From 74652e2e54a93e9ed775058c2ae6174eebabc620 Mon Sep 17 00:00:00 2001
From: advplyr <advplyr@protonmail.com>
Date: Sat, 29 Apr 2023 14:57:51 -0500
Subject: [PATCH] API route to generate waveform images

---
 client/pages/audiobook/_id/chapters.vue | 16 ++++++++++++++-
 server/controllers/ToolsController.js   | 27 +++++++++++++++++++++++++
 server/routers/ApiRouter.js             |  1 +
 server/utils/ffmpegHelpers.js           | 23 +++++++++++++++++++++
 4 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/client/pages/audiobook/_id/chapters.vue b/client/pages/audiobook/_id/chapters.vue
index 52cb1bbc..f0d83c0b 100644
--- a/client/pages/audiobook/_id/chapters.vue
+++ b/client/pages/audiobook/_id/chapters.vue
@@ -94,9 +94,16 @@
                     <span class="material-icons-outlined text-lg">error_outline</span>
                   </button>
                 </ui-tooltip>
+
+                <button class="w-7 h-7 rounded-full flex items-center justify-center text-white" @click="setShowWaveform(chapter.id)">
+                  <span class="material-icons-outlined text-lg">graphic_eq</span>
+                </button>
               </div>
             </div>
           </div>
+          <div v-if="showWaveform[chapter.id]" :key="`${chapter.id}-waveform`">
+            <img :src="`${baseUrl}/api/tools/item/${libraryItem.id}/waveform?start=${Math.max(0, chapter.start - 10)}&end=${Math.min(mediaDuration, chapter.start + 10)}&token=${userToken}`" />
+          </div>
         </template>
       </div>
 
@@ -246,7 +253,8 @@ export default {
       chapterData: null,
       showSecondInputs: false,
       audibleRegions: ['US', 'CA', 'UK', 'AU', 'FR', 'DE', 'JP', 'IT', 'IN', 'ES'],
-      hasChanges: false
+      hasChanges: false,
+      showWaveform: {}
     }
   },
   computed: {
@@ -256,6 +264,9 @@ export default {
     userToken() {
       return this.$store.getters['user/getToken']
     },
+    baseUrl() {
+      return process.env.serverUrl
+    },
     media() {
       return this.libraryItem.media || {}
     },
@@ -288,6 +299,9 @@ export default {
     }
   },
   methods: {
+    setShowWaveform(chapterId) {
+      this.$set(this.showWaveform, chapterId, true)
+    },
     setChaptersFromTracks() {
       let currentStartTime = 0
       let index = 0
diff --git a/server/controllers/ToolsController.js b/server/controllers/ToolsController.js
index 3f21c5dd..7302f01a 100644
--- a/server/controllers/ToolsController.js
+++ b/server/controllers/ToolsController.js
@@ -1,4 +1,5 @@
 const Logger = require('../Logger')
+const ffmpegHelpers = require('../utils/ffmpegHelpers')
 
 class ToolsController {
   constructor() { }
@@ -98,6 +99,32 @@ class ToolsController {
     res.sendStatus(200)
   }
 
+  getAudioFileWaveform(req, res) {
+    let start = Number(req.query.start || 0)
+    let end = Number(req.query.end || 0)
+    if (isNaN(start) || isNaN(end) || start < 0 || end > req.libraryItem.media.duration || end <= start || end - start < 5) {
+      return res.status(400).send('Invalid start/end query params')
+    }
+
+    const paths = []
+    let currentTime = 0
+    let startOffset = 0
+    for (const track of req.libraryItem.media.tracks) {
+      currentTime += track.duration
+      if (currentTime > start) {
+        if (!paths.length) startOffset = track.startOffset
+        paths.push(track.metadata.path)
+      }
+      if (currentTime > end) {
+        break
+      }
+    }
+    start -= startOffset
+    end -= startOffset
+
+    ffmpegHelpers.generateWaveform(paths, start, end, res)
+  }
+
   middleware(req, res, next) {
     if (!req.user.isAdminOrUp) {
       Logger.error(`[LibraryItemController] Non-root user attempted to access tools route`, req.user)
diff --git a/server/routers/ApiRouter.js b/server/routers/ApiRouter.js
index 1b2df155..6e34c2bd 100644
--- a/server/routers/ApiRouter.js
+++ b/server/routers/ApiRouter.js
@@ -275,6 +275,7 @@ class ApiRouter {
     this.router.delete('/tools/item/:id/encode-m4b', ToolsController.middleware.bind(this), ToolsController.cancelM4bEncode.bind(this))
     this.router.post('/tools/item/:id/embed-metadata', ToolsController.middleware.bind(this), ToolsController.embedAudioFileMetadata.bind(this))
     this.router.post('/tools/batch/embed-metadata', ToolsController.middleware.bind(this), ToolsController.batchEmbedMetadata.bind(this))
+    this.router.get('/tools/item/:id/waveform', ToolsController.middleware.bind(this), ToolsController.getAudioFileWaveform.bind(this))
 
     // 
     // RSS Feed Routes (Admin and up)
diff --git a/server/utils/ffmpegHelpers.js b/server/utils/ffmpegHelpers.js
index b82f9784..4190ffd9 100644
--- a/server/utils/ffmpegHelpers.js
+++ b/server/utils/ffmpegHelpers.js
@@ -152,3 +152,26 @@ module.exports.downloadPodcastEpisode = (podcastEpisodeDownload) => {
     ffmpeg.run()
   })
 }
+
+module.exports.generateWaveform = (filepaths, start, end, res) => {
+  let ffmpeg = null
+  if (filepaths.length === 1) ffmpeg = Ffmpeg(filepaths[0])
+  else {
+    ffmpeg = Ffmpeg(`concat:${filepaths.join('|')}`)
+  }
+  ffmpeg.inputOptions('-ss', start)
+  ffmpeg.inputOptions('-to', end)
+  ffmpeg.complexFilter('aformat=channel_layouts=mono,showwavespic=s=1280x240')
+  ffmpeg.frames(1)
+  ffmpeg.format('image2pipe')
+  ffmpeg.on('start', (cmd) => {
+    Logger.debug(`[FfmpegHelpers] generateWaveform: Cmd: ${cmd}`)
+  })
+  ffmpeg.on('error', (error) => {
+    Logger.error(`[FfmpegHelpers] generateWaveform: Error`, error)
+  }).on('end', () => {
+    Logger.debug(`[FfmpegHelpers] generateWaveform finished`)
+  }).pipe(res, {
+    end: true
+  })
+}
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