This patch will loop through the soundcard and return a list of available devices when the AudioI...

media/audio/mac/audio_manager_mac.cc

Index: media/audio/mac/audio_manager_mac.cc
===================================================================
--- media/audio/mac/audio_manager_mac.cc	(revision 106297)
+++ media/audio/mac/audio_manager_mac.cc	(working copy)
@@ -5,6 +5,7 @@
 #include <CoreAudio/AudioHardware.h>
 
 #include "base/mac/mac_util.h"
+#include "base/sys_string_conversions.h"
 #include "media/audio/fake_audio_input_stream.h"
 #include "media/audio/fake_audio_output_stream.h"
 #include "media/audio/mac/audio_input_mac.h"
@@ -65,6 +66,93 @@
       output_device_id != kAudioObjectUnknown;
 }
 
+static void GetAudioDeviceInfo(
+    bool is_input, media::AudioDeviceNames* device_names) {

[scherkus (not reviewing), 2011/10/19 17:38:51]

nit: should go on previous line and align parameters at (

[no longer working on chromium, 2011/10/19 18:13:21]

Done.

+  if (!device_names)
+    return;
+
+  device_names->clear();
+
+  // Query the number of total devices.
+  UInt32 size = 0;
+  OSStatus result = AudioHardwareGetPropertyInfo(kAudioHardwarePropertyDevices,
+                                                 &size,
+                                                 NULL);
+  if (result || !size)
+    return;
+
+  int device_count = 0;
+  device_count = size / sizeof(AudioDeviceID);
+
+  // Get the array of device id for each device.
+  scoped_ptr_malloc<AudioDeviceID>
+      devices(reinterpret_cast<AudioDeviceID*>(malloc(size)));
+  AudioDeviceID* device_ids = devices.get();
+  result = AudioHardwareGetProperty(kAudioHardwarePropertyDevices,

[scherkus (not reviewing), 2011/10/19 17:38:51]

I'm curious do we need malloc() or does new[] work?

[no longer working on chromium, 2011/10/19 18:13:21]

The Apple sample code is using malloc, I am not sure here but believe both new
should work.

+                                    &size,
+                                    device_ids);
+  if (result)
+    return;
+
+  // Iterate each device to gather information.
+  for (int i = 0; i < device_count; ++i) {
+    {

[scherkus (not reviewing), 2011/10/19 17:38:51]

why do we have the separate scope?

[no longer working on chromium, 2011/10/19 18:13:21]

Because it is in a loop and we need to allocate dynamic memory to the variable
"buffer", which may have differ size for each device. Putting it in a separate
scope is to free the memory. 

+      int channels = 0;
+      // Get the number of input or output channels of the device, exclude
+      // those devices without any right type of channel.
+      AudioDeviceGetPropertyInfo(device_ids[i],
+                                 0,
+                                 is_input,
+                                 kAudioDevicePropertyStreamConfiguration,
+                                 &size,
+                                 NULL);
+      scoped_ptr_malloc<AudioBufferList>
+          buffer(reinterpret_cast<AudioBufferList*>(malloc(size)));

[scherkus (not reviewing), 2011/10/19 17:38:51]

ditto

[no longer working on chromium, 2011/10/19 18:13:21]

ditto.

+      AudioBufferList* buffer_list = buffer.get();
+      AudioDeviceGetProperty(device_ids[i],
+                             0,
+                             is_input,
+                             kAudioDevicePropertyStreamConfiguration,
+                             &size,
+                             buffer_list);
+
+      for (uint32 j = 0; j < buffer_list->mNumberBuffers; ++j)
+        channels += buffer_list->mBuffers[j].mNumberChannels;
+
+      if (!channels)
+        continue;
+    }
+
+    // Get device UID.
+    CFStringRef uid = NULL;
+    size = sizeof(uid);
+    result = AudioDeviceGetProperty(device_ids[i],
+                                    0,
+                                    is_input,
+                                    kAudioDevicePropertyDeviceUID,
+                                    &size,
+                                    &uid);
+    if (result)
+      continue;
+
+    // Get device name.
+    CFStringRef name = NULL;
+    result = AudioDeviceGetProperty(device_ids[i],
+                                    0,
+                                    is_input,
+                                    kAudioObjectPropertyName,
+                                    &size,
+                                    &name);
+    if (result)
+      continue;
+
+    media::AudioDeviceName device_name;
+    device_name.device_name = base::SysCFStringRefToUTF8(name);
+    device_name.unique_id = base::SysCFStringRefToUTF8(uid);
+    device_names->push_back(device_name);
+  }
+}
+
 AudioManagerMac::AudioManagerMac()
     : num_output_streams_(0) {
 }
@@ -82,15 +170,15 @@
 
 void AudioManagerMac::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.
+  GetAudioDeviceInfo(true, device_names);
+  if (!device_names->empty()) {
+    // Prepend the default device to the list since we always want it to be
+    // on the top of the list for all platforms. There is no duplicate
+    // counting here since the default device has been abstracted out before.
     media::AudioDeviceName name;
     name.device_name = AudioManagerBase::kDefaultDeviceName;
     name.unique_id = "0";
-    device_names->push_back(name);
+    device_names->push_front(name);
   }
 }