Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2012 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/agc/utility.h"
      12             : 
      13             : #include <math.h>
      14             : 
      15             : static const double kLog10 = 2.30258509299;
      16             : static const double kLinear2DbScale = 20.0 / kLog10;
      17             : static const double kLinear2LoudnessScale = 13.4 / kLog10;
      18             : 
      19           0 : double Loudness2Db(double loudness) {
      20           0 :   return loudness * kLinear2DbScale / kLinear2LoudnessScale;
      21             : }
      22             : 
      23           0 : double Linear2Loudness(double rms) {
      24           0 :   if (rms == 0)
      25           0 :     return -15;
      26           0 :   return kLinear2LoudnessScale * log(rms);
      27             : }
      28             : 
      29           0 : double Db2Loudness(double db) {
      30           0 :   return db * kLinear2LoudnessScale / kLinear2DbScale;
      31             : }
      32             : 
      33           0 : double Dbfs2Loudness(double dbfs) {
      34           0 :   return Db2Loudness(90 + dbfs);
      35             : }