From 1aff2551703e97bf7fd05b255d46b40e16ba392e Mon Sep 17 00:00:00 2001
From: advplyr <advplyr@protonmail.com>
Date: Sat, 4 Sep 2021 14:17:26 -0500
Subject: [PATCH] Adding download tab and download manager, ffmpeg in worker
 thread

---
 client/components/modals/EditModal.vue        |  43 +++-
 .../components/modals/edit-tabs/Download.vue  | 154 +++++++++++++
 client/components/ui/Btn.vue                  |   5 +-
 client/layouts/default.vue                    |  42 ++++
 client/package.json                           |   2 +-
 client/pages/audiobook/_id/index.vue          |   6 +-
 client/plugins/toast.js                       |   1 -
 client/store/downloads.js                     |  36 +++
 index.js                                      |   1 +
 package.json                                  |   2 +-
 server/ApiController.js                       |  33 ++-
 server/Db.js                                  |   5 +-
 server/DownloadManager.js                     | 212 ++++++++++++++++++
 server/Scanner.js                             |   2 +-
 server/Server.js                              |   7 +-
 server/StreamManager.js                       |   2 +-
 server/{ => objects}/AudioFile.js             |   0
 server/{ => objects}/AudioTrack.js            |   2 +-
 server/{ => objects}/Audiobook.js             |   6 +-
 server/{ => objects}/AudiobookFile.js         |   0
 server/{ => objects}/Book.js                  |   5 +-
 server/objects/Download.js                    | 107 +++++++++
 server/{ => objects}/Stream.js                |  30 +--
 server/{ => objects}/User.js                  |   0
 server/utils/audioFileScanner.js              |   2 -
 server/utils/downloadWorker.js                |  68 ++++++
 server/utils/ffmpegHelpers.js                 |  37 +++
 server/utils/fileUtils.js                     |   7 +
 28 files changed, 757 insertions(+), 60 deletions(-)
 create mode 100644 client/components/modals/edit-tabs/Download.vue
 create mode 100644 client/store/downloads.js
 create mode 100644 server/DownloadManager.js
 rename server/{ => objects}/AudioFile.js (100%)
 rename server/{ => objects}/AudioTrack.js (98%)
 rename server/{ => objects}/Audiobook.js (98%)
 rename server/{ => objects}/AudiobookFile.js (100%)
 rename server/{ => objects}/Book.js (98%)
 create mode 100644 server/objects/Download.js
 rename server/{ => objects}/Stream.js (91%)
 rename server/{ => objects}/User.js (100%)
 create mode 100644 server/utils/downloadWorker.js
 create mode 100644 server/utils/ffmpegHelpers.js

diff --git a/client/components/modals/EditModal.vue b/client/components/modals/EditModal.vue
index 441d115a..0079f457 100644
--- a/client/components/modals/EditModal.vue
+++ b/client/components/modals/EditModal.vue
@@ -6,10 +6,9 @@
       </div>
     </template>
     <div class="absolute -top-10 left-0 w-full flex">
-      <div class="w-28 rounded-t-lg flex items-center justify-center mr-1 cursor-pointer hover:bg-bg font-book border-t border-l border-r border-black-300 tab" :class="selectedTab === 'details' ? 'tab-selected bg-bg pb-px' : 'bg-primary text-gray-400'" @click="selectTab('details')">Details</div>
-      <div class="w-28 rounded-t-lg flex items-center justify-center mr-1 cursor-pointer hover:bg-bg font-book border-t border-l border-r border-black-300 tab" :class="selectedTab === 'cover' ? 'tab-selected bg-bg pb-px' : 'bg-primary text-gray-400'" @click="selectTab('cover')">Cover</div>
-      <div class="w-28 rounded-t-lg flex items-center justify-center mr-1 cursor-pointer hover:bg-bg font-book border-t border-l border-r border-black-300 tab" :class="selectedTab === 'match' ? 'tab-selected bg-bg pb-px' : 'bg-primary text-gray-400'" @click="selectTab('match')">Match</div>
-      <div class="w-28 rounded-t-lg flex items-center justify-center cursor-pointer hover:bg-bg font-book border-t border-l border-r border-black-300 tab" :class="selectedTab === 'tracks' ? 'tab-selected bg-bg pb-px' : 'bg-primary text-gray-400'" @click="selectTab('tracks')">Tracks</div>
+      <template v-for="tab in tabs">
+        <div :key="tab.id" class="w-28 rounded-t-lg flex items-center justify-center mr-1 cursor-pointer hover:bg-bg font-book border-t border-l border-r border-black-300 tab" :class="selectedTab === tab.id ? 'tab-selected bg-bg pb-px' : 'bg-primary text-gray-400'" @click="selectTab(tab.id)">{{ tab.title }}</div>
+      </template>
     </div>
     <div class="px-4 w-full h-full text-sm py-6 rounded-b-lg rounded-tr-lg bg-bg shadow-lg border border-black-300">
       <keep-alive>
@@ -26,7 +25,34 @@ export default {
       selectedTab: 'details',
       processing: false,
       audiobook: null,
-      fetchOnShow: false
+      fetchOnShow: false,
+      tabs: [
+        {
+          id: 'details',
+          title: 'Details',
+          component: 'modals-edit-tabs-details'
+        },
+        {
+          id: 'cover',
+          title: 'Cover',
+          component: 'modals-edit-tabs-cover'
+        },
+        {
+          id: 'match',
+          title: 'Match',
+          component: 'modals-edit-tabs-match'
+        },
+        {
+          id: 'tracks',
+          title: 'Tracks',
+          component: 'modals-edit-tabs-tracks'
+        },
+        {
+          id: 'download',
+          title: 'Download',
+          component: 'modals-edit-tabs-download'
+        }
+      ]
     }
   },
   watch: {
@@ -54,11 +80,8 @@ export default {
       }
     },
     tabName() {
-      if (this.selectedTab === 'details') return 'modals-edit-tabs-details'
-      else if (this.selectedTab === 'cover') return 'modals-edit-tabs-cover'
-      else if (this.selectedTab === 'match') return 'modals-edit-tabs-match'
-      else if (this.selectedTab === 'tracks') return 'modals-edit-tabs-tracks'
-      return ''
+      var _tab = this.tabs.find((t) => t.id === this.selectedTab)
+      return _tab ? _tab.component : ''
     },
     selectedAudiobook() {
       return this.$store.state.selectedAudiobook || {}
diff --git a/client/components/modals/edit-tabs/Download.vue b/client/components/modals/edit-tabs/Download.vue
new file mode 100644
index 00000000..50c0346a
--- /dev/null
+++ b/client/components/modals/edit-tabs/Download.vue
@@ -0,0 +1,154 @@
+<template>
+  <div class="w-full h-full overflow-hidden overflow-y-auto px-1">
+    <div class="w-full border border-black-200 p-4 my-4">
+      <p class="text-center text-lg mb-4 pb-8 border-b border-black-200">
+        <span class="text-error">Experimental Feature!</span> If your audiobook is made up of multiple audio files, this will concatenate them into a single file. The file type will be the same as the first track. Preparing downloads can take anywhere from a few seconds to several minutes and will be stored in
+        <span class="bg-primary bg-opacity-75 font-mono p-1 text-base">/metadata/downloads</span>. After the download is ready, it will remain available for 10 minutes then get deleted.
+      </p>
+
+      <div class="flex items-center">
+        <p class="text-lg">Single audio file</p>
+        <div class="flex-grow" />
+        <div>
+          <p v-if="singleAudioDownloadFailed" class="text-error mb-2">Download Failed</p>
+          <p v-if="singleAudioDownloadReady" class="text-success mb-2">Download Ready!</p>
+          <p v-if="singleAudioDownloadExpired" class="text-error mb-2">Download Expired</p>
+
+          <ui-btn v-if="!singleAudioDownloadReady" :loading="singleAudioDownloadPending" :disabled="tempDisable" @click="startSingleAudioDownload">Start Download</ui-btn>
+          <ui-btn v-else @click="downloadWithProgress">Download</ui-btn>
+        </div>
+      </div>
+    </div>
+
+    <div v-if="isDownloading" class="absolute top-0 left-0 w-full h-full bg-black bg-opacity-50 z-50 flex items-center justify-center">
+      <div class="w-80 border border-black-400 bg-bg rounded-xl h-20">
+        <div class="w-full h-full flex items-center justify-center">
+          <p class="text-lg">Download.... {{ downloadPercent }}%</p>
+          <p class="w-24 font-mono pl-8 text-right">
+            {{ downloadAmount }}
+          </p>
+        </div>
+      </div>
+    </div>
+  </div>
+</template>
+
+<script>
+export default {
+  props: {
+    processing: Boolean,
+    audiobook: {
+      type: Object,
+      default: () => {}
+    }
+  },
+  data() {
+    return {
+      tempDisable: false,
+      isDownloading: false,
+      downloadPercent: '0',
+      downloadAmount: '0 KB'
+    }
+  },
+  watch: {
+    singleAudioDownloadPending(newVal) {
+      if (newVal) {
+        this.tempDisable = false
+      }
+    }
+  },
+  computed: {
+    audiobookId() {
+      return this.audiobook ? this.audiobook.id : null
+    },
+    downloads() {
+      return this.$store.getters['downloads/getDownloads'](this.audiobookId)
+    },
+    singleAudioDownload() {
+      return this.downloads.find((d) => d.type === 'singleAudio')
+    },
+    singleAudioDownloadPending() {
+      return this.singleAudioDownload && this.singleAudioDownload.isPending
+    },
+    singleAudioDownloadFailed() {
+      return this.singleAudioDownload && this.singleAudioDownload.isFailed
+    },
+    singleAudioDownloadReady() {
+      return this.singleAudioDownload && this.singleAudioDownload.isReady
+    },
+    singleAudioDownloadExpired() {
+      return this.singleAudioDownload && this.singleAudioDownload.isExpired
+    },
+    zipBundleDownload() {
+      return this.downloads.find((d) => d.type === 'zipBundle')
+    }
+  },
+  methods: {
+    startSingleAudioDownload() {
+      console.log('Download request received', this.audiobook)
+
+      this.tempDisable = true
+      setTimeout(() => {
+        this.tempDisable = false
+      }, 1000)
+
+      var downloadPayload = {
+        audiobookId: this.audiobook.id,
+        type: 'singleAudio'
+      }
+      this.$root.socket.emit('download', downloadPayload)
+    },
+    downloadWithProgress() {
+      var downloadId = this.singleAudioDownload.id
+      var downloadUrl = `${process.env.serverUrl}/api/download/${downloadId}`
+      var filename = this.singleAudioDownload.filename
+
+      this.isDownloading = true
+
+      var request = new XMLHttpRequest()
+      request.responseType = 'blob'
+      request.open('get', downloadUrl, true)
+      request.setRequestHeader('Authorization', `Bearer ${this.$store.getters['user/getToken']}`)
+      request.send()
+
+      request.onreadystatechange = () => {
+        if (request.readyState === 4) {
+          this.isDownloading = false
+        }
+        if (request.readyState == 4 && request.status == 200) {
+          const url = window.URL.createObjectURL(request.response)
+
+          const anchor = document.createElement('a')
+          anchor.href = url
+          anchor.download = filename
+          document.body.appendChild(anchor)
+          anchor.click()
+          setTimeout(() => {
+            if (anchor) anchor.remove()
+          }, 1000)
+        }
+      }
+
+      request.onerror = (err) => {
+        console.error('Download error', err)
+        this.isDownloading = false
+      }
+
+      request.onprogress = (e) => {
+        const percent_complete = Math.floor((e.loaded / e.total) * 100)
+        this.downloadAmount = this.$bytesPretty(e.loaded)
+        this.downloadPercent = percent_complete
+
+        // const duration = (new Date().getTime() - startTime) / 1000
+        // const bps = e.loaded / duration
+        // const kbps = Math.floor(bps / 1024)
+        // const time = (e.total - e.loaded) / bps
+        // const seconds = Math.floor(time % 60)
+        // const minutes = Math.floor(time / 60)
+        // console.log(`${percent_complete}% - ${kbps} Kbps - ${minutes} min ${seconds} sec remaining`)
+      }
+    }
+  },
+  mounted() {}
+}
+</script>
\ No newline at end of file
diff --git a/client/components/ui/Btn.vue b/client/components/ui/Btn.vue
index 501b13f7..734e0d76 100644
--- a/client/components/ui/Btn.vue
+++ b/client/components/ui/Btn.vue
@@ -1,5 +1,5 @@
 <template>
-  <button class="btn outline-none rounded-md shadow-md relative border border-gray-600" :disabled="loading" :type="type" :class="classList" @click="click">
+  <button class="btn outline-none rounded-md shadow-md relative border border-gray-600" :disabled="disabled || loading" :type="type" :class="classList" @click="click">
     <slot />
     <div v-if="loading" class="text-white absolute top-0 left-0 w-full h-full flex items-center justify-center text-opacity-100">
       <!-- <span class="material-icons animate-spin">refresh</span> -->
@@ -23,7 +23,8 @@ export default {
     },
     paddingX: Number,
     small: Boolean,
-    loading: Boolean
+    loading: Boolean,
+    disabled: Boolean
   },
   data() {
     return {}
diff --git a/client/layouts/default.vue b/client/layouts/default.vue
index df14e923..520dbdee 100644
--- a/client/layouts/default.vue
+++ b/client/layouts/default.vue
@@ -124,6 +124,41 @@ export default {
         this.$store.commit('user/setSettings', user.settings)
       }
     },
+    downloadStarted(download) {
+      var filename = download.filename
+      this.$toast.success(`Preparing download for "${filename}"`)
+
+      download.isPending = true
+      this.$store.commit('downloads/addUpdateDownload', download)
+    },
+    downloadReady(download) {
+      var filename = download.filename
+      this.$toast.success(`Download "${filename}" is ready!`)
+
+      download.isPending = false
+      this.$store.commit('downloads/addUpdateDownload', download)
+    },
+    downloadFailed(download) {
+      var filename = download.filename
+      this.$toast.error(`Download "${filename}" is failed`)
+
+      download.isFailed = true
+      download.isReady = false
+      download.isPending = false
+      this.$store.commit('downloads/addUpdateDownload', download)
+    },
+    downloadKilled(download) {
+      var filename = download.filename
+      this.$toast.error(`Download "${filename}" was terminated`)
+
+      this.$store.commit('downloads/removeDownload', download)
+    },
+    downloadExpired(download) {
+      download.isExpired = true
+      download.isReady = false
+      download.isPending = false
+      this.$store.commit('downloads/addUpdateDownload', download)
+    },
     initializeSocket() {
       this.socket = this.$nuxtSocket({
         name: process.env.NODE_ENV === 'development' ? 'dev' : 'prod',
@@ -164,6 +199,13 @@ export default {
       this.socket.on('scan_start', this.scanStart)
       this.socket.on('scan_complete', this.scanComplete)
       this.socket.on('scan_progress', this.scanProgress)
+
+      // Download Listeners
+      this.socket.on('download_started', this.downloadStarted)
+      this.socket.on('download_ready', this.downloadReady)
+      this.socket.on('download_failed', this.downloadFailed)
+      this.socket.on('download_killed', this.downloadKilled)
+      this.socket.on('download_expired', this.downloadExpired)
     }
   },
   mounted() {
diff --git a/client/package.json b/client/package.json
index 21a0c179..deea0e85 100644
--- a/client/package.json
+++ b/client/package.json
@@ -1,6 +1,6 @@
 {
   "name": "audiobookshelf-client",
-  "version": "0.9.90-beta",
+  "version": "0.9.92-beta",
   "description": "Audiobook manager and player",
   "main": "index.js",
   "scripts": {
diff --git a/client/pages/audiobook/_id/index.vue b/client/pages/audiobook/_id/index.vue
index d1a057e5..6e579e95 100644
--- a/client/pages/audiobook/_id/index.vue
+++ b/client/pages/audiobook/_id/index.vue
@@ -23,9 +23,9 @@
             {{ durationPretty }}<span class="px-4">{{ sizePretty }}</span>
           </p>
           <div class="flex items-center pt-4">
-            <ui-btn color="success" :padding-x="4" class="flex items-center" @click="startStream">
-              <span class="material-icons -ml-2 pr-1 text-white">play_arrow</span>
-              Play
+            <ui-btn :disabled="streaming" color="success" :padding-x="4" class="flex items-center" @click="startStream">
+              <span v-show="!streaming" class="material-icons -ml-2 pr-1 text-white">play_arrow</span>
+              {{ streaming ? 'Streaming' : 'Play' }}
             </ui-btn>
             <ui-btn :padding-x="4" class="flex items-center ml-4" @click="editClick"><span class="material-icons text-white pr-2" style="font-size: 18px">edit</span>Edit</ui-btn>
 
diff --git a/client/plugins/toast.js b/client/plugins/toast.js
index 4f703125..8e56f149 100644
--- a/client/plugins/toast.js
+++ b/client/plugins/toast.js
@@ -1,6 +1,5 @@
 import Vue from "vue";
 import Toast from "vue-toastification";
-// Import the CSS or use your own!
 import "vue-toastification/dist/index.css";
 
 const options = {
diff --git a/client/store/downloads.js b/client/store/downloads.js
new file mode 100644
index 00000000..351b0134
--- /dev/null
+++ b/client/store/downloads.js
@@ -0,0 +1,36 @@
+
+export const state = () => ({
+  downloads: []
+})
+
+export const getters = {
+  getDownloads: (state) => (audiobookId) => {
+    return state.downloads.filter(d => d.audiobookId === audiobookId)
+  }
+}
+
+export const actions = {
+
+}
+
+export const mutations = {
+  addUpdateDownload(state, download) {
+    // Remove older downloads of matching type
+    state.downloads = state.downloads.filter(d => {
+      if (d.id !== download.id && d.type === download.type) {
+        return false
+      }
+      return true
+    })
+
+    var index = state.downloads.findIndex(d => d.id === download.id)
+    if (index >= 0) {
+      state.downloads.splice(index, 1, download)
+    } else {
+      state.downloads.push(download)
+    }
+  },
+  removeDownload(state, download) {
+    state.downloads = state.downloads.filter(d => d.id !== download.id)
+  }
+}
\ No newline at end of file
diff --git a/index.js b/index.js
index 8ce02340..18055181 100644
--- a/index.js
+++ b/index.js
@@ -11,6 +11,7 @@ if (isDev) {
   process.env.CONFIG_PATH = devEnv.ConfigPath
   process.env.METADATA_PATH = devEnv.MetadataPath
   process.env.AUDIOBOOK_PATH = devEnv.AudiobookPath
+  process.env.FFMPEG_PATH = devEnv.FFmpegPath
 }
 
 const PORT = process.env.PORT || 80
diff --git a/package.json b/package.json
index 73b0f7f9..f06c2ea7 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "audiobookshelf",
-  "version": "0.9.90-beta",
+  "version": "0.9.92-beta",
   "description": "Self-hosted audiobook server for managing and playing audiobooks.",
   "main": "index.js",
   "scripts": {
diff --git a/server/ApiController.js b/server/ApiController.js
index 5aec56b9..fa843e78 100644
--- a/server/ApiController.js
+++ b/server/ApiController.js
@@ -1,15 +1,16 @@
 const express = require('express')
 const Logger = require('./Logger')
-const User = require('./User')
+const User = require('./objects/User')
 const { isObject } = require('./utils/index')
 
 class ApiController {
-  constructor(db, scanner, auth, streamManager, rssFeeds, emitter) {
+  constructor(db, scanner, auth, streamManager, rssFeeds, downloadManager, emitter) {
     this.db = db
     this.scanner = scanner
     this.auth = auth
     this.streamManager = streamManager
     this.rssFeeds = rssFeeds
+    this.downloadManager = downloadManager
     this.emitter = emitter
 
     this.router = express()
@@ -40,13 +41,13 @@ class ApiController {
     this.router.patch('/user/password', this.userChangePassword.bind(this))
     this.router.patch('/user/settings', this.userUpdateSettings.bind(this))
 
-
-
     this.router.post('/authorize', this.authorize.bind(this))
 
     this.router.get('/genres', this.getGenres.bind(this))
 
     this.router.post('/feed', this.openRssFeed.bind(this))
+
+    this.router.get('/download/:id', this.download.bind(this))
   }
 
   find(req, res) {
@@ -307,6 +308,30 @@ class ApiController {
     })
   }
 
+  async download(req, res) {
+    var downloadId = req.params.id
+    Logger.info('Download Request', downloadId)
+    var download = this.downloadManager.getDownload(downloadId)
+    if (!download) {
+      Logger.error('Download request not found', downloadId)
+      return res.sendStatus(404)
+    }
+
+    var options = {
+      headers: {
+        // 'Content-Disposition': `attachment; filename=${download.filename}`,
+        'Content-Type': download.mimeType
+        // 'Content-Length': download.size
+      }
+    }
+    Logger.info('Starting Download', options, 'SIZE', download.size)
+    res.download(download.fullPath, download.filename, options, (err) => {
+      if (err) {
+        Logger.error('Download Error', err)
+      }
+    })
+  }
+
   getGenres(req, res) {
     res.json({
       genres: this.db.getGenres()
diff --git a/server/Db.js b/server/Db.js
index f6d157ba..b7308826 100644
--- a/server/Db.js
+++ b/server/Db.js
@@ -1,10 +1,9 @@
-const fs = require('fs-extra')
 const Path = require('path')
 const njodb = require("njodb")
 const jwt = require('jsonwebtoken')
 const Logger = require('./Logger')
-const Audiobook = require('./Audiobook')
-const User = require('./User')
+const Audiobook = require('./objects/Audiobook')
+const User = require('./objects/User')
 
 class Db {
   constructor(CONFIG_PATH) {
diff --git a/server/DownloadManager.js b/server/DownloadManager.js
new file mode 100644
index 00000000..83ad3456
--- /dev/null
+++ b/server/DownloadManager.js
@@ -0,0 +1,212 @@
+const Path = require('path')
+const fs = require('fs-extra')
+
+const workerThreads = require('worker_threads')
+const Logger = require('./Logger')
+const Download = require('./objects/Download')
+const { writeConcatFile } = require('./utils/ffmpegHelpers')
+const { getFileSize } = require('./utils/fileUtils')
+
+class DownloadManager {
+  constructor(db, MetadataPath, emitter) {
+    this.db = db
+    this.MetadataPath = MetadataPath
+    this.emitter = emitter
+
+    this.downloadDirPath = Path.join(this.MetadataPath, 'downloads')
+
+    this.pendingDownloads = []
+    this.downloads = []
+  }
+
+  getDownload(downloadId) {
+    return this.downloads.find(d => d.id === downloadId)
+  }
+
+  async removeOrphanDownloads() {
+    try {
+      var dirs = await fs.readdir(this.downloadDirPath)
+      if (!dirs || !dirs.length) return true
+
+      await Promise.all(dirs.map(async (dirname) => {
+        var fullPath = Path.join(this.downloadDirPath, dirname)
+        Logger.info(`Removing Orphan Download ${dirname}`)
+        return fs.remove(fullPath)
+      }))
+      return true
+    } catch (error) {
+      return false
+    }
+  }
+
+  downloadSocketRequest(socket, payload) {
+    var client = socket.sheepClient
+    var audiobook = this.db.audiobooks.find(a => a.id === payload.audiobookId)
+    var options = {
+      ...payload
+    }
+    delete options.audiobookId
+    this.prepareDownload(client, audiobook, options)
+  }
+
+  getBestFileType(tracks) {
+    if (!tracks || !tracks.length) {
+      return null
+    }
+    var firstTrack = tracks[0]
+    return firstTrack.ext.substr(1)
+  }
+
+  async prepareDownload(client, audiobook, options = {}) {
+    var downloadId = (Math.trunc(Math.random() * 1000) + Date.now()).toString(36)
+    var dlpath = Path.join(this.downloadDirPath, downloadId)
+    Logger.info(`Start Download for ${audiobook.id} - DownloadId: ${downloadId} - ${dlpath}`)
+
+    await fs.ensureDir(dlpath)
+
+    var downloadType = options.type || 'singleAudio'
+    delete options.type
+
+    var filepath = null
+    var filename = null
+    var fileext = null
+    var audiobookDirname = Path.basename(audiobook.path)
+
+    if (downloadType === 'singleAudio') {
+      var audioFileType = options.audioFileType || this.getBestFileType(audiobook.tracks)
+      delete options.audioFileType
+      filename = audiobookDirname + '.' + audioFileType
+      fileext = '.' + audioFileType
+      filepath = Path.join(dlpath, filename)
+    }
+
+    var downloadData = {
+      id: downloadId,
+      audiobookId: audiobook.id,
+      type: downloadType,
+      options: options,
+      dirpath: dlpath,
+      fullPath: filepath,
+      filename,
+      ext: fileext,
+      userId: (client && client.user) ? client.user.id : null,
+      socket: (client && client.socket) ? client.socket : null
+    }
+    var download = new Download()
+    download.setData(downloadData)
+
+    if (downloadData.socket) {
+      downloadData.socket.emit('download_started', download.toJSON())
+    }
+
+    if (download.type === 'singleAudio') {
+      this.processSingleAudioDownload(audiobook, download)
+    }
+  }
+
+  async processSingleAudioDownload(audiobook, download) {
+    // var ffmpeg = Ffmpeg()
+    var concatFilePath = Path.join(download.dirpath, 'files.txt')
+    await writeConcatFile(audiobook.tracks, concatFilePath)
+
+    var workerData = {
+      input: concatFilePath,
+      inputFormat: 'concat',
+      inputOption: '-safe 0',
+      options: [
+        '-loglevel warning',
+        '-map 0:a',
+        '-c:a copy'
+      ],
+      output: download.fullPath
+    }
+    var worker = new workerThreads.Worker('./server/utils/downloadWorker.js', { workerData })
+    worker.on('message', (message) => {
+      if (message != null && typeof message === 'object') {
+        if (message.type === 'RESULT') {
+          this.sendResult(download, message)
+        }
+      } else {
+        Logger.error('Invalid worker message', message)
+      }
+    })
+    this.pendingDownloads.push({
+      id: download.id,
+      download,
+      worker
+    })
+  }
+
+  async downloadExpired(download) {
+    Logger.info(`[DownloadManager] Download ${download.id} expired`)
+
+    if (download.socket) {
+      download.socket.emit('download_expired', download.toJSON())
+    }
+    this.removeDownload(download)
+  }
+
+  async sendResult(download, result) {
+    // Remove pending download
+    this.pendingDownloads = this.pendingDownloads.filter(d => d.id !== download.id)
+
+    if (result.isKilled) {
+      if (download.socket) {
+        download.socket.emit('download_killed', download.toJSON())
+      }
+      return
+    }
+
+    if (!result.success) {
+      if (download.socket) {
+        download.socket.emit('download_failed', download.toJSON())
+      }
+      this.removeDownload(download)
+      return
+    }
+
+    // Remove files.txt if it was used
+    if (download.type === 'singleAudio') {
+      var concatFilePath = Path.join(download.dirpath, 'files.txt')
+      try {
+        await fs.remove(concatFilePath)
+      } catch (error) {
+        Logger.error('[DownloadManager] Failed to remove files.txt')
+      }
+    }
+
+    result.size = await getFileSize(download.fullPath)
+    download.setComplete(result)
+    if (download.socket) {
+      download.socket.emit('download_ready', download.toJSON())
+    }
+    download.setExpirationTimer(this.downloadExpired.bind(this))
+
+    this.downloads.push(download)
+    Logger.info(`[DownloadManager] Download Ready ${download.id}`)
+  }
+
+  async removeDownload(download) {
+    Logger.info('[DownloadManager] Removing download ' + download.id)
+
+    var pendingDl = this.pendingDownloads.find(d => d.id === download.id)
+
+    if (pendingDl) {
+      this.pendingDownloads = this.pendingDownloads.filter(d => d.id !== download.id)
+      Logger.warn(`[DownloadManager] Removing download in progress - stopping worker`)
+      try {
+        pendingDl.worker.postMessage('STOP')
+      } catch (error) {
+        Logger.error('[DownloadManager] Error posting stop message to worker', error)
+      }
+    }
+
+    await fs.remove(download.dirpath).then(() => {
+      Logger.info('[DownloadManager] Deleted download', download.dirpath)
+    }).catch((err) => {
+      Logger.error('[DownloadManager] Failed to delete download', err)
+    })
+    this.downloads = this.downloads.filter(d => d.id !== download.id)
+  }
+}
+module.exports = DownloadManager
\ No newline at end of file
diff --git a/server/Scanner.js b/server/Scanner.js
index 8e827993..ce5708bd 100644
--- a/server/Scanner.js
+++ b/server/Scanner.js
@@ -1,6 +1,6 @@
 const Logger = require('./Logger')
 const BookFinder = require('./BookFinder')
-const Audiobook = require('./Audiobook')
+const Audiobook = require('./objects/Audiobook')
 const audioFileScanner = require('./utils/audioFileScanner')
 const { getAllAudiobookFiles } = require('./utils/scandir')
 const { comparePaths, getIno } = require('./utils/index')
diff --git a/server/Server.js b/server/Server.js
index 44545b63..e125e31d 100644
--- a/server/Server.js
+++ b/server/Server.js
@@ -12,6 +12,7 @@ const ApiController = require('./ApiController')
 const HlsController = require('./HlsController')
 const StreamManager = require('./StreamManager')
 const RssFeeds = require('./RssFeeds')
+const DownloadManager = require('./DownloadManager')
 const Logger = require('./Logger')
 
 class Server {
@@ -32,10 +33,10 @@ class Server {
     this.scanner = new Scanner(this.AudiobookPath, this.MetadataPath, this.db, this.emitter.bind(this))
     this.streamManager = new StreamManager(this.db, this.MetadataPath)
     this.rssFeeds = new RssFeeds(this.Port, this.db)
-    this.apiController = new ApiController(this.db, this.scanner, this.auth, this.streamManager, this.rssFeeds, this.emitter.bind(this))
+    this.downloadManager = new DownloadManager(this.db, this.MetadataPath, this.emitter.bind(this))
+    this.apiController = new ApiController(this.db, this.scanner, this.auth, this.streamManager, this.rssFeeds, this.downloadManager, this.emitter.bind(this))
     this.hlsController = new HlsController(this.db, this.scanner, this.auth, this.streamManager, this.emitter.bind(this), this.MetadataPath)
 
-
     this.server = null
     this.io = null
 
@@ -90,6 +91,7 @@ class Server {
   async init() {
     Logger.info('[Server] Init')
     await this.streamManager.removeOrphanStreams()
+    await this.downloadManager.removeOrphanDownloads()
     await this.db.init()
     this.auth.init()
 
@@ -186,6 +188,7 @@ class Server {
       socket.on('open_stream', (audiobookId) => this.streamManager.openStreamSocketRequest(socket, audiobookId))
       socket.on('close_stream', () => this.streamManager.closeStreamRequest(socket))
       socket.on('stream_update', (payload) => this.streamManager.streamUpdate(socket, payload))
+      socket.on('download', (payload) => this.downloadManager.downloadSocketRequest(socket, payload))
       socket.on('test', () => {
         socket.emit('test_received', socket.id)
       })
diff --git a/server/StreamManager.js b/server/StreamManager.js
index 43e46fa9..3a4d0359 100644
--- a/server/StreamManager.js
+++ b/server/StreamManager.js
@@ -1,4 +1,4 @@
-const Stream = require('./Stream')
+const Stream = require('./objects/Stream')
 const StreamTest = require('./test/StreamTest')
 const Logger = require('./Logger')
 const fs = require('fs-extra')
diff --git a/server/AudioFile.js b/server/objects/AudioFile.js
similarity index 100%
rename from server/AudioFile.js
rename to server/objects/AudioFile.js
diff --git a/server/AudioTrack.js b/server/objects/AudioTrack.js
similarity index 98%
rename from server/AudioTrack.js
rename to server/objects/AudioTrack.js
index 2e32cc43..ef88a686 100644
--- a/server/AudioTrack.js
+++ b/server/objects/AudioTrack.js
@@ -1,4 +1,4 @@
-var { bytesPretty } = require('./utils/fileUtils')
+var { bytesPretty } = require('../utils/fileUtils')
 
 class AudioTrack {
   constructor(audioTrack = null) {
diff --git a/server/Audiobook.js b/server/objects/Audiobook.js
similarity index 98%
rename from server/Audiobook.js
rename to server/objects/Audiobook.js
index 2e9f611f..f2850efe 100644
--- a/server/Audiobook.js
+++ b/server/objects/Audiobook.js
@@ -1,7 +1,7 @@
 const Path = require('path')
-const { bytesPretty, elapsedPretty } = require('./utils/fileUtils')
-const { comparePaths, getIno } = require('./utils/index')
-const Logger = require('./Logger')
+const { bytesPretty, elapsedPretty } = require('../utils/fileUtils')
+const { comparePaths, getIno } = require('../utils/index')
+const Logger = require('../Logger')
 const Book = require('./Book')
 const AudioTrack = require('./AudioTrack')
 const AudioFile = require('./AudioFile')
diff --git a/server/AudiobookFile.js b/server/objects/AudiobookFile.js
similarity index 100%
rename from server/AudiobookFile.js
rename to server/objects/AudiobookFile.js
diff --git a/server/Book.js b/server/objects/Book.js
similarity index 98%
rename from server/Book.js
rename to server/objects/Book.js
index f636b86a..14419508 100644
--- a/server/Book.js
+++ b/server/objects/Book.js
@@ -1,6 +1,7 @@
 const Path = require('path')
-const Logger = require('./Logger')
-const parseAuthors = require('./utils/parseAuthors')
+const Logger = require('../Logger')
+const parseAuthors = require('../utils/parseAuthors')
+
 class Book {
   constructor(book = null) {
     this.olid = null
diff --git a/server/objects/Download.js b/server/objects/Download.js
new file mode 100644
index 00000000..22e10bfb
--- /dev/null
+++ b/server/objects/Download.js
@@ -0,0 +1,107 @@
+const DEFAULT_EXPIRATION = 1000 * 60 * 10 // 10 minutes
+
+class Download {
+  constructor(download) {
+    this.id = null
+    this.audiobookId = null
+    this.type = null
+    this.options = {}
+
+    this.dirpath = null
+    this.fullPath = null
+    this.ext = null
+    this.filename = null
+    this.size = 0
+
+    this.userId = null
+    this.socket = null // Socket to notify when complete
+    this.isReady = false
+
+    this.startedAt = null
+    this.finishedAt = null
+    this.expiresAt = null
+
+    this.expirationTimeMs = 0
+
+    if (download) {
+      this.construct(download)
+    }
+  }
+
+  get mimeType() {
+    if (this.ext === '.mp3' || this.ext === '.m4b' || this.ext === '.m4a') {
+      return 'audio/mpeg'
+    } else if (this.ext === '.mp4') {
+      return 'audio/mp4'
+    } else if (this.ext === '.ogg') {
+      return 'audio/ogg'
+    } else if (this.ext === '.aac' || this.ext === '.m4p') {
+      return 'audio/aac'
+    }
+    return 'audio/mpeg'
+  }
+
+  toJSON() {
+    return {
+      id: this.id,
+      audiobookId: this.audiobookId,
+      type: this.type,
+      options: this.options,
+      dirpath: this.dirpath,
+      fullPath: this.fullPath,
+      ext: this.ext,
+      filename: this.filename,
+      size: this.size,
+      userId: this.userId,
+      isReady: this.isReady,
+      startedAt: this.startedAt,
+      finishedAt: this.finishedAt,
+      expirationSeconds: this.expirationSeconds
+    }
+  }
+
+  construct(download) {
+    this.id = download.id
+    this.audiobookId = download.audiobookId
+    this.type = download.type
+    this.options = { ...download.options }
+
+    this.dirpath = download.dirpath
+    this.fullPath = download.fullPath
+    this.ext = download.ext
+    this.filename = download.filename
+    this.size = download.size || 0
+
+    this.userId = download.userId
+    this.socket = download.socket || null
+    this.isReady = !!download.isReady
+
+    this.startedAt = download.startedAt
+    this.finishedAt = download.finishedAt || null
+
+    this.expirationTimeMs = download.expirationTimeMs || DEFAULT_EXPIRATION
+    this.expiresAt = download.expiresAt || null
+  }
+
+  setData(downloadData) {
+    downloadData.startedAt = Date.now()
+    downloadData.isProcessing = true
+    this.construct(downloadData)
+  }
+
+  setComplete(fileSize) {
+    this.finishedAt = Date.now()
+    this.size = fileSize
+    this.isReady = true
+    this.expiresAt = this.finishedAt + this.expirationTimeMs
+  }
+
+  setExpirationTimer(callback) {
+    setTimeout(() => {
+      if (callback) {
+        callback(this)
+      }
+    }, this.expirationTimeMs)
+  }
+}
+module.exports = Download
\ No newline at end of file
diff --git a/server/Stream.js b/server/objects/Stream.js
similarity index 91%
rename from server/Stream.js
rename to server/objects/Stream.js
index ba8a419f..1669d597 100644
--- a/server/Stream.js
+++ b/server/objects/Stream.js
@@ -2,9 +2,10 @@ const Ffmpeg = require('fluent-ffmpeg')
 const EventEmitter = require('events')
 const Path = require('path')
 const fs = require('fs-extra')
-const Logger = require('./Logger')
-const { secondsToTimestamp } = require('./utils/fileUtils')
-const hlsPlaylistGenerator = require('./utils/hlsPlaylistGenerator')
+const Logger = require('../Logger')
+const { secondsToTimestamp } = require('../utils/fileUtils')
+const { writeConcatFile } = require('../utils/ffmpegHelpers')
+const hlsPlaylistGenerator = require('../utils/hlsPlaylistGenerator')
 
 class Stream extends EventEmitter {
   constructor(streamPath, client, audiobook) {
@@ -19,7 +20,7 @@ class Stream extends EventEmitter {
     this.streamPath = Path.join(streamPath, this.id)
     this.concatFilesPath = Path.join(this.streamPath, 'files.txt')
     this.playlistPath = Path.join(this.streamPath, 'output.m3u8')
-    this.fakePlaylistPath = Path.join(this.streamPath, 'fake-output.m3u8')
+    this.finalPlaylistPath = Path.join(this.streamPath, 'final-output.m3u8')
     this.startTime = 0
 
     this.ffmpeg = null
@@ -211,29 +212,12 @@ class Stream extends EventEmitter {
     }, 2000)
   }
 
-  escapeSingleQuotes(path) {
-    // return path.replace(/'/g, '\'\\\'\'')
-    return path.replace(/\\/g, '/').replace(/ /g, '\\ ').replace(/'/g, '\\\'')
-  }
-
   async start() {
     Logger.info(`[STREAM] START STREAM - Num Segments: ${this.numSegments}`)
 
     this.ffmpeg = Ffmpeg()
-    var currTrackEnd = 0
-    var startingTrack = this.tracks.find(t => {
-      currTrackEnd += t.duration
-      return this.startTime < currTrackEnd
-    })
-    var trackStartTime = currTrackEnd - startingTrack.duration
 
-    var tracksToInclude = this.tracks.filter(t => t.index >= startingTrack.index)
-    var trackPaths = tracksToInclude.map(t => {
-      var line = 'file ' + this.escapeSingleQuotes(t.fullPath) + '\n' + `duration ${t.duration}`
-      return line
-    })
-    var inputstr = trackPaths.join('\n\n')
-    await fs.writeFile(this.concatFilesPath, inputstr)
+    var trackStartTime = await writeConcatFile(this.tracks, this.concatFilesPath, this.startTime)
 
     this.ffmpeg.addInput(this.concatFilesPath)
     this.ffmpeg.inputFormat('concat')
@@ -266,7 +250,7 @@ class Stream extends EventEmitter {
     ])
     var segmentFilename = Path.join(this.streamPath, this.segmentBasename)
     this.ffmpeg.addOption(`-hls_segment_filename ${segmentFilename}`)
-    this.ffmpeg.output(this.fakePlaylistPath)
+    this.ffmpeg.output(this.finalPlaylistPath)
 
     this.ffmpeg.on('start', (command) => {
       Logger.info('[INFO] FFMPEG transcoding started with command: ' + command)
diff --git a/server/User.js b/server/objects/User.js
similarity index 100%
rename from server/User.js
rename to server/objects/User.js
diff --git a/server/utils/audioFileScanner.js b/server/utils/audioFileScanner.js
index dfda425a..f1b79525 100644
--- a/server/utils/audioFileScanner.js
+++ b/server/utils/audioFileScanner.js
@@ -1,8 +1,6 @@
 const Path = require('path')
 const Logger = require('../Logger')
 const prober = require('./prober')
-const AudioFile = require('../AudioFile')
-
 
 function getDefaultAudioStream(audioStreams) {
   if (audioStreams.length === 1) return audioStreams[0]
diff --git a/server/utils/downloadWorker.js b/server/utils/downloadWorker.js
new file mode 100644
index 00000000..a314446b
--- /dev/null
+++ b/server/utils/downloadWorker.js
@@ -0,0 +1,68 @@
+const Ffmpeg = require('fluent-ffmpeg')
+
+if (process.env.NODE_ENV !== 'production') {
+  Ffmpeg.setFfmpegPath(process.env.FFMPEG_PATH)
+}
+
+const { parentPort, workerData } = require("worker_threads")
+const Logger = require('../Logger')
+
+Logger.info('[DownloadWorker] Starting Worker...')
+
+
+const ffmpegCommand = Ffmpeg()
+const startTime = Date.now()
+
+ffmpegCommand.input(workerData.input)
+if (workerData.inputFormat) ffmpegCommand.inputFormat(workerData.inputFormat)
+if (workerData.inputOption) ffmpegCommand.inputOption(workerData.inputOption)
+if (workerData.options) ffmpegCommand.addOption(workerData.options)
+ffmpegCommand.output(workerData.output)
+
+var isKilled = false
+
+async function runFfmpeg() {
+  var success = await new Promise((resolve) => {
+    ffmpegCommand.on('start', (command) => {
+      Logger.info('[DownloadWorker] FFMPEG concat started with command: ' + command)
+    })
+
+    ffmpegCommand.on('stderr', (stdErrline) => {
+      Logger.info(stdErrline)
+    })
+
+    ffmpegCommand.on('error', (err, stdout, stderr) => {
+      if (err.message && err.message.includes('SIGKILL')) {
+        // This is an intentional SIGKILL
+        Logger.info('[DownloadWorker] User Killed singleAudio')
+      } else {
+        Logger.error('[DownloadWorker] Ffmpeg Err', err.message)
+      }
+      resolve(false)
+    })
+
+    ffmpegCommand.on('end', (stdout, stderr) => {
+      Logger.info('[DownloadWorker] singleAudio ended')
+      resolve(true)
+    })
+    ffmpegCommand.run()
+  })
+
+  var resultMessage = {
+    type: 'RESULT',
+    isKilled,
+    elapsed: Date.now() - startTime,
+    success
+  }
+  parentPort.postMessage(resultMessage)
+}
+
+parentPort.on('message', (message) => {
+  if (message === 'STOP') {
+    Logger.info('[DownloadWorker] Requested a hard stop')
+    isKilled = true
+    ffmpegCommand.kill()
+  }
+})
+
+runFfmpeg()
\ No newline at end of file
diff --git a/server/utils/ffmpegHelpers.js b/server/utils/ffmpegHelpers.js
new file mode 100644
index 00000000..62168dce
--- /dev/null
+++ b/server/utils/ffmpegHelpers.js
@@ -0,0 +1,37 @@
+const fs = require('fs-extra')
+
+function escapeSingleQuotes(path) {
+  // return path.replace(/'/g, '\'\\\'\'')
+  return path.replace(/\\/g, '/').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.fullPath) + '\n' + `duration ${t.duration}`
+    return line
+  })
+  var inputstr = trackPaths.join('\n\n')
+  await fs.writeFile(outputPath, inputstr)
+
+  return firstTrackStartTime
+}
+module.exports.writeConcatFile = writeConcatFile
\ No newline at end of file
diff --git a/server/utils/fileUtils.js b/server/utils/fileUtils.js
index e051a594..37d9ecd9 100644
--- a/server/utils/fileUtils.js
+++ b/server/utils/fileUtils.js
@@ -17,6 +17,13 @@ async function getFileStat(path) {
 }
 module.exports.getFileStat = getFileStat
 
+async function getFileSize(path) {
+  var stat = await getFileStat(path)
+  if (!stat) return 0
+  return stat.size || 0
+}
+module.exports.getFileSize = getFileSize
+
 function bytesPretty(bytes, decimals = 0) {
   if (bytes === 0) {
     return '0 Bytes'