Make error handling in DSound2 audio player more robust. When an error happened in the playback thread, the error_happened flag was set, but was never cleared when the error was detected in the main thread. Furthermore, the main thread didn't act upon the error besides showing it, it kept acting as if the playback thread was still alive and playing, causing the error to be triggered continuously requiring you to kill Aegisub to get out.

Made the error_happened event reset itself after being checked so the check only succeeds the first time. (The playback thread returns from its threadproc upon error.) Mark playback thread as dead when error is detected, such that a new thread will be created next time playback is started, effectively making errors non-fatal.
Playback still works as expected, however I haven't tested what actually happens now when an error occurs.

Originally committed to SVN as r2968.

aegisub/src/audio_player_dsound2.cpp

@@ -153,6 +153,7 @@ public:
 	int64_t GetCurrentFrame();
 	int64_t GetEndFrame();
 	double GetVolume();
+	bool IsDead();
 };
 
 
@@ -455,6 +456,8 @@ DWORD DirectSoundPlayer2Thread::FillAndUnlockBuffers(void *buf1, DWORD buf1sz, v
 
 
 void DirectSoundPlayer2Thread::CheckError()
+{
+	try
 	{
 		switch (WaitForSingleObject(error_happened, 0))
 		{
@@ -472,6 +475,13 @@ void DirectSoundPlayer2Thread::CheckError()
 			return;
 		}
 	}
+	catch (...)
+	{
+		ResetEvent(is_playing);
+		ResetEvent(thread_running);
+		throw;
+	}
+}
 
 
 DirectSoundPlayer2Thread::DirectSoundPlayer2Thread(AudioProvider *provider, int _WantedLatency, int _BufferLength)
@@ -484,7 +494,7 @@ DirectSoundPlayer2Thread::DirectSoundPlayer2Thread(AudioProvider *provider, int
 
 	thread_running        = CreateEvent(0,  TRUE, FALSE, 0);
 	is_playing            = CreateEvent(0,  TRUE, FALSE, 0);
-	error_happened        = CreateEvent(0,  TRUE, FALSE, 0);
+	error_happened        = CreateEvent(0, FALSE, FALSE, 0);
 
 	error_message = 0;
 	volume = 1.0;
@@ -610,6 +620,19 @@ double DirectSoundPlayer2Thread::GetVolume()
 }
 
 
+bool DirectSoundPlayer2Thread::IsDead()
+{
+	switch (WaitForSingleObject(thread_running, 0))
+	{
+	case WAIT_OBJECT_0:
+		return false;
+
+	default:
+		return true;
+	}
+}
+
+
 
 
 DirectSoundPlayer2::DirectSoundPlayer2()
@@ -634,9 +657,24 @@ DirectSoundPlayer2::~DirectSoundPlayer2()
 }
 
 
+bool DirectSoundPlayer2::IsThreadAlive()
+{
+	if (!thread) return false;
+	
+	if (thread->IsDead())
+	{
+		delete thread;
+		thread = 0;
+		return false;
+	}
+
+	return true;
+}
+
+
 void DirectSoundPlayer2::OpenStream()
 {
-	if (thread) return;
+	if (IsThreadAlive()) return;
 
 	try
 	{
@@ -652,7 +690,7 @@ void DirectSoundPlayer2::OpenStream()
 
 void DirectSoundPlayer2::CloseStream()
 {
-	if (!thread) return;
+	if (!IsThreadAlive()) return;
 
 	try
 	{
@@ -670,7 +708,7 @@ void DirectSoundPlayer2::SetProvider(AudioProvider *provider)
 {
 	try
 	{
-		if (thread && provider != GetProvider())
+		if (IsThreadAlive() && provider != GetProvider())
 		{
 			delete thread;
 			thread = new DirectSoundPlayer2Thread(provider, WantedLatency, BufferLength);
@@ -705,7 +743,7 @@ void DirectSoundPlayer2::Stop(bool timerToo)
 {
 	try
 	{
-		if (thread) thread->Stop();
+		if (IsThreadAlive()) thread->Stop();
 
 		if (timerToo && displayTimer) {
 			displayTimer->Stop();
@@ -722,7 +760,7 @@ bool DirectSoundPlayer2::IsPlaying()
 {
 	try
 	{
-		if (!thread) return false;
+		if (!IsThreadAlive()) return false;
 		return thread->IsPlaying();
 	}
 	catch (const wxChar *msg)
@@ -737,7 +775,7 @@ int64_t DirectSoundPlayer2::GetStartPosition()
 {
 	try
 	{
-		if (!thread) return 0;
+		if (!IsThreadAlive()) return 0;
 		return thread->GetStartFrame();
 	}
 	catch (const wxChar *msg)
@@ -752,7 +790,7 @@ int64_t DirectSoundPlayer2::GetEndPosition()
 {
 	try
 	{
-		if (!thread) return 0;
+		if (!IsThreadAlive()) return 0;
 		return thread->GetEndFrame();
 	}
 	catch (const wxChar *msg)
@@ -767,7 +805,7 @@ int64_t DirectSoundPlayer2::GetCurrentPosition()
 {
 	try
 	{
-		if (!thread) return 0;
+		if (!IsThreadAlive()) return 0;
 		return thread->GetCurrentFrame();
 	}
 	catch (const wxChar *msg)
@@ -782,7 +820,7 @@ void DirectSoundPlayer2::SetEndPosition(int64_t pos)
 {
 	try
 	{
-		if (thread) thread->SetEndFrame(pos);
+		if (IsThreadAlive()) thread->SetEndFrame(pos);
 	}
 	catch (const wxChar *msg)
 	{
@@ -795,7 +833,7 @@ void DirectSoundPlayer2::SetCurrentPosition(int64_t pos)
 {
 	try
 	{
-		if (thread) thread->Play(pos, thread->GetEndFrame()-pos);
+		if (IsThreadAlive()) thread->Play(pos, thread->GetEndFrame()-pos);
 	}
 	catch (const wxChar *msg)
 	{
@@ -808,7 +846,7 @@ void DirectSoundPlayer2::SetVolume(double vol)
 {
 	try
 	{
-		if (thread) thread->SetVolume(vol);
+		if (IsThreadAlive()) thread->SetVolume(vol);
 	}
 	catch (const wxChar *msg)
 	{
@@ -821,7 +859,7 @@ double DirectSoundPlayer2::GetVolume()
 {
 	try
 	{
-		if (!thread) return 0;
+		if (!IsThreadAlive()) return 0;
 		return thread->GetVolume();
 	}
 	catch (const wxChar *msg)

aegisub/src/audio_player_dsound2.h

@@ -49,6 +49,8 @@ protected:
 	int WantedLatency;
 	int BufferLength;
 
+	bool IsThreadAlive();
+
 public:
 	DirectSoundPlayer2();
 	~DirectSoundPlayer2();