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// Copyright 2014 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 THIRD_PARTY_BLINK_RENDERER_PLATFORM_MEDIASTREAM_MEDIA_STREAM_AUDIO_LEVEL_CALCULATOR_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_MEDIASTREAM_MEDIA_STREAM_AUDIO_LEVEL_CALCULATOR_H_
#include "base/memory/ref_counted.h"
#include "base/synchronization/lock.h"
#include "third_party/blink/renderer/platform/platform_export.h"
namespace media {
class AudioBus;
}
namespace blink {
// This class is used by the WebRtcAudioCapturer to calculate the level of the
// audio signal. And the audio level will be eventually used by the volume
// animation UI.
//
// The algorithm used by this class is the same as how it is done in
// third_party/webrtc/voice_engine/level_indicator.cc.
class PLATFORM_EXPORT MediaStreamAudioLevelCalculator {
public:
// Provides thread-safe access to the current signal level. This object is
// intended to be passed to modules running on other threads that poll for the
// current signal level.
class PLATFORM_EXPORT Level : public base::RefCountedThreadSafe<Level> {
public:
float GetCurrent() const;
private:
friend class MediaStreamAudioLevelCalculator;
friend class base::RefCountedThreadSafe<Level>;
Level();
~Level();
void Set(float level);
mutable base::Lock lock_;
float level_;
};
MediaStreamAudioLevelCalculator();
~MediaStreamAudioLevelCalculator();
const scoped_refptr<Level>& level() const { return level_; }
// Scans the audio signal in |audio_bus| and computes a new signal level
// exposed by Level. If |assume_nonzero_energy| is true, then a completely
// zero'ed-out |audio_bus| will be accounted for as having a very faint,
// non-zero level.
void Calculate(const media::AudioBus& audio_bus, bool assume_nonzero_energy);
private:
int counter_;
float max_amplitude_;
const scoped_refptr<Level> level_;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_MEDIASTREAM_MEDIA_STREAM_AUDIO_LEVEL_CALCULATOR_H_
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