Handle audio device changes on Windows.

media/audio/win/audio_device_listener_win.cc

Index: media/audio/win/audio_device_listener_win.cc
diff --git a/media/audio/win/audio_device_listener_win.cc b/media/audio/win/audio_device_listener_win.cc
new file mode 100644
index 0000000000000000000000000000000000000000..77eea2e2ddd7919cf7f39cda6a7792c24e112b4f
--- /dev/null
+++ b/media/audio/win/audio_device_listener_win.cc
@@ -0,0 +1,143 @@
+// 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/win/audio_device_listener_win.h"
+
+#include <Audioclient.h>
+#include <Functiondiscoverykeys_devpkey.h>
+
+#include "base/logging.h"
+#include "base/utf_string_conversions.h"
+#include "base/win/scoped_co_mem.h"
+#include "base/win/windows_version.h"
+
+using base::win::ScopedCoMem;
+
+namespace media {
+
+// TODO(henrika): Move to CoreAudioUtil class.

[henrika (OOO until Aug 14), 2012/10/23 07:38:06]

Nit, is is actually a bunch of static media::win::foo() methods.

+static ScopedComPtr<IMMDeviceEnumerator> CreateDeviceEnumerator() {
+  ScopedComPtr<IMMDeviceEnumerator> device_enumerator;
+  HRESULT hr = CoCreateInstance(__uuidof(MMDeviceEnumerator),
+                                NULL,
+                                CLSCTX_INPROC_SERVER,
+                                __uuidof(IMMDeviceEnumerator),
+                                device_enumerator.ReceiveVoid());
+  DLOG_IF(ERROR, FAILED(hr)) << "CoCreateInstance(IMMDeviceEnumerator): "
+                             << std::hex << hr;
+  return device_enumerator;
+}
+
+AudioDeviceListenerWin::AudioDeviceListenerWin(
+    AudioManager::AudioDeviceListener* listener)
+    : listener_(listener) {
+  // Windows Core Audio is only supported on Vista or higher.
+  if (base::win::GetVersion() < base::win::VERSION_VISTA)
+    return;
+
+  device_enumerator_ = CreateDeviceEnumerator();
+  if (!device_enumerator_)
+    return;
+
+  HRESULT hr = device_enumerator_->RegisterEndpointNotificationCallback(this);
+  if (FAILED(hr)) {
+    DLOG(ERROR)  << "RegisterEndpointNotificationCallback failed";
+    return;
+  }
+
+  ScopedComPtr<IMMDevice> endpoint_device;
+  hr = device_enumerator_->GetDefaultAudioEndpoint(

[henrika (OOO until Aug 14), 2012/10/23 07:38:06]

Should we comment on the fact that you are hard coding for default rendering
here? I mean, you store default_device and it is not clear what flow direction
it is. My point is that we will use the same base for capture as well.

[DaleCurtis, 2012/10/24 00:09:27]

I've renamed the variable to default_render_device_id_. I've added some
clarifying comments to class description and a TODO for capture side.

+      eRender, eConsole, endpoint_device.Receive());
+  // This will fail if there are no audio devices currently plugged in, so we
+  // still want to keep our endpoint registered.
+  if (FAILED(hr)) {
+    DLOG(ERROR) << "GetDefaultAudioEndpoint() failed.  No devices?";

[henrika (OOO until Aug 14), 2012/10/23 07:38:06]

Easier to debug if you add << std::hex << hr.

[DaleCurtis, 2012/10/24 00:09:27]

Done.

+    return;
+  }
+
+  ScopedCoMem<WCHAR> device_id;
+  hr = endpoint_device->GetId(&device_id);
+  if (FAILED(hr)) {
+    DLOG(ERROR) << "GetId() failed";

[henrika (OOO until Aug 14), 2012/10/23 07:38:06]

dito

[DaleCurtis, 2012/10/24 00:09:27]

Done.

+    return;
+  }
+
+  default_device_id_ = WideToUTF8(static_cast<WCHAR*>(device_id));
+  DVLOG(1) << "Default Device: " << default_device_id_;

[henrika (OOO until Aug 14), 2012/10/23 07:38:06]

render

[DaleCurtis, 2012/10/24 00:09:27]

Done.

+}
+
+AudioDeviceListenerWin::~AudioDeviceListenerWin() {
+  if (device_enumerator_)
+    device_enumerator_->UnregisterEndpointNotificationCallback(this);
+}
+
+ULONG AudioDeviceListenerWin::AddRef() {
+  return 1;
+}
+
+ULONG AudioDeviceListenerWin::Release() {
+  return 1;
+}
+
+HRESULT AudioDeviceListenerWin::QueryInterface(REFIID iid, void** object) {
+  if (iid == IID_IUnknown || iid == __uuidof(IMMNotificationClient)) {
+    *object = static_cast < IMMNotificationClient*>(this);
+  } else {
+    return E_NOINTERFACE;
+  }
+  return S_OK;
+}
+
+HRESULT AudioDeviceListenerWin::OnPropertyValueChanged(LPCWSTR device_id,
+                                                       const PROPERTYKEY key) {
+  // TODO(dalecurtis): We need to handle changes for the current default device

[henrika (OOO until Aug 14), 2012/10/23 07:38:06]

I have written code that would work here but it is tricky and it is not worth
adding it now. Ping me when you need help.

+  // here.  It's tricky because this method may be called many (20+) times for
+  // a single change like sample rate.  http://crbug.com/153056
+  return S_OK;
+}
+
+HRESULT AudioDeviceListenerWin::OnDeviceAdded(LPCWSTR device_id) {
+  // We don't care when devices are added.
+  return S_OK;
+}
+
+HRESULT AudioDeviceListenerWin::OnDeviceRemoved(LPCWSTR device_id) {
+  // We don't care when devices are removed.
+  return S_OK;
+}
+
+HRESULT AudioDeviceListenerWin::OnDeviceStateChanged(LPCWSTR device_id,
+                                                     DWORD new_state) {
+  // TODO(dalecurtis): Are there any events we need to handle here?

[henrika (OOO until Aug 14), 2012/10/23 07:38:06]

Not at this stage. These events are very early and we can't use them as
indicator to restart. Useful for debugging.

[DaleCurtis, 2012/10/24 00:09:27]

Done.

+  return S_OK;
+}
+
+HRESULT AudioDeviceListenerWin::OnDefaultDeviceChanged(
+    EDataFlow flow, ERole role, LPCWSTR new_default_device_id) {
+  // Only listen for output device changes right now...

[henrika (OOO until Aug 14), 2012/10/23 07:38:06]

TODO?

[DaleCurtis, 2012/10/24 00:09:27]

Added to class docs.

+  if (flow != eConsole && role != eRender)
+    return S_OK;
+
+  // If no device is now available, |new_default_device_id| will be NULL.
+  std::string new_device_id = "";
+  if (new_default_device_id) {
+    new_device_id = WideToUTF8(static_cast<const WCHAR*>(
+        new_default_device_id));
+  }
+
+  // Only fire a state change event if the device has actually changed.
+  if (new_device_id.compare(default_device_id_) == 0)

[henrika (OOO until Aug 14), 2012/10/23 07:38:06]

I also prefer using STL here. Another way could be to work with WCHAR and use
wcscmp(). I vote for some extra WideTo.. and STL.

[DaleCurtis, 2012/10/23 20:09:08]

I'm a complete windows string noob, so if you've got a better way please let me
know :)

+    return S_OK;
+
+  default_device_id_ = new_device_id;
+
+  // TODO(dalecurtis): This still seems to fire an extra event on my machine for

[henrika (OOO until Aug 14), 2012/10/23 07:38:06]

Still true?

[DaleCurtis, 2012/10/24 00:09:27]

Yes.

+  // an unplug event (probably others too); e.g., we get two transitions to a
+  // new default device id.
+  listener_->OnDeviceChange();
+
+  return S_OK;
+}
+
+}  // namespace media