Introduce AudioOutputResampler for browser side resampling.

media/audio/audio_output_resampler.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.
+//
+// AudioOutputResampler is a browser-side resampler which ensures audio data is
+// always output at the configured hardware parameters.

[scherkus (not reviewing), 2012/09/07 13:30:17]

move to class def instead of top of file

[DaleCurtis, 2012/09/10 12:06:24]

Done.

+
+#ifndef MEDIA_AUDIO_AUDIO_OUTPUT_RESAMPLER_H_
+#define MEDIA_AUDIO_AUDIO_OUTPUT_RESAMPLER_H_
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
+#include "base/time.h"
+#include "media/audio/audio_io.h"
+#include "media/audio/audio_manager.h"
+#include "media/audio/audio_output_dispatcher.h"
+#include "media/audio/audio_parameters.h"
+
+namespace media {
+class AudioFifo;

[scherkus (not reviewing), 2012/09/07 13:30:17]

nit: blank line before

[DaleCurtis, 2012/09/10 12:06:24]

Done.

+class MultiChannelResampler;
+
+class MEDIA_EXPORT AudioOutputResampler
+    : public AudioOutputDispatcher,
+      public AudioOutputStream::AudioSourceCallback {
+ public:
+  AudioOutputResampler(AudioManager* audio_manager,
+                       const AudioParameters& params,
+                       const base::TimeDelta& close_delay);
+
+  // AudioOutputDispatcher interface.
+  virtual bool OpenStream() OVERRIDE;
+  virtual bool StartStream(AudioOutputStream::AudioSourceCallback* callback,
+                           AudioOutputProxy* stream_proxy) OVERRIDE;
+  virtual void StopStream(AudioOutputProxy* stream_proxy) OVERRIDE;
+  virtual void StreamVolumeSet(AudioOutputProxy* stream_proxy,
+                               double volume) OVERRIDE;
+  virtual void CloseStream(AudioOutputProxy* stream_proxy) OVERRIDE;
+  virtual void Shutdown() OVERRIDE;
+
+  // AudioSourceCallback interface.
+  virtual int OnMoreData(AudioBus* audio_bus,
+                         AudioBuffersState buffers_state) OVERRIDE;
+  virtual void OnError(AudioOutputStream* stream, int code) OVERRIDE;
+  virtual void WaitTillDataReady() OVERRIDE;
+
+ private:
+  friend class base::RefCountedThreadSafe<AudioOutputResampler>;
+  virtual ~AudioOutputResampler();
+
+  // ProvideInput() will be called by MultiChannelResampler when more data is
+  // necessary.
+  void ProvideInput(AudioBus* audio_bus);
+
+  // Handles resampling.
+  scoped_ptr<MultiChannelResampler> resampler_;
+
+  // Dispatcher to proxy all AudioOutputDispatcher calls too.
+  scoped_refptr<AudioOutputDispatcher> dispatcher_;
+
+  // Source callback and associated lock.
+  base::Lock source_lock_;
+  AudioOutputStream::AudioSourceCallback* source_callback_;
+
+  AudioBuffersState current_buffers_state_;
+  int outstanding_audio_bytes_;
+  int current_filled_audio_bytes_;
+
+  scoped_ptr<AudioBus> temp_bus_;
+  scoped_ptr<AudioFifo> audio_fifo_;
+
+  double io_ratio_;
+  int output_bytes_per_frame_;
+  int input_bytes_per_frame_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioOutputResampler);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_AUDIO_OUTPUT_RESAMPLER_H_