Fix normalization of noise estimate in NoiseSuppressor

webrtc/modules/audio_processing/noise_suppression_impl.cc

Index: webrtc/modules/audio_processing/noise_suppression_impl.cc
diff --git a/webrtc/modules/audio_processing/noise_suppression_impl.cc b/webrtc/modules/audio_processing/noise_suppression_impl.cc
index a9d9f4a93bbf8086105ea4cb28fc0ee181be644b..ec0446d2736221d97f5b316aa8b47d16d1c91060 100644
--- a/webrtc/modules/audio_processing/noise_suppression_impl.cc
+++ b/webrtc/modules/audio_processing/noise_suppression_impl.cc
@@ -177,20 +177,19 @@ std::vector<float> NoiseSuppressionImpl::NoiseEstimate() {
   rtc::CritScope cs(crit_);
   std::vector<float> noise_estimate;
 #if defined(WEBRTC_NS_FLOAT)
-  const float kNormalizationFactor = 1.f / (1 << 15);
   noise_estimate.assign(WebRtcNs_num_freq(), 0.f);
   for (auto& suppressor : suppressors_) {
     const float* noise = WebRtcNs_noise_estimate(suppressor->state());
     for (size_t i = 0; i < noise_estimate.size(); ++i) {
-      noise_estimate[i] +=
-          kNormalizationFactor * noise[i] / suppressors_.size();
+      noise_estimate[i] += noise[i] / suppressors_.size();
     }
   }
 #elif defined(WEBRTC_NS_FIXED)
-  const float kNormalizationFactor = 1.f / (1 << 23);
   noise_estimate.assign(WebRtcNsx_num_freq(), 0.f);
   for (auto& suppressor : suppressors_) {
     const uint32_t* noise = WebRtcNsx_noise_estimate(suppressor->state());

[turaj, 2016/03/31 15:20:48]

Just a suggestion, up to you if you want to change, noise estimate can be
implemented 

const uint32_t* WebRtcNsx_noise_estimate(const ns_state*, int* domain) 

So there will be only one function call. As the domain is adaptive anytime one
asks for the noise estimate has to ask for domain as well. And it avoids making
mistake of not accounting for the domain. 

[aluebs-webrtc, 2016/03/31 17:48:13]

In general I think it can be confusing when passing in an int*, because it is
not clear if it is an input or output. And also, I tried to keep both
interfaces, fixed and float, the most similar possible. But I see your point,
that it is really easy for a user of this component to forget to get the domain
and normalize if it is a separate function, so I implemented your suggestion. 

+    const float kNormalizationFactor =
+        1.f / (1 << WebRtcNsx_noise_estimate_domain(suppressor->state()));
     for (size_t i = 0; i < noise_estimate.size(); ++i) {
       noise_estimate[i] += kNormalizationFactor *
           static_cast<float>(noise[i]) / suppressors_.size();