From a74bb33967a9154af100b6a5fdcde403b4213e70 Mon Sep 17 00:00:00 2001
From: Mylloon <kennel.anri@tutanota.com>
Date: Wed, 18 Sep 2024 01:10:28 +0200
Subject: [PATCH] compute audio tracks final bitrate

---
 src/main.ts             | 20 +++++++++++---------
 src/preload.ts          |  4 ++--
 src/scripts/renderer.ts |  6 +++---
 src/utils/misc.ts       |  8 +++++---
 4 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/src/main.ts b/src/main.ts
index fb381d6..814ed76 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -89,9 +89,9 @@ app.whenReady().then(() => {
     const tmpFile = getNewFilename(file, "TMP_");
     let outFile;
 
-    const nbTracks = getNumberOfAudioTracks(file);
+    const audioTracks = getNumberOfAudioTracks(file);
 
-    switch (nbTracks) {
+    switch (audioTracks.length) {
       case 2:
         // Merge 2 audio
         // See: https://trac.ffmpeg.org/wiki/AudioChannelManipulation#a2stereostereo
@@ -137,7 +137,7 @@ app.whenReady().then(() => {
       title: outFile,
       size: stats.size / 1024 / 1024,
       duration,
-      nbTracks,
+      audioTracks,
     };
   };
 
@@ -145,9 +145,11 @@ app.whenReady().then(() => {
   const reduceSize = async (
     file: string,
     bitrate: number,
-    nbTracks: number
+    audioTracks: number[]
   ) => {
-    const audioBitrate = 500; // keep some room
+    const audioBitrate = Math.ceil(
+      audioTracks.reduce((sum, current) => current + sum, 0)
+    );
     let videoBitrate = bitrate - audioBitrate;
 
     const finalFile = getNewFilename(file, "Compressed - ");
@@ -156,7 +158,7 @@ app.whenReady().then(() => {
     const nul = process.platform === "win32" ? "NUL" : "/dev/null";
 
     // Mapping of tracks for FFMPEG, adding 1 for the video stream
-    const mappingTracks = Array(nbTracks + 1)
+    const mappingTracks = Array(audioTracks.length + 1)
       .fill("-map 0:")
       .map((str, index) => {
         return str + index;
@@ -173,7 +175,7 @@ app.whenReady().then(() => {
       hwAcc = "-hwaccel cuda";
 
       // Increase video bitrate
-      videoBitrate = Math.floor(videoBitrate * 1.7);
+      videoBitrate = Math.floor(videoBitrate);
     }
 
     // Compress the video
@@ -229,8 +231,8 @@ app.whenReady().then(() => {
   ipcMain.handle("mergeAudio", (_, file: string) => mergeAudio(file));
   ipcMain.handle(
     "reduceSize",
-    (_, file: string, bitrate: number, nbTracks: number) =>
-      reduceSize(file, bitrate, nbTracks)
+    (_, file: string, bitrate: number, audioTracks: number[]) =>
+      reduceSize(file, bitrate, audioTracks)
   );
   ipcMain.handle("moveMetadata", (_, file: string) => moveMetadata(file));
   ipcMain.handle("exit", () => (error ? {} : app.quit()));
diff --git a/src/preload.ts b/src/preload.ts
index e14b9a6..bda47ba 100644
--- a/src/preload.ts
+++ b/src/preload.ts
@@ -13,8 +13,8 @@ contextBridge.exposeInMainWorld("internals", {
     ipcRenderer.invoke("getFilename", filepath),
   askFiles: () => ipcRenderer.invoke("askFiles"),
   mergeAudio: (file: string) => ipcRenderer.invoke("mergeAudio", file),
-  reduceSize: (file: string, bitrate: number, nbTracks: number) =>
-    ipcRenderer.invoke("reduceSize", file, bitrate, nbTracks),
+  reduceSize: (file: string, bitrate: number, audioTracks: number[]) =>
+    ipcRenderer.invoke("reduceSize", file, bitrate, audioTracks),
   moveMetadata: (file: string) => ipcRenderer.invoke("moveMetadata", file),
   exit: () => ipcRenderer.invoke("exit"),
   confirmation: (text: string) => ipcRenderer.invoke("confirmation", text),
diff --git a/src/scripts/renderer.ts b/src/scripts/renderer.ts
index 05f8a9a..eb44b56 100644
--- a/src/scripts/renderer.ts
+++ b/src/scripts/renderer.ts
@@ -11,12 +11,12 @@ let internals: {
     title: string;
     duration: number;
     size: number;
-    nbTracks: number;
+    audioTracks: number[];
   }>;
   reduceSize: (
     file: string,
     bitrate: number,
-    nbTracks: number
+    audioTracks: number[]
   ) => Promise<string>;
   moveMetadata: (file: string) => Promise<string>;
   confirmation: (text: string) => Promise<void>;
@@ -135,7 +135,7 @@ const main = async () => {
       finalTitle = await internals.reduceSize(
         newFile.title,
         bitrate,
-        newFile.nbTracks
+        newFile.audioTracks
       );
     } else {
       updateMessage(`\nPréparation pour le partage...`, true, Mode.Append);
diff --git a/src/utils/misc.ts b/src/utils/misc.ts
index c372635..a3b5a6d 100644
--- a/src/utils/misc.ts
+++ b/src/utils/misc.ts
@@ -22,10 +22,12 @@ export const getVideoDuration = (file: string) => {
 };
 
 /** Return the number of audio tracks */
-export const getNumberOfAudioTracks = (file: string) => {
-  const command = `"${ffprobePath}" -v error -show_entries stream=index -select_streams a -of json "${file}"`;
+export const getNumberOfAudioTracks = (file: string): number[] => {
+  const command = `"${ffprobePath}" -v error -show_entries stream=bit_rate -select_streams a -of json "${file}"`;
   const result = child_process.execSync(command, { encoding: "utf8" });
-  return JSON.parse(result).streams.length;
+  return JSON.parse(result).streams.map(
+    (v: { bit_rate: string }) => Number(v.bit_rate) / 1000
+  );
 };
 
 /** Print an error to the console and open the dev tool panel */