1 /* 2 * Copyright (c) 2014 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #include "webrtc/modules/audio_processing/rms_level.h" 12 13 #include <assert.h> 14 #include <math.h> 15 16 namespace webrtc { 17 18 static const float kMaxSquaredLevel = 32768 * 32768; 19 20 RMSLevel::RMSLevel() 21 : sum_square_(0), 22 sample_count_(0) {} 23 24 RMSLevel::~RMSLevel() {} 25 26 void RMSLevel::Reset() { 27 sum_square_ = 0; 28 sample_count_ = 0; 29 } 30 31 void RMSLevel::Process(const int16_t* data, size_t length) { 32 for (size_t i = 0; i < length; ++i) { 33 sum_square_ += data[i] * data[i]; 34 } 35 sample_count_ += length; 36 } 37 38 void RMSLevel::ProcessMuted(size_t length) { 39 sample_count_ += length; 40 } 41 42 int RMSLevel::RMS() { 43 if (sample_count_ == 0 || sum_square_ == 0) { 44 Reset(); 45 return kMinLevel; 46 } 47 48 // Normalize by the max level. 49 float rms = sum_square_ / (sample_count_ * kMaxSquaredLevel); 50 // 20log_10(x^0.5) = 10log_10(x) 51 rms = 10 * log10(rms); 52 assert(rms <= 0); 53 if (rms < -kMinLevel) 54 rms = -kMinLevel; 55 56 rms = -rms; 57 Reset(); 58 return static_cast<int>(rms + 0.5); 59 } 60 61 } // namespace webrtc 62
