From 4990b8910bc0fe5d576f92396f761a79b3f1a7e3 Mon Sep 17 00:00:00 2001
From: magumagu <magumagu9@gmail.com>
Date: Wed, 9 Apr 2014 13:41:27 -0700
Subject: [PATCH] DSound: use DSound notifications to produce sound.

Pretty straightforward; IDirectSoundNotify lets you register for
notifications after a certain amount of sound has played, so use that
instead of depending on Update() notifications from the CPU thread.

Also, while I'm here, reduce the buffer size by a factor of 4; this seems
to reduce the latency, although the difference is sort of subtle.
---
 Source/Core/AudioCommon/DSoundStream.cpp | 26 ++++++++++++++++--------
 Source/Core/AudioCommon/DSoundStream.h   |  5 ++---
 2 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/Source/Core/AudioCommon/DSoundStream.cpp b/Source/Core/AudioCommon/DSoundStream.cpp
index 2ffbe9794b..13ddb6b5b2 100644
--- a/Source/Core/AudioCommon/DSoundStream.cpp
+++ b/Source/Core/AudioCommon/DSoundStream.cpp
@@ -27,7 +27,7 @@ bool DSound::CreateBuffer()
 
 	// Fill out DSound buffer description.
 	dsbdesc.dwSize  = sizeof(DSBUFFERDESC);
-	dsbdesc.dwFlags = DSBCAPS_GETCURRENTPOSITION2 | DSBCAPS_CTRLVOLUME | DSBCAPS_GLOBALFOCUS;
+	dsbdesc.dwFlags = DSBCAPS_GETCURRENTPOSITION2 | DSBCAPS_CTRLVOLUME | DSBCAPS_GLOBALFOCUS | DSBCAPS_CTRLPOSITIONNOTIFY;
 	dsbdesc.dwBufferBytes = bufferSize = BUFSIZE;
 	dsbdesc.lpwfxFormat = (WAVEFORMATEX *)&pcmwf;
 	dsbdesc.guid3DAlgorithm = DS3DALG_DEFAULT;
@@ -37,6 +37,20 @@ bool DSound::CreateBuffer()
 	{
 		dsBuffer->SetCurrentPosition(0);
 		dsBuffer->SetVolume(m_volume);
+
+		soundSyncEvent = CreateEvent(NULL, TRUE, FALSE, TEXT("DSound Buffer Notification"));
+
+		IDirectSoundNotify *dsnotify;
+		dsBuffer->QueryInterface(IID_IDirectSoundNotify, (void**)&dsnotify);
+		DSBPOSITIONNOTIFY notify_positions[3];
+		for (unsigned i = 0; i < ARRAYSIZE(notify_positions); ++i)
+		{
+			notify_positions[i].dwOffset = i * (BUFSIZE / ARRAYSIZE(notify_positions));
+			notify_positions[i].hEventNotify = soundSyncEvent;
+		}
+		dsnotify->SetNotificationPositions(ARRAYSIZE(notify_positions), notify_positions);
+		dsnotify->Release();
+
 		return true;
 	}
 	else
@@ -101,7 +115,7 @@ void DSound::SoundLoop()
 			WriteDataToBuffer(lastPos, (char*)realtimeBuffer, numBytesToRender);
 			lastPos = ModBufferSize(lastPos + numBytesToRender);
 		}
-		soundSyncEvent.Wait();
+		WaitForSingleObject(soundSyncEvent, INFINITE);
 	}
 }
 
@@ -134,11 +148,6 @@ void DSound::SetVolume(int volume)
 		dsBuffer->SetVolume(m_volume);
 }
 
-void DSound::Update()
-{
-	soundSyncEvent.Set();
-}
-
 void DSound::Clear(bool mute)
 {
 	m_muted = mute;
@@ -160,11 +169,12 @@ void DSound::Stop()
 {
 	threadData = 1;
 	// kick the thread if it's waiting
-	soundSyncEvent.Set();
+	SetEvent(soundSyncEvent);
 
 	thread.join();
 	dsBuffer->Stop();
 	dsBuffer->Release();
 	ds->Release();
+	CloseHandle(soundSyncEvent);
 }
 
diff --git a/Source/Core/AudioCommon/DSoundStream.h b/Source/Core/AudioCommon/DSoundStream.h
index 331c4581d3..d653272087 100644
--- a/Source/Core/AudioCommon/DSoundStream.h
+++ b/Source/Core/AudioCommon/DSoundStream.h
@@ -12,14 +12,14 @@
 #include <mmsystem.h>
 #include <dsound.h>
 
-#define BUFSIZE (1024 * 8 * 4)
+#define BUFSIZE (256 * 8 * 4)
 #endif
 
 class DSound final : public SoundStream
 {
 #ifdef _WIN32
 	std::thread thread;
-	Common::Event soundSyncEvent;
+	HANDLE soundSyncEvent;
 	void  *hWnd;
 
 	IDirectSound8* ds;
@@ -65,7 +65,6 @@ public:
 	virtual void Stop();
 	virtual void Clear(bool mute);
 	static bool isValid() { return true; }
-	virtual void Update();
 
 #else
 public: