audiobookshelf/server/utils/ffmpegHelpers.js

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

function escapeSingleQuotes(path) {
  // A ' within a quoted string is escaped with '\'' in ffmpeg (see https://www.ffmpeg.org/ffmpeg-utils.html#Quoting-and-escaping)
  return filePathToPOSIX(path).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) => {
    /** @type {import('../libs/fluentFfmpeg/index').FfmpegCommand} */
    var ffmpeg = Ffmpeg(filepath)
    ffmpeg.addOption(['-map 0:v:0', '-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) => {
    /** @type {import('../libs/fluentFfmpeg/index').FfmpegCommand} */
    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

/**
 *
 * @param {import('../objects/PodcastEpisodeDownload')} podcastEpisodeDownload
 * @returns {Promise<{success: boolean, isRequestError?: boolean}>}
 */
module.exports.downloadPodcastEpisode = (podcastEpisodeDownload) => {
  return new Promise(async (resolve) => {
    // Some podcasts fail due to user agent strings
    // See: https://github.com/advplyr/audiobookshelf/issues/3246 (requires iTMS user agent)
    // See: https://github.com/advplyr/audiobookshelf/issues/4401 (requires no iTMS user agent)
    const userAgents = ['audiobookshelf (+https://audiobookshelf.org; like iTMS)', 'audiobookshelf (+https://audiobookshelf.org)']

    let response = null
    let lastError = null

    for (const userAgent of userAgents) {
      try {
        response = await axios({
          url: podcastEpisodeDownload.url,
          method: 'GET',
          responseType: 'stream',
          headers: {
            Accept: '*/*',
            'User-Agent': userAgent
          },
          timeout: global.PodcastDownloadTimeout
        })

        Logger.debug(`[ffmpegHelpers] Successfully connected with User-Agent: ${userAgent}`)
        break
      } catch (error) {
        lastError = error
        Logger.warn(`[ffmpegHelpers] Failed to download podcast episode with User-Agent "${userAgent}" for url "${podcastEpisodeDownload.url}"`, error.message)

        // If this is the last attempt, log the full error
        if (userAgent === userAgents[userAgents.length - 1]) {
          Logger.error(`[ffmpegHelpers] All User-Agent attempts failed for url "${podcastEpisodeDownload.url}"`, lastError)
        }
      }
    }

    if (!response) {
      return resolve({
        success: false,
        isRequestError: true
      })
    }

    /** @type {import('../libs/fluentFfmpeg/index').FfmpegCommand} */
    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')

    /** @type {import('../models/Podcast')} */
    const podcast = podcastEpisodeDownload.libraryItem.media
    const podcastEpisode = podcastEpisodeDownload.rssPodcastEpisode
    const finalSizeInBytes = Number(podcastEpisode.enclosure?.length || 0)

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

/**
 * Generates ffmetadata file content from the provided metadata object and chapters array.
 * @param {Object} metadata - The input metadata object.
 * @param {Array|null} chapters - An array of chapter objects.
 * @returns {string} - The ffmetadata file content.
 */
function generateFFMetadata(metadata, chapters) {
  let ffmetadataContent = ';FFMETADATA1\n'

  // Add global metadata
  for (const key in metadata) {
    if (metadata[key]) {
      ffmetadataContent += `${key}=${escapeFFMetadataValue(metadata[key])}\n`
    }
  }

  // Add chapters
  if (chapters) {
    chapters.forEach((chapter) => {
      ffmetadataContent += '\n[CHAPTER]\n'
      ffmetadataContent += `TIMEBASE=1/1000\n`
      ffmetadataContent += `START=${Math.floor(chapter.start * 1000)}\n`
      ffmetadataContent += `END=${Math.floor(chapter.end * 1000)}\n`
      if (chapter.title) {
        ffmetadataContent += `title=${escapeFFMetadataValue(chapter.title)}\n`
      }
    })
  }

  return ffmetadataContent
}

module.exports.generateFFMetadata = generateFFMetadata

/**
 * Writes FFmpeg metadata file with the given metadata and chapters.
 *
 * @param {Object} metadata - The metadata object.
 * @param {Array} chapters - The array of chapter objects.
 * @param {string} ffmetadataPath - The path to the FFmpeg metadata file.
 * @returns {Promise<boolean>} - A promise that resolves to true if the file was written successfully, false otherwise.
 */
async function writeFFMetadataFile(metadata, chapters, ffmetadataPath) {
  try {
    await fs.writeFile(ffmetadataPath, generateFFMetadata(metadata, chapters))
    Logger.debug(`[ffmpegHelpers] Wrote ${ffmetadataPath}`)
    return true
  } catch (error) {
    Logger.error(`[ffmpegHelpers] Write ${ffmetadataPath} failed`, error)
    return false
  }
}

module.exports.writeFFMetadataFile = writeFFMetadataFile

/**
 * Adds an ffmetadata and optionally a cover image to an audio file using fluent-ffmpeg.
 *
 * @param {string} audioFilePath - Path to the input audio file.
 * @param {string|null} coverFilePath - Path to the cover image file.
 * @param {string} metadataFilePath - Path to the ffmetadata file.
 * @param {number} track - The track number to embed in the audio file.
 * @param {string} mimeType - The MIME type of the audio file.
 * @param {function(number): void|null} progressCB - A callback function to report progress.
 * @param {import('../libs/fluentFfmpeg/index').FfmpegCommand} ffmpeg - The Ffmpeg instance to use (optional). Used for dependency injection in tests.
 * @param {function(string, string): Promise<void>} copyFunc - The function to use for copying files (optional). Used for dependency injection in tests.
 * @returns {Promise<void>} A promise that resolves if the operation is successful, rejects otherwise.
 */
async function addCoverAndMetadataToFile(audioFilePath, coverFilePath, metadataFilePath, track, mimeType, progressCB = null, ffmpeg = Ffmpeg(), copyFunc = copyToExisting) {
  const isMp4 = mimeType === 'audio/mp4'
  const isMp3 = mimeType === 'audio/mpeg'

  const audioFileDir = Path.dirname(audioFilePath)
  const audioFileExt = Path.extname(audioFilePath)
  const audioFileBaseName = Path.basename(audioFilePath, audioFileExt)
  const tempFilePath = filePathToPOSIX(Path.join(audioFileDir, `${audioFileBaseName}.tmp${audioFileExt}`))

  return new Promise((resolve, reject) => {
    ffmpeg.input(audioFilePath).input(metadataFilePath).outputOptions([
      '-map 0:a', // map audio stream from input file
      '-map_metadata 1', // map metadata tags from metadata file first
      '-map_metadata 0', // add additional metadata tags from input file
      '-map_chapters 1', // map chapters from metadata file
      '-c copy' // copy streams
    ])

    if (track && !isNaN(track)) {
      ffmpeg.outputOptions(['-metadata track=' + track])
    }

    if (isMp4) {
      ffmpeg.outputOptions([
        '-f mp4' // force output format to mp4
      ])
    } else if (isMp3) {
      ffmpeg.outputOptions([
        '-id3v2_version 3' // set ID3v2 version to 3
      ])
    }

    if (coverFilePath) {
      ffmpeg.input(coverFilePath).outputOptions([
        '-map 2:v', // map video stream from cover image file
        '-disposition:v:0 attached_pic', // set cover image as attached picture
        '-metadata:s:v',
        'title=Cover', // add title metadata to cover image stream
        '-metadata:s:v',
        'comment=Cover' // add comment metadata to cover image stream
      ])
      const ext = Path.extname(coverFilePath).toLowerCase()
      if (ext === '.webp') {
        ffmpeg.outputOptions([
          '-c:v mjpeg' // convert webp images to jpeg
        ])
      }
    } else {
      ffmpeg.outputOptions([
        '-map 0:v?' // retain video stream from input file if exists
      ])
    }

    ffmpeg
      .output(tempFilePath)
      .on('start', (commandLine) => {
        Logger.debug('[ffmpegHelpers] Spawned Ffmpeg with command: ' + commandLine)
      })
      .on('progress', (progress) => {
        if (!progressCB || !progress.percent) return
        Logger.debug(`[ffmpegHelpers] Progress: ${progress.percent}%`)
        progressCB(progress.percent)
      })
      .on('end', async (stdout, stderr) => {
        Logger.debug('[ffmpegHelpers] ffmpeg stdout:', stdout)
        Logger.debug('[ffmpegHelpers] ffmpeg stderr:', stderr)
        Logger.debug('[ffmpegHelpers] Moving temp file to audio file path:', `"${tempFilePath}"`, '->', `"${audioFilePath}"`)
        try {
          await copyFunc(tempFilePath, audioFilePath)
          await fs.remove(tempFilePath)
          resolve()
        } catch (error) {
          Logger.error(`[ffmpegHelpers] Failed to move temp file to audio file path: "${tempFilePath}" -> "${audioFilePath}"`, error)
          reject(error)
        }
      })
      .on('error', (err, stdout, stderr) => {
        if (err.message && err.message.includes('SIGKILL')) {
          Logger.info(`[ffmpegHelpers] addCoverAndMetadataToFile Killed by User`)
          reject(new Error('FFMPEG_CANCELED'))
        } else {
          Logger.error('Error adding cover image and metadata:', err)
          Logger.error('ffmpeg stdout:', stdout)
          Logger.error('ffmpeg stderr:', stderr)
          reject(err)
        }
      })

    ffmpeg.run()
  })
}

module.exports.addCoverAndMetadataToFile = addCoverAndMetadataToFile

function escapeFFMetadataValue(value) {
  return value.replace(/([;=\n\\#])/g, '\\$1')
}

/**
 * Retrieves the FFmpeg metadata object for a given library item.
 *
 * @param {import('../models/LibraryItem')} libraryItem - The library item containing the media metadata.
 * @param {number} audioFilesLength - The length of the audio files.
 * @returns {Object} - The FFmpeg metadata object.
 */
function getFFMetadataObject(libraryItem, audioFilesLength) {
  const ffmetadata = {
    title: libraryItem.media.title,
    artist: libraryItem.media.authorName,
    album_artist: libraryItem.media.authorName,
    album: (libraryItem.media.title || '') + (libraryItem.media.subtitle ? `: ${libraryItem.media.subtitle}` : ''),
    TIT3: libraryItem.media.subtitle, // mp3 only
    genre: libraryItem.media.genres?.join('; '),
    date: libraryItem.media.publishedYear,
    comment: libraryItem.media.description,
    description: libraryItem.media.description,
    composer: (libraryItem.media.narrators || []).join(', '),
    copyright: libraryItem.media.publisher,
    publisher: libraryItem.media.publisher, // mp3 only
    TRACKTOTAL: `${audioFilesLength}`, // mp3 only
    grouping: libraryItem.media.series?.map((s) => s.name + (s.bookSeries.sequence ? ` #${s.bookSeries.sequence}` : '')).join('; ')
  }
  Object.keys(ffmetadata).forEach((key) => {
    if (!ffmetadata[key]) {
      delete ffmetadata[key]
    }
  })

  return ffmetadata
}

module.exports.getFFMetadataObject = getFFMetadataObject

/**
 * Merges audio files into a single output file using FFmpeg.
 *
 * @param {import('../models/Book').AudioFileObject} audioTracks - The audio tracks to merge.
 * @param {number} duration - The total duration of the audio tracks.
 * @param {string} itemCachePath - The path to the item cache.
 * @param {string} outputFilePath - The path to the output file.
 * @param {import('../managers/AbMergeManager').AbMergeEncodeOptions} encodingOptions - The options for encoding the audio.
 * @param {Function} [progressCB=null] - The callback function to track the progress of the merge.
 * @param {import('../libs/fluentFfmpeg/index').FfmpegCommand} [ffmpeg=Ffmpeg()] - The FFmpeg instance to use for merging.
 * @returns {Promise<void>} A promise that resolves when the audio files are merged successfully.
 */
async function mergeAudioFiles(audioTracks, duration, itemCachePath, outputFilePath, encodingOptions, progressCB = null, ffmpeg = Ffmpeg()) {
  const audioBitrate = encodingOptions.bitrate || '128k'
  const audioCodec = encodingOptions.codec || 'aac'
  const audioChannels = encodingOptions.channels || 2

  const audioRequiresEncode = audioCodec !== 'copy'

  const firstTrackIsM4b = audioTracks[0].metadata.ext.toLowerCase() === '.m4b'
  const isOneTrack = audioTracks.length === 1

  let concatFilePath = null
  if (!isOneTrack) {
    concatFilePath = Path.join(itemCachePath, 'files.txt')
    if ((await writeConcatFile(audioTracks, concatFilePath)) == null) {
      throw new Error('Failed to write concat file')
    }
    ffmpeg.input(concatFilePath).inputOptions(['-safe 0', '-f concat'])
  } else {
    ffmpeg.input(audioTracks[0].metadata.path).inputOptions(firstTrackIsM4b ? ['-f mp4'] : [])
  }

  //const logLevel = process.env.NODE_ENV === 'production' ? 'error' : 'warning'
  ffmpeg.outputOptions(['-f mp4'])

  if (audioRequiresEncode) {
    ffmpeg.outputOptions(['-map 0:a', `-acodec ${audioCodec}`, `-ac ${audioChannels}`, `-b:a ${audioBitrate}`])
  } else {
    ffmpeg.outputOptions(['-max_muxing_queue_size 1000'])

    if (isOneTrack && firstTrackIsM4b) {
      ffmpeg.outputOptions(['-c copy'])
    } else {
      ffmpeg.outputOptions(['-c:a copy'])
    }
  }

  ffmpeg.output(outputFilePath)

  return new Promise((resolve, reject) => {
    ffmpeg
      .on('start', (cmd) => {
        Logger.debug(`[ffmpegHelpers] Merge Audio Files ffmpeg command: ${cmd}`)
      })
      .on('progress', (progress) => {
        if (!progressCB || !progress.timemark || !duration) return
        // Cannot rely on progress.percent as it is not accurate for concat
        const percent = (ffmpgegUtils.timemarkToSeconds(progress.timemark) / duration) * 100
        progressCB(percent)
      })
      .on('end', async (stdout, stderr) => {
        if (concatFilePath) await fs.remove(concatFilePath)
        Logger.debug('[ffmpegHelpers] ffmpeg stdout:', stdout)
        Logger.debug('[ffmpegHelpers] ffmpeg stderr:', stderr)
        Logger.debug(`[ffmpegHelpers] Audio Files Merged Successfully`)
        resolve()
      })
      .on('error', async (err, stdout, stderr) => {
        if (concatFilePath) await fs.remove(concatFilePath)
        if (err.message && err.message.includes('SIGKILL')) {
          Logger.info(`[ffmpegHelpers] Merge Audio Files Killed by User`)
          reject(new Error('FFMPEG_CANCELED'))
        } else {
          Logger.error(`[ffmpegHelpers] Merge Audio Files Error ${err}`)
          Logger.error('ffmpeg stdout:', stdout)
          Logger.error('ffmpeg stderr:', stderr)
          reject(err)
        }
      })

    ffmpeg.run()
  })
}

module.exports.mergeAudioFiles = mergeAudioFiles