Injectable output rate calculater for AudioMixer.

webrtc/modules/audio_mixer/audio_mixer_impl.h

 /*
  *  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.
  */
 
 #ifndef WEBRTC_MODULES_AUDIO_MIXER_AUDIO_MIXER_IMPL_H_
 #define WEBRTC_MODULES_AUDIO_MIXER_AUDIO_MIXER_IMPL_H_
 
 #include <memory>
 #include <vector>
 
 #include "webrtc/api/audio/audio_mixer.h"
 #include "webrtc/base/scoped_ref_ptr.h"
 #include "webrtc/base/thread_annotations.h"
 #include "webrtc/base/race_checker.h"
+#include "webrtc/modules/audio_mixer/output_rate_calculator.h"
 #include "webrtc/modules/audio_processing/include/audio_processing.h"
 #include "webrtc/modules/include/module_common_types.h"
 #include "webrtc/system_wrappers/include/critical_section_wrapper.h"
 #include "webrtc/voice_engine_configurations.h"
 
 namespace webrtc {
 
 typedef std::vector<AudioFrame*> AudioFrameList;
 
 class AudioMixerImpl : public AudioMixer {
  public:
   struct SourceStatus {
     SourceStatus(Source* audio_source, bool is_mixed, float gain)
         : audio_source(audio_source), is_mixed(is_mixed), gain(gain) {}
     Source* audio_source = nullptr;
     bool is_mixed = false;
     float gain = 0.0f;
 
     // A frame that will be passed to audio_source->GetAudioFrameWithInfo.
     AudioFrame audio_frame;
   };
 
   using SourceStatusList = std::vector<std::unique_ptr<SourceStatus>>;
 
   // AudioProcessing only accepts 10 ms frames.
   static const int kFrameDurationInMs = 10;
   static const int kMaximumAmountOfMixedAudioSources = 3;
-  static const int kDefaultFrequency = 48000;
 
   static rtc::scoped_refptr<AudioMixerImpl> Create();
+  static rtc::scoped_refptr<AudioMixerImpl> CreateWithOutputRateCalculator(
+      std::unique_ptr<OutputRateCalculator> output_rate_calculator);
 
   ~AudioMixerImpl() override;
 
   // AudioMixer functions
   bool AddSource(Source* audio_source) override;
   void RemoveSource(Source* audio_source) override;
 
   void Mix(size_t number_of_channels,
            AudioFrame* audio_frame_for_mixing) override LOCKS_EXCLUDED(crit_);
 
   // Returns true if the source was mixed last round. Returns
   // false and logs an error if the source was never added to the
   // mixer.
   bool GetAudioSourceMixabilityStatusForTest(Source* audio_source) const;
 
  protected:
-  explicit AudioMixerImpl(std::unique_ptr<AudioProcessing> limiter);
+  AudioMixerImpl(std::unique_ptr<AudioProcessing> limiter,
+                 std::unique_ptr<OutputRateCalculator> output_rate_calculator);
 
  private:
-  // Set/get mix frequency
-  void SetOutputFrequency(int frequency);
+  // Set mixing frequency through OutputFrequencyCalculator.
+  void CalculateOutputFrequency();
+  // Get mixing frequency.
   int OutputFrequency() const;
 
   // Compute what audio sources to mix from audio_source_list_. Ramp
   // in and out. Update mixed status. Mixes up to
   // kMaximumAmountOfMixedAudioSources audio sources.
   AudioFrameList GetAudioFromSources() EXCLUSIVE_LOCKS_REQUIRED(crit_);
 
   // Add/remove the MixerAudioSource to the specified
   // MixerAudioSource list.
   bool AddAudioSourceToList(Source* audio_source,
                             SourceStatusList* audio_source_list) const;
   bool RemoveAudioSourceFromList(Source* remove_audio_source,
                                  SourceStatusList* audio_source_list) const;
 
   bool LimitMixedAudio(AudioFrame* mixed_audio) const;
 
   // The critical section lock guards audio source insertion and
   // removal, which can be done from any thread. The race checker
   // checks that mixing is done sequentially.
   rtc::CriticalSection crit_;
   rtc::RaceChecker race_checker_;
 
+  std::unique_ptr<OutputRateCalculator> output_rate_calculator_;
   // The current sample frequency and sample size when mixing.
   int output_frequency_ GUARDED_BY(race_checker_);
   size_t sample_size_ GUARDED_BY(race_checker_);
 
   // List of all audio sources. Note all lists are disjunct
   SourceStatusList audio_source_list_ GUARDED_BY(crit_);  // May be mixed.
 
   // Determines if we will use a limiter for clipping protection during
   // mixing.
   bool use_limiter_ GUARDED_BY(race_checker_);
 
   uint32_t time_stamp_ GUARDED_BY(race_checker_);
 
   // Used for inhibiting saturation in mixing.
   std::unique_ptr<AudioProcessing> limiter_ GUARDED_BY(race_checker_);
 
   RTC_DISALLOW_COPY_AND_ASSIGN(AudioMixerImpl);
 };
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_MIXER_AUDIO_MIXER_IMPL_H_