Hiroshi/output always running mode

modules/audio_device/audio_engine_device.h

@@ -17,7 +17,6 @@
 #ifndef SDK_OBJC_NATIVE_SRC_AUDIO_AUDIO_DEVICE_AUDIOENGINE_H_
 #define SDK_OBJC_NATIVE_SRC_AUDIO_AUDIO_DEVICE_AUDIOENGINE_H_
 
-#include <atomic>
 #include <memory>
 
 #include "api/scoped_refptr.h"
@@ -137,6 +136,7 @@ class AudioEngineDevice : public AudioDeviceModule, public AudioSessionObserver
     bool output_available = true;
     bool input_available = true;
 
+    bool output_running_persistent_mode = false;
     bool input_enabled_persistent_mode = false;
 
     bool input_muted = true;
@@ -161,6 +161,7 @@ class AudioEngineDevice : public AudioDeviceModule, public AudioSessionObserver
       return input_enabled == rhs.input_enabled && input_running == rhs.input_running &&
              output_enabled == rhs.output_enabled && output_running == rhs.output_running &&
              input_available == rhs.input_available && output_available == rhs.output_available &&
+             output_running_persistent_mode == rhs.output_running_persistent_mode &&
              input_enabled_persistent_mode == rhs.input_enabled_persistent_mode &&
              input_muted == rhs.input_muted && is_interrupted == rhs.is_interrupted &&
              render_mode == rhs.render_mode && mute_mode == rhs.mute_mode &&
@@ -178,9 +179,8 @@ class AudioEngineDevice : public AudioDeviceModule, public AudioSessionObserver
     // AUDIO STATE LOGIC
     //
     // Device Mode:
-    // - Output follows input only when voice_processing_enabled=true (for AEC)
+    // - Output follows input to keep AVAudioEngine IO active for capture.
     // - Input respects mute mode restrictions (RestartEngine + input_muted)
-    // - Independent operation when voice processing is disabled
     //
     // Manual Mode:
     // - Bidirectional coupling: if ANY component is enabled/running, BOTH are considered
@@ -192,21 +192,23 @@ class AudioEngineDevice : public AudioDeviceModule, public AudioSessionObserver
 
     bool IsOutputEnabled() const {
       if (!output_available) return false;
+      if (output_running_persistent_mode) return true;
 
       switch (render_mode) {
         case RenderMode::Device:
-          return voice_processing_enabled ? (IsInputEnabled() || output_enabled) : output_enabled;
+          return IsInputEnabled() || output_enabled;
         case RenderMode::Manual:
           return output_enabled || input_enabled || input_enabled_persistent_mode;
       }
     }
 
     bool IsOutputRunning() const {
       if (!output_available) return false;
+      if (output_running_persistent_mode) return true;
 
       switch (render_mode) {
         case RenderMode::Device:
-          return voice_processing_enabled ? (IsInputRunning() || output_running) : output_running;
+          return IsInputRunning() || output_running;
         case RenderMode::Manual:
           return output_running || input_running;
       }
@@ -220,7 +222,8 @@ class AudioEngineDevice : public AudioDeviceModule, public AudioSessionObserver
           return !(mute_mode == MuteMode::RestartEngine && input_muted) &&
                  (input_enabled || input_enabled_persistent_mode);
         case RenderMode::Manual:
-          return input_enabled || input_enabled_persistent_mode || output_enabled;
+          return (input_enabled || input_enabled_persistent_mode) ||
+                 (output_enabled || output_running_persistent_mode);
       }
     }
 
@@ -231,7 +234,7 @@ class AudioEngineDevice : public AudioDeviceModule, public AudioSessionObserver
         case RenderMode::Device:
           return !(mute_mode == MuteMode::RestartEngine && input_muted) && input_running;
         case RenderMode::Manual:
-          return input_running || output_running;
+          return input_running || (output_running || output_running_persistent_mode);
       }
     }
 
@@ -367,6 +370,9 @@ class AudioEngineDevice : public AudioDeviceModule, public AudioSessionObserver
   int32_t SetDuckingLevel(AudioDuckingLevel level);
   int32_t DuckingLevel(AudioDuckingLevel* level);
 
+  int32_t SetOutputRunningPersistentMode(bool enable);
+  int32_t OutputRunningPersistentMode(bool* enabled);
+
   int32_t SetInitRecordingPersistentMode(bool enable);
   int32_t InitRecordingPersistentMode(bool* enabled);
 
@@ -429,11 +435,7 @@ class AudioEngineDevice : public AudioDeviceModule, public AudioSessionObserver
 
     bool DidUpdateMuteMode() const { return prev.mute_mode != next.mute_mode; }
 
-    bool IsEngineRestartRequired() const {
-      return DidUpdateAudioGraph() ||
-             // Voice processing enable state updates
-             DidUpdateVoiceProcessingEnabled();
-    }
+    bool IsEngineRestartRequired() const { return DidUpdateAudioGraph(); }
 
     bool IsEngineRecreateRequired() const {
       // Device id specified
@@ -448,7 +450,11 @@ class AudioEngineDevice : public AudioDeviceModule, public AudioSessionObserver
       bool special_case = (prev.IsOutputEnabled() && next.IsOutputEnabled()) &&
                           (prev.IsInputEnabled() && !next.IsInputEnabled());
 
-      return device || default_device || special_case;
+      // Toggling voice processing requires a full engine recreate to ensure
+      // a clean audio hardware state.
+      bool voice_processing = DidUpdateVoiceProcessingEnabled();
+
+      return device || default_device || special_case || voice_processing;
     }
 
     bool DidEnableManualRenderingMode() const {