Adding fraction of filter divergence in AEC metrics.

webrtc/modules/audio_processing/aec/aec_core.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.
  */
 
 /*
  * The core AEC algorithm, which is presented with time-aligned signals.
  */
 
 #include "webrtc/modules/audio_processing/aec/aec_core.h"
 
 #ifdef WEBRTC_AEC_DEBUG_DUMP
 #include <stdio.h>
 #endif
 
+#include <algorithm>
 #include <assert.h>
 #include <math.h>
 #include <stddef.h>  // size_t
 #include <stdlib.h>
 #include <string.h>
 
 extern "C" {
 #include "webrtc/common_audio/ring_buffer.h"
 }
 #include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
@@ skipping 12 matching lines @@
 namespace webrtc {
 
 // Buffer size (samples)
 static const size_t kBufSizePartitions = 250;  // 1 second of audio in 16 kHz.
 
 // Metrics
 static const size_t kSubCountLen = 4;
 static const size_t kCountLen = 50;
 static const int kDelayMetricsAggregationWindow = 1250;  // 5 seconds at 16 kHz.
 
+// Divergence metric is based on audio level, which gets updated every
+// |kCountLen + 1| * 10 milliseconds. Divergence metric takes the statistics of
+// |kDivergentFilterFractionAggregationWindowSize| samples. Current value
+// corresponds to 0.5 seconds at 16 kHz.
+static const int kDivergentFilterFractionAggregationWindowSize = 25;
+
 // Quantities to control H band scaling for SWB input
 static const float cnScaleHband = 0.4f;  // scale for comfort noise in H band.
 // Initial bin for averaging nlp gain in low band
 static const int freqAvgIc = PART_LEN / 2;
 
 // Matlab code to produce table:
 // win = sqrt(hanning(63)); win = [0 ; win(1:32)];
 // fprintf(1, '\t%.14f, %.14f, %.14f,\n', win);
 ALIGN16_BEG const float ALIGN16_END WebRtcAec_sqrtHanning[65] = {
     0.00000000000000f, 0.02454122852291f, 0.04906767432742f, 0.07356456359967f,
@@ skipping 80 matching lines @@
 WebRtcAecWindowData WebRtcAec_WindowData;
 
 __inline static float MulRe(float aRe, float aIm, float bRe, float bIm) {
   return aRe * bRe - aIm * bIm;
 }
 
 __inline static float MulIm(float aRe, float aIm, float bRe, float bIm) {
   return aRe * bIm + aIm * bRe;
 }
 
+// TODO(minyue): Due to a legacy bug, |framelevel| and |averagelevel| use a
+// window, of which the length is 1 unit longer than indicated. Remove "+1" when
+// the code is refactored.
 PowerLevel::PowerLevel()
-// TODO(minyue): Due to a legacy bug, |framelevel| and |averagelevel| use a
-// window, of which the length is 1 unit longer than indicated. Remove "+1"
-// when the code is refactored.
-: framelevel(kSubCountLen + 1),
-  averagelevel(kCountLen + 1) {
+    : framelevel(kSubCountLen + 1),
+      averagelevel(kCountLen + 1) {
+}
+
+DivergentFilterFraction::DivergentFilterFraction()
+    : count_(0),
+      occurrence_(0),
+      fraction_(-1.0) {
+}
+
+void DivergentFilterFraction::Reset() {
+  Clear();
+  fraction_ = -1.0;
+}
+
+void DivergentFilterFraction::AddObservation(const PowerLevel& nearlevel,
+                                             const PowerLevel& linoutlevel,
+                                             const PowerLevel& nlpoutlevel) {
+  const float near_level = nearlevel.framelevel.GetLatestMean();
+  const float level_increase =
+      linoutlevel.framelevel.GetLatestMean() - near_level;
+  const bool output_signal_active = nlpoutlevel.framelevel.GetLatestMean() >
+          40.0 * nlpoutlevel.minlevel;
+  // Level increase should be, in principle, negative, when the filter
+  // does not diverge. Here we allow some margin (0.01 * near end level) and
+  // numerical error (1.0). We count divergence only when the AEC output
+  // signal is active.
+  if (output_signal_active &&
+      level_increase > std::max(0.01 * near_level, 1.0))
+    occurrence_++;
+  ++count_;
+  if (count_ == kDivergentFilterFractionAggregationWindowSize) {
+    fraction_ = static_cast<float>(occurrence_) /
+        kDivergentFilterFractionAggregationWindowSize;
+    Clear();
+  }
+}
+
+float DivergentFilterFraction::GetLatestFraction() const {
+  return fraction_;
+}
+
+void DivergentFilterFraction::Clear() {
+  count_ = 0;
+  occurrence_ = 0;
 }
 
 // TODO(minyue): Moving some initialization from WebRtcAec_CreateAec() to ctor.
 AecCore::AecCore() = default;
 
 static int CmpFloat(const void* a, const void* b) {
   const float* da = (const float*)a;
   const float* db = (const float*)b;
 
   return (*da > *db) - (*da < *db);
@@ skipping 386 matching lines @@
   self->stateCounter = 0;
   InitLevel(&self->farlevel);
   InitLevel(&self->nearlevel);
   InitLevel(&self->linoutlevel);
   InitLevel(&self->nlpoutlevel);
 
   InitStats(&self->erl);
   InitStats(&self->erle);
   InitStats(&self->aNlp);
   InitStats(&self->rerl);
+
+  self->divergent_filter_fraction.Reset();
 }
 
 static float CalculatePower(const float* in, size_t num_samples) {
   size_t k;
   float energy = 0.0f;
 
   for (k = 0; k < num_samples; ++k) {
     energy += in[k] * in[k];
   }
   return energy / num_samples;
@@ skipping 23 matching lines @@
 
   const float noisyPower = 300000.0f;
 
   float actThreshold;
   float echo, suppressedEcho;
 
   if (aec->echoState) {  // Check if echo is likely present
     aec->stateCounter++;
   }
 
+  if (aec->linoutlevel.framelevel.EndOfBlock()) {
+    aec->divergent_filter_fraction.AddObservation(aec->nearlevel,
+                                                  aec->linoutlevel,
+                                                  aec->nlpoutlevel);
+  }
+
   if (aec->farlevel.averagelevel.EndOfBlock()) {
     if (aec->farlevel.minlevel < noisyPower) {
       actThreshold = actThresholdClean;
     } else {
       actThreshold = actThresholdNoisy;
     }
 
     const float far_average_level = aec->farlevel.averagelevel.GetLatestMean();
 
     // The last condition is to let estimation be made in active far-end
@@ skipping 1274 matching lines @@
 
 int WebRtcAec_system_delay(AecCore* self) {
   return self->system_delay;
 }
 
 void WebRtcAec_SetSystemDelay(AecCore* self, int delay) {
   assert(delay >= 0);
   self->system_delay = delay;
 }
 }  // namespace webrtc