M CHANGES → CHANGES

@@ -25,6 +25,7 @@ - GBA Video: Latch scanline at end of Hblank (fixes mgba.io/i/1319)
  - GBA Video: Fix Hblank timing
  - SM83: Emulate HALT bug
 Other fixes:
+ - 3DS: Redo video sync to be more precise
  - All: Improve export headers (fixes mgba.io/i/1738)
  - Core: Ensure ELF regions can be written before trying
  - Debugger: Don't skip undefined instructions when debugger attached

M src/platform/3ds/main.c → src/platform/3ds/main.c

@@ -95,7 +95,7 @@ static int activeOutputTexture = 0;
 static ndspWaveBuf dspBuffer[DSP_BUFFERS];
 static int bufferId = 0;
 static bool frameLimiter = true;
-static u64 tickCounter;
+static u32 frameCounter;
 
 static C3D_RenderTarget* topScreen[2];
 static C3D_RenderTarget* bottomScreen[2];
@@ -213,11 +213,17 @@ if (frameStarted) {
 		return;
 	}
 	frameStarted = true;
+
+	int screen = screenMode >= SM_PA_TOP ? GSP_SCREEN_TOP : GSP_SCREEN_BOTTOM;
 	if (frameLimiter) {
-		if (tickCounter + 4481000 > svcGetSystemTick()) {
-			C3D_FrameSync();
+		u32 oldFrame = frameCounter;
+		frameCounter = C3D_FrameCounter(screen);
+		while (oldFrame == frameCounter) {
+			gspWaitForAnyEvent();
+			frameCounter = C3D_FrameCounter(screen);
 		}
-		tickCounter = svcGetSystemTick();
+	} else {
+		frameCounter = C3D_FrameCounter(screen);
 	}
 	C3D_FrameBegin(0);
 	ctrStartFrame();
@@ -350,7 +356,7 @@ break;
 	}
 	osSetSpeedupEnable(true);
 
-	double ratio = GBAAudioCalculateRatio(1, 59.8260982880808, 1);
+	double ratio = GBAAudioCalculateRatio(1, 268111856.f / 4481136.f, 1);
 	blip_set_rates(runner->core->getAudioChannel(runner->core, 0), runner->core->frequency(runner->core), 32768 * ratio);
 	blip_set_rates(runner->core->getAudioChannel(runner->core, 1), runner->core->frequency(runner->core), 32768 * ratio);
 	if (hasSound != NO_SOUND) {
@@ -659,7 +665,6 @@ if (frameLimiter == limit) {
 		return;
 	}
 	frameLimiter = limit;
-	tickCounter = svcGetSystemTick();
 }
 
 static bool _running(struct mGUIRunner* runner) {