MuteSource Audio During Full Screen Cast

media/audio/win/audio_low_latency_input_win.cc

Index: media/audio/win/audio_low_latency_input_win.cc
diff --git a/media/audio/win/audio_low_latency_input_win.cc b/media/audio/win/audio_low_latency_input_win.cc
index 949d681945f058919e25758b9509bfb3aaa295b9..98f692f6b74f2db1d636f2a0be39da12a3358e37 100644
--- a/media/audio/win/audio_low_latency_input_win.cc
+++ b/media/audio/win/audio_low_latency_input_win.cc
@@ -4,6 +4,7 @@
 
 #include "media/audio/win/audio_low_latency_input_win.h"
 
+#include <endpointvolume.h>
 #include <memory>
 
 #include "base/logging.h"
@@ -35,7 +36,8 @@ WASAPIAudioInputStream::WASAPIAudioInputStream(AudioManagerWin* manager,
       perf_count_to_100ns_units_(0.0),
       ms_to_frame_count_(0.0),
       sink_(NULL),
-      audio_bus_(media::AudioBus::Create(params)) {
+      audio_bus_(media::AudioBus::Create(params)),
+      mute_done_(false) {
   DCHECK(manager_);
 
   // Load the Avrt DLL if not already loaded. Required to support MMCSS.
@@ -165,6 +167,19 @@ void WASAPIAudioInputStream::Stop() {
   if (!started_)
     return;
 
+  if (device_id_ == AudioDeviceDescription::kLoopbackWithMuteDeviceId &&

[henrika (OOO until Aug 14), 2016/07/25 08:38:19]

Add a comment on 169 explaining what you do here.

[qiangchen, 2016/07/25 22:42:22]

Done.

+      mute_done_) {
+    IAudioEndpointVolume* pVolume = NULL;
+    HRESULT hr =
+        endpoint_device_->Activate(__uuidof(IAudioEndpointVolume), CLSCTX_ALL,
+                                   NULL, reinterpret_cast<void**>(&pVolume));

[henrika (OOO until Aug 14), 2016/07/25 08:38:19]

Can you use base::win::ScopedComPtr<IAudioEndpointVolume> here as well (your
style is not in line with the rest of the file)?

[qiangchen, 2016/07/25 22:42:22]

Done.

+
+    if (SUCCEEDED(hr)) {
+      hr = pVolume->SetMute(false, NULL);
+      mute_done_ = false;
+    }
+  }
+
   // Stops periodic AGC microphone measurements.
   StopAgc();
 
@@ -471,6 +486,23 @@ HRESULT WASAPIAudioInputStream::SetCaptureDevice() {
   } else if (device_id_ == AudioDeviceDescription::kCommunicationsDeviceId) {
     hr = enumerator->GetDefaultAudioEndpoint(eCapture, eCommunications,
                                              endpoint_device_.Receive());
+  } else if (device_id_ == AudioDeviceDescription::kLoopbackWithMuteDeviceId) {
+    // Capture the default playback stream.
+    hr = enumerator->GetDefaultAudioEndpoint(eRender, eConsole,
+                                             endpoint_device_.Receive());
+
+    IAudioEndpointVolume* pVolume = NULL;

[henrika (OOO until Aug 14), 2016/07/25 08:38:19]

See comments above. Also, you duplicate code here. Can you break out a static
helper to avoid that.

[qiangchen, 2016/07/25 22:42:22]

Done.

+    HRESULT hr2 =

[henrika (OOO until Aug 14), 2016/07/25 08:38:19]

Try to clean this up and avoid using a second HRESULT here. Makes it hare to
follow the error handling IMHO. 

[qiangchen, 2016/07/25 22:42:22]

Done.

+        endpoint_device_->Activate(__uuidof(IAudioEndpointVolume), CLSCTX_ALL,
+                                   NULL, reinterpret_cast<void**>(&pVolume));
+    if (SUCCEEDED(hr2) && pVolume) {
+      BOOL muted = false;
+      hr2 = pVolume->GetMute(&muted);
+      if (SUCCEEDED(hr2) && !muted) {

[henrika (OOO until Aug 14), 2016/07/25 08:38:19]

Improve comments and explain why you always mute here.

[qiangchen, 2016/07/25 22:42:22]

Done.

+        hr2 = pVolume->SetMute(true, NULL);
+        mute_done_ = true;
+      }
+    }
   } else if (device_id_ == AudioDeviceDescription::kLoopbackInputDeviceId) {
     // Capture the default playback stream.
     hr = enumerator->GetDefaultAudioEndpoint(eRender, eConsole,
@@ -572,7 +604,8 @@ HRESULT WASAPIAudioInputStream::InitializeAudioEngine() {
   // Use event-driven mode only fo regular input devices. For loopback the
   // EVENTCALLBACK flag is specified when intializing
   // |audio_render_client_for_loopback_|.
-  if (device_id_ == AudioDeviceDescription::kLoopbackInputDeviceId) {
+  if (device_id_ == AudioDeviceDescription::kLoopbackInputDeviceId ||
+      device_id_ == AudioDeviceDescription::kLoopbackWithMuteDeviceId) {
     flags = AUDCLNT_STREAMFLAGS_LOOPBACK | AUDCLNT_STREAMFLAGS_NOPERSIST;
   } else {
     flags = AUDCLNT_STREAMFLAGS_EVENTCALLBACK | AUDCLNT_STREAMFLAGS_NOPERSIST;
@@ -646,7 +679,8 @@ HRESULT WASAPIAudioInputStream::InitializeAudioEngine() {
   //   samples from the capture endpoint buffer.
   //
   // http://msdn.microsoft.com/en-us/library/windows/desktop/dd316551(v=vs.85).aspx
-  if (device_id_ == AudioDeviceDescription::kLoopbackInputDeviceId) {
+  if (device_id_ == AudioDeviceDescription::kLoopbackInputDeviceId ||
+      device_id_ == AudioDeviceDescription::kLoopbackWithMuteDeviceId) {
     hr = endpoint_device_->Activate(
         __uuidof(IAudioClient), CLSCTX_INPROC_SERVER, NULL,
         audio_render_client_for_loopback_.ReceiveVoid());