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// Copyright (c) 2011 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 "chrome/browser/chromeos/audio_handler.h"
#include <algorithm>
#include <cmath>
#include "base/logging.h"
#include "base/memory/singleton.h"
#include "chrome/browser/chromeos/audio_mixer_alsa.h"
#include "content/public/browser/browser_thread.h"
using std::max;
using std::min;
namespace chromeos {
namespace {
// A value of less than one adjusts quieter volumes in larger steps (giving
// finer resolution in the higher volumes).
const double kVolumeBias = 0.5;
static AudioHandler* g_audio_handler = NULL;
} // namespace
// static
void AudioHandler::Initialize() {
CHECK(!g_audio_handler);
g_audio_handler = new AudioHandler();
}
// static
void AudioHandler::Shutdown() {
// We may call Shutdown without calling Initialize, e.g. if we exit early.
if (g_audio_handler) {
delete g_audio_handler;
g_audio_handler = NULL;
}
}
// static
AudioHandler* AudioHandler::GetInstance() {
VLOG_IF(1, !g_audio_handler)
<< "AudioHandler::GetInstance() called with NULL global instance.";
return g_audio_handler;
}
bool AudioHandler::IsInitialized() {
return mixer_->IsInitialized();
}
double AudioHandler::GetVolumePercent() {
return VolumeDbToPercent(mixer_->GetVolumeDb());
}
void AudioHandler::SetVolumePercent(double volume_percent) {
volume_percent = min(max(volume_percent, 0.0), 100.0);
mixer_->SetVolumeDb(PercentToVolumeDb(volume_percent));
}
void AudioHandler::AdjustVolumeByPercent(double adjust_by_percent) {
const double old_volume_db = mixer_->GetVolumeDb();
const double old_percent = VolumeDbToPercent(old_volume_db);
SetVolumePercent(old_percent + adjust_by_percent);
}
bool AudioHandler::IsMuted() {
return mixer_->IsMuted();
}
void AudioHandler::SetMuted(bool mute) {
mixer_->SetMuted(mute);
}
AudioHandler::AudioHandler()
: mixer_(new AudioMixerAlsa()) {
mixer_->Init();
}
AudioHandler::~AudioHandler() {
mixer_.reset();
};
// VolumeDbToPercent() and PercentToVolumeDb() conversion functions allow us
// complete control over how the 0 to 100% range is mapped to actual loudness.
//
// The mapping is confined to these two functions to make it easy to adjust and
// have everything else just work. The range is biased to give finer resolution
// in the higher volumes if kVolumeBias is less than 1.0.
double AudioHandler::VolumeDbToPercent(double volume_db) const {
double min_volume_db, max_volume_db;
mixer_->GetVolumeLimits(&min_volume_db, &max_volume_db);
if (volume_db < min_volume_db)
return 0.0;
// TODO(derat): Choose a better mapping between percent and decibels. The
// bottom twenty-five percent or so is useless on a CR-48's internal speakers;
// it's all inaudible.
return 100.0 * pow((volume_db - min_volume_db) /
(max_volume_db - min_volume_db), 1/kVolumeBias);
}
double AudioHandler::PercentToVolumeDb(double volume_percent) const {
double min_volume_db, max_volume_db;
mixer_->GetVolumeLimits(&min_volume_db, &max_volume_db);
return pow(volume_percent / 100.0, kVolumeBias) *
(max_volume_db - min_volume_db) + min_volume_db;
}
} // namespace chromeos
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