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..9cbd7ade98f76a9a83800c9657690ab3bcd7eb31
--- /dev/null
+++ b/media/audio/win/audio_device_listener_win.cc
@@ -0,0 +1,155 @@
+// 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/stringprintf.h"

[henrika (OOO until Aug 14), 2012/10/21 09:00:20]

Not used.

[DaleCurtis, 2012/10/23 01:49:42]

Done.

+#include "base/utf_string_conversions.h"
+#include "base/win/scoped_co_mem.h"
+#include "base/win/windows_version.h"
+#include "media/audio/win/avrt_wrapper_win.h"

[henrika (OOO until Aug 14), 2012/10/21 09:00:20]

Don't need this one.

[DaleCurtis, 2012/10/23 01:49:42]

Done.

+
+using base::win::ScopedCoMem;
+
+namespace media {
+
+static ScopedComPtr<IMMDeviceEnumerator> CreateDeviceEnumerator() {

[henrika (OOO until Aug 14), 2012/10/21 09:00:20]

TODO(henrika)

[DaleCurtis, 2012/10/23 01:49:42]

Done.

+  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;
+
+  bool avrt_init = avrt::Initialize();

[henrika (OOO until Aug 14), 2012/10/21 09:00:20]

Don't need this for the notification parts. Only required in combination with
MMCSS to boost up thread prios.

[henrika (OOO until Aug 14), 2012/10/21 09:00:20]

Don't need the avrt-part. Only required in combination with MMCSS to boost
thread prios.

[DaleCurtis, 2012/10/23 01:49:42]

Done.

+  DCHECK(avrt_init) << "Failed to load the avrt.dll";
+
+  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;

[henrika (OOO until Aug 14), 2012/10/21 09:00:20]

The last part of this method is for logging only; correct?

[DaleCurtis, 2012/10/23 01:49:42]

No we need the default_device_id to filter OnDefaultDeviceChanged notifications.

+  hr = device_enumerator_->GetDefaultAudioEndpoint(
+      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?";
+    return;
+  }
+
+  ScopedCoMem<WCHAR> device_id;
+  hr = endpoint_device->GetId(&device_id);
+  if (FAILED(hr)) {
+    DLOG(ERROR) << "GetId() failed";
+    return;
+  }
+
+  default_device_id_ = WideToUTF8(static_cast<WCHAR*>(device_id));
+  DLOG(ERROR) << "Default Device: " << default_device_id_;

[henrika (OOO until Aug 14), 2012/10/21 09:00:20]

Why ERROR?

[DaleCurtis, 2012/10/23 01:49:42]

Done.

+}
+
+AudioDeviceListenerWin::~AudioDeviceListenerWin() {
+  if (device_enumerator_)
+    device_enumerator_->UnregisterEndpointNotificationCallback(this);
+}
+
+ULONG AudioDeviceListenerWin::AddRef() {
+  NOTREACHED() << "IMMNotificationClient should not use this method.";
+  return 1;
+}
+
+ULONG AudioDeviceListenerWin::Release() {
+  NOTREACHED() << "IMMNotificationClient should not use this method.";
+  return 1;
+}
+
+HRESULT AudioDeviceListenerWin::QueryInterface(REFIID iid, void** object) {
+  NOTREACHED() << "IMMNotificationClient should not use this method.";
+  // TODO(dalecurtis): Why do we have this code under NOTREACHED()? Henrik?

[henrika (OOO until Aug 14), 2012/10/21 09:00:20]

The IMMNotification implementation feels like a hack if you ask me and I don't
remember now why I added NOTREACHED. They can most likely be removed. Let me
check some more. 

[henrika (OOO until Aug 14), 2012/10/22 10:40:24]

The interface requires that we add implementations for AddRef/Release and
QueryInterface but the doc states that we should not use them(see
http://msdn.microsoft.com/en-us/library/windows/desktop/dd371403(v=VS.85).aspx).
I guess we can remove NOTREACHED. I just added it as an extra sanity.

[DaleCurtis, 2012/10/23 01:49:42]

Done.

+  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), 2012/10/22 13:44:31]

Hhmm, what if we have three devices, A, B and C and the user changes props for C
but A is default. Then we should not do anything....
Hence, the notifier must know that the change is for the default device and
ignore change if not.

[DaleCurtis, 2012/10/23 01:49:42]

We can use the default_device_id_ saved in construction to filter this.  For now
lets just focus on the more common device change problem.

+  // here.  It's tricky because this method may be called many (20+) times for
+  // a single change like sample rate.

[scherkus (not reviewing), 2012/10/22 23:51:05]

this seems like a worthy follow-up optimization... file bug?

[DaleCurtis, 2012/10/23 01:49:42]

Done.

+  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;
+}
+
+STDMETHODIMP AudioDeviceListenerWin::OnDeviceStateChanged(LPCWSTR device_id,
+                                                          DWORD new_state) {
+  // TODO(dalecurtis): Are there any events we need to handle here?
+  return S_OK;
+}
+
+STDMETHODIMP AudioDeviceListenerWin::OnDefaultDeviceChanged(
+    EDataFlow flow, ERole role, LPCWSTR new_default_device_id) {
+  // Only listen for output device changes right now...
+  // TODO(dalecurtis): This is slightly different for exclusive mode right?  We

[henrika (OOO until Aug 14), 2012/10/21 09:00:20]

Not related to exclusive mode. Notifications should similar for this method.
Might be differences in OnProperty. Not sure.

[DaleCurtis, 2012/10/23 01:49:42]

Done.

+  // shouldn't be hard coding eConsole, eRender...
+  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.

[henrika (OOO until Aug 14), 2012/10/21 09:00:20]

Let me do some more tests on Monday and get back with feedback.
Note that there are three types of default devices on Windows. Default, Default
communication and Default multimedia. Not my idea...

[henrika (OOO until Aug 14), 2012/10/22 13:39:01]

I think we must take this off line. It is actually not trivial to make a perfect
detection here and the sequence depends on how your system is configured. Case
1) Two devices A and B where A is default and B is default comm. Now, set B to
Default instead.
Case 2) Two devices A and B where A is Default and B is disabled. Now enable B
=> another sequence.
In addition, all sequences will also call as eMultimedia is modified.

[DaleCurtis, 2012/10/23 01:49:42]

This will still work in that case, it's just that the audio will continue to
output to the old device, right? If so, I think that's fine for now. I'm really
only worried about the when USB audio devices are added / removed or hardware
mute is applied. 

+  // TODO(dalecurtis): Is this correct??  We get 3 of OnDefaultDeviceChanged()
+  // events for our flow and role.  Why??
+  if (new_device_id.compare(default_device_id_) == 0)
+    return S_OK;
+
+  default_device_id_ = new_device_id;
+
+  // TODO(dalecurtis): This still seems to fire an extra event on my machine for
+  // an unplug event (probably others too); e.g., we get two transitions to a
+  // new default device id.
+  listener_->OnDeviceChange();

[henrika (OOO until Aug 14), 2012/10/21 09:00:20]

Should we comment on the fact that is call will come from an internal MMDevice
thread dedicated for notifications.

[DaleCurtis, 2012/10/23 01:49:42]

Done.

+
+  return S_OK;
+}
+
+}  // namespace media