[Chromecast] Correct libcast_governor behavior.

chromecast/media/cma/backend/alsa/post_processors/governor_shlib.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "chromecast/media/cma/backend/alsa/post_processors/governor_shlib.h"
+
 #include <memory>
 #include <string>
 
 #include "base/logging.h"
-#include "base/macros.h"
+#include "base/memory/ptr_util.h"
 #include "base/values.h"
 #include "chromecast/base/serializers.h"
 #include "chromecast/media/cma/backend/alsa/slew_volume.h"
-#include "chromecast/public/media/audio_post_processor_shlib.h"
 
 namespace chromecast {
 namespace media {
 
 namespace {
 const int kNoSampleRate = -1;
+const int kNoVolume = -1;
 
 // Configuration strings:
 const char kOnsetVolumeKey[] = "onset_volume";
 const char kClampMultiplierKey[] = "clamp_multiplier";
 
 }  // namespace
 
-// Provides a flat reduction in output volume if the input volume is above a
-// given threshold.
-// Used to protect speakers at high output levels
-// while providing dyanmic range at low output level.
-// The configuration string for this plugin is:
-//  {"onset_volume": |VOLUME_TO_CLAMP|, "clamp_multiplier": |CLAMP_MULTIPLIER|}
-// Input volumes > |VOLUME_TO_CLAMP| will be attenuated by |CLAMP_MULTIPLIER|.
-class Governor : public AudioPostProcessor {
- public:
-  Governor(const std::string& config, int channels);
-  ~Governor() override;
-
-  bool SetSampleRate(int sample_rate) override;
-  int ProcessFrames(const std::vector<float*>& data,
-                    int frames,
-                    float volume) override;
-  int GetRingingTimeInFrames() override;
-
- private:
-  float GetGovernorMultiplier();
-
-  int channels_;
-  int sample_rate_;
-  float volume_;
-  double onset_volume_;
-  double clamp_multiplier_;
-  SlewVolume governor_;
-  DISALLOW_COPY_AND_ASSIGN(Governor);
-};
-
 Governor::Governor(const std::string& config, int channels)
-    : channels_(channels), sample_rate_(kNoSampleRate), volume_(1.0) {
+    : channels_(channels),
+      sample_rate_(kNoSampleRate),
+      volume_(kNoVolume),
+      slew_volume_(base::MakeUnique<SlewVolume>()) {
   auto config_dict = base::DictionaryValue::From(DeserializeFromJson(config));
   CHECK(config_dict) << "Governor config is not valid json: " << config;
   CHECK(config_dict->GetDouble(kOnsetVolumeKey, &onset_volume_));
   CHECK(config_dict->GetDouble(kClampMultiplierKey, &clamp_multiplier_));
   DCHECK_EQ(channels_, 2);
-  governor_.SetVolume(1.0);
+  slew_volume_->SetVolume(1.0);
   LOG(INFO) << "Created a governor: onset_volume = " << onset_volume_
             << ", clamp_multiplier = " << clamp_multiplier_;
 }
 
 Governor::~Governor() = default;
 
 bool Governor::SetSampleRate(int sample_rate) {
   sample_rate_ = sample_rate;
-  governor_.SetSampleRate(sample_rate);
+  slew_volume_->SetSampleRate(sample_rate);
   return true;
 }
 
 int Governor::ProcessFrames(const std::vector<float*>& data,
                             int frames,
                             float volume) {
   DCHECK_EQ(data.size(), static_cast<size_t>(channels_));
 
+  if (volume_ == kNoVolume) {
+    slew_volume_->Interrupted();
+  }
+
   if (volume != volume_) {
     volume_ = volume;
-    governor_.SetVolume(GetGovernorMultiplier());
+    slew_volume_->SetVolume(GetGovernorMultiplier());
   }
 
   for (int c = 0; c < channels_; ++c) {
     DCHECK(data[c]);
-    governor_.ProcessFMAC(c != 0 /* repeat_transition */, data[c], frames,
-                          data[c]);
+    slew_volume_->ProcessFMUL(c != 0 /* repeat_transition */, data[c], frames,
+                              data[c]);
   }
 
   return 0;  // No delay in this pipeline.
 }
 
 int Governor::GetRingingTimeInFrames() {
   return 0;
 }
 
 float Governor::GetGovernorMultiplier() {
   if (volume_ >= onset_volume_) {
     return clamp_multiplier_;
   }
   return 1.0;
 }
 
+void Governor::SetSlewTimeMsForTest(int slew_time_ms) {
+  slew_volume_->SetMaxSlewTimeMs(slew_time_ms);
+}
+
 }  // namespace media
 }  // namespace chromecast
 
 chromecast::media::AudioPostProcessor* AudioPostProcessorShlib_Create(
     const std::string& config,
     int channels) {
   return static_cast<chromecast::media::AudioPostProcessor*>(
       new chromecast::media::Governor(config, channels));
 }