Adds support for Bluetooth headsets to the iOS audio layer

webrtc/modules/audio_device/ios/audio_device_ios.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 137 matching lines @@
   void ClearPlayoutWarning() override {}
   void ClearPlayoutError() override {}
   void ClearRecordingWarning() override {}
   void ClearRecordingError() override {}
 
  private:
   // Uses current |playout_parameters_| and |record_parameters_| to inform the
   // audio device buffer (ADB) about our internal audio parameters.
   void UpdateAudioDeviceBuffer();
 
+  // Registers observers for the AVAudioSessionRouteChangeNotification and
+  // AVAudioSessionInterruptionNotification notifications.
+  void RegisterNotificationObservers();
+  void UnregisterNotificationObservers();
+
   // Since the preferred audio parameters are only hints to the OS, the actual
   // values may be different once the AVAudioSession has been activated.
   // This method asks for the current hardware parameters and takes actions
   // if they should differ from what we have asked for initially. It also
   // defines |playout_parameters_| and |record_parameters_|.
   void SetupAudioBuffersForActiveAudioSession();
 
   // Creates a Voice-Processing I/O unit and configures it for full-duplex
   // audio. The selected stream format is selected to avoid internal resampling
   // and to match the 10ms callback rate for WebRTC as well as possible.
   // This method also initializes the created audio unit.
   bool SetupAndInitializeVoiceProcessingAudioUnit();
 
+  // Restarts active audio streams using a new sample rate. Required when e.g.
+  // a BT headset is enabled or disabled.
+  bool RestartAudioUnitWithNewFormat(float sample_rate);
+
   // Activates our audio session, creates and initializes the voice-processing
   // audio unit and verifies that we got the preferred native audio parameters.
   bool InitPlayOrRecord();
 
   // Closes and deletes the voice-processing I/O unit.
   bool ShutdownPlayOrRecord();
 
   // Callback function called on a real-time priority I/O thread from the audio
   // unit. This method is used to signal that recorded audio is available.
   static OSStatus RecordedDataIsAvailable(
@@ skipping 14 matching lines @@
   static OSStatus GetPlayoutData(void* in_ref_con,
                                  AudioUnitRenderActionFlags* io_action_flags,
                                  const AudioTimeStamp* time_stamp,
                                  UInt32 in_bus_number,
                                  UInt32 in_number_frames,
                                  AudioBufferList* io_data);
   OSStatus OnGetPlayoutData(AudioUnitRenderActionFlags* io_action_flags,
                             UInt32 in_number_frames,
                             AudioBufferList* io_data);
 
- private:
   // Ensures that methods are called from the same thread as this object is
   // created on.
   rtc::ThreadChecker thread_checker_;
 
   // Raw pointer handle provided to us in AttachAudioBuffer(). Owned by the
   // AudioDeviceModuleImpl class and called by AudioDeviceModuleImpl::Create().
   // The AudioDeviceBuffer is a member of the AudioDeviceModuleImpl instance
   // and therefore outlives this object.
   AudioDeviceBuffer* audio_device_buffer_;
 
@@ skipping 53 matching lines @@
   bool initialized_;
 
   // Set to true after successful call to InitRecording(), false otherwise.
   bool rec_is_initialized_;
 
   // Set to true after successful call to InitPlayout(), false otherwise.
   bool play_is_initialized_;
 
   // Audio interruption observer instance.
   void* audio_interruption_observer_;
+  void* route_change_observer_;
+
+  // Contains the audio data format specification for a stream of audio.
+  AudioStreamBasicDescription application_format_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_DEVICE_IOS_AUDIO_DEVICE_IOS_H_