Fixed bug 4605 - WASAPI_WaitDevice hang

Matt Brocklehurst

We've noticed that if you are playing audio on Windows via the WASAPI interface and you unplug and reconnect the device a few times the program hangs.

We've debugged the problem down to

static void
WASAPI_WaitDevice(_THIS)
{

   ... snip ...
 if (WaitForSingleObjectEx(this->hidden->event, INFINITE, FALSE) == WAIT_OBJECT_0) {
   ... snip ...
}

This WaitForSingleObjectEx does not havbe a time out defined, so it hangs there forever.

Our suggested fix we found was to include a time out of say 200mSec

We have done quite a bit of testing with this fix in place on various hardware configurations and it seems to have resolved the issue.

src/audio/wasapi/SDL_wasapi.c

@@ -312,8 +312,8 @@ static void
 WASAPI_WaitDevice(_THIS)
 {
     while (RecoverWasapiIfLost(this) && this->hidden->client && this->hidden->event) {
-        /*SDL_Log("WAITDEVICE");*/
-        if (WaitForSingleObjectEx(this->hidden->event, INFINITE, FALSE) == WAIT_OBJECT_0) {
+        DWORD waitResult = WaitForSingleObjectEx(this->hidden->event, 200, FALSE);
+        if (waitResult == WAIT_OBJECT_0) {
             const UINT32 maxpadding = this->spec.samples;
             UINT32 padding = 0;
             if (!WasapiFailed(this, IAudioClient_GetCurrentPadding(this->hidden->client, &padding))) {
@@ -322,7 +322,7 @@ WASAPI_WaitDevice(_THIS)
                     break;
                 }
             }
-        } else {
+        } else if (waitResult != WAIT_TIMEOUT) {
             /*SDL_Log("WASAPI FAILED EVENT!");*/
             IAudioClient_Stop(this->hidden->client);
             SDL_OpenedAudioDeviceDisconnected(this);