Remove the return value from NativeMix, correct mixing with other channel numbers than 2

Common/System/NativeApp.h

@@ -59,13 +59,11 @@ void NativeMouseDelta(float dx, float dy);
 void NativeFrame(GraphicsContext *graphicsContext);
 
 // This should render num_samples 44khz stereo samples.
-// Try not to make too many assumptions on the granularity
-// of num_samples.
-// This function may be called from a totally separate thread from
-// the rest of the game, so be careful with synchronization.
-// Returns the number of samples actually output. The app should do everything it can
-// to fill the buffer completely.
-int NativeMix(short *audio, int num_samples, int sampleRateHz, void *userdata);
+// Try not to make too many assumptions on the granularity of num_samples.
+// This function will likely be called from a totally separate thread from
+// the rest of the app, so be careful with synchronization.
+// The app must fill the buffer completely, doing its own internal buffering if needed.
+void NativeMix(short *audio, int num_samples, int sampleRateHz, void *userdata);
 
 // Called when it's time to shutdown. After this has been called,
 // no more calls to any other function will be made from the framework

Core/HW/StereoResampler.cpp

@@ -160,9 +160,9 @@ inline int16_t MixSingleSample(int16_t s1, int16_t s2, uint16_t frac) {
 }
 
 // Executed from sound stream thread, pulling sound out of the buffer.
-unsigned int StereoResampler::Mix(short* samples, unsigned int numSamples, bool consider_framelimit, int sample_rate) {
+void StereoResampler::Mix(s16 *samples, unsigned int numSamples, bool consider_framelimit, int sample_rate) {
 	if (!samples)
-		return 0;
+		return;
 
 	unsigned int currentSample;
 
@@ -242,9 +242,6 @@ unsigned int StereoResampler::Mix(short* samples, unsigned int numSamples, bool
 
 	// Flush cached variable
 	indexR_.store(indexR);
-
-	// TODO: What should we actually return here?
-	return currentSample / 2;
 }
 
 // Executes on the emulator thread, pushing sound into the buffer.

Core/HW/StereoResampler.h

@@ -32,7 +32,7 @@ public:
 	~StereoResampler();
 
 	// Called from audio threads
-	unsigned int Mix(short* samples, unsigned int numSamples, bool consider_framelimit, int sampleRate);
+	void Mix(s16 *samples, unsigned int numSamples, bool consider_framelimit, int sampleRate);
 
 	// Called from main thread
 	// This clamps the samples to 16-bit before starting to work on them.

Qt/QtMain.cpp

@@ -792,9 +792,8 @@ void MainAudio::run() {
 
 void MainAudio::timerEvent(QTimerEvent *) {
 	memset(mixbuf, 0, mixlen);
-	size_t frames = NativeMix((short *)mixbuf, AUDIO_BUFFERS*AUDIO_SAMPLES, AUDIO_FREQ);
-	if (frames > 0)
-		feed->write(mixbuf, sizeof(short) * AUDIO_CHANNELS * frames);
+	NativeMix((short *)mixbuf, AUDIO_BUFFERS * AUDIO_SAMPLES, AUDIO_FREQ);
+	feed->write(mixbuf, sizeof(short) * AUDIO_CHANNELS * frames);
 }
 
 #endif

UI/AudioCommon.cpp

@@ -7,13 +7,11 @@ StereoResampler g_resampler;
 
 // numFrames is number of stereo frames.
 // This is called from *outside* the emulator thread.
-int NativeMix(int16_t *outStereo, int numFrames, int sampleRateHz, void *userdata) {
-	int validFrames = g_resampler.Mix(outStereo, numFrames, false, sampleRateHz);
+void NativeMix(int16_t *outStereo, int numFrames, int sampleRateHz, void *userdata) {
+	g_resampler.Mix(outStereo, numFrames, false, sampleRateHz);
 
 	// Mix sound effects on top.
-	g_BackgroundAudio.SFX().Mix(outStereo, validFrames, sampleRateHz);
-
-	return validFrames;
+	g_BackgroundAudio.SFX().Mix(outStereo, numFrames, sampleRateHz);
 }
 
 void System_AudioGetDebugStats(char *buf, size_t bufSize) {

UI/NativeApp.cpp

@@ -803,19 +803,27 @@ void NativeInit(int argc, const char *argv[], const char *savegame_dir, const ch
 void CallbackPostRender(UIContext *dc, void *userdata);
 bool CreateGlobalPipelines();
 
+// TODO: Add faster special case for channels == 2.
 void NativeMixWrapper(float *dest, int framesToWrite, int channels, int sampleRateHz, void *userdata) {
 	static int16_t *buffer;
 	static int bufSize;
-	if (bufSize < framesToWrite * channels) {
-		buffer = new int16_t[framesToWrite * channels];
-		bufSize = framesToWrite * channels;
+	if (bufSize < framesToWrite * 2) {
+		buffer = new int16_t[framesToWrite * 2];
+		bufSize = framesToWrite * 2;
 	}
 
 	NativeMix(buffer, framesToWrite, sampleRateHz, userdata);
 
-	for (int i = 0; i < framesToWrite * channels; i++) {
-		int16_t value = buffer[i];
-		dest[i] = (float)value * (float)(1.0f / 32767.0f);
+	for (int i = 0; i < framesToWrite; i++) {
+		int16_t lvalue = buffer[i * 2];
+		int16_t rvalue = buffer[i * 2 + 1];
+		dest[i * channels] = (float)lvalue * (float)(1.0f / 32767.0f);
+		if (channels > 1) {
+			dest[i * channels + 1] = (float)lvalue * (float)(1.0f / 32767.0f);
+		}
+		for (int j = 2; j < channels; j++) {
+			dest[i * channels + j] = 0.0f;
+		}
 	}
 }
 

Windows/WASAPIContext.cpp

@@ -10,11 +10,12 @@
 #include <vector>
 #include <string_view>
 
+#include "Common/Log.h"
 #include "WASAPIContext.h"
 
 static std::string ConvertWStringToUTF8(const std::wstring &wstr) {
-	int len = (int)wstr.size();
-	int size = (int)WideCharToMultiByte(CP_UTF8, 0, wstr.c_str(), len, 0, 0, NULL, NULL);
+	const int len = (int)wstr.size();
+	const int size = WideCharToMultiByte(CP_UTF8, 0, wstr.c_str(), len, 0, 0, NULL, NULL);
 	std::string s;
 	s.resize(size);
 	if (size > 0) {
@@ -24,8 +25,8 @@ static std::string ConvertWStringToUTF8(const std::wstring &wstr) {
 }
 
 static std::wstring ConvertUTF8ToWString(const std::string_view source) {
-	int len = (int)source.size();
-	int size = (int)MultiByteToWideChar(CP_UTF8, 0, source.data(), len, NULL, 0);
+	const int len = (int)source.size();
+	const int size = MultiByteToWideChar(CP_UTF8, 0, source.data(), len, NULL, 0);
 	std::wstring str;
 	str.resize(size);
 	if (size > 0) {
@@ -58,6 +59,11 @@ void WASAPIContext::EnumerateDevices(std::vector<AudioDeviceDesc> *output, bool
 	IMMDeviceCollection *collection = nullptr;
 	enumerator_->EnumAudioEndpoints(captureDevices ? eCapture : eRender, DEVICE_STATE_ACTIVE, &collection);
 
+	if (!collection) {
+		ERROR_LOG(Log::Audio, "Failed to enumerate devices");
+		return;
+	}
+
 	UINT count = 0;
 	collection->GetCount(&count);
 
@@ -124,7 +130,7 @@ bool WASAPIContext::InitOutputDevice(std::string_view uniqueId, LatencyMode late
 		audioClient3_->GetMixFormat(&format_);
 		audioClient3_->GetSharedModeEnginePeriod(format_, &defaultPeriodFrames, &fundamentalPeriodFrames, &minPeriodFrames, &maxPeriodFrames);
 
-		printf("default: %d fundamental: %d min: %d max: %d\n", defaultPeriodFrames, fundamentalPeriodFrames, minPeriodFrames, maxPeriodFrames);
+		printf("default: %d fundamental: %d min: %d max: %d\n", (int)defaultPeriodFrames, (int)fundamentalPeriodFrames, (int)minPeriodFrames, (int)maxPeriodFrames);
 		printf("initializing with %d frame period at %d Hz, meaning %0.1fms\n", (int)minPeriodFrames, (int)format_->nSamplesPerSec, FramesToMs(minPeriodFrames, format_->nSamplesPerSec));
 
 		audioEvent_ = CreateEvent(nullptr, FALSE, FALSE, nullptr);
@@ -218,7 +224,7 @@ void WASAPIContext::FrameUpdate(bool allowAutoChange) {
 
 void WASAPIContext::AudioLoop() {
 	DWORD taskID = 0;
-	HANDLE mmcssHandle = NULL;
+	HANDLE mmcssHandle = nullptr;
 	if (latencyMode_ == LatencyMode::Aggressive) {
 		mmcssHandle = AvSetMmThreadCharacteristics(L"Pro Audio", &taskID);
 	}
@@ -244,7 +250,7 @@ void WASAPIContext::AudioLoop() {
 		else
 			audioClient_->GetCurrentPadding(&padding), audioClient_->GetBufferSize(&available);
 
-		UINT32 framesToWrite = available - padding;
+		const UINT32 framesToWrite = available - padding;
 		BYTE* buffer = nullptr;
 		if (framesToWrite > 0 && SUCCEEDED(renderClient_->GetBuffer(framesToWrite, &buffer))) {
 			callback_((float *)buffer, framesToWrite, 2, format_->nSamplesPerSec, userdata_);

ios/AudioEngine.mm

@@ -19,7 +19,7 @@ static volatile BOOL done = 0;
 #define SAMPLE_SIZE 44100
 static short stream[SAMPLE_SIZE];
 
-int NativeMix(short *audio, int numSamples, int sampleRateHz, void *userdata);
+void NativeMix(short *audio, int numSamples, int sampleRateHz, void *userdata);
 
 @interface AudioEngine ()
 
@@ -121,16 +121,15 @@ int NativeMix(short *audio, int numSamples, int sampleRateHz, void *userdata);
 {
     dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void){
         const int sampleRateHz = 44100;
-        while (!done)
-        {
-            size_t frames_ready;
-            if (![self playing])
-                frames_ready = NativeMix(stream, SAMPLE_SIZE / 2, sampleRateHz, 0);
-            else
+        while (!done) {
+            if (![self playing]) {
+                NativeMix(stream, SAMPLE_SIZE / 2, sampleRateHz, 0);
+                frames_ready = SAMPLE_SIZE / 2;
+            } else {
                 frames_ready = 0;
+            }
 
-            if (frames_ready > 0)
-            {
+            if (frames_ready > 0) {
                 const size_t bytes_ready = frames_ready * sizeof(short) * 2;
                 alSourcei(source, AL_BUFFER, 0);
                 alBufferData(buffer, AL_FORMAT_STEREO16, stream, bytes_ready, sampleRateHz);
@@ -139,9 +138,9 @@ int NativeMix(short *audio, int numSamples, int sampleRateHz, void *userdata);
 
                 // TODO: Maybe this could get behind?
                 usleep((1000000 * frames_ready) / sampleRateHz);
-            }
-            else
+            } else {
                 usleep(100);
+            }
             pthread_yield_np();
         }
     });

ios/iOSCoreAudio.mm

@@ -74,41 +74,21 @@ void iOSCoreAudioSetDisplayConnected(bool connected) {
 	iOSCoreAudioUpdateSession();
 }
 
-int NativeMix(short *audio, int numSamples, int sampleRate, void *userdata);
+void NativeMix(short *audio, int numSamples, int sampleRate, void *userdata);
 
 OSStatus iOSCoreAudioCallback(void *inRefCon,
 							  AudioUnitRenderActionFlags *ioActionFlags,
 							  const AudioTimeStamp *inTimeStamp,
 							  UInt32 inBusNumber,
 							  UInt32 inNumberFrames,
-							  AudioBufferList *ioData)
-{
-	// see if we have any sound to play
+							  AudioBufferList *ioData) {
 	short *output = (short *)ioData->mBuffers[0].mData;
-	UInt32 framesReady = NativeMix(output, inNumberFrames, SAMPLE_RATE, nullptr);
-	
-	if (framesReady == 0) {
-		// oops, we don't currently have any sound, so return silence
-		*ioActionFlags |= kAudioUnitRenderAction_OutputIsSilence;
-	}
-	
-	/* 
-	 * You'd think iOS would want to know how many frames were
-	 * actually generated in case it was less than asked for, but
-	 * apparently that causes micro-stuttering and everything just
-	 * works better if we lie and say we successfully generated as
-	 * many frames as it wanted... weird. We still get micro-stuttering
-	 * but it's less noticeable this way.
-	 */ 
-	//UInt32 bytesReady = framesReady * sizeof(short) * 2;
-	UInt32 bytesReady = inNumberFrames * sizeof(short) * 2;
-	ioData->mBuffers[0].mDataByteSize = bytesReady;
-	
+	NativeMix(output, inNumberFrames, SAMPLE_RATE, nullptr);
+	ioData->mBuffers[0].mDataByteSize = inNumberFrames * sizeof(short) * 2;
 	return noErr;
 }
 
-void iOSCoreAudioInit()
-{
+void iOSCoreAudioInit() {
 	iOSCoreAudioUpdateSession();
 
 	NSError *error = nil;