Bug 1103824 - Ensure first initialization of IAudioClient happens on STA thread. r=padenot

dom/media/CubebUtils.cpp

@@ -131,6 +131,15 @@ void InitLibrary()
   Preferences::RegisterCallback(PrefChanged, PREF_VOLUME_SCALE);
   PrefChanged(PREF_CUBEB_LATENCY, nullptr);
   Preferences::RegisterCallback(PrefChanged, PREF_CUBEB_LATENCY);
+
+#if defined(XP_WIN)
+  // Ensure the first call to cubeb_init is made from the main thread.
+  MOZ_ASSERT(NS_IsMainThread() && !sCubebContext);
+  cubeb * context;
+  if (cubeb_init(&context, "FirstInitContext") == CUBEB_OK) {
+    cubeb_destroy(context);
+  }
+#endif
 }
 
 void ShutdownLibrary()

media/libcubeb/src/cubeb_wasapi.cpp

@@ -144,28 +144,17 @@ private:
 };
 
 struct auto_com {
-  auto_com() {
+  auto_com(DWORD dwCoInit = COINIT_MULTITHREADED) {
-    result = CoInitializeEx(NULL, COINIT_MULTITHREADED);
+    result = CoInitializeEx(NULL, dwCoInit);
   }
   ~auto_com() {
-    if (result == RPC_E_CHANGED_MODE) {
+    if (ok()) {
-      // This is not an error, COM was not initialized by this function, so it is
-      // not necessary to uninit it.
-      LOG("COM already initialized in STA.\n");
-    } else if (result == S_FALSE) {
-      // This is not an error. We are allowed to call CoInitializeEx more than
-      // once, as long as it is matches by an CoUninitialize call.
-      // We do that in the dtor which is guaranteed to be called.
-      LOG("COM already initialized in MTA\n");
-    }
-    if (SUCCEEDED(result)) {
       CoUninitialize();
     }
   }
   bool ok() {
-    return result == RPC_E_CHANGED_MODE || SUCCEEDED(result);
+    return SUCCEEDED(result);
   }
-private:
   HRESULT result;
 };
 
@@ -492,6 +481,7 @@ wasapi_stream_render_loop(LPVOID stream)
   auto_com com;
   if (!com.ok()) {
     LOG("COM initialization failed on render_loop thread.\n");
+    stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR);
     return 0;
   }
 
@@ -688,14 +678,19 @@ HRESULT get_default_endpoint(IMMDevice ** device)
 
   return ERROR_SUCCESS;
 }
+
+owned_critical_section g_first_init_lock;
+bool g_first_init = false;
 } // namespace anonymous
 
 extern "C" {
 int wasapi_init(cubeb ** context, char const * context_name)
 {
-  HRESULT hr;
+  auto_lock lock(&g_first_init_lock);
-  auto_com com;
+  if (!g_first_init) {
-  if (!com.ok()) {
+    // Per the MSDN documentation for IAudioClient, the first use *must* be made from an STA thread.
+    auto_com com(COINIT_APARTMENTTHREADED);
+    if (FAILED(com.result)) {
       return CUBEB_ERROR;
     }
 
@@ -703,12 +698,37 @@ int wasapi_init(cubeb ** context, char const * context_name)
        so that this backend is not incorrectly enabled on platforms that don't
        support WASAPI. */
     IMMDevice * device;
-  hr = get_default_endpoint(&device);
+    HRESULT hr = get_default_endpoint(&device);
     if (FAILED(hr)) {
-    LOG("Could not get device.\n");
+      LOG("Could not get device: %x\n", hr);
       return CUBEB_ERROR;
     }
+    IAudioClient * client;
+    hr = device->Activate(__uuidof(IAudioClient),
+                          CLSCTX_INPROC_SERVER,
+                          NULL, (void **)&client);
+    if (SUCCEEDED(hr)) {
+      WAVEFORMATEX * mix_format;
+      hr = client->GetMixFormat(&mix_format);
+      if (SUCCEEDED(hr)) {
+        hr = client->Initialize(AUDCLNT_SHAREMODE_SHARED,
+                                AUDCLNT_STREAMFLAGS_EVENTCALLBACK |
+                                AUDCLNT_STREAMFLAGS_NOPERSIST,
+                                ms_to_hns(100),
+                                0,
+                                mix_format,
+                                NULL);
+        CoTaskMemFree(mix_format);
+        g_first_init = true;
+      }
+      SafeRelease(client);
+    }
     SafeRelease(device);
+    if (FAILED(hr)) {
+      LOG("Could not initialize IAudioClient: %x\n", hr);
+      return CUBEB_ERROR;
+    }
+  }
 
   cubeb * ctx = (cubeb *)calloc(1, sizeof(cubeb));
 
@@ -784,10 +804,8 @@ wasapi_get_max_channel_count(cubeb * ctx, uint32_t * max_channels)
   HRESULT hr;
   IAudioClient * client;
   WAVEFORMATEX * mix_format;
-  auto_com com;
+  XASSERT(g_first_init);
-  if (!com.ok()) {
+  auto_com com; /* don't care what COM mode we're in here */
-    return CUBEB_ERROR;
-  }
 
   XASSERT(ctx && max_channels);
 
@@ -825,10 +843,8 @@ wasapi_get_min_latency(cubeb * ctx, cubeb_stream_params params, uint32_t * laten
   HRESULT hr;
   IAudioClient * client;
   REFERENCE_TIME default_period;
-  auto_com com;
+  XASSERT(g_first_init);
-  if (!com.ok()) {
+  auto_com com; /* don't care what COM mode we're in here */
-    return CUBEB_ERROR;
-  }
 
   IMMDevice * device;
   hr = get_default_endpoint(&device);
@@ -872,10 +888,8 @@ wasapi_get_preferred_sample_rate(cubeb * ctx, uint32_t * rate)
   HRESULT hr;
   IAudioClient * client;
   WAVEFORMATEX * mix_format;
-  auto_com com;
+  XASSERT(g_first_init);
-  if (!com.ok()) {
+  auto_com com; /* don't care what COM mode we're in here */
-    return CUBEB_ERROR;
-  }
 
   IMMDevice * device;
   hr = get_default_endpoint(&device);