Add new variance update option and unittests for intelligibility

webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.cc

Index: webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.cc
diff --git a/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.cc b/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.cc
index 3029e21619a981917f377afb78075bfd66def952..3e5063bbf82287c10a6c4b8848fa5171d992b474 100644
--- a/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.cc
+++ b/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.cc
@@ -42,6 +42,9 @@ const float IntelligibilityEnhancer::kClipFreq = 200.0f;
 const float IntelligibilityEnhancer::kConfigRho = 0.02f;
 const float IntelligibilityEnhancer::kKbdAlpha = 1.5f;
 

[hlundin-webrtc, 2015/06/30 14:00:52]

Delete empty line.

[ekm, 2015/07/01 23:48:25]

Done.

+const float IntelligibilityEnhancer::kLambdaBot = -1.0;

[hlundin-webrtc, 2015/06/30 14:00:52]

Are all of these constants only used locally in this .cc file? If so, you can
move them out of the class and simply declare them in an anonymous namespace in
this file. E.g.,

namespace {
static const int kErbResolution = 2;
...
}  // namespace

[ekm, 2015/07/01 23:48:25]

Done.

+const float IntelligibilityEnhancer::kLambdaTop = -10e-18f;
+
 // To disable gain update smoothing, set gain limit to be VERY high.
 // TODO(ekmeyerson): Add option to disable gain smoothing altogether
 // to avoid the extra computation.
@@ -239,18 +242,25 @@ void IntelligibilityEnhancer::AnalyzeClearBlock(float power_target) {
   FilterVariance(clear_variance_.variance(), filtered_clear_var_.get());
   FilterVariance(noise_variance_.variance(), filtered_noise_var_.get());
 
-  // Bisection search for optimal |lambda|
-
-  float lambda_bot = -1.0f, lambda_top = -10e-18f, lambda;
-  float power_bot, power_top, power;
-  SolveForGainsGivenLambda(lambda_top, start_freq_, gains_eq_.get());
+  float power_bot, power_top;

[hlundin-webrtc, 2015/06/30 14:00:51]

Premature declaration of variables. Declare them when they are used:
float power_top = DotProduct(...);

[ekm, 2015/07/01 23:48:25]

Done.

+  SolveForGainsGivenLambda(kLambdaTop, start_freq_, gains_eq_.get());
   power_top =
       DotProduct(gains_eq_.get(), filtered_clear_var_.get(), bank_size_);
-  SolveForGainsGivenLambda(lambda_bot, start_freq_, gains_eq_.get());
+  SolveForGainsGivenLambda(kLambdaBot, start_freq_, gains_eq_.get());
   power_bot =
       DotProduct(gains_eq_.get(), filtered_clear_var_.get(), bank_size_);
-  DCHECK(power_target >= power_bot && power_target <= power_top);
+  if(power_target >= power_bot && power_target <= power_top) {
+    SolveForLambda(power_target, power_bot, power_top);
+    UpdateErbGains();
+  }  // Else experiencing variance underflow, so do nothing.
+}
 
+void IntelligibilityEnhancer::SolveForLambda(float power_target,
+                                             float power_bot,
+                                             float power_top) {
+  float lambda_bot = kLambdaBot;
+  float lambda_top = kLambdaTop;
+  float lambda, power;

[hlundin-webrtc, 2015/06/30 14:00:52]

Skip declaration of lambda and power here and declare them when used inside the
loop.

[ekm, 2015/07/01 23:48:25]

Done.

   float power_ratio = 2.0f;  // Ratio of achieved power to target power.
   const float kConvergeThresh = 0.001f;  // TODO(ekmeyerson): Find best values
   const int kMaxIters = 100;             // for these, based on experiments.
@@ -267,7 +277,9 @@ void IntelligibilityEnhancer::AnalyzeClearBlock(float power_target) {
     power_ratio = fabs(power / power_target);
     ++iters;
   }
+}
 
+void IntelligibilityEnhancer::UpdateErbGains() {
   // (ERB gain) = filterbank' * (freq gain)
   float* gains = gain_applier_.target();
   for (int i = 0; i < freqs_; ++i) {