Adding GetAudioInputDeviceNames() to AudioManager, which allows for device enumeration.

The current version only supports the default device and isn't fully implemented for Mac/Windows yet.

Patch by xians@chromium.org:
http://codereview.chromium.org/7060011/

BUG=none
TEST=media_unittests

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@87493 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 91 insertions, 4 deletions

diff --git a/media/audio/linux/audio_manager_linux.cc b/media/audio/linux/audio_manager_linux.cc
index b1108be..58b4c0e 100644
--- a/media/audio/linux/audio_manager_linux.cc
+++ b/media/audio/linux/audio_manager_linux.cc
@@ -23,6 +23,30 @@ static const size_t kMaxOutputStreams = 50;
 
 static const int kMaxInputChannels = 2;
 
+// Since "default", "pulse" and "dmix" devices are virtual devices mapped to
+// real devices, we remove them from the list to avoiding duplicate counting.
+// In addition, note that we support no more than 2 channels for recording,
+// hence surround devices are not stored in the list.
+static const char* kInvalidAudioInputDevices[] = {
+  "default",
+  "null",
+  "pulse",
+  "dmix",
+  "surround",
+};
+
+static bool IsValidAudioInputDevice(const char* device_name) {
+  if (!device_name)
+    return false;
+
+  for (size_t i = 0; i < arraysize(kInvalidAudioInputDevices); ++i) {
+    if (strcmp(kInvalidAudioInputDevices[i], device_name) == 0)
+      return false;
+  }
+
+  return true;
+}
+
 // Implementation of AudioManager.
 bool AudioManagerLinux::HasAudioOutputDevices() {
   // TODO(ajwong): Make this actually query audio devices.
@@ -30,8 +54,31 @@ bool AudioManagerLinux::HasAudioOutputDevices() {
 }
 
 bool AudioManagerLinux::HasAudioInputDevices() {
-  // TODO(satish): Make this actually query audio devices.
-  return true;
+  if (!initialized()) {
+    return false;
+  }
+
+  // Constants specified by the ALSA API for device hints.
+  static const int kGetAllDevices = -1;
+  static const char kPcmInterfaceName[] = "pcm";
+  bool has_device = false;
+  void** hints = NULL;
+
+  // Use the same approach to find the devices as in
+  // AlsaPcmOutputStream::FindDeviceForChannels
+  // Get Alsa device hints.
+  int error = wrapper_->DeviceNameHint(kGetAllDevices,
+                                       kPcmInterfaceName,
+                                       &hints);
+  if (error == 0) {
+    has_device = HasAnyValidAudioInputDevice(hints);
+  } else {
+    LOG(ERROR) << "Unable to get device hints: " << wrapper_->StrError(error);
+  }
+
+  // Destroy the hint now that we're done with it.
+  wrapper_->DeviceNameFreeHint(hints);
+  return has_device;
 }
 
 AudioOutputStream* AudioManagerLinux::MakeAudioOutputStream(
@@ -96,8 +143,8 @@ AudioManagerLinux::AudioManagerLinux() {
 }
 
 AudioManagerLinux::~AudioManagerLinux() {
-  // Make sure we stop the thread first. If we let the default destructor to
-  // destruct the members, we may destroy audio streams before stopping the
+  // Make sure we stop the thread first. If we allow the default destructor to
+  // destroy the members, we may destroy audio streams before stopping the
   // thread, resulting an unexpected behavior.
   // This way we make sure activities of the audio streams are all stopped
   // before we destroy them.
@@ -147,6 +194,42 @@ void AudioManagerLinux::ShowAudioInputSettings() {
   base::LaunchApp(CommandLine(FilePath(command)), false, false, NULL);
 }
 
+void AudioManagerLinux::GetAudioInputDeviceNames(
+    media::AudioDeviceNames* device_names) {
+  // TODO(xians): query a full list of valid devices.
+  if (HasAudioInputDevices()) {
+    // Add the default device to the list.
+    // We use index 0 to make up the unique_id to identify the
+    // default devices.
+    media::AudioDeviceName name;
+    name.device_name = AudioManagerBase::kDefaultDeviceName;
+    name.unique_id = "0";
+    device_names->push_back(name);
+  }
+}
+
+bool AudioManagerLinux::HasAnyValidAudioInputDevice(void** hints) {
+  static const char kIoHintName[] = "IOID";
+  static const char kNameHintName[] = "NAME";
+  static const char kOutputDevice[] = "Output";
+
+  for (void** hint_iter = hints; *hint_iter != NULL; hint_iter++) {
+    // Only examine devices that are input capable.  Valid values are
+    // "Input", "Output", and NULL which means both input and output.
+    scoped_ptr_malloc<char> io(wrapper_->DeviceNameGetHint(*hint_iter,
+                                                           kIoHintName));
+    if (io != NULL && strcmp(kOutputDevice, io.get()) == 0)
+      continue;
+
+    scoped_ptr_malloc<char> hint_device_name(
+        wrapper_->DeviceNameGetHint(*hint_iter, kNameHintName));
+    if (IsValidAudioInputDevice(hint_device_name.get()))
+      return true;
+  }
+
+  return false;
+}
+
 // static
 AudioManager* AudioManager::CreateAudioManager() {
   return new AudioManagerLinux();
diff --git a/media/audio/linux/audio_manager_linux.h b/media/audio/linux/audio_manager_linux.h
index b7d43f0..6a5d287 100644
--- a/media/audio/linux/audio_manager_linux.h
+++ b/media/audio/linux/audio_manager_linux.h
@@ -30,6 +30,7 @@ class AudioManagerLinux : public AudioManagerBase {
   virtual AudioInputStream* MakeAudioInputStream(AudioParameters params);
   virtual bool CanShowAudioInputSettings();
   virtual void ShowAudioInputSettings();
+  virtual void GetAudioInputDeviceNames(media::AudioDeviceNames* device_names);
 
   virtual void MuteAll();
   virtual void UnMuteAll();
@@ -40,6 +41,9 @@ class AudioManagerLinux : public AudioManagerBase {
   virtual ~AudioManagerLinux();
 
  private:
+  // Helper method to query if there is any valid input device
+  bool HasAnyValidAudioInputDevice(void** hint);
+
   scoped_ptr<AlsaWrapper> wrapper_;
 
   base::Lock lock_;