Make use of new APM statistics interface.

webrtc/modules/audio_processing/audio_processing_impl.cc

Index: webrtc/modules/audio_processing/audio_processing_impl.cc
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.cc b/webrtc/modules/audio_processing/audio_processing_impl.cc
index f63cb206b5c6aaf72a4bc30b47ebd0b6c7c8680b..3be029171bb6ffda39b4d14c6c311edfce7a64c6 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.cc
+++ b/webrtc/modules/audio_processing/audio_processing_impl.cc
@@ -120,6 +120,16 @@ int FindNativeProcessRateToUse(int minimum_rate, bool band_splitting_required) {
   return uppermost_native_rate;
 }
 
+webrtc::AudioProcessing::Statistic FixStatistic(
+    const webrtc::AudioProcessing::Statistic& stat) {
+  webrtc::AudioProcessing::Statistic result = stat;
+  if (result.average == -100 || result.instant == -100 ||
+      result.maximum == -100 || result.minimum == -100) {
+    result.average = result.instant = result.maximum = result.minimum = -100;
+  }
+  return result;
+}
+
 // Maximum length that a frame of samples can have.
 static const size_t kMaxAllowedValuesOfSamplesPerFrame = 160;
 // Maximum number of frames to buffer in the render queue.
@@ -1489,12 +1499,13 @@ AudioProcessing::AudioProcessingStatistics AudioProcessingImpl::GetStatistics()
   EchoCancellation::Metrics metrics;
   int success = public_submodules_->echo_cancellation->GetMetrics(&metrics);
   if (success == Error::kNoError) {
-    stats.a_nlp.Set(metrics.a_nlp);
+    stats.a_nlp.Set(FixStatistic(metrics.a_nlp));

[peah-webrtc, 2016/11/10 10:36:09]

What you do here is basically to ensure that if any of the metrics.* struct
members is -100, then all is set to -100, right?

That makes sense and seems like the correct way to report the metrics.

It is, however, weird that the APM should ensure that the metrics in the AEC are
correctly reported. 
That constitutes an unneccessary dependency of APM on the implementation of the
AEC.

I think it would make more sense to move this correction into the AEC where the
metrics are computed. In that way APM would not need to be concerned about the
implementation of the AEC metrics.

WDYT?

[ossu, 2016/11/10 11:29:47]

peah: Did you read my analysis of the problem in question? Do you see any
problems with it? I'd prefer it if the problem could be solved at the source,
rather than plastering it over afterwards.

     stats.divergent_filter_fraction = metrics.divergent_filter_fraction;
-    stats.echo_return_loss.Set(metrics.echo_return_loss);
+    stats.echo_return_loss.Set(FixStatistic(metrics.echo_return_loss));
     stats.echo_return_loss_enhancement.Set(
-        metrics.echo_return_loss_enhancement);
-    stats.residual_echo_return_loss.Set(metrics.residual_echo_return_loss);
+        FixStatistic(metrics.echo_return_loss_enhancement));
+    stats.residual_echo_return_loss.Set(
+        FixStatistic(metrics.residual_echo_return_loss));
   }
   public_submodules_->echo_cancellation->GetDelayMetrics(
       &stats.delay_median, &stats.delay_standard_deviation,