| /* |
| * 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, size_t length) { |
| for (size_t i = 0; i < length; ++i) { |
| sum_square_ += data[i] * data[i]; |
| } |
| sample_count_ += length; |
| } |
| |
| void RMSLevel::ProcessMuted(size_t 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 |