From c5b2856126927b65ae2d264c1f6a0e712a84c703 Mon Sep 17 00:00:00 2001
From: Zion Huang <zionhuang1107@gmail.com>
Date: Tue, 29 Oct 2024 09:01:57 +0800
Subject: [PATCH] Revert "Better audio normalization"

This reverts commit c0ad7dcca80904fddf94d1b70c99d66339a7c0a8.
---
 .../zionhuang/music/playback/MusicService.kt  | 34 ++++++-------------
 1 file changed, 10 insertions(+), 24 deletions(-)

diff --git a/app/src/main/java/com/zionhuang/music/playback/MusicService.kt b/app/src/main/java/com/zionhuang/music/playback/MusicService.kt
index 378f74a8a..dbae89d14 100644
--- a/app/src/main/java/com/zionhuang/music/playback/MusicService.kt
+++ b/app/src/main/java/com/zionhuang/music/playback/MusicService.kt
@@ -6,7 +6,6 @@ import android.content.Context
 import android.content.Intent
 import android.database.SQLException
 import android.media.audiofx.AudioEffect
-import android.media.audiofx.LoudnessEnhancer
 import android.net.ConnectivityManager
 import android.os.Binder
 import androidx.core.content.getSystemService
@@ -135,6 +134,8 @@ import java.net.SocketTimeoutException
 import java.net.UnknownHostException
 import java.time.LocalDateTime
 import javax.inject.Inject
+import kotlin.math.min
+import kotlin.math.pow
 import kotlin.time.Duration.Companion.seconds
 
 
@@ -170,10 +171,9 @@ class MusicService : MediaLibraryService(),
         database.format(mediaMetadata?.id)
     }
 
+    private val normalizeFactor = MutableStateFlow(1f)
     val playerVolume = MutableStateFlow(dataStore.get(PlayerVolumeKey, 1f).coerceIn(0f, 1f))
 
-    private var loudnessEnhancer: LoudnessEnhancer? = null
-
     lateinit var sleepTimer: SleepTimer
 
     @Inject
@@ -243,7 +243,9 @@ class MusicService : MediaLibraryService(),
 
         connectivityManager = getSystemService()!!
 
-        playerVolume.collectLatest(scope) {
+        combine(playerVolume, normalizeFactor) { playerVolume, normalizeFactor ->
+            playerVolume * normalizeFactor
+        }.collectLatest(scope) {
             player.volume = it
         }
 
@@ -296,25 +298,10 @@ class MusicService : MediaLibraryService(),
         ) { format, normalizeAudio ->
             format to normalizeAudio
         }.collectLatest(scope) { (format, normalizeAudio) ->
-            runCatching {
-                if (!normalizeAudio) {
-                    loudnessEnhancer?.enabled = false
-                    loudnessEnhancer?.release()
-                    loudnessEnhancer = null
-                } else {
-                    if (loudnessEnhancer == null) {
-                        loudnessEnhancer = LoudnessEnhancer(player.audioSessionId)
-                    }
-                    fun Float?.toMb() = ((this ?: 0f) * 100).toInt()
-
-                    var loudnessMb = format?.loudnessDb?.toFloat().toMb()
-                    if (loudnessMb !in -2000..2000) {
-                        // Extreme loudness value detected, turning off normalization for this song
-                        loudnessMb = 0
-                    }
-                    loudnessEnhancer?.setTargetGain(5f.toMb() - loudnessMb)
-                    loudnessEnhancer?.enabled = true
-                }
+            normalizeFactor.value = if (normalizeAudio && format?.loudnessDb != null) {
+                min(10f.pow(-format.loudnessDb.toFloat() / 20), 1f)
+            } else {
+                1f
             }
         }
 
@@ -789,7 +776,6 @@ class MusicService : MediaLibraryService(),
         player.removeListener(this)
         player.removeListener(sleepTimer)
         player.release()
-        loudnessEnhancer?.release()
         super.onDestroy()
     }