Browser-wide audio mirroring for TabCapture API

media/audio/virtual_audio_input_stream.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.
+//
+// A fake implementation of AudioInputStream, useful for testing purpose.
+
+#ifndef MEDIA_AUDIO_VIRTUAL_AUDIO_INPUT_STREAM_H_
+#define MEDIA_AUDIO_VIRTUAL_AUDIO_INPUT_STREAM_H_
+
+#include <map>
+
+#include "base/cancelable_callback.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/time.h"
+#include "media/audio/audio_io.h"
+#include "media/audio/audio_manager_base.h"
+#include "media/audio/audio_parameters.h"
+#include "media/base/audio_transform.h"
+
+namespace media {
+
+class VirtualAudioOutputStream;
+class LoopbackAudioConverter;
+
+class MEDIA_EXPORT VirtualAudioInputStream
+    : public AudioInputStream {
+ public:
+  static AudioInputStream* MakeStream(AudioManagerBase* manager,
+                                      const AudioParameters& params);
+
+  virtual bool Open() OVERRIDE;
+  virtual void Start(AudioInputCallback* callback) OVERRIDE;
+  virtual void Stop() OVERRIDE;
+  virtual void Close() OVERRIDE;
+  virtual double GetMaxVolume() OVERRIDE;
+  virtual void SetVolume(double volume) OVERRIDE;
+  virtual double GetVolume() OVERRIDE;
+  virtual void SetAutomaticGainControl(bool enabled) OVERRIDE;
+  virtual bool GetAutomaticGainControl() OVERRIDE;
+
+ private:
+  typedef std::map<AudioParameters, LoopbackAudioConverter*> AudioTransformsMap;
+  typedef std::map<AudioOutputStream*, AudioParameters> RegisteredStreamParams;
+
+  void DoCallback();
+  void UpdateResamplersIfNecessary();
+
+  VirtualAudioInputStream(AudioManagerBase* manager,
+                       const AudioParameters& params);
+
+  virtual ~VirtualAudioInputStream();
+
+  AudioManagerBase* audio_manager_;
+  AudioInputCallback* callback_;
+  int buffer_size_;
+  scoped_array<uint8> buffer_;
+  AudioParameters params_;
+  scoped_ptr<AudioBus> audio_bus_;
+  base::CancelableClosure on_more_data_cb_;
+  AudioTransformsMap transforms_;
+  AudioConverter mixer_;
+
+  // Mirrors the Audio Manager's output stream list so we know which ones to
+  // add/remove from our transforms map.
+  AudioManagerBase::AudioOutputStreamList registered_streams_;
+  RegisteredStreamParams registered_streams_params_;
+
+  DISALLOW_COPY_AND_ASSIGN(VirtualAudioInputStream);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_FAKE_AUDIO_INPUT_STREAM_H_