Pass more detailed audio hardware configuration information to the renderer

media/audio/mac/audio_manager_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_manager_mac.h"
 
 #include <CoreAudio/AudioHardware.h>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 246 matching lines @@
 }
 
 bool AudioManagerMac::HasAudioOutputDevices() {
   return HasAudioHardware(kAudioHardwarePropertyDefaultOutputDevice);
 }
 
 bool AudioManagerMac::HasAudioInputDevices() {
   return HasAudioHardware(kAudioHardwarePropertyDefaultInputDevice);
 }
 
+// TODO(crogers): There are several places on the OSX specific code which
+// could benefit from this helper function.
+bool AudioManagerMac::GetDefaultOutputDevice(
+    AudioDeviceID* device) {
+  CHECK(device);
+
+  // Obtain the current output device selected by the user.
+  static const AudioObjectPropertyAddress kAddress = {
+      kAudioHardwarePropertyDefaultOutputDevice,
+      kAudioObjectPropertyScopeGlobal,
+      kAudioObjectPropertyElementMaster
+  };
+
+  UInt32 size = sizeof(*device);
+
+  OSStatus result = AudioObjectGetPropertyData(
+      kAudioObjectSystemObject,
+      &kAddress,
+      0,
+      0,
+      &size,
+      device);
+
+  if ((result != kAudioHardwareNoError) || (*device == kAudioDeviceUnknown)) {
+    DLOG(ERROR) << "Error getting default output AudioDevice.";
+    return false;
+  }
+
+  return true;
+}
+
+bool AudioManagerMac::GetDefaultOutputChannels(
+    int* channels, int* channels_per_frame) {
+  AudioDeviceID device;
+  if (!GetDefaultOutputDevice(&device))
+    return false;
+
+  return GetDeviceChannels(device,
+                           kAudioDevicePropertyScopeOutput,
+                           channels,
+                           channels_per_frame);
+}
+
+bool AudioManagerMac::GetDeviceChannels(
+    AudioDeviceID device,
+    AudioObjectPropertyScope scope,
+    int* channels,
+    int* channels_per_frame) {
+  CHECK(channels);
+  CHECK(channels_per_frame);
+
+  // Get stream configuration.
+  AudioObjectPropertyAddress pa;
+  pa.mSelector = kAudioDevicePropertyStreamConfiguration;
+  pa.mScope = scope;
+  pa.mElement = kAudioObjectPropertyElementMaster;
+
+  UInt32 size;
+  OSStatus result = AudioObjectGetPropertyDataSize(device, &pa, 0, 0, &size);
+  if (result != noErr || !size)
+    return false;
+
+  // 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);
+  if (result != noErr)
+    return false;
+
+  // 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 true;
+}
+
 void AudioManagerMac::GetAudioInputDeviceNames(
     media::AudioDeviceNames* device_names) {
   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 =  AudioManagerBase::kDefaultDeviceId;
@@ skipping 49 matching lines @@
   AudioDeviceID audio_device_id = GetAudioDeviceIdByUId(true, device_id);
   AudioInputStream* stream = NULL;
   if (audio_device_id != kAudioObjectUnknown)
     stream = new AUAudioInputStream(this, params, audio_device_id);
 
   return stream;
 }
 
 AudioParameters AudioManagerMac::GetPreferredOutputStreamParameters(
     const AudioParameters& input_params) {
-  ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
+  int hardware_channels = 2;
+  int hardware_channels_per_frame;
+  GetDefaultOutputChannels(&hardware_channels, &hardware_channels_per_frame);

[DaleCurtis, 2013/03/11 19:21:50]

Check return value? hardware_channels_per_frame should be initialized to 0 since
its possible for this function to leave it uninitialized.

[Chris Rogers, 2013/03/12 22:32:31]

Fixed - although hardware_channels_per_frame is unused here - it's best to have
a default value of 1 which means non-interleaved.  0 is not valid.

+
+  ChannelLayout channel_layout = GuessChannelLayout(hardware_channels);
+
   int buffer_size = kDefaultLowLatencyBufferSize;
+  int user_buffer_size = GetUserBufferSize();
+  if (user_buffer_size)
+    buffer_size = user_buffer_size;
+
   int input_channels = 0;
   if (input_params.IsValid()) {
-    channel_layout = input_params.channel_layout();
     input_channels = input_params.input_channels();
 
     if (input_channels > 0) {
       // TODO(crogers): given the limitations of the AudioOutputStream
       // back-ends used with synchronized I/O, we hard-code to stereo.
       // Specifically, this is a limitation of AudioSynchronizedStream which
       // can be removed as part of the work to consolidate these back-ends.
       channel_layout = CHANNEL_LAYOUT_STEREO;
     }
   }
 
-  int user_buffer_size = GetUserBufferSize();
-  if (user_buffer_size)
-    buffer_size = user_buffer_size;
+  AudioParameters params(
+      AudioParameters::AUDIO_PCM_LOW_LATENCY,
+      channel_layout,
+      input_channels,
+      AUAudioOutputStream::HardwareSampleRate(),
+      16,
+      buffer_size);
 
-  return AudioParameters(
-      AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout, input_channels,
-      AUAudioOutputStream::HardwareSampleRate(), 16, buffer_size);
+  if (channel_layout == CHANNEL_LAYOUT_UNSUPPORTED)
+    params.SetDiscreteChannels(hardware_channels);
+
+  return params;
 }
 
 void AudioManagerMac::CreateDeviceListener() {
   DCHECK(GetMessageLoop()->BelongsToCurrentThread());
   output_device_listener_.reset(new AudioDeviceListenerMac(base::Bind(
       &AudioManagerMac::DelayedDeviceChange, base::Unretained(this))));
 }
 
 void AudioManagerMac::DestroyDeviceListener() {
   DCHECK(GetMessageLoop()->BelongsToCurrentThread());
   output_device_listener_.reset();
 }
 
 void AudioManagerMac::DelayedDeviceChange() {
   // TODO(dalecurtis): This is ridiculous, but we need to delay device changes
   // to workaround threading issues with OSX property listener callbacks.  See
   // http://crbug.com/158170
   GetMessageLoop()->PostDelayedTask(FROM_HERE, base::Bind(
       &AudioManagerMac::NotifyAllOutputDeviceChangeListeners,
       base::Unretained(this)), base::TimeDelta::FromSeconds(2));
 }
 
 AudioManager* CreateAudioManager() {
   return new AudioManagerMac();
 }
 
 }  // namespace media