Fix normalization of noise estimate in NoiseSuppressor

webrtc/modules/audio_processing/noise_suppression_impl.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.
  */
 
@@ skipping 159 matching lines @@
   // TODO(peah): Returning error code as a float! Remove this.
   // Currently not available for the fixed point implementation.
   return AudioProcessing::kUnsupportedFunctionError;
 #endif
 }
 
 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();
     }
   }
 #endif
   return noise_estimate;
 }
 
 size_t NoiseSuppressionImpl::num_noise_bins() {
 #if defined(WEBRTC_NS_FLOAT)
   return WebRtcNs_num_freq();
 #elif defined(WEBRTC_NS_FIXED)
   return WebRtcNsx_num_freq();
 #endif
 }
 
 }  // namespace webrtc