Add recording capability to AudioManager, and implemented on windows using the WaveIn APIs.

media/audio/win/wavein_input_win.h

+// Copyright (c) 2010 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.
+
+#ifndef MEDIA_AUDIO_WIN_WAVEIN_INPUT_WIN_H_
+#define MEDIA_AUDIO_WIN_WAVEIN_INPUT_WIN_H_
+
+#include <windows.h>
+#include <mmsystem.h>
+
+#include "base/basictypes.h"
+#include "base/scoped_handle_win.h"
+#include "media/audio/audio_io.h"
+
+class AudioManagerWin;
+
+class PCMWaveInAudioInputStream : public AudioInputStream {
+ public:
+  // The ctor takes all the usual parameters, plus |manager| which is the
+  // the audio manager who is creating this object and |device_id| which
+  // is provided by the operating system.
+  PCMWaveInAudioInputStream(AudioManagerWin* manager, int channels,
+                            int sampling_rate, int num_buffers,
+                            char bits_per_sample, uint32 samples_per_packet,
+                            UINT device_id);
+  virtual ~PCMWaveInAudioInputStream();
+
+  // Implementation of AudioInputStream.
+  virtual bool Open();
+  virtual void Start(AudioInputCallback* callback);
+  virtual void Stop();
+  virtual void Close();
+
+ private:
+  enum State {
+    kStateEmpty,      // Initial state.
+    kStateReady,      // Device obtained and ready to record.
+    kStateRecording,  // Recording audio.
+    kStateStopping,   // Trying to stop, waiting for callback to finish.
+    kStateStopped,    // Stopped. Device was reset.
+    kStateClosed      // Device has been released.
+  };
+
+  // Windows calls us back with the recorded audio data here. See msdn
+  // documentation for 'waveInProc' for details about the parameters.
+  static void CALLBACK WaveCallback(HWAVEIN hwi, UINT msg, DWORD_PTR instance,
+                                    DWORD_PTR param1, DWORD_PTR param2);
+
+  // If windows reports an error this function handles it and passes it to
+  // the attached AudioInputCallback::OnError().
+  void HandleError(MMRESULT error);
+
+  // Allocates and prepares the memory that will be used for recording.
+  void SetupBuffers();
+
+  // Deallocates the memory allocated in SetupBuffers.
+  void FreeBuffers();
+
+  // Sends a buffer to the audio driver for recording.
+  void QueueNextPacket(WAVEHDR* buffer);
+
+  // Reader beware. Visual C has stronger guarantees on volatile vars than
+  // most people expect. In fact, it has release semantics on write and
+  // acquire semantics on reads. See the msdn documentation.
+  volatile State state_;
+
+  // The audio manager that created this input stream. We notify it when
+  // we close so it can release its own resources.
+  AudioManagerWin* manager_;
+
+  // We use the callback mostly to periodically give the recorded audio data.
+  AudioInputCallback* callback_;
+
+  // The number of buffers of size |buffer_size_| each to use.
+  const int num_buffers_;
+
+  // The size in bytes of each audio buffer.
+  uint32 buffer_size_;
+
+  // Channels, 1 or 2.
+  const int channels_;
+
+  // The id assigned by the operating system to the selected wave output
+  // hardware device. Usually this is just -1 which means 'default device'.
+  UINT device_id_;
+
+  // Windows native structure to encode the format parameters.
+  WAVEFORMATEX format_;
+
+  // Handle to the instance of the wave device.
+  HWAVEIN wavein_;
+
+  // Pointer to the first allocated audio buffer. This object owns it.
+  WAVEHDR* buffer_;
+
+  // An event that is signaled when the callback thread is ready to stop.
+  ScopedHandle stopped_event_;
+
+  DISALLOW_COPY_AND_ASSIGN(PCMWaveInAudioInputStream);
+};
+
+#endif  // MEDIA_AUDIO_WIN_WAVEIN_INPUT_WIN_H_