AudioUnit: Don't rely on category switch for mic indicator to turn off (#52)

* progress

* tweak

* clean

* simplify audio unit restart

call to SetupAudioBuffersForActiveAudioSession() might not be needed since sample rate won't change during restart. This might help reduce the unwanted noise when restarting audio unit.

* clean

Author: hiroshihorie

sdk/objc/components/audio/RTCAudioSession+Private.h

@@ -35,8 +35,6 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property(nonatomic, assign) BOOL isInterrupted;
 
-@property(nonatomic, strong) NSString *activeCategory;
-
 /** Adds the delegate to the list of delegates, and places it at the front of
  *  the list. This delegate will be notified before other delegates of
  *  audio events.

sdk/objc/components/audio/RTCAudioSession.h

@@ -102,9 +102,6 @@ RTC_OBJC_EXPORT
 - (void)audioSession:(RTC_OBJC_TYPE(RTCAudioSession) *)audioSession
     audioUnitStartFailedWithError:(NSError *)error;
 
-/** Called when audio session changed from output-only to input & output */
-- (void)audioSessionDidChangeRecordingEnabled:(RTC_OBJC_TYPE(RTCAudioSession) *)audioSession;
-
 @end
 
 /** This is a protocol used to inform RTCAudioSession when the audio session

sdk/objc/components/audio/RTCAudioSession.mm

@@ -114,8 +114,6 @@ - (instancetype)initWithAudioSession:(id)audioSession {
                   options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld
                   context:(__bridge void *)RTC_OBJC_TYPE(RTCAudioSession).class];
 
-    _activeCategory = _session.category;
-
     RTCLog(@"RTC_OBJC_TYPE(RTCAudioSession) (%p): init.", self);
   }
   return self;
@@ -543,13 +541,6 @@ - (void)handleRouteChangeNotification:(NSNotification *)notification {
       break;
     case AVAudioSessionRouteChangeReasonCategoryChange:
       RTCLog(@"Audio route changed: CategoryChange to :%@", self.session.category);
-      {
-        if (![_session.category isEqualToString:_activeCategory]) {
-          _activeCategory = _session.category;
-          RTCLog(@"Audio route changed: Restarting Audio Unit");
-          [self notifyDidChangeAudioSessionRecordingEnabled];
-        }
-      }
       break;
     case AVAudioSessionRouteChangeReasonOverride:
       RTCLog(@"Audio route changed: Override");
@@ -1005,13 +996,4 @@ - (void)notifyFailedToSetActive:(BOOL)active error:(NSError *)error {
   }
 }
 
-- (void)notifyDidChangeAudioSessionRecordingEnabled {
-  for (auto delegate : self.delegates) {
-    SEL sel = @selector(audioSessionDidChangeRecordingEnabled:);
-    if ([delegate respondsToSelector:sel]) {
-      [delegate audioSessionDidChangeRecordingEnabled:self];
-    }
-  }
-}
-
 @end

sdk/objc/components/audio/RTCNativeAudioSessionDelegateAdapter.mm

@@ -86,9 +86,4 @@ - (void)audioSession:(RTC_OBJC_TYPE(RTCAudioSession) *)audioSession
   _observer->OnChangedOutputVolume();
 }
 
-- (void)audioSessionDidChangeRecordingEnabled:(RTC_OBJC_TYPE(RTCAudioSession) *)session {
-  // re-trigger audio unit init, by using interrupt ended callback
-  _observer->OnChangedRecordingEnabled();
-}
-
 @end

sdk/objc/native/src/audio/audio_device_ios.h

@@ -147,7 +147,6 @@ class AudioDeviceIOS : public AudioDeviceGeneric,
   void OnValidRouteChange() override;
   void OnCanPlayOrRecordChange(bool can_play_or_record) override;
   void OnChangedOutputVolume() override;
-  void OnChangedRecordingEnabled() override;
 
   // VoiceProcessingAudioUnitObserver methods.
   OSStatus OnDeliverRecordedData(AudioUnitRenderActionFlags* flags,
@@ -175,7 +174,8 @@ class AudioDeviceIOS : public AudioDeviceGeneric,
   void HandleSampleRateChange();
   void HandlePlayoutGlitchDetected();
   void HandleOutputVolumeChange();
-  void HandleAudioSessionRecordingEnabledChange();
+
+  bool RestartAudioUnit(bool enable_input);
 
   // Uses current `playout_parameters_` and `record_parameters_` to inform the
   // audio device buffer (ADB) about our internal audio parameters.
@@ -205,7 +205,7 @@ class AudioDeviceIOS : public AudioDeviceGeneric,
 
   // Activates our audio session, creates and initializes the voice-processing
   // audio unit and verifies that we got the preferred native audio parameters.
-  bool InitPlayOrRecord();
+  bool InitPlayOrRecord(bool enable_input);
 
   // Closes and deletes the voice-processing I/O unit.
   void ShutdownPlayOrRecord();
@@ -269,19 +269,21 @@ class AudioDeviceIOS : public AudioDeviceGeneric,
   // will be changed dynamically to account for this behavior.
   rtc::BufferT<int16_t> record_audio_buffer_;
 
+  // Set to 1 when recording is initialized and 0 otherwise.
+  volatile int recording_is_initialized_;
+
   // Set to 1 when recording is active and 0 otherwise.
   volatile int recording_;
 
+  // Set to 1 when playout is initialized and 0 otherwise.
+  volatile int playout_is_initialized_;
+
   // Set to 1 when playout is active and 0 otherwise.
   volatile int playing_;
 
   // Set to true after successful call to Init(), false otherwise.
   bool initialized_ RTC_GUARDED_BY(thread_checker_);
 
-  // Set to true after successful call to InitRecording() or InitPlayout(),
-  // false otherwise.
-  bool audio_is_initialized_;
-
   // Set to true if audio session is interrupted, false otherwise.
   bool is_interrupted_;