WASAPI: Try fixing an automatic stream routing bug.

Automatic stream routing should only be used when the ma_device object
is initialized with a device ID of NULL. When it's non-NULL (i.e. an
explicit device) it should not perform automatic stream routing. It
looks like the WASAPI backend is not respecting this requirements and
is enabling automatic stream routing in all cases.

Public issue #127

miniaudio.h

@@ -2516,11 +2516,13 @@ MA_ALIGNED_STRUCT(MA_SIMD_ALIGNMENT) ma_device
             ma_bool32 hasDefaultCaptureDeviceChanged;          /* <-- Make sure this is always a whole 32-bits because we use atomic assignments. */
             ma_uint32 periodSizeInFramesPlayback;
             ma_uint32 periodSizeInFramesCapture;
-            ma_bool32 isStartedCapture;
-            ma_bool32 isStartedPlayback;
-            ma_bool32 noAutoConvertSRC;     /* When set to true, disables the use of AUDCLNT_STREAMFLAGS_AUTOCONVERTPCM. */
-            ma_bool32 noDefaultQualitySRC;  /* When set to true, disables the use of AUDCLNT_STREAMFLAGS_SRC_DEFAULT_QUALITY. */
-            ma_bool32 noHardwareOffloading;
+            ma_bool32 isStartedCapture;                        /* <-- Make sure this is always a whole 32-bits because we use atomic assignments. */
+            ma_bool32 isStartedPlayback;                       /* <-- Make sure this is always a whole 32-bits because we use atomic assignments. */
+            ma_bool32 noAutoConvertSRC               : 1;      /* When set to true, disables the use of AUDCLNT_STREAMFLAGS_AUTOCONVERTPCM. */
+            ma_bool32 noDefaultQualitySRC            : 1;      /* When set to true, disables the use of AUDCLNT_STREAMFLAGS_SRC_DEFAULT_QUALITY. */
+            ma_bool32 noHardwareOffloading           : 1;
+            ma_bool32 allowCaptureAutoStreamRouting  : 1;
+            ma_bool32 allowPlaybackAutoStreamRouting : 1;
         } wasapi;
 #endif
 #ifdef MA_SUPPORT_DSOUND
@@ -7832,6 +7834,12 @@ HRESULT STDMETHODCALLTYPE ma_IMMNotificationClient_OnDefaultDeviceChanged(ma_IMM
         return S_OK;
     }
 
+    /* Don't do automatic stream routing if we're not allowed. */
+    if ((dataFlow == ma_eRender  && pThis->pDevice->wasapi.allowPlaybackAutoStreamRouting == MA_FALSE) ||
+        (dataFlow == ma_eCapture && pThis->pDevice->wasapi.allowCaptureAutoStreamRouting  == MA_FALSE)) {
+        return S_OK;
+    }
+
     /*
     Not currently supporting automatic stream routing in exclusive mode. This is not working correctly on my machine due to
     AUDCLNT_E_DEVICE_IN_USE errors when reinitializing the device. If this is a bug in miniaudio, we can try re-enabling this once
@@ -9124,23 +9132,32 @@ ma_result ma_device_init__wasapi(ma_context* pContext, const ma_device_config* p
     */
 #ifdef MA_WIN32_DESKTOP
     if (pConfig->wasapi.noAutoStreamRouting == MA_FALSE) {
-        ma_IMMDeviceEnumerator* pDeviceEnumerator;
-        HRESULT hr = ma_CoCreateInstance(pContext, MA_CLSID_MMDeviceEnumerator, NULL, CLSCTX_ALL, MA_IID_IMMDeviceEnumerator, (void**)&pDeviceEnumerator);
-        if (FAILED(hr)) {
-            ma_device_uninit__wasapi(pDevice);
-            return ma_post_error(pDevice, MA_LOG_LEVEL_ERROR, "[WASAPI] Failed to create device enumerator.", MA_FAILED_TO_OPEN_BACKEND_DEVICE);
+        if ((pConfig->deviceType == ma_device_type_capture || pConfig->deviceType == ma_device_type_duplex) && pConfig->capture.pDeviceID == NULL) {
+            pDevice->wasapi.allowCaptureAutoStreamRouting = MA_TRUE;
+        }
+        if ((pConfig->deviceType == ma_device_type_playback || pConfig->deviceType == ma_device_type_duplex) && pConfig->playback.pDeviceID != NULL) {
+            pDevice->wasapi.allowPlaybackAutoStreamRouting = MA_TRUE;
         }
 
-        pDevice->wasapi.notificationClient.lpVtbl  = (void*)&g_maNotificationCientVtbl;
-        pDevice->wasapi.notificationClient.counter = 1;
-        pDevice->wasapi.notificationClient.pDevice = pDevice;
+        if (pDevice->wasapi.allowCaptureAutoStreamRouting || pDevice->wasapi.allowPlaybackAutoStreamRouting) {
+            ma_IMMDeviceEnumerator* pDeviceEnumerator;
+            HRESULT hr = ma_CoCreateInstance(pContext, MA_CLSID_MMDeviceEnumerator, NULL, CLSCTX_ALL, MA_IID_IMMDeviceEnumerator, (void**)&pDeviceEnumerator);
+            if (FAILED(hr)) {
+                ma_device_uninit__wasapi(pDevice);
+                return ma_post_error(pDevice, MA_LOG_LEVEL_ERROR, "[WASAPI] Failed to create device enumerator.", MA_FAILED_TO_OPEN_BACKEND_DEVICE);
+            }
 
-        hr = pDeviceEnumerator->lpVtbl->RegisterEndpointNotificationCallback(pDeviceEnumerator, &pDevice->wasapi.notificationClient);
-        if (SUCCEEDED(hr)) {
-            pDevice->wasapi.pDeviceEnumerator = (ma_ptr)pDeviceEnumerator;
-        } else {
-            /* Not the end of the world if we fail to register the notification callback. We just won't support automatic stream routing. */
-            ma_IMMDeviceEnumerator_Release(pDeviceEnumerator);
+            pDevice->wasapi.notificationClient.lpVtbl  = (void*)&g_maNotificationCientVtbl;
+            pDevice->wasapi.notificationClient.counter = 1;
+            pDevice->wasapi.notificationClient.pDevice = pDevice;
+
+            hr = pDeviceEnumerator->lpVtbl->RegisterEndpointNotificationCallback(pDeviceEnumerator, &pDevice->wasapi.notificationClient);
+            if (SUCCEEDED(hr)) {
+                pDevice->wasapi.pDeviceEnumerator = (ma_ptr)pDeviceEnumerator;
+            } else {
+                /* Not the end of the world if we fail to register the notification callback. We just won't support automatic stream routing. */
+                ma_IMMDeviceEnumerator_Release(pDeviceEnumerator);
+            }
         }
     }
 #endif
@@ -35859,6 +35876,7 @@ REVISION HISTORY
 ================
 v0.9.10 - 2020-01-xx
   - Fix compilation errors due to #if/#endif mismatches.
+  - WASAPI: Fix a bug where automatic stream routing is being performed for devices that are initialized with an explicit device ID.
   - iOS: Fix a crash on device uninitialization.
 
 v0.9.9 - 2020-01-09