port: make audio tick at 30hz, add hack to prevent popping

this is a shit solution, but it'll do for now

port/include/audio.h

@@ -5,6 +5,7 @@
 
 s32 audioInit(void);
 s32 audioGetBytesBuffered(void);
+s32 audioGetSamplesBuffered(void);
 void audioSetNextBuffer(const s16 *buf, u32 len);
 void audioEndFrame(void);
 

port/src/audio.c

@@ -3,9 +3,6 @@
 #include <SDL.h>
 #include "audio.h"
 
-#define SAMPLES_HIGH 736
-#define SAMPLES_LOW 720
-
 static SDL_AudioDeviceID dev;
 static const s16 *nextBuf;
 static u32 nextSize = 0;
@@ -19,7 +16,7 @@ s32 audioInit(void)
 
 	SDL_AudioSpec want, have;
 	SDL_zero(want);
-	want.freq = 22020;
+	want.freq = 22020; // TODO: this might cause trouble for some platforms
 	want.format = AUDIO_S16SYS;
 	want.channels = 2;
 	want.samples = 512;
@@ -43,6 +40,11 @@ s32 audioGetBytesBuffered(void)
 	return SDL_GetQueuedAudioSize(dev);
 }
 
+s32 audioGetSamplesBuffered(void)
+{
+	return audioGetBytesBuffered() / 4;
+}
+
 void audioSetNextBuffer(const s16 *buf, u32 len)
 {
 	nextBuf = buf;
@@ -52,7 +54,9 @@ void audioSetNextBuffer(const s16 *buf, u32 len)
 void audioEndFrame(void)
 {
 	if (nextBuf && nextSize) {
-		SDL_QueueAudio(dev, nextBuf, nextSize);
+		if (audioGetSamplesBuffered() < 8192) {
+			SDL_QueueAudio(dev, nextBuf, nextSize);
+		}
 		nextBuf = NULL;
 		nextSize = 0;
 	}

port/src/libultra.c

@@ -145,23 +145,8 @@ void osViSetYScale(f32 value)
 
 s32 osAiSetFrequency(u32 frequency)
 {
-	register unsigned int dacRate;
-	register char bitRate;
-	register float f;
-	f = osViClock / (float)frequency + .5f;
-	dacRate = f;
-
-	if (dacRate < AI_MIN_DAC_RATE) {
-		return -1;
-	}
-
-	bitRate = dacRate / 66;
-
-	if (bitRate > AI_MAX_BIT_RATE) {
-		bitRate = AI_MAX_BIT_RATE;
-	}
-
-	return osViClock / (s32)dacRate;
+	// we can allow for any freq
+	return (s32)frequency;
 }
 
 u32 osAiGetLength(void)

port/src/pdsched.c

@@ -235,11 +235,13 @@ void schedStartFrame(OSSched *sc)
 
 void schedAudioFrame(OSSched *sc)
 {
-	if (!g_SndDisabled)
-	{
+	// audio ticks at 30hz
+	static s32 runFrame = 0;
+	if (!g_SndDisabled && runFrame) {
 		amgrFrame();
 		audioEndFrame();
 	}
+	runFrame ^= 1;
 }
 
 /**

src/lib/audiomgr.c

@@ -258,6 +258,10 @@ void amgrHandleFrameMsg(AudioInfo *info, AudioInfo *previnfo)
 	somevalue = IO_READ(OS_PHYSICAL_TO_K1(AI_LEN_REG)) / 4;
 #else
 	somevalue = osAiGetLength() / 4;
+	// HACK: only allow small frames if really needed
+	if (somevalue < 1100) {
+		somevalue = 248;
+	}
 #endif
 	datastart = g_AudioManager.ACMDList[var8005cf90];
 	outbuffer = (s16 *) osVirtualToPhysical(info->data);