[Chromecast] Implement new volume control API

chromecast/media/cma/backend/alsa/volume_control.cc

Index: chromecast/media/cma/backend/alsa/volume_control.cc
diff --git a/chromecast/media/cma/backend/alsa/volume_control.cc b/chromecast/media/cma/backend/alsa/volume_control.cc
new file mode 100644
index 0000000000000000000000000000000000000000..090e13c051e35265452caa5d4dff19e83879af20
--- /dev/null
+++ b/chromecast/media/cma/backend/alsa/volume_control.cc
@@ -0,0 +1,294 @@
+// 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/public/volume_control.h"
+
+#include <algorithm>
+#include <cmath>
+#include <map>
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/lazy_instance.h"
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/thread.h"
+#include "base/values.h"
+#include "chromecast/base/init_command_line_shlib.h"
+#include "chromecast/base/serializers.h"
+#include "chromecast/media/cma/backend/alsa/stream_mixer_alsa.h"
+
+namespace chromecast {
+namespace media {
+
+namespace {
+
+const float kDefaultMediaDbFS = -25.0f;
+const float kDefaultAlarmDbFS = -20.0f;
+const float kDefaultCommunicationDbFS = -25.0f;
+
+const float kMinDbFS = -120.0f;
+
+const char kKeyMediaDbFS[] = "dbfs.media";
+const char kKeyAlarmDbFS[] = "dbfs.alarm";
+const char kKeyCommunicationDbFS[] = "dbfs.communication";
+
+struct LevelToDb {
+  float level;
+  float db;
+};
+
+const LevelToDb kVolumeMap[] = {{0.0f, kMinDbFS},
+                                {0.01f, -58.0f},
+                                {0.090909f, -48.0f},
+                                {0.818182f, -8.0f},
+                                {1.0f, 0.0f}};
+
+float DbFsToScale(float db) {
+  if (db <= kMinDbFS) {
+    return 0.0f;
+  }
+  return std::pow(10, db / 20);
+}
+
+std::string ContentTypeToDbFSKey(AudioContentType type) {
+  switch (type) {
+    case AudioContentType::kAlarm:
+      return kKeyAlarmDbFS;
+    case AudioContentType::kCommunication:
+      return kKeyCommunicationDbFS;
+    default:
+      return kKeyMediaDbFS;
+  }
+}
+
+class VolumeControlInternal {
+ public:
+  VolumeControlInternal() : thread_("VolumeControl") {
+    stored_values_.SetDouble(kKeyMediaDbFS, kDefaultMediaDbFS);
+    stored_values_.SetDouble(kKeyAlarmDbFS, kDefaultAlarmDbFS);
+    stored_values_.SetDouble(kKeyCommunicationDbFS, kDefaultCommunicationDbFS);
+
+    auto types = {AudioContentType::kMedia, AudioContentType::kAlarm,
+                  AudioContentType::kCommunication};
+    double volume;
+
+    storage_path_ = base::GetHomeDir().Append("saved_volumes");
+    auto old_stored_data = DeserializeJsonFromFile(storage_path_);
+    base::DictionaryValue* old_stored_dict;
+    if (old_stored_data && old_stored_data->GetAsDictionary(&old_stored_dict)) {
+      for (auto type : types) {
+        if (old_stored_dict->GetDouble(ContentTypeToDbFSKey(type), &volume)) {
+          stored_values_.SetDouble(ContentTypeToDbFSKey(type), volume);
+        }
+      }
+    }
+
+    for (auto type : types) {
+      CHECK(stored_values_.GetDouble(ContentTypeToDbFSKey(type), &volume));
+      volumes_[type] = VolumeControl::DbFSToVolume(volume);
+      StreamMixerAlsa::Get()->SetVolume(type, DbFsToScale(volume));
+
+      // Note that mute state is not persisted across reboots.
+      muted_[type] = false;
+    }
+
+    thread_.Start();
+  }
+
+  void AddVolumeObserver(VolumeObserver* observer) {
+    base::AutoLock lock(observer_lock_);
+    volume_observers_.push_back(observer);
+  }
+
+  void RemoveVolumeObserver(VolumeObserver* observer) {
+    base::AutoLock lock(observer_lock_);
+    volume_observers_.erase(std::remove(volume_observers_.begin(),
+                                        volume_observers_.end(), observer),
+                            volume_observers_.end());
+  }
+
+  float GetVolume(AudioContentType type) {
+    base::AutoLock lock(volume_lock_);
+    return volumes_[type];
+  }
+
+  void SetVolume(AudioContentType type, float level) {
+    level = std::max(0.0f, std::min(level, 1.0f));
+    thread_.task_runner()->PostTask(
+        FROM_HERE, base::Bind(&VolumeControlInternal::SetVolumeOnThread,
+                              base::Unretained(this), type, level));
+  }
+
+  bool IsMuted(AudioContentType type) {
+    base::AutoLock lock(volume_lock_);
+    return muted_[type];
+  }
+
+  void SetMuted(AudioContentType type, bool muted) {
+    thread_.task_runner()->PostTask(
+        FROM_HERE, base::Bind(&VolumeControlInternal::SetMutedOnThread,
+                              base::Unretained(this), type, muted));
+  }
+
+  void SetOutputLimit(AudioContentType type, float limit) {
+    limit = std::max(0.0f, std::min(limit, 1.0f));
+    StreamMixerAlsa::Get()->SetOutputLimit(
+        type, DbFsToScale(VolumeControl::VolumeToDbFS(limit)));
+  }
+
+ private:
+  void SetVolumeOnThread(AudioContentType type, float level) {
+    DCHECK(thread_.task_runner()->BelongsToCurrentThread());
+    {
+      base::AutoLock lock(volume_lock_);
+      if (level == volumes_[type]) {
+        return;
+      }
+      volumes_[type] = level;
+    }
+
+    float dbfs = VolumeControl::VolumeToDbFS(level);
+    StreamMixerAlsa::Get()->SetVolume(type, DbFsToScale(dbfs));
+
+    {
+      base::AutoLock lock(observer_lock_);
+      for (VolumeObserver* observer : volume_observers_) {
+        observer->OnVolumeChange(type, level);
+      }
+    }
+
+    stored_values_.SetDouble(ContentTypeToDbFSKey(type), dbfs);
+    SerializeJsonToFile(storage_path_, stored_values_);
+  }
+
+  void SetMutedOnThread(AudioContentType type, bool muted) {
+    {
+      base::AutoLock lock(volume_lock_);
+      if (muted == muted_[type]) {
+        return;
+      }
+      muted_[type] = muted;
+    }
+
+    StreamMixerAlsa::Get()->SetMuted(type, muted);
+
+    {
+      base::AutoLock lock(observer_lock_);
+      for (VolumeObserver* observer : volume_observers_) {
+        observer->OnMuteChange(type, muted);
+      }
+    }
+  }
+
+  base::FilePath storage_path_;
+  base::DictionaryValue stored_values_;
+
+  base::Lock volume_lock_;
+  std::map<AudioContentType, float> volumes_;
+  std::map<AudioContentType, bool> muted_;
+
+  base::Lock observer_lock_;
+  std::vector<VolumeObserver*> volume_observers_;
+
+  base::Thread thread_;
+
+  DISALLOW_COPY_AND_ASSIGN(VolumeControlInternal);
+};
+
+base::LazyInstance<VolumeControlInternal> g_volume_control =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+// static
+void VolumeControl::Initialize(const std::vector<std::string>& argv) {
+  chromecast::InitCommandLineShlib(argv);
+}
+
+// static
+void VolumeControl::Finalize() {
+  // Nothing to do.
+}
+
+// static
+void VolumeControl::AddVolumeObserver(VolumeObserver* observer) {
+  g_volume_control.Get().AddVolumeObserver(observer);
+}
+
+// static
+void VolumeControl::RemoveVolumeObserver(VolumeObserver* observer) {
+  g_volume_control.Get().RemoveVolumeObserver(observer);
+}
+
+// static
+float VolumeControl::GetVolume(AudioContentType type) {
+  return g_volume_control.Get().GetVolume(type);
+}
+
+// static
+void VolumeControl::SetVolume(AudioContentType type, float level) {
+  g_volume_control.Get().SetVolume(type, level);
+}
+
+// static
+bool VolumeControl::IsMuted(AudioContentType type) {
+  return g_volume_control.Get().IsMuted(type);
+}
+
+// static
+void VolumeControl::SetMuted(AudioContentType type, bool muted) {
+  g_volume_control.Get().SetMuted(type, muted);
+}
+
+// static
+void VolumeControl::SetOutputLimit(AudioContentType type, float limit) {
+  g_volume_control.Get().SetOutputLimit(type, limit);
+}
+
+// static
+float VolumeControl::VolumeToDbFS(float volume) {
+  if (volume <= kVolumeMap[0].level) {
+    return kVolumeMap[0].db;
+  }
+  for (size_t i = 1; i < arraysize(kVolumeMap); ++i) {
+    if (volume < kVolumeMap[i].level) {
+      const float x_diff = kVolumeMap[i].level - kVolumeMap[i - 1].level;
+      const float y_diff = kVolumeMap[i].db - kVolumeMap[i - 1].db;
+
+      return kVolumeMap[i - 1].db +
+             (volume - kVolumeMap[i - 1].level) * y_diff / x_diff;
+    }
+  }
+  return kVolumeMap[arraysize(kVolumeMap) - 1].db;
+}
+
+// static
+float VolumeControl::DbFSToVolume(float db) {
+  if (db <= kVolumeMap[0].db) {
+    return kVolumeMap[0].level;
+  }
+  for (size_t i = 1; i < arraysize(kVolumeMap); ++i) {
+    if (db < kVolumeMap[i].db) {
+      const float x_diff = kVolumeMap[i].db - kVolumeMap[i - 1].db;
+      const float y_diff = kVolumeMap[i].level - kVolumeMap[i - 1].level;
+
+      return kVolumeMap[i - 1].level +
+             (db - kVolumeMap[i - 1].db) * y_diff / x_diff;
+    }
+  }
+  return kVolumeMap[arraysize(kVolumeMap) - 1].level;
+}
+
+}  // namespace media
+}  // namespace chromecast