From e8f8f6037ca2b7f9c2f48cb65bb9e8b245acbddb Mon Sep 17 00:00:00 2001
From: aluebs <aluebs@webrtc.org>
Date: Wed, 8 Jun 2016 09:53:18 -0700
Subject: [PATCH] Only update Intelligibility Enhancer gains every 10 chunks

This reduces its complexity by a factor of 2.7x total.
The mean error introduced by this is in the 6 different noise scenarios and 6 different speech signals tested is below -52dB.

Review-Url: https://codereview.webrtc.org/2035213002
Cr-Commit-Position: refs/heads/master@{#13072}
---
 .../intelligibility/intelligibility_enhancer.cc               | 4 +++-
 .../intelligibility/intelligibility_enhancer.h                | 2 ++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.cc b/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.cc
index ae7f911921..a10d10a75e 100644
--- a/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.cc
+++ b/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.cc
@@ -40,6 +40,7 @@ const float kRho = 0.0004f;  // Default production and interpretation SNR.
 const float kPowerNormalizationFactor = 1.f / (1 << 30);
 const float kMaxActiveSNR = 128.f;  // 21dB
 const float kMinInactiveSNR = 32.f;  // 15dB
+const size_t kGainUpdatePeriod = 10u;
 
 // Returns dot product of vectors |a| and |b| with size |length|.
 float DotProduct(const float* a, const float* b, size_t length) {
@@ -88,6 +89,7 @@ IntelligibilityEnhancer::IntelligibilityEnhancer(int sample_rate_hz,
       is_speech_(false),
       snr_(kMaxActiveSNR),
       is_active_(false),
+      num_chunks_(0u),
       noise_estimation_buffer_(num_noise_bins),
       noise_estimation_queue_(kMaxNumNoiseEstimatesToBuffer,
                               std::vector<float>(num_noise_bins),
@@ -144,7 +146,7 @@ void IntelligibilityEnhancer::ProcessAudioBlock(
     clear_power_estimator_.Step(in_block[0]);
   }
   SnrBasedEffectActivation();
-  if (is_active_) {
+  if (is_active_ && num_chunks_++ % kGainUpdatePeriod == 0) {
     MapToErbBands(clear_power_estimator_.power().data(), render_filter_bank_,
                   filtered_clear_pow_.data());
     MapToErbBands(noise_power_estimator_.power().data(), capture_filter_bank_,
diff --git a/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.h b/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.h
index 63ae80e2c4..389f6ae567 100644
--- a/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.h
+++ b/webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.h
@@ -112,6 +112,8 @@ class IntelligibilityEnhancer : public LappedTransform::Callback {
   float snr_;
   bool is_active_;
 
+  size_t num_chunks_;
+
   std::vector<float> noise_estimation_buffer_;
   SwapQueue<std::vector<float>, RenderQueueItemVerifier<float>>
       noise_estimation_queue_;