const Logger = require('../Logger')
const { filePathToPOSIX } = require('./fileUtils')

function escapeSingleQuotes(path) {
  // return path.replace(/'/g, '\'\\\'\'')
  return filePathToPOSIX(path).replace(/ /g, '\\ ').replace(/'/g, '\\\'')
}

// Returns first track start time
// startTime is for streams starting an encode part-way through an audiobook
async function writeConcatFile(tracks, outputPath, startTime = 0) {
  var trackToStartWithIndex = 0
  var firstTrackStartTime = 0

  // Find first track greater than startTime
  if (startTime > 0) {
    var currTrackEnd = 0
    var startingTrack = tracks.find(t => {
      currTrackEnd += t.duration
      return startTime < currTrackEnd
    })
    if (startingTrack) {
      firstTrackStartTime = currTrackEnd - startingTrack.duration
      trackToStartWithIndex = startingTrack.index
    }
  }

  var tracksToInclude = tracks.filter(t => t.index >= trackToStartWithIndex)
  var trackPaths = tracksToInclude.map(t => {
    var line = 'file ' + escapeSingleQuotes(t.metadata.path) + '\n' + `duration ${t.duration}`
    return line
  })
  var inputstr = trackPaths.join('\n\n')

  try {
    await fs.writeFile(outputPath, inputstr)
    return firstTrackStartTime
  } catch (error) {
    Logger.error(`[ffmpegHelpers] Failed to write stream concat file at "${outputPath}"`, error)
    return null
  }
}
module.exports.writeConcatFile = writeConcatFile

async function extractCoverArt(filepath, outputpath) {
  var dirname = Path.dirname(outputpath)
  await fs.ensureDir(dirname)

  return new Promise((resolve) => {
    var ffmpeg = Ffmpeg(filepath)
    ffmpeg.addOption(['-map 0:v', '-frames:v 1'])
    ffmpeg.output(outputpath)

    ffmpeg.on('start', (cmd) => {
      Logger.debug(`[FfmpegHelpers] Extract Cover Cmd: ${cmd}`)
    })
    ffmpeg.on('error', (err, stdout, stderr) => {
      Logger.error(`[FfmpegHelpers] Extract Cover Error ${err}`)
      resolve(false)
    })
    ffmpeg.on('end', () => {
      Logger.debug(`[FfmpegHelpers] Cover Art Extracted Successfully`)
      resolve(outputpath)
    })
    ffmpeg.run()
  })
}
module.exports.extractCoverArt = extractCoverArt

//This should convert based on the output file extension as well
async function resizeImage(filePath, outputPath, width, height) {
  return new Promise((resolve) => {
    var ffmpeg = Ffmpeg(filePath)
    ffmpeg.addOption(['-vf', `scale=${width || -1}:${height || -1}`])
    ffmpeg.addOutput(outputPath)
    ffmpeg.on('start', (cmd) => {
      Logger.debug(`[FfmpegHelpers] Resize Image Cmd: ${cmd}`)
    })
    ffmpeg.on('error', (err, stdout, stderr) => {
      Logger.error(`[FfmpegHelpers] Resize Image Error ${err} ${stdout} ${stderr}`)
      resolve(false)
    })
    ffmpeg.on('end', () => {
      Logger.debug(`[FfmpegHelpers] Image resized Successfully`)
      resolve(outputPath)
    })
    ffmpeg.run()
  })
}
module.exports.resizeImage = resizeImage

module.exports.downloadPodcastEpisode = (podcastEpisodeDownload) => {
  return new Promise(async (resolve) => {
    const response = await axios({
      url: podcastEpisodeDownload.url,
      method: 'GET',
      responseType: 'stream',
      timeout: 30000
    }).catch((error) => {
      Logger.error(`[ffmpegHelpers] Failed to download podcast episode with url "${podcastEpisodeDownload.url}"`, error)
      return null
    })
    if (!response) return resolve(false)

    const ffmpeg = Ffmpeg(response.data)
    ffmpeg.addOption('-loglevel debug') // Debug logs printed on error
    ffmpeg.outputOptions(
      '-c:a', 'copy',
      '-map', '0:a',
      '-metadata', 'podcast=1'
    )

    const podcastMetadata = podcastEpisodeDownload.libraryItem.media.metadata
    const podcastEpisode = podcastEpisodeDownload.podcastEpisode
    const finalSizeInBytes = Number(podcastEpisode.enclosure?.length || 0)

    const taggings = {
      'album': podcastMetadata.title,
      'album-sort': podcastMetadata.title,
      'artist': podcastMetadata.author,
      'artist-sort': podcastMetadata.author,
      'comment': podcastEpisode.description,
      'subtitle': podcastEpisode.subtitle,
      'disc': podcastEpisode.season,
      'genre': podcastMetadata.genres.length ? podcastMetadata.genres.join(';') : null,
      'language': podcastMetadata.language,
      'MVNM': podcastMetadata.title,
      'MVIN': podcastEpisode.episode,
      'track': podcastEpisode.episode,
      'series-part': podcastEpisode.episode,
      'title': podcastEpisode.title,
      'title-sort': podcastEpisode.title,
      'year': podcastEpisode.pubYear,
      'date': podcastEpisode.pubDate,
      'releasedate': podcastEpisode.pubDate,
      'itunes-id': podcastMetadata.itunesId,
      'podcast-type': podcastMetadata.type,
      'episode-type': podcastMetadata.episodeType
    }

    for (const tag in taggings) {
      if (taggings[tag]) {
        if (taggings[tag].length > 10000) {
          Logger.warn(`[ffmpegHelpers] Episode download tag "${tag}" is too long (${taggings[tag].length} characters) - trimming it down`)
          taggings[tag] = taggings[tag].slice(0, 10000)
        }
        ffmpeg.addOption('-metadata', `${tag}=${taggings[tag]}`)
      }
    }

    ffmpeg.addOutput(podcastEpisodeDownload.targetPath)

    const stderrLines = []
    ffmpeg.on('stderr', (stderrLine) => {
      if (typeof stderrLine === 'string') {
        stderrLines.push(stderrLine)
      }
    })
    ffmpeg.on('start', (cmd) => {
      Logger.debug(`[FfmpegHelpers] downloadPodcastEpisode: Cmd: ${cmd}`)
    })
    ffmpeg.on('error', (err) => {
      Logger.error(`[FfmpegHelpers] downloadPodcastEpisode: Error ${err}`)
      if (stderrLines.length) {
        Logger.error(`Full stderr dump for episode url "${podcastEpisodeDownload.url}": ${stderrLines.join('\n')}`)
      }
      resolve(false)
    })
    ffmpeg.on('progress', (progress) => {
      let progressPercent = 0
      if (finalSizeInBytes && progress.targetSize && !isNaN(progress.targetSize)) {
        const finalSizeInKb = Math.floor(finalSizeInBytes / 1000)
        progressPercent = Math.min(1, progress.targetSize / finalSizeInKb) * 100
      }
      Logger.debug(`[FfmpegHelpers] downloadPodcastEpisode: Progress estimate ${progressPercent.toFixed(0)}% (${progress?.targetSize || 'N/A'} KB) for "${podcastEpisodeDownload.url}"`)
    })
    ffmpeg.on('end', () => {
      Logger.debug(`[FfmpegHelpers] downloadPodcastEpisode: Complete`)
      resolve(podcastEpisodeDownload.targetPath)
    })
    ffmpeg.run()
  })
}