fix(android): block direct audio without passthrough

android/app/src/main/kotlin/com/edde746/plezy/exoplayer/AudioOutputPolicy.kt

@@ -0,0 +1,19 @@
+package com.edde746.plezy.exoplayer
+
+import androidx.media3.common.MimeTypes
+
+internal fun isPassthroughAudioMimeType(mimeType: String): Boolean = when (mimeType) {
+  "audio/ac3",
+  "audio/eac3",
+  "audio/eac3-joc",
+  "audio/ac4",
+  "audio/vnd.dts",
+  "audio/vnd.dts.hd",
+  "audio/vnd.dts.uhd",
+  MimeTypes.AUDIO_TRUEHD -> true
+  else -> false
+}
+
+internal fun shouldBlockDirectOutputForPassthrough(mimeType: String, audioPassthroughEnabled: Boolean): Boolean {
+  return !audioPassthroughEnabled && isPassthroughAudioMimeType(mimeType)
+}

android/app/src/main/kotlin/com/edde746/plezy/exoplayer/ExoPlayerCore.kt

@@ -188,10 +188,11 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
   // Loudness normalization (#1289): audiofx effects only process non-tunneled
   // PCM mixer streams, so while enabled we block direct/bitstream output and
   // disable tunneling.
+  private var audioPassthroughEnabled: Boolean = false
   private var audioNormalizationEnabled: Boolean = false
   private val audioNormalization = AudioNormalizationEffect(::emitLog)
   private var pendingAudioRendererBounce: Boolean = false
-  private val audioBounceTimeout = Runnable { completeAudioRendererBounce("audio-normalization bounce timeout") }
+  private val audioBounceTimeout = Runnable { completeAudioRendererBounce("audio renderer bounce timeout") }
   private var lastSeekable: Boolean? = null
   private var forceSeekable: Boolean = false
 
@@ -370,13 +371,18 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
     return decision.mode
   }
 
-  fun initialize(bufferSizeBytes: Int? = null, tunnelingEnabled: Boolean = true): Boolean {
+  fun initialize(
+    bufferSizeBytes: Int? = null,
+    tunnelingEnabled: Boolean = true,
+    audioPassthroughEnabled: Boolean = false
+  ): Boolean {
     if (isInitialized) {
       Log.d(TAG, "Already initialized")
       return true
     }
 
     tunnelingUserEnabled = tunnelingEnabled
+    this.audioPassthroughEnabled = audioPassthroughEnabled
     this.dvMode = getConfiguredDvMode()
     DoviBridge.logSupportSummary(activity)
     Log.i(
@@ -1840,6 +1846,7 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
     val mimeType = format.sampleMimeType ?: return false
     // Loudness normalization needs decoded PCM for the audiofx chain to act on.
     if (audioNormalizationEnabled && isEncodedAudioMimeType(mimeType)) return true
+    if (shouldBlockDirectOutputForPassthrough(mimeType, audioPassthroughEnabled)) return true
     if (directAudioOutputBlockedAfterFailure.contains(mimeType)) {
       if (loggedDirectAudioRecoveryBlocks.add("$mimeType|$reason")) {
         emitLog(
@@ -2720,6 +2727,25 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
     }
   }
 
+  fun setAudioPassthrough(enabled: Boolean) {
+    if (audioPassthroughEnabled == enabled) return
+    audioPassthroughEnabled = enabled
+    emitLog("info", "audio", "Audio passthrough ${if (enabled) "enabled" else "disabled"}")
+
+    if (exoPlayer == null) return
+    val outputEncoding = lastAudioTrackConfig?.encoding
+    val selectedMime = selectedAudioFormat()?.sampleMimeType
+    val needsBounce = outputEncoding != null &&
+      selectedMime != null &&
+      isPassthroughAudioMimeType(selectedMime) &&
+      (if (enabled) isPcmEncoding(outputEncoding) else !isPcmEncoding(outputEncoding))
+    if (needsBounce) {
+      startAudioRendererBounce("audio-passthrough")
+    } else {
+      updateTunnelingState("audio-passthrough")
+    }
+  }
+
   private fun attachNormalizationEffect() {
     val sessionId = exoPlayer?.audioSessionId ?: C.AUDIO_SESSION_ID_UNSET
     if (sessionId == C.AUDIO_SESSION_ID_UNSET) {
@@ -2737,7 +2763,7 @@ class ExoPlayerCore(private val activity: Activity) : Player.Listener {
   private fun startAudioRendererBounce(reason: String) {
     if (pendingAudioRendererBounce) return
     pendingAudioRendererBounce = true
-    emitLog("info", "audio-normalization", "Bouncing audio renderer to re-evaluate output path (reason=$reason)")
+    emitLog("info", "audio", "Bouncing audio renderer to re-evaluate output path (reason=$reason)")
     applyTrackSelectorPolicy(reason = "$reason (audio renderer off)", audioDisabled = true)
     handler.postDelayed(audioBounceTimeout, AUDIO_BOUNCE_TIMEOUT_MS)
   }

android/app/src/test/kotlin/com/edde746/plezy/exoplayer/AudioOutputPolicyTest.kt

@@ -0,0 +1,47 @@
+package com.edde746.plezy.exoplayer
+
+import androidx.media3.common.MimeTypes
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class AudioOutputPolicyTest {
+
+  @Test
+  fun passthroughDisabledBlocksBitstreamFormats() {
+    val bitstreamFormats = listOf(
+      "audio/ac3",
+      "audio/eac3",
+      "audio/eac3-joc",
+      "audio/ac4",
+      "audio/vnd.dts",
+      "audio/vnd.dts.hd",
+      "audio/vnd.dts.uhd",
+      MimeTypes.AUDIO_TRUEHD
+    )
+
+    for (mimeType in bitstreamFormats) {
+      assertTrue(mimeType, shouldBlockDirectOutputForPassthrough(mimeType, audioPassthroughEnabled = false))
+    }
+  }
+
+  @Test
+  fun passthroughEnabledAllowsBitstreamFormats() {
+    assertFalse(shouldBlockDirectOutputForPassthrough("audio/ac3", audioPassthroughEnabled = true))
+    assertFalse(shouldBlockDirectOutputForPassthrough(MimeTypes.AUDIO_TRUEHD, audioPassthroughEnabled = true))
+  }
+
+  @Test
+  fun passthroughDisabledLeavesDecodedFormatsAvailable() {
+    val decodedFormats = listOf(
+      MimeTypes.AUDIO_AAC,
+      MimeTypes.AUDIO_OPUS,
+      MimeTypes.AUDIO_RAW,
+      MimeTypes.AUDIO_FLAC
+    )
+
+    for (mimeType in decodedFormats) {
+      assertFalse(mimeType, shouldBlockDirectOutputForPassthrough(mimeType, audioPassthroughEnabled = false))
+    }
+  }
+}