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/*
* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "webrtc/modules/audio_processing/rms_level.h"
#include <assert.h>
#include <math.h>
namespace webrtc {
static const float kMaxSquaredLevel = 32768 * 32768;
RMSLevel::RMSLevel()
: sum_square_(0),
sample_count_(0) {}
RMSLevel::~RMSLevel() {}
void RMSLevel::Reset() {
sum_square_ = 0;
sample_count_ = 0;
}
void RMSLevel::Process(const int16_t* data, int length) {
for (int i = 0; i < length; ++i) {
sum_square_ += data[i] * data[i];
}
sample_count_ += length;
}
void RMSLevel::ProcessMuted(int length) {
sample_count_ += length;
}
int RMSLevel::RMS() {
if (sample_count_ == 0 || sum_square_ == 0) {
Reset();
return kMinLevel;
}
// Normalize by the max level.
float rms = sum_square_ / (sample_count_ * kMaxSquaredLevel);
// 20log_10(x^0.5) = 10log_10(x)
rms = 10 * log10(rms);
assert(rms <= 0);
if (rms < -kMinLevel)
rms = -kMinLevel;
rms = -rms;
Reset();
return static_cast<int>(rms + 0.5);
}
} // namespace webrtc
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