chromeos: Simplify audio mixer code.

This cleans up the code that talks to ALSA.  All changes are
now made asynchronously on a background thread.  The volume
and muting states are now tracked separately, as well.

This makes it possible to make some requested changes to the
behavior of the volume keys.  I'm hoping that there's also a
chance that it'll fix some related bugs that people have
been seeing, or at least make it easier to debug them.

BUG=chromium-os:17588,chromium-os:14058,chromium-os:13618,chromium-os:8473
TEST=manual: cleared audio prefs and made sure that reasonable defaults were used; pressed volume keys just after boot and checked that nothing happened; waited a few seconds more and started seeing volume bubble; checked that muting and going to min and max volume worked as expected

Review URL: http://codereview.chromium.org/7508006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@94579 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 34 insertions, 170 deletions

diff --git a/chrome/browser/chromeos/audio_handler.cc b/chrome/browser/chromeos/audio_handler.cc
index 30fbcf7..890f2ee 100644
--- a/chrome/browser/chromeos/audio_handler.cc
+++ b/chrome/browser/chromeos/audio_handler.cc
@@ -4,225 +4,89 @@
 
 #include "chrome/browser/chromeos/audio_handler.h"
 
-#include <math.h>
+#include <algorithm>
+#include <cmath>
 
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 #include "chrome/browser/chromeos/audio_mixer_alsa.h"
 #include "content/browser/browser_thread.h"
 
+using std::max;
+using std::min;
+
 namespace chromeos {
 
 namespace {
 
-const double kMinVolumeDb = -90.0;
-// Choosing 6.0dB here instead of 0dB to give user chance to amplify audio some
-// in case sounds or their setup is too quiet for them.
-const double kMaxVolumeDb = 6.0;
 // A value of less than one adjusts quieter volumes in larger steps (giving
 // finer resolution in the higher volumes).
 const double kVolumeBias = 0.5;
-// If a connection is lost, we try again this many times
-const int kMaxReconnectTries = 4;
-// A flag to disable mixer.
-bool g_disabled = false;
 
 }  // namespace
 
-// chromeos:  This class will set the volume using ALSA to adjust volume and
-// mute, and handle the volume level logic.
+bool AudioHandler::IsInitialized() {
+  return mixer_->IsInitialized();
+}
 
 double AudioHandler::GetVolumePercent() {
-  if (!VerifyMixerConnection())
-    return 0;
-
   return VolumeDbToPercent(mixer_->GetVolumeDb());
 }
 
-// Set volume using our internal 0-100% range.  Notice 0% is a special case of
-// silence, so we set the mixer volume to kSilenceDb instead of min_volume_db_.
 void AudioHandler::SetVolumePercent(double volume_percent) {
-  if (!VerifyMixerConnection())
-    return;
-  DCHECK_GE(volume_percent, 0.0);
-
-  double vol_db;
-  if (volume_percent <= 0)
-    vol_db = AudioMixer::kSilenceDb;
-  else
-    vol_db = PercentToVolumeDb(volume_percent);
-
-  mixer_->SetVolumeDb(vol_db);
+  volume_percent = min(max(volume_percent, 0.0), 100.0);
+  mixer_->SetVolumeDb(PercentToVolumeDb(volume_percent));
 }
 
 void AudioHandler::AdjustVolumeByPercent(double adjust_by_percent) {
-  if (!VerifyMixerConnection())
-    return;
-
-  DVLOG(1) << "Adjusting Volume by " << adjust_by_percent << " percent";
-
-  double volume = mixer_->GetVolumeDb();
-  double pct = VolumeDbToPercent(volume);
-
-  if (pct < 0)
-    pct = 0;
-  pct = pct + adjust_by_percent;
-  if (pct > 100.0)
-    pct = 100.0;
-
-  double new_volume;
-  if (pct <= 0.1)
-    new_volume = AudioMixer::kSilenceDb;
-  else
-    new_volume = PercentToVolumeDb(pct);
-
-  if (new_volume != volume)
-    mixer_->SetVolumeDb(new_volume);
-}
-
-bool AudioHandler::IsMute() {
-  if (!VerifyMixerConnection())
-    return false;
-
-  return mixer_->IsMute();
-}
-
-void AudioHandler::SetMute(bool do_mute) {
-  if (!VerifyMixerConnection())
-    return;
-  DVLOG(1) << "Setting Mute to " << do_mute;
-  mixer_->SetMute(do_mute);
+  const double old_volume_db = mixer_->GetVolumeDb();
+  const double old_percent = VolumeDbToPercent(old_volume_db);
+  SetVolumePercent(old_percent + adjust_by_percent);
 }
 
-void AudioHandler::Disconnect() {
-  mixer_.reset();
+bool AudioHandler::IsMuted() {
+  return mixer_->IsMuted();
 }
 
-void AudioHandler::Disable() {
-  g_disabled = true;
-}
-
-bool AudioHandler::TryToConnect(bool async) {
-  if (mixer_type_ == MIXER_TYPE_ALSA) {
-    VLOG(1) << "Trying to connect to ALSA";
-    mixer_.reset(new AudioMixerAlsa());
-  } else {
-    VLOG(1) << "Cannot find valid volume mixer";
-    mixer_.reset();
-    return false;
-  }
-
-  if (async) {
-    mixer_->Init(NewCallback(this, &AudioHandler::OnMixerInitialized));
-  } else {
-    if (!mixer_->InitSync()) {
-      VLOG(1) << "Unable to reconnect to Mixer";
-      return false;
-    }
-  }
-  return true;
-}
-
-static void ClipVolume(double* min_volume, double* max_volume) {
-  if (*min_volume < kMinVolumeDb)
-    *min_volume = kMinVolumeDb;
-  if (*max_volume > kMaxVolumeDb)
-    *max_volume = kMaxVolumeDb;
-}
-
-void AudioHandler::OnMixerInitialized(bool success) {
-  connected_ = success;
-  DVLOG(1) << "OnMixerInitialized, success = " << success;
-
-  if (connected_) {
-    if (mixer_->GetVolumeLimits(&min_volume_db_, &max_volume_db_)) {
-      ClipVolume(&min_volume_db_, &max_volume_db_);
-    }
-    return;
-  }
-
-  VLOG(1) << "Unable to connect to mixer";
-  mixer_type_ = MIXER_TYPE_NONE;
-
-  // This frees the mixer on the UI thread
-  BrowserThread::PostTask(
-      BrowserThread::UI, FROM_HERE,
-      NewRunnableMethod(this, &AudioHandler::TryToConnect, true));
+void AudioHandler::SetMuted(bool mute) {
+  mixer_->SetMuted(mute);
 }
 
 AudioHandler::AudioHandler()
-    : connected_(false),
-      reconnect_tries_(0),
-      max_volume_db_(kMaxVolumeDb),
-      min_volume_db_(kMinVolumeDb),
-      mixer_type_(g_disabled ? MIXER_TYPE_NONE : MIXER_TYPE_ALSA) {
-  // Start trying to connect to mixers asynchronously, starting with the current
-  // mixer_type_.  If the connection fails, another TryToConnect() for the next
-  // mixer will be posted at that time.
-  TryToConnect(true);
+    : mixer_(new AudioMixerAlsa()) {
+  mixer_->Init();
 }
 
 AudioHandler::~AudioHandler() {
-  Disconnect();
+  mixer_.reset();
 };
 
-bool AudioHandler::VerifyMixerConnection() {
-  if (mixer_ == NULL)
-    return false;
-
-  AudioMixer::State mixer_state = mixer_->GetState();
-  if (mixer_state == AudioMixer::READY)
-    return true;
-  if (connected_) {
-    // Something happened and the mixer is no longer valid after having been
-    // initialized earlier.
-    connected_ = false;
-    LOG(ERROR) << "Lost connection to mixer";
-  } else {
-    LOG(ERROR) << "Mixer not valid";
-  }
-
-  if ((mixer_state == AudioMixer::INITIALIZING) ||
-      (mixer_state == AudioMixer::SHUTTING_DOWN))
-    return false;
-
-  if (reconnect_tries_ < kMaxReconnectTries) {
-    reconnect_tries_++;
-    VLOG(1) << "Re-connecting to mixer attempt " << reconnect_tries_ << "/"
-            << kMaxReconnectTries;
-
-    connected_ = TryToConnect(false);
-
-    if (connected_) {
-      reconnect_tries_ = 0;
-      return true;
-    }
-    LOG(ERROR) << "Unable to re-connect to mixer";
-  }
-  return false;
-}
-
 // VolumeDbToPercent() and PercentToVolumeDb() conversion functions allow us
 // complete control over how the 0 to 100% range is mapped to actual loudness.
-// Volume range is from min_volume_db_ at just above 0% to max_volume_db_
-// at 100% with a special case at 0% which maps to kSilenceDb.
 //
 // 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.
 
-// static
 double AudioHandler::VolumeDbToPercent(double volume_db) const {
-  if (volume_db < min_volume_db_)
-    return 0;
-  return 100.0 * pow((volume_db - min_volume_db_) /
-      (max_volume_db_ - min_volume_db_), 1/kVolumeBias);
+  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);
 }
 
-// static
 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_;
+      (max_volume_db - min_volume_db) + min_volume_db;
 }
 
 // static