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      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_conference_mixer/source/audio_frame_manipulator.h"
     12 #include "webrtc/modules/include/module_common_types.h"
     13 #include "webrtc/typedefs.h"
     14 
     15 namespace {
     16 // Linear ramping over 80 samples.
     17 // TODO(hellner): ramp using fix point?
     18 const float rampArray[] = {0.0000f, 0.0127f, 0.0253f, 0.0380f,
     19                            0.0506f, 0.0633f, 0.0759f, 0.0886f,
     20                            0.1013f, 0.1139f, 0.1266f, 0.1392f,
     21                            0.1519f, 0.1646f, 0.1772f, 0.1899f,
     22                            0.2025f, 0.2152f, 0.2278f, 0.2405f,
     23                            0.2532f, 0.2658f, 0.2785f, 0.2911f,
     24                            0.3038f, 0.3165f, 0.3291f, 0.3418f,
     25                            0.3544f, 0.3671f, 0.3797f, 0.3924f,
     26                            0.4051f, 0.4177f, 0.4304f, 0.4430f,
     27                            0.4557f, 0.4684f, 0.4810f, 0.4937f,
     28                            0.5063f, 0.5190f, 0.5316f, 0.5443f,
     29                            0.5570f, 0.5696f, 0.5823f, 0.5949f,
     30                            0.6076f, 0.6203f, 0.6329f, 0.6456f,
     31                            0.6582f, 0.6709f, 0.6835f, 0.6962f,
     32                            0.7089f, 0.7215f, 0.7342f, 0.7468f,
     33                            0.7595f, 0.7722f, 0.7848f, 0.7975f,
     34                            0.8101f, 0.8228f, 0.8354f, 0.8481f,
     35                            0.8608f, 0.8734f, 0.8861f, 0.8987f,
     36                            0.9114f, 0.9241f, 0.9367f, 0.9494f,
     37                            0.9620f, 0.9747f, 0.9873f, 1.0000f};
     38 const size_t rampSize = sizeof(rampArray)/sizeof(rampArray[0]);
     39 }  // namespace
     40 
     41 namespace webrtc {
     42 void CalculateEnergy(AudioFrame& audioFrame)
     43 {
     44     audioFrame.energy_ = 0;
     45     for(size_t position = 0; position < audioFrame.samples_per_channel_;
     46         position++)
     47     {
     48         // TODO(andrew): this can easily overflow.
     49         audioFrame.energy_ += audioFrame.data_[position] *
     50                               audioFrame.data_[position];
     51     }
     52 }
     53 
     54 void RampIn(AudioFrame& audioFrame)
     55 {
     56     assert(rampSize <= audioFrame.samples_per_channel_);
     57     for(size_t i = 0; i < rampSize; i++)
     58     {
     59         audioFrame.data_[i] = static_cast<int16_t>(rampArray[i] *
     60                                                    audioFrame.data_[i]);
     61     }
     62 }
     63 
     64 void RampOut(AudioFrame& audioFrame)
     65 {
     66     assert(rampSize <= audioFrame.samples_per_channel_);
     67     for(size_t i = 0; i < rampSize; i++)
     68     {
     69         const size_t rampPos = rampSize - 1 - i;
     70         audioFrame.data_[i] = static_cast<int16_t>(rampArray[rampPos] *
     71                                                    audioFrame.data_[i]);
     72     }
     73     memset(&audioFrame.data_[rampSize], 0,
     74            (audioFrame.samples_per_channel_ - rampSize) *
     75            sizeof(audioFrame.data_[0]));
     76 }
     77 }  // namespace webrtc
     78