From e0ff53614074feabc637598000f5799b480179c3 Mon Sep 17 00:00:00 2001
From: zment <jani.karkkainen@gmail.com>
Date: Tue, 16 Aug 2022 20:18:31 +0300
Subject: [PATCH] Copy audio buffer and send for playback without blocking,
 fixes Windows audio choppyness

---
 src/xaudio2.cpp | 60 +++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 51 insertions(+), 9 deletions(-)

diff --git a/src/xaudio2.cpp b/src/xaudio2.cpp
index 72190b4..bb9d5be 100644
--- a/src/xaudio2.cpp
+++ b/src/xaudio2.cpp
@@ -35,6 +35,25 @@ struct xaudio2_object
 	LPWSTR devicename;
 };
 
+class VoiceCallbacks : public IXAudio2VoiceCallback
+{
+public:
+	void OnBufferEnd(void* pBufferContext) {
+		if (pBufferContext != NULL)
+		{
+			free((void*)pBufferContext);
+		}
+	}
+
+	// Stubs for all interface callbacks
+	void OnStreamEnd() { }
+	void OnVoiceProcessingPassEnd() { }
+	void OnVoiceProcessingPassStart(UINT32 SamplesRequired) { }
+	void OnBufferStart(void* pBufferContext) { }
+	void OnLoopEnd(void* pBufferContext) { }
+	void OnVoiceError(void* pBufferContext, HRESULT Error) { }
+} voiceCallbacks;
+
 void
 xaudio2_object_close(struct audio_object *object);
 
@@ -59,7 +78,7 @@ xaudio2_object_open(struct audio_object *object,
 	if (FAILED(hr))
 		goto error;
 
- 	hr = self->audio->CreateSourceVoice(&self->source, self->format);
+ 	hr = self->audio->CreateSourceVoice(&self->source, self->format, 0, 2.0f, &voiceCallbacks);
 	if (FAILED(hr))
 		goto error;
 
@@ -110,6 +129,16 @@ xaudio2_object_drain(struct audio_object *object)
 {
 	struct xaudio2_object *self = to_xaudio2_object(object);
 
+	while (true)
+	{
+		Sleep(10);
+
+		XAUDIO2_VOICE_STATE state = { 0 };
+		self->source->GetState(&state);
+		if (state.pCurrentBufferContext == NULL && state.BuffersQueued == 0)
+			break;
+	}
+
 	return S_OK;
 }
 
@@ -128,27 +157,40 @@ xaudio2_object_write(struct audio_object *object,
 {
 	struct xaudio2_object *self = to_xaudio2_object(object);
 
-	XAUDIO2_BUFFER buffer = {0};
+	BYTE* buf_data = (BYTE *)malloc(bytes);
+	memcpy(buf_data, data, bytes);
+
+	XAUDIO2_BUFFER buffer = { 0 };
 	buffer.AudioBytes = bytes;
-	buffer.pAudioData = (const BYTE *)data;
+	buffer.pAudioData = buf_data;
+	buffer.pContext = buf_data;
 
 	HRESULT hr = S_OK;
 	if (SUCCEEDED(hr))
 		hr = self->source->SubmitSourceBuffer(&buffer);
 
-	if (SUCCEEDED(hr))
-		hr = self->source->Start(0);
+	XAUDIO2_VOICE_STATE state = { 0 };
+	self->source->GetState(&state);
+	UINT32 buffersQueued = state.BuffersQueued;
 
-	if (SUCCEEDED(hr)) while (true)
+	while (FAILED(hr))
 	{
 		Sleep(10);
 
-		XAUDIO2_VOICE_STATE state = { 0 };
 		self->source->GetState(&state);
-		if (state.pCurrentBufferContext == NULL && state.BuffersQueued == 0)
-			return hr;
+		if (state.BuffersQueued < buffersQueued)
+		{
+			hr = self->source->SubmitSourceBuffer(&buffer);
+
+			self->source->GetState(&state);
+			buffersQueued = state.BuffersQueued;
+		}
 	}
 
+
+	if (SUCCEEDED(hr))
+		hr = self->source->Start(0);
+
 	return hr;
 }
 
-- 
2.35.1