Pass more detailed audio hardware configuration information to the renderer

media/audio/mac/audio_unified_mac.cc

 // Copyright (c) 2012 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 "media/audio/mac/audio_unified_mac.h"
 
 #include <CoreServices/CoreServices.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
@@ skipping 377 matching lines @@
 
   return audio_output->Render(
       device,
       now,
       input_data,
       input_time,
       output_data,
       output_time);
 }
 
+bool AudioHardwareUnifiedStream::GetDefaultOutputDevice(

[DaleCurtis, 2013/03/06 19:19:30]

I think this code should live in AudioManagerMac. Additionally this
GetDefaultOutputDevice code has at least 3 or 4 copies around the OSX code base.
It should be deduplicated.

[Chris Rogers, 2013/03/07 00:34:17]

I've moved the functions to AudioManagerMac.  I agree about the code
duplication, but I'm cautious to change all the potential benefactors of these
new functions in this CL, since I'd like to be careful about that move and it
will involve other specific testing.  I'm just trying to keep the number of
changes sane in the CL and work in smaller work units.

Adding TODO in latest patchset.

+    AudioDeviceID* device) {
+  if (!device)
+    return false;
+
+  // Obtain the current output device selected by the user.
+  AudioObjectPropertyAddress pa;
+  pa.mSelector = kAudioHardwarePropertyDefaultOutputDevice;
+  pa.mScope = kAudioObjectPropertyScopeGlobal;
+  pa.mElement = kAudioObjectPropertyElementMaster;
+
+  UInt32 size = sizeof(*device);
+
+  OSStatus result = AudioObjectGetPropertyData(
+      kAudioObjectSystemObject,
+      &pa,
+      0,
+      0,
+      &size,
+      device);
+
+  if ((result != kAudioHardwareNoError) || (*device == kAudioDeviceUnknown)) {
+    LOG(ERROR) << "Error getting default output AudioDevice.";
+    return false;
+  }
+
+  return true;
+}
+
+bool AudioHardwareUnifiedStream::GetDefaultOutputChannels(
+    int* channels, int* channels_per_frame) {
+  AudioDeviceID device;
+  if (!GetDefaultOutputDevice(&device))
+    return false;
+
+  return GetDeviceChannels(device,
+                           kAudioDevicePropertyScopeOutput,
+                           channels,
+                           channels_per_frame);
+}
+
+bool AudioHardwareUnifiedStream::GetDeviceChannels(
+    AudioDeviceID device,
+    AudioObjectPropertyScope scope,
+    int* channels,
+    int* channels_per_frame) {
+  if (!channels || !channels_per_frame)
+    return false;
+
+  // Get stream configuration.
+  AudioObjectPropertyAddress pa;
+  pa.mSelector = kAudioDevicePropertyStreamConfiguration;
+  pa.mScope = scope;
+  pa.mElement = kAudioObjectPropertyElementMaster;
+
+  UInt32 size;
+  OSStatus result = AudioObjectGetPropertyDataSize(device, &pa, 0, 0, &size);
+  OSSTATUS_DCHECK(result == noErr, result);
+
+  if (result == noErr && size > 0) {
+    // Allocate storage.
+    scoped_array<uint8> list_storage(new uint8[size]);
+    AudioBufferList& buffer_list =
+        *reinterpret_cast<AudioBufferList*>(list_storage.get());
+
+    result = AudioObjectGetPropertyData(
+        device,
+        &pa,
+        0,
+        0,
+        &size,
+        &buffer_list);
+    OSSTATUS_DCHECK(result == noErr, result);
+
+    if (result == noErr) {
+      // Determine number of input channels.
+      *channels_per_frame = buffer_list.mNumberBuffers > 0 ?
+          buffer_list.mBuffers[0].mNumberChannels : 0;
+      if (*channels_per_frame == 1 && buffer_list.mNumberBuffers > 1) {
+        // Non-interleaved.
+        *channels = buffer_list.mNumberBuffers;
+      } else {
+        // Interleaved.
+        *channels = *channels_per_frame;
+      }
+    }
+  }
+
+  return result == noErr;
+}
+
 }  // namespace media