From fe8206e3def11d4e16e3cc1079f7f77a53100e93 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Tue, 31 Mar 2026 12:54:04 +0000
Subject: [PATCH] Fix Oboe audio silence by correcting BASS device routing
 order

Reordered audio initialization steps in OboeAudioRedirector.cs to ensure
that BASS source mixers are moved to the "No Sound" device (Device 0)
before being plugged into the Oboe master mixer.

BASS automatically detaches channels from mixers when their device
context is changed (via ChannelSetDevice). The previous implementation
was adding sources to the mixer and then changing their device, causing
immediate detachment and resulting in pure silence.

Additionally improved the restoration logic to correctly move mixers
back to the default device (Device 1), enabling clean toggling of the
Oboe feature without a restart.
---
 osu.Android/OboeAudioRedirector.cs | 45 +++++++++++++++---------------
 1 file changed, 22 insertions(+), 23 deletions(-)

diff --git a/osu.Android/OboeAudioRedirector.cs b/osu.Android/OboeAudioRedirector.cs
index 145da4f5d9e3..9dc29b251853 100644
--- a/osu.Android/OboeAudioRedirector.cs
+++ b/osu.Android/OboeAudioRedirector.cs
@@ -60,7 +60,8 @@ public void RefreshMixers(int hardwareSampleRate)
             }
 
             // User requested Low-Latency Oboe: we MUST use Oboe.
-            // Silence the default device immediately to prevent duplicated audio.
+            // Silence the default device and setup routing.
+            // Order is critical: Device init -> Create Master -> Move Sources -> Add to Master.
             silenceDefaultAudio();
             setupMasterMixer();
 
@@ -93,6 +94,11 @@ private void setupMasterMixer()
                 return;
             }
 
+            // Move the master mixer to the silent device immediately.
+            // This ensures all following operations happen on the same device context.
+            if (!Bass.ChannelSetDevice(masterMixer, 0))
+                Debug.WriteLine($"[osu!] Failed to move master mixer to silent device: {Bass.LastError}");
+
             // Disable BASS-internal buffering for the master mixer.
             // This ensures BASS renders as fast as possible when we call ChannelGetData.
             // This is key for "lowest possible latency" as requested.
@@ -112,6 +118,11 @@ private void setupMasterMixer()
                         Debug.WriteLine($"[osu!] Failed to hijack mixer {handle} from parent {parent}: {Bass.LastError}");
                 }
 
+                // Move source mixer to the silent device before adding to master.
+                // Changing device automatically removes it from any existing mixer.
+                if (!Bass.ChannelSetDevice(handle, 0))
+                    Debug.WriteLine($"[osu!] Failed to move source mixer {handle} to silent device: {Bass.LastError}");
+
                 // Add redirected mixers as sources to our master mixer.
                 // We remove BASS_MIXER_BUFFER to eliminate internal BASS buffering latency,
                 // relying entirely on the Oboe callback timing for rock-solid sync.
@@ -120,9 +131,6 @@ private void setupMasterMixer()
                     Debug.WriteLine($"[osu!] Failed to add mixer {handle} to master mixer: {Bass.LastError}");
                 }
             }
-
-            // Move the master mixer to the silent device too.
-            Bass.ChannelSetDevice(masterMixer, 0);
         }
 
         private void silenceDefaultAudio()
@@ -137,22 +145,7 @@ private void silenceDefaultAudio()
                     return;
                 }
 
-                bool allSuccess = true;
-
-                // Move all redirected mixers to the silent device.
-                foreach (int handle in mixerHandles)
-                {
-                    if (!Bass.ChannelSetDevice(handle, 0))
-                    {
-                        Debug.WriteLine($"[osu!] Failed to move mixer {handle} to silent device: {Bass.LastError}");
-                        allSuccess = false;
-                    }
-                }
-
-                devicesSilenced = allSuccess;
-
-                if (allSuccess && mixerHandles.Count > 0)
-                    Debug.WriteLine($"[osu!] BASS mixers ({mixerHandles.Count}) moved to silent device 0 (Oboe active)");
+                devicesSilenced = true;
             }
             catch (Exception e)
             {
@@ -180,14 +173,20 @@ private void restoreDefaultAudio()
                     // Restore to framework's original parent mixer if we hijacked it.
                     if (originalParents.TryGetValue(handle, out int parent))
                     {
+                        // MUST move back to default device (1) before re-adding to framework parent.
+                        if (!Bass.ChannelSetDevice(handle, 1))
+                            Debug.WriteLine($"[osu!] Failed to restore mixer {handle} to default device: {Bass.LastError}");
+
                         if (BassMix.MixerAddChannel(parent, handle, BassFlags.MixerChanNoRampin))
                             Debug.WriteLine($"[osu!] Restored mixer {handle} to framework parent {parent}");
                         else
                             Debug.WriteLine($"[osu!] Failed to restore mixer {handle} to framework parent {parent}: {Bass.LastError}");
                     }
-
-                    if (!Bass.ChannelSetDevice(handle, 1))
-                        Debug.WriteLine($"[osu!] Failed to restore mixer {handle} to default device: {Bass.LastError}");
+                    else
+                    {
+                        // Even if no parent, restore to default device.
+                        Bass.ChannelSetDevice(handle, 1);
+                    }
                 }
 
                 originalParents.Clear();