Adds support for 16kHz input sample rate and mono channel config. in WebRTC.

media/audio/win/audio_low_latency_input_win.h

 // Copyright (c) 2011 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.
 //
 // Implementation of AudioInputStream for Windows using Windows Core Audio
 // WASAPI for low latency capturing.
 //
 // Overview of operation:
 //
 // - An object of WASAPIAudioInputStream is created by the AudioManager
@@ skipping 71 matching lines @@
   // The dtor is typically called by the AudioManager only and it is usually
   // triggered by calling AudioInputStream::Close().
   virtual ~WASAPIAudioInputStream();
 
   // Implementation of AudioInputStream.
   virtual bool Open() OVERRIDE;
   virtual void Start(AudioInputCallback* callback) OVERRIDE;
   virtual void Stop() OVERRIDE;
   virtual void Close() OVERRIDE;
 
-  // Retrieves the stream format that the audio engine uses for its internal
+  // Retrieves the sample rate used by the audio engine for its internal
   // processing/mixing of shared-mode streams.
   static double HardwareSampleRate(ERole device_role);
 
+  // Retrieves the number of audio channels used by the audio engine for its
+  // internal processing/mixing of shared-mode streams.
+  static uint32 HardwareChannelCount(ERole device_role);
+
   bool started() const { return started_; }
 
  private:
   // DelegateSimpleThread::Delegate implementation.
   virtual void Run() OVERRIDE;
 
   // Issues the OnError() callback to the |sink_|.
   void HandleError(HRESULT err);
 
   // The Open() method is divided into these sub methods.
   HRESULT SetCaptureDevice();
   HRESULT ActivateCaptureDevice();
   HRESULT GetAudioEngineStreamFormat();
   bool DesiredFormatIsSupported();
   HRESULT InitializeAudioEngine();
 
+  // Retrieves the stream format that the audio engine uses for its internal
+  // processing/mixing of shared-mode streams.
+  static HRESULT GetMixFormat(ERole device_role, WAVEFORMATEX** device_format);
+
   // Initializes the COM library for use by the calling thread and set the
   // thread's concurrency model to multi-threaded.
   base::win::ScopedCOMInitializer com_init_;
 
   // Our creator, the audio manager needs to be notified when we close.
   AudioManagerWin* manager_;
 
   // Capturing is driven by this thread (which has no message loop).
   // All OnData() callbacks will be called from this thread.
   base::DelegateSimpleThread* capture_thread_;
@@ skipping 54 matching lines @@
   // recorded.
   base::win::ScopedHandle audio_samples_ready_event_;
 
   // This event will be signaled when capturing shall stop.
   base::win::ScopedHandle stop_capture_event_;
 
   DISALLOW_COPY_AND_ASSIGN(WASAPIAudioInputStream);
 };
 
 #endif  // MEDIA_AUDIO_WIN_AUDIO_LOW_LATENCY_INPUT_WIN_H_