76 lines
2.9 KiB
C++
76 lines
2.9 KiB
C++
/*
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* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef AUDIO_AUDIO_LEVEL_H_
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#define AUDIO_AUDIO_LEVEL_H_
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#include "rtc_base/synchronization/mutex.h"
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#include "rtc_base/thread_annotations.h"
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namespace webrtc {
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class AudioFrame;
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namespace voe {
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// This class is thread-safe. However, TotalEnergy() and TotalDuration() are
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// related, so if you call ComputeLevel() on a different thread than you read
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// these values, you still need to use lock to read them as a pair.
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class AudioLevel {
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public:
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AudioLevel();
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~AudioLevel();
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void Reset();
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// Returns the current audio level linearly [0,32767], which gets updated
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// every "kUpdateFrequency+1" call to ComputeLevel() based on the maximum
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// audio level of any audio frame, decaying by a factor of 1/4 each time
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// LevelFullRange() gets updated.
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// Called on "API thread(s)" from APIs like VoEBase::CreateChannel(),
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// VoEBase::StopSend().
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int16_t LevelFullRange() const;
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void ResetLevelFullRange();
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// See the description for "totalAudioEnergy" in the WebRTC stats spec
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// (https://w3c.github.io/webrtc-stats/#dom-rtcaudiohandlerstats-totalaudioenergy)
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// In our implementation, the total audio energy increases by the
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// energy-equivalent of LevelFullRange() at the time of ComputeLevel(), rather
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// than the energy of the samples in that specific audio frame. As a result,
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// we may report a higher audio energy and audio level than the spec mandates.
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// TODO(https://crbug.com/webrtc/10784): We should either do what the spec
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// says or update the spec to match our implementation. If we want to have a
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// decaying audio level we should probably update both the spec and the
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// implementation to reduce the complexity of the definition. If we want to
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// continue to have decaying audio we should have unittests covering the
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// behavior of the decay.
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double TotalEnergy() const;
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double TotalDuration() const;
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// Called on a native capture audio thread (platform dependent) from the
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// AudioTransport::RecordedDataIsAvailable() callback.
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// In Chrome, this method is called on the AudioInputDevice thread.
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void ComputeLevel(const AudioFrame& audioFrame, double duration);
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private:
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enum { kUpdateFrequency = 10 };
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mutable Mutex mutex_;
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int16_t abs_max_ RTC_GUARDED_BY(mutex_);
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int16_t count_ RTC_GUARDED_BY(mutex_);
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int16_t current_level_full_range_ RTC_GUARDED_BY(mutex_);
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double total_energy_ RTC_GUARDED_BY(mutex_) = 0.0;
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double total_duration_ RTC_GUARDED_BY(mutex_) = 0.0;
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};
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} // namespace voe
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} // namespace webrtc
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#endif // AUDIO_AUDIO_LEVEL_H_
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