Adds Analog Gain Control (AGC) to the WebRTC client.

content/renderer/media/audio_input_device.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Low-latency audio capturing unit utilizing audio input stream provided
 // by browser process through IPC.
 //
 // Relationship of classes:
 //
 //  AudioInputController                 AudioInputDevice
@@ skipping 51 matching lines @@
 //
 // - Start() is asynchronous/non-blocking.
 // - Stop() is synchronous/blocking.
 // - SetDevice() is asynchronous/non-blocking.
 // - The user must call Stop() before deleting the class instance.
 
 #ifndef CONTENT_RENDERER_MEDIA_AUDIO_INPUT_DEVICE_H_
 #define CONTENT_RENDERER_MEDIA_AUDIO_INPUT_DEVICE_H_
 #pragma once
 
+#include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/shared_memory.h"
 #include "content/common/content_export.h"
 #include "content/renderer/media/audio_device_thread.h"
 #include "content/renderer/media/audio_input_message_filter.h"
 #include "content/renderer/media/scoped_loop_observer.h"
 #include "media/audio/audio_parameters.h"
 
 // TODO(henrika): This class is based on the AudioDevice class and it has
 // many components in common. Investigate potential for re-factoring.
 // TODO(henrika): Add support for event handling (e.g. OnStateChanged,
 // OnCaptureStopped etc.) and ensure that we can deliver these notifications
 // to any clients using this class.
 class CONTENT_EXPORT AudioInputDevice
     : public AudioInputMessageFilter::Delegate,
       NON_EXPORTED_BASE(public ScopedLoopObserver),
       public base::RefCountedThreadSafe<AudioInputDevice> {
  public:
   class CONTENT_EXPORT CaptureCallback {
    public:
     virtual void Capture(const std::vector<float*>& audio_data,
                          size_t number_of_frames,
-                         size_t audio_delay_milliseconds) = 0;
+                         size_t audio_delay_milliseconds,
+                         double volume) = 0;
     virtual void OnCaptureError() = 0;
    protected:
     virtual ~CaptureCallback() {}
   };
 
   class CONTENT_EXPORT CaptureEventHandler {
    public:
     // Notification to the client that the device with the specific |device_id|
     // has been started.
     // This callback is triggered as a result of StartDevice().
@@ skipping 28 matching lines @@
   void Stop();
 
   // Sets the capture volume scaling, with range [0.0, 1.0] inclusive.
   // Returns |true| on success.
   bool SetVolume(double volume);
 
   // Gets the capture volume scaling, with range [0.0, 1.0] inclusive.
   // Returns |true| on success.
   bool GetVolume(double* volume);
 
+  // Sets the Automatic Gain Control state to on or off.
+  // This method must be called before Start(). It will not have any effect
+  // if it is called while capturing has already started.
+  void SetAutomaticGainControl(bool enabled);
+
   double sample_rate() const { return audio_parameters_.sample_rate; }
   size_t buffer_size() const { return audio_parameters_.samples_per_packet; }
 
   // Methods called on IO thread ----------------------------------------------
-  // AudioInputMessageFilter::Delegate impl., called by AudioInputMessageFilter
+  // AudioInputMessageFilter::Delegate impl., called by AudioInputMessageFilter.
   virtual void OnStreamCreated(base::SharedMemoryHandle handle,
                                base::SyncSocket::Handle socket_handle,
                                uint32 length) OVERRIDE;
   virtual void OnVolume(double volume) OVERRIDE;
   virtual void OnStateChanged(AudioStreamState state) OVERRIDE;
   virtual void OnDeviceReady(const std::string& device_id) OVERRIDE;
 
  private:
   // Methods called on IO thread ----------------------------------------------
   // The following methods are tasks posted on the IO thread that needs to
   // be executed on that thread. They interact with AudioInputMessageFilter and
   // sends IPC messages on that thread.
   void InitializeOnIOThread();
   void SetSessionIdOnIOThread(int session_id);
   void StartOnIOThread();
   void ShutDownOnIOThread();
   void SetVolumeOnIOThread(double volume);
+  void SetAutomaticGainControlOnIOThread(bool enabled);
 
   void Send(IPC::Message* message);
 
   // MessageLoop::DestructionObserver implementation for the IO loop.
   // If the IO loop dies before we do, we shut down the audio thread from here.
   virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
 
   // Format
   AudioParameters audio_parameters_;
 
@@ skipping 10 matching lines @@
   int32 stream_id_;
 
   // The media session ID used to identify which input device to be started.
   // Only modified on the IO thread.
   int session_id_;
 
   // State variable used to indicate it is waiting for a OnDeviceReady()
   // callback. Only modified on the IO thread.
   bool pending_device_ready_;
 
+  // Stores the Automatic Gain Control state. Default is false.
+  // Only modified on the IO thread.
+  bool agc_is_enabled_;
+
   // Our audio thread callback class.  See source file for details.
   class AudioThreadCallback;
 
   // In order to avoid a race between OnStreamCreated and Stop(), we use this
   // guard to control stopping and starting the audio thread.
   base::Lock audio_thread_lock_;
   AudioDeviceThread audio_thread_;
   scoped_ptr<AudioInputDevice::AudioThreadCallback> audio_callback_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioInputDevice);
 };
 
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_INPUT_DEVICE_H_