Pull the Voice Activity Detector out from the AGC

webrtc/modules/audio_processing/vad/pitch_internal.cc

 /*
  *  Copyright (c) 2012 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/agc/pitch_internal.h"
+#include "webrtc/modules/audio_processing/vad/pitch_internal.h"
 
 #include <cmath>
 
 // A 4-to-3 linear interpolation.
 // The interpolation constants are derived as following:
 // Input pitch parameters are updated every 7.5 ms. Within a 30-ms interval
 // we are interested in pitch parameters of 0-5 ms, 10-15ms and 20-25ms. This is
 // like interpolating 4-to-6 and keep the odd samples.
 // The reason behind this is that LPC coefficients are computed for the first
 // half of each 10ms interval.
 static void PitchInterpolation(double old_val, const double* in, double* out) {
   out[0] = 1. / 6. * old_val + 5. / 6. * in[0];
   out[1] = 5. / 6. * in[1] + 1. / 6. * in[2];
   out[2] = 0.5 * in[2] + 0.5 * in[3];
 }
 
-
 void GetSubframesPitchParameters(int sampling_rate_hz,
                                  double* gains,
                                  double* lags,
                                  int num_in_frames,
                                  int num_out_frames,
                                  double* log_old_gain,
                                  double* old_lag,
                                  double* log_pitch_gain,
                                  double* pitch_lag_hz) {
   // Gain interpolation is in log-domain, also returned in log-domain.
   for (int n = 0; n < num_in_frames; n++)
     gains[n] = log(gains[n] + 1e-12);
 
   // Interpolate lags and gains.
   PitchInterpolation(*log_old_gain, gains, log_pitch_gain);
   *log_old_gain = gains[num_in_frames - 1];
   PitchInterpolation(*old_lag, lags, pitch_lag_hz);
   *old_lag = lags[num_in_frames - 1];
 
   // Convert pitch-lags to Hertz.
   for (int n = 0; n < num_out_frames; n++) {
     pitch_lag_hz[n] = (sampling_rate_hz) / (pitch_lag_hz[n]);
   }
 }