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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef MEDIA_AUDIO_WIN_WAVEIN_INPUT_WIN_H_
      6 #define MEDIA_AUDIO_WIN_WAVEIN_INPUT_WIN_H_
      7 
      8 #include <string>
      9 
     10 #include <windows.h>
     11 #include <mmsystem.h>
     12 
     13 #include "base/basictypes.h"
     14 #include "base/compiler_specific.h"
     15 #include "base/synchronization/lock.h"
     16 #include "base/threading/thread_checker.h"
     17 #include "base/win/scoped_handle.h"
     18 #include "media/audio/audio_io.h"
     19 #include "media/audio/audio_parameters.h"
     20 
     21 namespace media {
     22 
     23 class AudioManagerWin;
     24 
     25 class PCMWaveInAudioInputStream : public AudioInputStream {
     26  public:
     27   // The ctor takes all the usual parameters, plus |manager| which is the
     28   // the audio manager who is creating this object and |device_id| which
     29   // is provided by the operating system.
     30   PCMWaveInAudioInputStream(AudioManagerWin* manager,
     31                             const AudioParameters& params,
     32                             int num_buffers,
     33                             const std::string& device_id);
     34   virtual ~PCMWaveInAudioInputStream();
     35 
     36   // Implementation of AudioInputStream.
     37   virtual bool Open() OVERRIDE;
     38   virtual void Start(AudioInputCallback* callback) OVERRIDE;
     39   virtual void Stop() OVERRIDE;
     40   virtual void Close() OVERRIDE;
     41   // TODO(henrika): Add volume support using the Audio Mixer API.
     42   virtual double GetMaxVolume() OVERRIDE;
     43   virtual void SetVolume(double volume) OVERRIDE;
     44   virtual double GetVolume() OVERRIDE;
     45   virtual void SetAutomaticGainControl(bool enabled) OVERRIDE;
     46   virtual bool GetAutomaticGainControl() OVERRIDE;
     47 
     48  private:
     49   enum State {
     50     kStateEmpty,      // Initial state.
     51     kStateReady,      // Device obtained and ready to record.
     52     kStateRecording,  // Recording audio.
     53     kStateStopping,   // Trying to stop, waiting for callback to finish.
     54     kStateStopped,    // Stopped. Device was reset.
     55     kStateClosed      // Device has been released.
     56   };
     57 
     58   // Allow unit tests to query the device ID.
     59   friend class AudioManagerTest;
     60 
     61   // Windows calls us back with the recorded audio data here. See msdn
     62   // documentation for 'waveInProc' for details about the parameters.
     63   static void CALLBACK WaveCallback(HWAVEIN hwi, UINT msg, DWORD_PTR instance,
     64                                     DWORD_PTR param1, DWORD_PTR param2);
     65 
     66   // If windows reports an error this function handles it and passes it to
     67   // the attached AudioInputCallback::OnError().
     68   void HandleError(MMRESULT error);
     69 
     70   // Allocates and prepares the memory that will be used for recording.
     71   void SetupBuffers();
     72 
     73   // Deallocates the memory allocated in SetupBuffers.
     74   void FreeBuffers();
     75 
     76   // Sends a buffer to the audio driver for recording.
     77   void QueueNextPacket(WAVEHDR* buffer);
     78 
     79   // Converts the stored device id string into an unsigned integer which
     80   // can be used by waveInOpen() to open the specified capture device.
     81   bool GetDeviceId(UINT* device_index);
     82 
     83   base::ThreadChecker thread_checker_;
     84 
     85   // Reader beware. Visual C has stronger guarantees on volatile vars than
     86   // most people expect. In fact, it has release semantics on write and
     87   // acquire semantics on reads. See the msdn documentation.
     88   volatile State state_;
     89 
     90   // The audio manager that created this input stream. We notify it when
     91   // we close so it can release its own resources.
     92   AudioManagerWin* manager_;
     93 
     94   // We use the callback mostly to periodically give the recorded audio data.
     95   AudioInputCallback* callback_;
     96 
     97   // The number of buffers of size |buffer_size_| each to use.
     98   const int num_buffers_;
     99 
    100   // The size in bytes of each audio buffer.
    101   uint32 buffer_size_;
    102 
    103   // Channels, 1 or 2.
    104   const int channels_;
    105 
    106   // Contains the unique name of the selected endpoint device.
    107   // Note that AudioManagerBase::kDefaultDeviceId represents the default
    108   // device role and is not a valid ID as such.
    109   std::string device_id_;
    110 
    111   // Windows native structure to encode the format parameters.
    112   WAVEFORMATEX format_;
    113 
    114   // Handle to the instance of the wave device.
    115   HWAVEIN wavein_;
    116 
    117   // Pointer to the first allocated audio buffer. This object owns it.
    118   WAVEHDR* buffer_;
    119 
    120   // An event that is signaled when the callback thread is ready to stop.
    121   base::win::ScopedHandle stopped_event_;
    122 
    123   // Lock used to avoid conflicts when Stop() is called during a callback.
    124   base::Lock lock_;
    125 
    126   DISALLOW_COPY_AND_ASSIGN(PCMWaveInAudioInputStream);
    127 };
    128 
    129 }  // namespace media
    130 
    131 #endif  // MEDIA_AUDIO_WIN_WAVEIN_INPUT_WIN_H_
    132