Pull the Voice Activity Detector out from the AGC

webrtc/modules/audio_processing/vad/vad_audio_proc.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/agc_audio_proc.h"
+#include "webrtc/modules/audio_processing/vad/vad_audio_proc.h"
 
 #include <math.h>
 #include <stdio.h>
 
 #include "webrtc/common_audio/fft4g.h"
-#include "webrtc/modules/audio_processing/agc/agc_audio_proc_internal.h"
-#include "webrtc/modules/audio_processing/agc/pitch_internal.h"
-#include "webrtc/modules/audio_processing/agc/pole_zero_filter.h"
+#include "webrtc/modules/audio_processing/vad/vad_audio_proc_internal.h"
+#include "webrtc/modules/audio_processing/vad/pitch_internal.h"
+#include "webrtc/modules/audio_processing/vad/pole_zero_filter.h"
 extern "C" {
 #include "webrtc/modules/audio_coding/codecs/isac/main/source/codec.h"
 #include "webrtc/modules/audio_coding/codecs/isac/main/source/lpc_analysis.h"
 #include "webrtc/modules/audio_coding/codecs/isac/main/source/pitch_estimator.h"
 #include "webrtc/modules/audio_coding/codecs/isac/main/source/structs.h"
 }
 #include "webrtc/modules/interface/module_common_types.h"
 
 namespace webrtc {
 
 // The following structures are declared anonymous in iSAC's structs.h. To
 // forward declare them, we use this derived class trick.
-struct AgcAudioProc::PitchAnalysisStruct : public ::PitchAnalysisStruct {};
-struct AgcAudioProc::PreFiltBankstr : public ::PreFiltBankstr {};
+struct VadAudioProc::PitchAnalysisStruct : public ::PitchAnalysisStruct {};
+struct VadAudioProc::PreFiltBankstr : public ::PreFiltBankstr {};
 
-static const float kFrequencyResolution = kSampleRateHz /
-    static_cast<float>(AgcAudioProc::kDftSize);
+static const float kFrequencyResolution =
+    kSampleRateHz / static_cast<float>(VadAudioProc::kDftSize);
 static const int kSilenceRms = 5;
 
-// TODO(turajs): Make a Create or Init for AgcAudioProc.
-AgcAudioProc::AgcAudioProc()
+// TODO(turajs): Make a Create or Init for VadAudioProc.
+VadAudioProc::VadAudioProc()
     : audio_buffer_(),
       num_buffer_samples_(kNumPastSignalSamples),
       log_old_gain_(-2),
       old_lag_(50),  // Arbitrary but valid as pitch-lag (in samples).
       pitch_analysis_handle_(new PitchAnalysisStruct),
       pre_filter_handle_(new PreFiltBankstr),
-      high_pass_filter_(PoleZeroFilter::Create(
-          kCoeffNumerator, kFilterOrder, kCoeffDenominator, kFilterOrder)) {
+      high_pass_filter_(PoleZeroFilter::Create(kCoeffNumerator,
+                                               kFilterOrder,
+                                               kCoeffDenominator,
+                                               kFilterOrder)) {
   static_assert(kNumPastSignalSamples + kNumSubframeSamples ==
                     sizeof(kLpcAnalWin) / sizeof(kLpcAnalWin[0]),
                 "lpc analysis window incorrect size");
   static_assert(kLpcOrder + 1 == sizeof(kCorrWeight) / sizeof(kCorrWeight[0]),
                 "correlation weight incorrect size");
 
   // TODO(turajs): Are we doing too much in the constructor?
   float data[kDftSize];
   // Make FFT to initialize.
   ip_[0] = 0;
   WebRtc_rdft(kDftSize, 1, data, ip_, w_fft_);
   // TODO(turajs): Need to initialize high-pass filter.
 
   // Initialize iSAC components.
   WebRtcIsac_InitPreFilterbank(pre_filter_handle_.get());
   WebRtcIsac_InitPitchAnalysis(pitch_analysis_handle_.get());
 }
 
-AgcAudioProc::~AgcAudioProc() {}
+VadAudioProc::~VadAudioProc() {
+}
 
-void AgcAudioProc::ResetBuffer() {
+void VadAudioProc::ResetBuffer() {
   memcpy(audio_buffer_, &audio_buffer_[kNumSamplesToProcess],
          sizeof(audio_buffer_[0]) * kNumPastSignalSamples);
   num_buffer_samples_ = kNumPastSignalSamples;
 }
 
-int AgcAudioProc::ExtractFeatures(const int16_t* frame,
+int VadAudioProc::ExtractFeatures(const int16_t* frame,
                                   int length,
                                   AudioFeatures* features) {
   features->num_frames = 0;
   if (length != kNumSubframeSamples) {
     return -1;
   }
 
   // High-pass filter to remove the DC component and very low frequency content.
   // We have experienced that this high-pass filtering improves voice/non-voiced
   // classification.
   if (high_pass_filter_->Filter(frame, kNumSubframeSamples,
                                 &audio_buffer_[num_buffer_samples_]) != 0) {
-      return -1;
+    return -1;
   }
 
   num_buffer_samples_ += kNumSubframeSamples;
   if (num_buffer_samples_ < kBufferLength) {
     return 0;
   }
   assert(num_buffer_samples_ == kBufferLength);
   features->num_frames = kNum10msSubframes;
   features->silence = false;
 
   Rms(features->rms, kMaxNumFrames);
   for (int i = 0; i < kNum10msSubframes; ++i) {
     if (features->rms[i] < kSilenceRms) {
       // PitchAnalysis can cause NaNs in the pitch gain if it's fed silence.
       // Bail out here instead.
       features->silence = true;
       ResetBuffer();
       return 0;
     }
   }
 
   PitchAnalysis(features->log_pitch_gain, features->pitch_lag_hz,
                 kMaxNumFrames);
   FindFirstSpectralPeaks(features->spectral_peak, kMaxNumFrames);
   ResetBuffer();
   return 0;
 }
 
 // Computes |kLpcOrder + 1| correlation coefficients.
-void AgcAudioProc::SubframeCorrelation(double* corr, int length_corr,
+void VadAudioProc::SubframeCorrelation(double* corr,
+                                       int length_corr,
                                        int subframe_index) {
   assert(length_corr >= kLpcOrder + 1);
   double windowed_audio[kNumSubframeSamples + kNumPastSignalSamples];
   int buffer_index = subframe_index * kNumSubframeSamples;
 
   for (int n = 0; n < kNumSubframeSamples + kNumPastSignalSamples; n++)
     windowed_audio[n] = audio_buffer_[buffer_index++] * kLpcAnalWin[n];
 
-  WebRtcIsac_AutoCorr(corr, windowed_audio, kNumSubframeSamples +
-                      kNumPastSignalSamples, kLpcOrder);
+  WebRtcIsac_AutoCorr(corr, windowed_audio,
+                      kNumSubframeSamples + kNumPastSignalSamples, kLpcOrder);
 }
 
 // Compute |kNum10msSubframes| sets of LPC coefficients, one per 10 ms input.
 // The analysis window is 15 ms long and it is centered on the first half of
 // each 10ms sub-frame. This is equivalent to computing LPC coefficients for the
 // first half of each 10 ms subframe.
-void AgcAudioProc::GetLpcPolynomials(double* lpc, int length_lpc) {
+void VadAudioProc::GetLpcPolynomials(double* lpc, int length_lpc) {
   assert(length_lpc >= kNum10msSubframes * (kLpcOrder + 1));
   double corr[kLpcOrder + 1];
   double reflec_coeff[kLpcOrder];
   for (int i = 0, offset_lpc = 0; i < kNum10msSubframes;
-      i++, offset_lpc += kLpcOrder + 1) {
+       i++, offset_lpc += kLpcOrder + 1) {
     SubframeCorrelation(corr, kLpcOrder + 1, i);
     corr[0] *= 1.0001;
     // This makes Lev-Durb a bit more stable.
     for (int k = 0; k < kLpcOrder + 1; k++) {
       corr[k] *= kCorrWeight[k];
     }
     WebRtcIsac_LevDurb(&lpc[offset_lpc], reflec_coeff, corr, kLpcOrder);
   }
 }
 
 // Fit a second order curve to these 3 points and find the location of the
 // extremum. The points are inverted before curve fitting.
-static float QuadraticInterpolation(float prev_val, float curr_val,
+static float QuadraticInterpolation(float prev_val,
+                                    float curr_val,
                                     float next_val) {
   // Doing the interpolation in |1 / A(z)|^2.
   float fractional_index = 0;
   next_val = 1.0f / next_val;
   prev_val = 1.0f / prev_val;
   curr_val = 1.0f / curr_val;
 
-  fractional_index = -(next_val - prev_val) * 0.5f / (next_val + prev_val -
-      2.f * curr_val);
+  fractional_index =
+      -(next_val - prev_val) * 0.5f / (next_val + prev_val - 2.f * curr_val);
   assert(fabs(fractional_index) < 1);
   return fractional_index;
 }
 
 // 1 / A(z), where A(z) is defined by |lpc| is a model of the spectral envelope
 // of the input signal. The local maximum of the spectral envelope corresponds
 // with the local minimum of A(z). It saves complexity, as we save one
 // inversion. Furthermore, we find the first local maximum of magnitude squared,
 // to save on one square root.
-void AgcAudioProc::FindFirstSpectralPeaks(double* f_peak, int length_f_peak) {
+void VadAudioProc::FindFirstSpectralPeaks(double* f_peak, int length_f_peak) {
   assert(length_f_peak >= kNum10msSubframes);
   double lpc[kNum10msSubframes * (kLpcOrder + 1)];
   // For all sub-frames.
   GetLpcPolynomials(lpc, kNum10msSubframes * (kLpcOrder + 1));
 
   const int kNumDftCoefficients = kDftSize / 2 + 1;
   float data[kDftSize];
 
   for (int i = 0; i < kNum10msSubframes; i++) {
     // Convert to float with zero pad.
     memset(data, 0, sizeof(data));
     for (int n = 0; n < kLpcOrder + 1; n++) {
       data[n] = static_cast<float>(lpc[i * (kLpcOrder + 1) + n]);
     }
     // Transform to frequency domain.
     WebRtc_rdft(kDftSize, 1, data, ip_, w_fft_);
 
     int index_peak = 0;
     float prev_magn_sqr = data[0] * data[0];
     float curr_magn_sqr = data[2] * data[2] + data[3] * data[3];
     float next_magn_sqr;
     bool found_peak = false;
     for (int n = 2; n < kNumDftCoefficients - 1; n++) {
-      next_magn_sqr = data[2 * n] * data[2 * n] +
-          data[2 * n + 1] * data[2 * n + 1];
+      next_magn_sqr =
+          data[2 * n] * data[2 * n] + data[2 * n + 1] * data[2 * n + 1];
       if (curr_magn_sqr < prev_magn_sqr && curr_magn_sqr < next_magn_sqr) {
         found_peak = true;
         index_peak = n - 1;
         break;
       }
       prev_magn_sqr = curr_magn_sqr;
       curr_magn_sqr = next_magn_sqr;
     }
     float fractional_index = 0;
     if (!found_peak) {
       // Checking if |kNumDftCoefficients - 1| is the local minimum.
       next_magn_sqr = data[1] * data[1];
       if (curr_magn_sqr < prev_magn_sqr && curr_magn_sqr < next_magn_sqr) {
         index_peak = kNumDftCoefficients - 1;
       }
     } else {
       // A peak is found, do a simple quadratic interpolation to get a more
       // accurate estimate of the peak location.
-      fractional_index = QuadraticInterpolation(prev_magn_sqr, curr_magn_sqr,
-                                                next_magn_sqr);
+      fractional_index =
+          QuadraticInterpolation(prev_magn_sqr, curr_magn_sqr, next_magn_sqr);
     }
     f_peak[i] = (index_peak + fractional_index) * kFrequencyResolution;
   }
 }
 
 // Using iSAC functions to estimate pitch gains & lags.
-void AgcAudioProc::PitchAnalysis(double* log_pitch_gains, double* pitch_lags_hz,
+void VadAudioProc::PitchAnalysis(double* log_pitch_gains,
+                                 double* pitch_lags_hz,
                                  int length) {
   // TODO(turajs): This can be "imported" from iSAC & and the next two
   // constants.
   assert(length >= kNum10msSubframes);
   const int kNumPitchSubframes = 4;
   double gains[kNumPitchSubframes];
   double lags[kNumPitchSubframes];
 
   const int kNumSubbandFrameSamples = 240;
   const int kNumLookaheadSamples = 24;
 
   float lower[kNumSubbandFrameSamples];
   float upper[kNumSubbandFrameSamples];
   double lower_lookahead[kNumSubbandFrameSamples];
   double upper_lookahead[kNumSubbandFrameSamples];
   double lower_lookahead_pre_filter[kNumSubbandFrameSamples +
                                     kNumLookaheadSamples];
 
   // Split signal to lower and upper bands
-  WebRtcIsac_SplitAndFilterFloat(&audio_buffer_[kNumPastSignalSamples],
-                                 lower, upper, lower_lookahead, upper_lookahead,
+  WebRtcIsac_SplitAndFilterFloat(&audio_buffer_[kNumPastSignalSamples], lower,
+                                 upper, lower_lookahead, upper_lookahead,
                                  pre_filter_handle_.get());
   WebRtcIsac_PitchAnalysis(lower_lookahead, lower_lookahead_pre_filter,
                            pitch_analysis_handle_.get(), lags, gains);
 
   // Lags are computed on lower-band signal with sampling rate half of the
   // input signal.
-  GetSubframesPitchParameters(kSampleRateHz / 2, gains, lags,
-                              kNumPitchSubframes, kNum10msSubframes,
-                              &log_old_gain_, &old_lag_,
-                              log_pitch_gains, pitch_lags_hz);
+  GetSubframesPitchParameters(
+      kSampleRateHz / 2, gains, lags, kNumPitchSubframes, kNum10msSubframes,
+      &log_old_gain_, &old_lag_, log_pitch_gains, pitch_lags_hz);
 }
 
-void AgcAudioProc::Rms(double* rms, int length_rms) {
+void VadAudioProc::Rms(double* rms, int length_rms) {
   assert(length_rms >= kNum10msSubframes);
   int offset = kNumPastSignalSamples;
   for (int i = 0; i < kNum10msSubframes; i++) {
     rms[i] = 0;
     for (int n = 0; n < kNumSubframeSamples; n++, offset++)
       rms[i] += audio_buffer_[offset] * audio_buffer_[offset];
-    rms[i] =  sqrt(rms[i] / kNumSubframeSamples);
+    rms[i] = sqrt(rms[i] / kNumSubframeSamples);
   }
 }
 
 }  // namespace webrtc