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-rw-r--r--media/audio/audio_input_stream_impl.h71
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diff --git a/media/audio/audio_input_stream_impl.h b/media/audio/audio_input_stream_impl.h
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--- a/media/audio/audio_input_stream_impl.h
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-// 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.
-
-#ifndef MEDIA_AUDIO_AUDIO_INPUT_STREAM_IMPL_H_
-#define MEDIA_AUDIO_AUDIO_INPUT_STREAM_IMPL_H_
-
-#include "base/compiler_specific.h"
-#include "base/synchronization/lock.h"
-#include "base/time.h"
-#include "media/audio/audio_io.h"
-
-namespace media {
-
-// AudioInputStreamImpl implements platform-independent parts of the
-// AudioInputStream interface. Each platform dependent implementation
-// should derive from this class.
-// TODO(henrika): we can probably break out more parts from our current
-// AudioInputStream implementation and move out to this class.
-class MEDIA_EXPORT AudioInputStreamImpl : public AudioInputStream {
- public:
- AudioInputStreamImpl();
- virtual ~AudioInputStreamImpl();
-
- // Sets the automatic gain control (AGC) to on or off. When AGC is enabled,
- // the microphone volume is queried periodically and the volume level is
- // provided in each AudioInputCallback::OnData() callback and fed to the
- // render-side AGC.
- virtual void SetAutomaticGainControl(bool enabled) OVERRIDE;
-
- // Gets the current automatic gain control state.
- virtual bool GetAutomaticGainControl() OVERRIDE;
-
- protected:
- // Stores a new volume level by asking the audio hardware.
- // This method only has an effect if AGC is enabled.
- void UpdateAgcVolume();
-
- // Gets the latest stored volume level if AGC is enabled and if
- // more than one second has passed since the volume was updated the last time.
- void QueryAgcVolume(double* normalized_volume);
-
- private:
- // Takes a volume sample and stores it in |normalized_volume_|.
- void GetNormalizedVolume();
-
- // True when automatic gain control is enabled, false otherwise.
- // Guarded by |lock_|.
- bool agc_is_enabled_;
-
- // Stores the maximum volume which is used for normalization to a volume
- // range of [0.0, 1.0].
- double max_volume_;
-
- // Contains last result of internal call to GetVolume(). We save resources
- // but not querying the capture volume for each callback. Guarded by |lock_|.
- // The range is normalized to [0.0, 1.0].
- double normalized_volume_;
-
- // Protects |agc_is_enabled_| and |volume_| .
- base::Lock lock_;
-
- // Keeps track of the last time the microphone volume level was queried.
- base::Time last_volume_update_time_;
-
- DISALLOW_COPY_AND_ASSIGN(AudioInputStreamImpl);
-};
-
-} // namespace media
-
-#endif // MEDIA_AUDIO_AUDIO_INPUT_STREAM_IMPL_H_