Allow intelligibility to compile in apm

webrtc/modules/audio_processing/intelligibility/intelligibility_enhancer.h

 /*
  *  Copyright (c) 2014 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.
  */
 
+//
+//  Specifies core class for intelligbility enhancement.
+//
+
 #ifndef WEBRTC_MODULES_AUDIO_PROCESSING_INTELLIGIBILITY_INTELLIGIBILITY_ENHANCER_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_INTELLIGIBILITY_INTELLIGIBILITY_ENHANCER_H_
 
 #include <complex>
 
+#include "webrtc/base/scoped_ptr.h"
 #include "webrtc/common_audio/lapped_transform.h"
 #include "webrtc/modules/audio_processing/intelligibility/intelligibility_utils.h"
-#include "webrtc/system_wrappers/interface/scoped_ptr.h"
 
 struct WebRtcVadInst;
 typedef struct WebRtcVadInst VadInst;
 
 namespace webrtc {
 
 // Speech intelligibility enhancement module. Reads render and capture
 // audio streams and modifies the render stream with a set of gains per
 // frequency bin to enhance speech against the noise background.
+// Note: assumes speech and noise streams are already separated.
 class IntelligibilityEnhancer {
  public:
   // Construct a new instance with the given filter bank resolution,
   // sampling rate, number of channels and analysis rates.
   // |analysis_rate| sets the number of input blocks (containing speech!)
   // to elapse before a new gain computation is made. |variance_rate| specifies
   // the number of gain recomputations after which the variances are reset.
   // |cv_*| are parameters for the VarianceArray constructor for the
-  // lear speech stream.
+  // clear speech stream.
   // TODO(bercic): the |cv_*|, |*_rate| and |gain_limit| parameters should
   // probably go away once fine tuning is done. They override the internal
   // constants in the class (kGainChangeLimit, kAnalyzeRate, kVarianceRate).
-  IntelligibilityEnhancer(int erb_resolution, int sample_rate_hz, int channels,
-                          int cv_type, float cv_alpha, int cv_win,
-                          int analysis_rate, int variance_rate,
+  IntelligibilityEnhancer(int erb_resolution,
+                          int sample_rate_hz,
+                          int channels,
+                          int cv_type,
+                          float cv_alpha,
+                          int cv_win,
+                          int analysis_rate,
+                          int variance_rate,
                           float gain_limit);
   ~IntelligibilityEnhancer();
 
+  // Reads and processes chunk of noise stream in time domain.
+  void ProcessCaptureAudio(float* const* audio);
+
+  // Reads chunk of speech in time domain and updates with modified signal.
   void ProcessRenderAudio(float* const* audio);
-  void ProcessCaptureAudio(float* const* audio);
 
  private:
   enum AudioSource {
-    kRenderStream = 0,
-    kCaptureStream,
+    kRenderStream = 0,  // Clear speech stream.
+    kCaptureStream,  // Noise stream.
   };
 
+  // Provides access point to the frequency domain.
   class TransformCallback : public LappedTransform::Callback {
    public:
     TransformCallback(IntelligibilityEnhancer* parent, AudioSource source);
+
+    // All in frequency domain, receives input |in_block|, applies
+    // intelligibility enhancement, and writes result to |out_block|.
     virtual void ProcessAudioBlock(const std::complex<float>* const* in_block,
-                                   int in_channels, int frames,
+                                   int in_channels,
+                                   int frames,
                                    int out_channels,
                                    std::complex<float>* const* out_block);
 
    private:
     IntelligibilityEnhancer* parent_;
     AudioSource source_;
   };
   friend class TransformCallback;
 
-  void DispatchAudio(AudioSource source, const std::complex<float>* in_block,
+  // Sends streams to ProcessClearBlock or ProcessNoiseBlock based on source.
+  void DispatchAudio(AudioSource source,
+                     const std::complex<float>* in_block,
                      std::complex<float>* out_block);
+
+  // Updates variance computation and analysis with |in_block_|,
+  // and writes modified speech to |out_block|.
   void ProcessClearBlock(const std::complex<float>* in_block,
                          std::complex<float>* out_block);
+
+  // Computes and sets modified gains.
   void AnalyzeClearBlock(float power_target);
+
+  // Updates variance calculation for noise input with |in_block|.
   void ProcessNoiseBlock(const std::complex<float>* in_block,
                          std::complex<float>* out_block);
 
+  // Returns number of ERB filters.
   static int GetBankSize(int sample_rate, int erb_resolution);
+
+  // Initializes ERB filterbank.
   void CreateErbBank();
-  void SolveEquation14(float lambda, int start_freq, float* sols);
+
+  // Analytically solves quadratic for optimal gains given |lambda|.
+  // Negative gains are set to 0. Stores the results in |sols|.
+  void SolveForGainsGivenLambda(float lambda, int start_freq, float* sols);
+
+  // Computes variance across ERB filters from freq variance |var|.
+  // Stores in |result|.
   void FilterVariance(const float* var, float* result);
+
+  // Returns dot product of vectors specified by size |length| arrays |a|,|b|.
   static float DotProduct(const float* a, const float* b, int length);
 
   static const int kErbResolution;
   static const int kWindowSizeMs;
   static const int kChunkSizeMs;
-  static const int kAnalyzeRate;
-  static const int kVarianceRate;
+  static const int kAnalyzeRate;   // Default for |analysis_rate_|.
+  static const int kVarianceRate;  // Default for |variance_rate_|.
   static const float kClipFreq;
-  static const float kConfigRho;
+  static const float kConfigRho;  // Default production and interpretation SNR.
   static const float kKbdAlpha;
   static const float kGainChangeLimit;
 
-  const int freqs_;
-  const int window_size_;  // window size in samples; also the block size
-  const int chunk_length_;  // chunk size in samples
-  const int bank_size_;
+  const int freqs_;         // Num frequencies in frequency domain.
+  const int window_size_;   // Window size in samples; also the block size.
+  const int chunk_length_;  // Chunk size in samples.
+  const int bank_size_;     // Num ERB filters.
   const int sample_rate_hz_;
   const int erb_resolution_;
-  const int channels_;
-  const int analysis_rate_;
-  const int variance_rate_;
+  const int channels_;       // Num channels.
+  const int analysis_rate_;  // Num blocks before gains recalculated.
+  const int variance_rate_;  // Num recalculations before history is cleared.
 
   intelligibility::VarianceArray clear_variance_;
   intelligibility::VarianceArray noise_variance_;
-  scoped_ptr<float[]> filtered_clear_var_;
-  scoped_ptr<float[]> filtered_noise_var_;
-  float** filter_bank_;
-  scoped_ptr<float[]> center_freqs_;
+  rtc::scoped_ptr<float[]> filtered_clear_var_;
+  rtc::scoped_ptr<float[]> filtered_noise_var_;
+  float** filter_bank_;  // TODO(ekmeyerson): Switch to using ChannelBuffer.
+  rtc::scoped_ptr<float[]> center_freqs_;
   int start_freq_;
-  scoped_ptr<float[]> rho_;
-  scoped_ptr<float[]> gains_eq_;
+  rtc::scoped_ptr<float[]> rho_;  // Production and interpretation SNR.
+                                  // for each ERB band.
+  rtc::scoped_ptr<float[]> gains_eq_;  // Pre-filter modified gains.
   intelligibility::GainApplier gain_applier_;
 
   // Destination buffer used to reassemble blocked chunks before overwriting
   // the original input array with modifications.
+  // TODO(ekmeyerson): Switch to using ChannelBuffer.
   float** temp_out_buffer_;
-  scoped_ptr<float*[]> input_audio_;
-  scoped_ptr<float[]> kbd_window_;
+
+  rtc::scoped_ptr<float* []> input_audio_;
+  rtc::scoped_ptr<float[]> kbd_window_;
   TransformCallback render_callback_;
   TransformCallback capture_callback_;
-  scoped_ptr<LappedTransform> render_mangler_;
-  scoped_ptr<LappedTransform> capture_mangler_;
+  rtc::scoped_ptr<LappedTransform> render_mangler_;
+  rtc::scoped_ptr<LappedTransform> capture_mangler_;
   int block_count_;
   int analysis_step_;
 
   // TODO(bercic): Quick stopgap measure for voice detection in the clear
   // and noise streams.
+  // Note: VAD currently does not affect anything in IntelligibilityEnhancer.
   VadInst* vad_high_;
   VadInst* vad_low_;
-  scoped_ptr<int16_t[]> vad_tmp_buffer_;
-  bool has_voice_low_;
+  rtc::scoped_ptr<int16_t[]> vad_tmp_buffer_;
+  bool has_voice_low_;  // Whether voice detected in speech stream.
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_INTELLIGIBILITY_INTELLIGIBILITY_ENHANCER_H_
-