AGC2 dummy module: fixed gain param, APM integration, audioproc_f adaptation

webrtc/modules/audio_processing/agc2/gain_controller2.h

 /*
  *  Copyright (c) 2017 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.
  */
 
 #ifndef WEBRTC_MODULES_AUDIO_PROCESSING_AGC2_GAIN_CONTROLLER2_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_AGC2_GAIN_CONTROLLER2_H_
 
 #include <memory>
 #include <string>
 
-#include "webrtc/modules/audio_processing/agc2/digital_gain_applier.h"
 #include "webrtc/modules/audio_processing/include/audio_processing.h"
 #include "webrtc/rtc_base/constructormagic.h"
 
 namespace webrtc {
 
 class ApmDataDumper;
 class AudioBuffer;
 
 // Gain Controller 2 aims to automatically adjust levels by acting on the
 // microphone gain and/or applying digital gain.
 //
-// It temporarily implements a hard-coded gain mode only.
+// It temporarily implements a fixed gain mode with hard-clipping.
 class GainController2 {
  public:
-  explicit GainController2(int sample_rate_hz);
+  explicit GainController2(const float fixed_gain_db);
   ~GainController2();
 
   int sample_rate_hz() { return sample_rate_hz_; }
 
+  void Initialize(int sample_rate_hz);
   void Process(AudioBuffer* audio);
 
   static bool Validate(const AudioProcessing::Config::GainController2& config);

[aleloi, 2017/08/15 14:34:03]

Since we already have a Config::GainController2, can we use it in the c-tor?

[AleBzk, 2017/09/14 09:21:55]

Done, but using ApplyConfig() and having no args in the ctor.

   static std::string ToString(
       const AudioProcessing::Config::GainController2& config);
 
  private:
   int sample_rate_hz_;
   std::unique_ptr<ApmDataDumper> data_dumper_;
-  DigitalGainApplier digital_gain_applier_;
   static int instance_count_;

[aleloi, 2017/08/15 14:34:03]

Should this be atomic similarly to other instance counters? Or are we sure it's
not a problem/we never need more than one/gain controllers will always be
created from one thread?

[AleBzk, 2017/09/14 09:21:55]

I initially did what you suggest here, but then simplified as done in level
controller. I guess it's ok since AGC2 is a private sub-module.

-  // TODO(alessiob): Remove once a meaningful gain controller mode is
-  // implemented.
-  const float gain_;
+  const float fixed_gain_;
+
   RTC_DISALLOW_COPY_AND_ASSIGN(GainController2);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AGC2_GAIN_CONTROLLER2_H_