diff --git a/server/Server.js b/server/Server.js
index 83e7ca3e7e..c9810cc8c3 100644
--- a/server/Server.js
+++ b/server/Server.js
@@ -16,11 +16,10 @@ const Logger = require('./Logger')
 const Auth = require('./Auth')
 const Watcher = require('./Watcher')
 const Scanner = require('./scanner/Scanner')
+const LibraryScanner = require('./scanner/LibraryScanner')
 const Database = require('./Database')
 const SocketAuthority = require('./SocketAuthority')
 
-const routes = require('./routes/index')
-
 const ApiRouter = require('./routers/ApiRouter')
 const HlsRouter = require('./routers/HlsRouter')
 
@@ -78,6 +77,7 @@ class Server {
     this.rssFeedManager = new RssFeedManager()
 
     this.scanner = new Scanner(this.coverManager, this.taskManager)
+    this.libraryScanner = new LibraryScanner(this.coverManager, this.taskManager)
     this.cronManager = new CronManager(this.scanner, this.podcastManager)
 
     // Routers
diff --git a/server/controllers/LibraryController.js b/server/controllers/LibraryController.js
index e64bc8d668..176b7f2d8e 100644
--- a/server/controllers/LibraryController.js
+++ b/server/controllers/LibraryController.js
@@ -977,6 +977,8 @@ class LibraryController {
     }
     res.sendStatus(200)
     await this.scanner.scan(req.library, options)
+    // TODO: New library scanner
+    // await this.libraryScanner.scan(req.library, options)
     await Database.resetLibraryIssuesFilterData(req.library.id)
     Logger.info('[LibraryController] Scan complete')
   }
diff --git a/server/models/Book.js b/server/models/Book.js
index d478587cdf..1c7d89a606 100644
--- a/server/models/Book.js
+++ b/server/models/Book.js
@@ -18,6 +18,31 @@ const Logger = require('../Logger')
  * @property {string} title
  */
 
+/**
+ * @typedef AudioFileObject
+ * @property {number} index
+ * @property {string} ino
+ * @property {{filename:string, ext:string, path:string, relPath:string, size:number, mtimeMs:number, ctimeMs:number, birthtimeMs:number}} metadata
+ * @property {number} addedAt
+ * @property {number} updatedAt
+ * @property {number} trackNumFromMeta
+ * @property {number} discNumFromMeta
+ * @property {number} trackNumFromFilename
+ * @property {number} discNumFromFilename
+ * @property {boolean} manuallyVerified
+ * @property {string} format
+ * @property {number} duration
+ * @property {number} bitRate
+ * @property {string} language
+ * @property {string} codec
+ * @property {string} timeBase
+ * @property {number} channels
+ * @property {string} channelLayout
+ * @property {ChapterObject[]} chapters
+ * @property {Object} metaTags
+ * @property {string} mimeType
+ */
+
 class Book extends Model {
   constructor(values, options) {
     super(values, options)
@@ -52,7 +77,7 @@ class Book extends Model {
     this.duration
     /** @type {string[]} */
     this.narrators
-    /** @type {Object} */
+    /** @type {AudioFileObject[]} */
     this.audioFiles
     /** @type {EBookFileObject} */
     this.ebookFile
diff --git a/server/models/LibraryItem.js b/server/models/LibraryItem.js
index c9bded996e..fa288cdec4 100644
--- a/server/models/LibraryItem.js
+++ b/server/models/LibraryItem.js
@@ -3,6 +3,8 @@ const Logger = require('../Logger')
 const oldLibraryItem = require('../objects/LibraryItem')
 const libraryFilters = require('../utils/queries/libraryFilters')
 const { areEquivalent } = require('../utils/index')
+const Book = require('./Book')
+const Podcast = require('./Podcast')
 
 /**
  * @typedef LibraryFileObject
@@ -791,6 +793,11 @@ class LibraryItem extends Model {
     return this.getOldLibraryItem(libraryItem)
   }
 
+  /**
+   * 
+   * @param {import('sequelize').FindOptions} options 
+   * @returns {Promise<Book|Podcast>}
+   */
   getMedia(options) {
     if (!this.mediaType) return Promise.resolve(null)
     const mixinMethodName = `get${this.sequelize.uppercaseFirst(this.mediaType)}`
diff --git a/server/objects/files/AudioFile.js b/server/objects/files/AudioFile.js
index be16cf9294..6e43e73b5b 100644
--- a/server/objects/files/AudioFile.js
+++ b/server/objects/files/AudioFile.js
@@ -64,7 +64,7 @@ class AudioFile {
       channelLayout: this.channelLayout,
       chapters: this.chapters,
       embeddedCoverArt: this.embeddedCoverArt,
-      metaTags: this.metaTags ? this.metaTags.toJSON() : {},
+      metaTags: this.metaTags?.toJSON() || {},
       mimeType: this.mimeType
     }
   }
@@ -163,11 +163,16 @@ class AudioFile {
     return new AudioFile(this.toJSON())
   }
 
+  /**
+   * 
+   * @param {AudioFile} scannedAudioFile 
+   * @returns {boolean} true if updates were made
+   */
   updateFromScan(scannedAudioFile) {
     let hasUpdated = false
 
     const newjson = scannedAudioFile.toJSON()
-    const ignoreKeys = ['manuallyVerified', 'exclude', 'addedAt', 'updatedAt']
+    const ignoreKeys = ['manuallyVerified', 'ctimeMs', 'addedAt', 'updatedAt']
 
     for (const key in newjson) {
       if (key === 'metadata') {
diff --git a/server/routers/ApiRouter.js b/server/routers/ApiRouter.js
index 0dc49dffd9..5b61c8bfcb 100644
--- a/server/routers/ApiRouter.js
+++ b/server/routers/ApiRouter.js
@@ -40,6 +40,7 @@ class ApiRouter {
   constructor(Server) {
     this.auth = Server.auth
     this.scanner = Server.scanner
+    this.libraryScanner = Server.libraryScanner
     this.playbackSessionManager = Server.playbackSessionManager
     this.abMergeManager = Server.abMergeManager
     this.backupManager = Server.backupManager
diff --git a/server/scanner/AudioFileScanner.js b/server/scanner/AudioFileScanner.js
index cd596f8645..01251bfd9a 100644
--- a/server/scanner/AudioFileScanner.js
+++ b/server/scanner/AudioFileScanner.js
@@ -1,6 +1,197 @@
+const Path = require('path')
+const Logger = require('../Logger')
+const prober = require('../utils/prober')
+const LibraryItem = require('../models/LibraryItem')
+const AudioFile = require('../objects/files/AudioFile')
+
 class AudioFileScanner {
   constructor() { }
 
+  /**
+   * Is array of numbers sequential, i.e. 1, 2, 3, 4
+   * @param {number[]} nums 
+   * @returns {boolean}
+   */
+  isSequential(nums) {
+    if (!nums?.length) return false
+    if (nums.length === 1) return true
+    let prev = nums[0]
+    for (let i = 1; i < nums.length; i++) {
+      if (nums[i] - prev > 1) return false
+      prev = nums[i]
+    }
+    return true
+  }
+
+  /**
+   * Remove 
+   * @param {number[]} nums 
+   * @returns {number[]}
+   */
+  removeDupes(nums) {
+    if (!nums || !nums.length) return []
+    if (nums.length === 1) return nums
+
+    let nodupes = [nums[0]]
+    nums.forEach((num) => {
+      if (num > nodupes[nodupes.length - 1]) nodupes.push(num)
+    })
+    return nodupes
+  }
+
+  /**
+   * Order audio files by track/disc number
+   * @param {import('../models/Book')} book 
+   * @param {import('../models/Book').AudioFileObject[]} audioFiles 
+   * @returns {import('../models/Book').AudioFileObject[]}
+   */
+  runSmartTrackOrder(book, audioFiles) {
+    let discsFromFilename = []
+    let tracksFromFilename = []
+    let discsFromMeta = []
+    let tracksFromMeta = []
+
+    audioFiles.forEach((af) => {
+      if (af.discNumFromFilename !== null) discsFromFilename.push(af.discNumFromFilename)
+      if (af.discNumFromMeta !== null) discsFromMeta.push(af.discNumFromMeta)
+      if (af.trackNumFromFilename !== null) tracksFromFilename.push(af.trackNumFromFilename)
+      if (af.trackNumFromMeta !== null) tracksFromMeta.push(af.trackNumFromMeta)
+    })
+    discsFromFilename.sort((a, b) => a - b)
+    discsFromMeta.sort((a, b) => a - b)
+    tracksFromFilename.sort((a, b) => a - b)
+    tracksFromMeta.sort((a, b) => a - b)
+
+    let discKey = null
+    if (discsFromMeta.length === audioFiles.length && this.isSequential(discsFromMeta)) {
+      discKey = 'discNumFromMeta'
+    } else if (discsFromFilename.length === audioFiles.length && this.isSequential(discsFromFilename)) {
+      discKey = 'discNumFromFilename'
+    }
+
+    let trackKey = null
+    tracksFromFilename = this.removeDupes(tracksFromFilename)
+    tracksFromMeta = this.removeDupes(tracksFromMeta)
+    if (tracksFromFilename.length > tracksFromMeta.length) {
+      trackKey = 'trackNumFromFilename'
+    } else {
+      trackKey = 'trackNumFromMeta'
+    }
+
+    if (discKey !== null) {
+      Logger.debug(`[AudioFileScanner] Smart track order for "${book.title}" using disc key ${discKey} and track key ${trackKey}`)
+      audioFiles.sort((a, b) => {
+        let Dx = a[discKey] - b[discKey]
+        if (Dx === 0) Dx = a[trackKey] - b[trackKey]
+        return Dx
+      })
+    } else {
+      Logger.debug(`[AudioFileScanner] Smart track order for "${book.title}" using track key ${trackKey}`)
+      audioFiles.sort((a, b) => a[trackKey] - b[trackKey])
+    }
+
+    for (let i = 0; i < audioFiles.length; i++) {
+      audioFiles[i].index = i + 1
+    }
+    return audioFiles
+  }
+
+  /**
+   * Get track and disc number from audio filename
+   * @param {{title:string, subtitle:string, series:string, sequence:string, publishedYear:string, narrators:string}} mediaMetadataFromScan 
+   * @param {LibraryItem.LibraryFileObject} audioLibraryFile 
+   * @returns {{trackNumber:number, discNumber:number}}
+   */
+  getTrackAndDiscNumberFromFilename(mediaMetadataFromScan, audioLibraryFile) {
+    const { title, author, series, publishedYear } = mediaMetadataFromScan
+    const { filename, path } = audioLibraryFile.metadata
+    let partbasename = Path.basename(filename, Path.extname(filename))
+
+    // Remove title, author, series, and publishedYear from filename if there
+    if (title) partbasename = partbasename.replace(title, '')
+    if (author) partbasename = partbasename.replace(author, '')
+    if (series) partbasename = partbasename.replace(series, '')
+    if (publishedYear) partbasename = partbasename.replace(publishedYear)
+
+    // Look for disc number
+    let discNumber = null
+    const discMatch = partbasename.match(/\b(disc|cd) ?(\d\d?)\b/i)
+    if (discMatch && discMatch.length > 2 && discMatch[2]) {
+      if (!isNaN(discMatch[2])) {
+        discNumber = Number(discMatch[2])
+      }
+
+      // Remove disc number from filename
+      partbasename = partbasename.replace(/\b(disc|cd) ?(\d\d?)\b/i, '')
+    }
+
+    // Look for disc number in folder path e.g. /Book Title/CD01/audiofile.mp3
+    const pathdir = Path.dirname(path).split('/').pop()
+    if (pathdir && /^cd\d{1,3}$/i.test(pathdir)) {
+      const discFromFolder = Number(pathdir.replace(/cd/i, ''))
+      if (!isNaN(discFromFolder) && discFromFolder !== null) discNumber = discFromFolder
+    }
+
+    const numbersinpath = partbasename.match(/\d{1,4}/g)
+    const trackNumber = numbersinpath && numbersinpath.length ? parseInt(numbersinpath[0]) : null
+    return {
+      trackNumber,
+      discNumber
+    }
+  }
+
+  /**
+   * 
+   * @param {string} mediaType 
+   * @param {LibraryItem.LibraryFileObject} libraryFile 
+   * @param {{title:string, subtitle:string, series:string, sequence:string, publishedYear:string, narrators:string}} mediaMetadataFromScan 
+   * @returns {Promise<AudioFile>}
+   */
+  async scan(mediaType, libraryFile, mediaMetadataFromScan) {
+    const probeData = await prober.probe(libraryFile.metadata.path)
+
+    if (probeData.error) {
+      Logger.error(`[MediaFileScanner] ${probeData.error} : "${libraryFile.metadata.path}"`)
+      return null
+    }
+
+    if (!probeData.audioStream) {
+      Logger.error('[MediaFileScanner] Invalid audio file no audio stream')
+      return null
+    }
+
+    const audioFile = new AudioFile()
+    audioFile.trackNumFromMeta = probeData.audioMetaTags.trackNumber
+    audioFile.discNumFromMeta = probeData.audioMetaTags.discNumber
+    if (mediaType === 'book') {
+      const { trackNumber, discNumber } = this.getTrackAndDiscNumberFromFilename(mediaMetadataFromScan, libraryFile)
+      audioFile.trackNumFromFilename = trackNumber
+      audioFile.discNumFromFilename = discNumber
+    }
+    audioFile.setDataFromProbe(libraryFile, probeData)
+
+    return audioFile
+  }
+
+  /**
+   * Scan LibraryFiles and return AudioFiles
+   * @param {string} mediaType
+   * @param {import('./LibraryItemScanData')} libraryItemScanData 
+   * @param {LibraryItem.LibraryFileObject[]} audioLibraryFiles
+   * @returns {Promise<AudioFile[]>}
+   */
+  async executeMediaFileScans(mediaType, libraryItemScanData, audioLibraryFiles) {
+    const batchSize = 32
+    const results = []
+    for (let batch = 0; batch < audioLibraryFiles.length; batch += batchSize) {
+      const proms = []
+      for (let i = batch; i < Math.min(batch + batchSize, audioLibraryFiles.length); i++) {
+        proms.push(this.scan(mediaType, audioLibraryFiles[i], libraryItemScanData.mediaMetadata))
+      }
+      results.push(...await Promise.all(proms).then((scanResults) => scanResults.filter(sr => sr)))
+    }
 
+    return results
+  }
 }
 module.exports = new AudioFileScanner()
\ No newline at end of file
diff --git a/server/scanner/LibraryItemScanData.js b/server/scanner/LibraryItemScanData.js
index 8e8cb10ed5..1b40452437 100644
--- a/server/scanner/LibraryItemScanData.js
+++ b/server/scanner/LibraryItemScanData.js
@@ -1,6 +1,7 @@
 const packageJson = require('../../package.json')
 const { LogLevel } = require('../utils/constants')
 const LibraryItem = require('../models/LibraryItem')
+const globals = require('../utils/globals')
 
 class LibraryItemScanData {
   constructor(data) {
@@ -33,11 +34,41 @@ class LibraryItemScanData {
     /** @type {boolean} */
     this.hasPathChange
     /** @type {LibraryItem.LibraryFileObject[]} */
-    this.libraryFilesRemoved
+    this.libraryFilesRemoved = []
     /** @type {LibraryItem.LibraryFileObject[]} */
-    this.libraryFilesAdded
+    this.libraryFilesAdded = []
     /** @type {LibraryItem.LibraryFileObject[]} */
-    this.libraryFilesModified
+    this.libraryFilesModified = []
+  }
+
+  /** @type {boolean} */
+  get hasLibraryFileChanges() {
+    return this.libraryFilesRemoved.length + this.libraryFilesModified.length + this.libraryFilesAdded.length
+  }
+
+  /** @type {boolean} */
+  get hasAudioFileChanges() {
+    return this.audioLibraryFilesRemoved.length + this.audioLibraryFilesAdded.length + this.audioLibraryFilesModified
+  }
+
+  /** @type {LibraryItem.LibraryFileObject[]} */
+  get audioLibraryFilesModified() {
+    return this.libraryFilesModified.filter(lf => globals.SupportedAudioTypes.includes(lf.metadata.ext?.slice(1).toLowerCase() || ''))
+  }
+
+  /** @type {LibraryItem.LibraryFileObject[]} */
+  get audioLibraryFilesRemoved() {
+    return this.libraryFilesRemoved.filter(lf => globals.SupportedAudioTypes.includes(lf.metadata.ext?.slice(1).toLowerCase() || ''))
+  }
+
+  /** @type {LibraryItem.LibraryFileObject[]} */
+  get audioLibraryFilesAdded() {
+    return this.libraryFilesAdded.filter(lf => globals.SupportedAudioTypes.includes(lf.metadata.ext?.slice(1).toLowerCase() || ''))
+  }
+
+  /** @type {LibraryItem.LibraryFileObject[]} */
+  get audioLibraryFiles() {
+    return this.libraryFiles.filter(lf => globals.SupportedAudioTypes.includes(lf.metadata.ext?.slice(1).toLowerCase() || ''))
   }
 
   /**
@@ -46,7 +77,7 @@ class LibraryItemScanData {
    * @param {import('./LibraryScan')} libraryScan
    */
   async checkLibraryItemData(existingLibraryItem, libraryScan) {
-    const keysToCompare = ['libraryFolderId', 'ino', 'mtimeMs', 'ctimeMs', 'birthtimeMs', 'path', 'relPath', 'isFile']
+    const keysToCompare = ['libraryFolderId', 'ino', 'path', 'relPath', 'isFile']
     this.hasChanges = false
     this.hasPathChange = false
     for (const key of keysToCompare) {
@@ -61,6 +92,23 @@ class LibraryItemScanData {
       }
     }
 
+    // Check mtime, ctime and birthtime
+    if (existingLibraryItem.mtime.valueOf() !== this.mtimeMs) {
+      libraryScan.addLog(LogLevel.DEBUG, `Library item "${existingLibraryItem.relPath}" key "mtime" changed from "${existingLibraryItem.mtime.valueOf()}" to "${this.mtimeMs}"`)
+      existingLibraryItem.mtime = this.mtimeMs
+      this.hasChanges = true
+    }
+    if (existingLibraryItem.birthtime.valueOf() !== this.birthtimeMs) {
+      libraryScan.addLog(LogLevel.DEBUG, `Library item "${existingLibraryItem.relPath}" key "birthtime" changed from "${existingLibraryItem.birthtime.valueOf()}" to "${this.birthtimeMs}"`)
+      existingLibraryItem.birthtime = this.birthtimeMs
+      this.hasChanges = true
+    }
+    if (existingLibraryItem.ctime.valueOf() !== this.ctimeMs) {
+      libraryScan.addLog(LogLevel.DEBUG, `Library item "${existingLibraryItem.relPath}" key "ctime" changed from "${existingLibraryItem.ctime.valueOf()}" to "${this.ctimeMs}"`)
+      existingLibraryItem.ctime = this.ctimeMs
+      this.hasChanges = true
+    }
+
     this.libraryFilesRemoved = []
     this.libraryFilesModified = []
     let libraryFilesAdded = this.libraryFiles.map(lf => lf)
@@ -98,15 +146,24 @@ class LibraryItemScanData {
       }
     }
 
+    this.libraryFilesAdded = libraryFilesAdded
+
     if (this.hasChanges) {
+      existingLibraryItem.size = 0
+      existingLibraryItem.libraryFiles.forEach((lf) => existingLibraryItem.size += lf.metadata.size)
+
       existingLibraryItem.lastScan = Date.now()
       existingLibraryItem.lastScanVersion = packageJson.version
+
+      libraryScan.addLog(LogLevel.DEBUG, `Library item "${existingLibraryItem.path}" changed: [${existingLibraryItem.changed()?.join(',') || ''}]`)
+
+      if (this.hasLibraryFileChanges) {
+        existingLibraryItem.changed('libraryFiles', true)
+      }
       await existingLibraryItem.save()
     } else {
       libraryScan.addLog(LogLevel.DEBUG, `Library item "${existingLibraryItem.path}" is up-to-date`)
     }
-
-    this.libraryFilesAdded = libraryFilesAdded
   }
 
   /**
@@ -126,6 +183,10 @@ class LibraryItemScanData {
     }
 
     for (const key in existingLibraryFile.metadata) {
+      if (existingLibraryFile.metadata.relPath === 'metadata.json' || existingLibraryFile.metadata.relPath === 'metadata.abs') {
+        if (key === 'mtimeMs' || key === 'size') continue
+      }
+
       if (existingLibraryFile.metadata[key] !== scannedLibraryFile.metadata[key]) {
         if (key !== 'path' && key !== 'relPath') {
           libraryScan.addLog(LogLevel.DEBUG, `Library file "${existingLibraryFile.metadata.path}" for library item "${libraryItemPath}" key "${key}" changed from "${existingLibraryFile.metadata[key]}" to "${scannedLibraryFile.metadata[key]}"`)
@@ -143,5 +204,20 @@ class LibraryItemScanData {
 
     return hasChanges
   }
+
+  /**
+   * Check if existing audio file on Book was removed
+   * @param {import('../models/Book').AudioFileObject} existingAudioFile 
+   * @returns {boolean} true if audio file was removed
+   */
+  checkAudioFileRemoved(existingAudioFile) {
+    if (!this.audioLibraryFilesRemoved.length) return false
+    // First check exact path
+    if (this.audioLibraryFilesRemoved.some(af => af.metadata.path === existingAudioFile.metadata.path)) {
+      return true
+    }
+    // Fallback to check inode value
+    return this.audioLibraryFilesRemoved.some(af => af.ino === existingAudioFile.ino)
+  }
 }
 module.exports = LibraryItemScanData
\ No newline at end of file
diff --git a/server/scanner/LibraryScanner.js b/server/scanner/LibraryScanner.js
index 4ca08e7551..5cccfaa44c 100644
--- a/server/scanner/LibraryScanner.js
+++ b/server/scanner/LibraryScanner.js
@@ -7,7 +7,12 @@ const fs = require('../libs/fsExtra')
 const fileUtils = require('../utils/fileUtils')
 const scanUtils = require('../utils/scandir')
 const { ScanResult, LogLevel } = require('../utils/constants')
+const AudioFileScanner = require('./AudioFileScanner')
+const ScanOptions = require('./ScanOptions')
+const LibraryScan = require('./LibraryScan')
 const LibraryItemScanData = require('./LibraryItemScanData')
+const AudioFile = require('../objects/files/AudioFile')
+const Book = require('../models/Book')
 
 class LibraryScanner {
   constructor(coverManager, taskManager) {
@@ -102,7 +107,7 @@ class LibraryScanner {
       where: {
         libraryId: libraryScan.libraryId
       },
-      attributes: ['id', 'mediaId', 'mediaType', 'path', 'relPath', 'ino', 'isMissing', 'mtime', 'ctime', 'birthtime', 'libraryFiles', 'libraryFolderId']
+      attributes: ['id', 'mediaId', 'mediaType', 'path', 'relPath', 'ino', 'isMissing', 'isFile', 'mtime', 'ctime', 'birthtime', 'libraryFiles', 'libraryFolderId', 'size']
     })
 
     const libraryItemIdsMissing = []
@@ -129,8 +134,8 @@ class LibraryScanner {
         }
       } else {
         await libraryItemData.checkLibraryItemData(existingLibraryItem, libraryScan)
-        if (libraryItemData.hasChanges) {
-          await this.rescanLibraryItem(existingLibraryItem, libraryItemData)
+        if (libraryItemData.hasLibraryFileChanges || libraryItemData.hasPathChange) {
+          await this.rescanLibraryItem(existingLibraryItem, libraryItemData, libraryScan)
         }
       }
     }
@@ -222,9 +227,92 @@ class LibraryScanner {
    * 
    * @param {import('../models/LibraryItem')} existingLibraryItem 
    * @param {LibraryItemScanData} libraryItemData 
+   * @param {LibraryScan} libraryScan
    */
-  async rescanLibraryItem(existingLibraryItem, libraryItemData) {
+  async rescanLibraryItem(existingLibraryItem, libraryItemData, libraryScan) {
+
+    if (existingLibraryItem.mediaType === 'book') {
+      /** @type {Book} */
+      const media = await existingLibraryItem.getMedia({
+        include: [
+          {
+            model: Database.authorModel,
+            through: {
+              attributes: ['createdAt']
+            }
+          },
+          {
+            model: Database.seriesModel,
+            through: {
+              attributes: ['sequence', 'createdAt']
+            }
+          }
+        ]
+      })
+
+      let hasMediaChanges = libraryItemData.hasAudioFileChanges
+      if (libraryItemData.hasAudioFileChanges || libraryItemData.audioLibraryFiles.length !== media.audioFiles.length) {
+        // Filter out audio files that were removed
+        media.audioFiles = media.audioFiles.filter(af => libraryItemData.checkAudioFileRemoved(af))
+
+        // Update audio files that were modified
+        if (libraryItemData.audioLibraryFilesModified.length) {
+          let scannedAudioFiles = await AudioFileScanner.executeMediaFileScans(existingLibraryItem.mediaType, libraryItemData, libraryItemData.audioLibraryFilesModified)
+          media.audioFiles = media.audioFiles.map((audioFileObj) => {
+            let matchedScannedAudioFile = scannedAudioFiles.find(saf => saf.metadata.path === audioFileObj.metadata.path)
+            if (!matchedScannedAudioFile) {
+              matchedScannedAudioFile = scannedAudioFiles.find(saf => saf.ino === audioFileObj.ino)
+            }
+
+            if (matchedScannedAudioFile) {
+              scannedAudioFiles = scannedAudioFiles.filter(saf => saf !== matchedScannedAudioFile)
+              const audioFile = new AudioFile(audioFileObj)
+              audioFile.updateFromScan(matchedScannedAudioFile)
+              return audioFile.toJSON()
+            }
+            return audioFileObj
+          })
+          // Modified audio files that were not found on the book
+          if (scannedAudioFiles.length) {
+            media.audioFiles.push(...scannedAudioFiles)
+          }
+        }
+
+        // Add new audio files scanned in
+        if (libraryItemData.audioLibraryFilesAdded.length) {
+          const scannedAudioFiles = await AudioFileScanner.executeMediaFileScans(existingLibraryItem.mediaType, libraryItemData, libraryItemData.audioLibraryFilesAdded)
+          media.audioFiles.push(...scannedAudioFiles)
+        }
 
+        // Add audio library files that are not already set on the book (safety check)
+        let audioLibraryFilesToAdd = []
+        for (const audioLibraryFile of libraryItemData.audioLibraryFiles) {
+          if (!media.audioFiles.some(af => af.ino === audioLibraryFile.ino)) {
+            libraryScan.addLog(LogLevel.DEBUG, `Existing audio library file "${audioLibraryFile.metadata.relPath}" was not set on book "${media.title}" so setting it now`)
+            audioLibraryFilesToAdd.push(audioLibraryFile)
+          }
+        }
+        if (audioLibraryFilesToAdd.length) {
+          const scannedAudioFiles = await AudioFileScanner.executeMediaFileScans(existingLibraryItem.mediaType, libraryItemData, audioLibraryFilesToAdd)
+          media.audioFiles.push(...scannedAudioFiles)
+        }
+
+        media.audioFiles = AudioFileScanner.runSmartTrackOrder(media, media.audioFiles)
+
+        media.duration = 0
+        media.audioFiles.forEach((af) => {
+          if (!isNaN(af.duration)) {
+            media.duration += af.duration
+          }
+        })
+
+        media.changed('audioFiles', true)
+      }
+
+      if (hasMediaChanges) {
+        await media.save()
+      }
+    }
   }
 }
 module.exports = LibraryScanner
\ No newline at end of file
diff --git a/server/utils/prober.js b/server/utils/prober.js
index 17aecfbd95..8e29305365 100644
--- a/server/utils/prober.js
+++ b/server/utils/prober.js
@@ -278,7 +278,12 @@ function parseProbeData(data, verbose = false) {
   }
 }
 
-// Updated probe returns MediaProbeData object
+/**
+ * Run ffprobe on audio filepath
+ * @param {string} filepath 
+ * @param {boolean} [verbose=false] 
+ * @returns {import('../scanner/MediaProbeData')|{error:string}}
+ */
 function probe(filepath, verbose = false) {
   if (process.env.FFPROBE_PATH) {
     ffprobe.FFPROBE_PATH = process.env.FFPROBE_PATH