Audio: Show granular mixer stats in the audio debug overlay

Queue fill and cap (in granules and ms), under/overruns, output rate, read
size and frame time, replacing the "no stats yet" placeholder.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Core/HW/GranularMixer.cpp

@@ -6,6 +6,7 @@
 #include <chrono>
 #include <algorithm>
 #include <cmath>
+#include <cstdio>
 #include <cstring>
 
 #include "Common/CommonTypes.h"
@@ -80,6 +81,7 @@ void GranularMixer::Mix(s16 *samples, u32 num_samples, int outSampleRate, float
 	memset(samples, 0, num_samples * 2 * sizeof(s16));
 	// The estimate is 0 until a second has gone by.
 	frameTimeEstimate_ = 1.0f / std::max(fpsEstimate, 1.0f);
+	outSampleRate_ = outSampleRate;
 
 	smoothedReadSize_ = smoothedReadSize_ == 0 ? num_samples : (smoothedReadSize_ * 0.95f + num_samples * 0.05f);
 
@@ -309,3 +311,35 @@ void GranularMixer::GetStats(GranularStats *stats) {
 	queuedGranulesMin_ = 10000;
 	queuedGranulesMax_ = 0;
 }
+
+void GranularMixer::GetAudioDebugStats(char *buf, size_t bufSize) {
+	GranularStats stats;
+	GetStats(&stats);
+	// Each queued granule holds GRANULE_OVERLAP new samples.
+	const double msPerGranule = GRANULE_OVERLAP * 1000.0 / 44100.0;
+	snprintf(buf, bufSize,
+		"Granular mixer\n"
+		"Queued: %0.1f granules (%0.1fms)\n"
+		"Queued min/max: %d / %d\n"
+		"Cap: %d granules (%0.1fms, %d samples)\n"
+		"Underruns: %d\n"
+		"Overruns: %d\n"
+		"Output sample rate: %d\n"
+		"Read size: %0.1f\n"
+		"Frame time estimate: %0.1fms\n"
+		"Fade volume: %0.2f%s\n",
+		stats.smoothedQueuedGranules, stats.smoothedQueuedGranules * msPerGranule,
+		stats.queuedGranulesMin, stats.queuedGranulesMax,
+		stats.targetQueueSize, stats.targetQueueSize * msPerGranule, stats.queuedSamplesTarget,
+		stats.underruns,
+		stats.overruns,
+		outSampleRate_,
+		stats.smoothedReadSize,
+		stats.frameTimeEstimate * 1000.0f,
+		stats.fadeVolume, stats.looping ? " (looping)" : "");
+}
+
+void GranularMixer::ResetStatCounters() {
+	underruns_ = 0;
+	overruns_ = 0;
+}

Core/HW/GranularMixer.h

@@ -46,6 +46,9 @@ public:
 	void PushSamples(const s32 *samples, u32 num_samples, float volume);
 
 	void GetStats(GranularStats *stats);
+	// Text for the audio debug overlay.
+	void GetAudioDebugStats(char *buf, size_t bufSize);
+	void ResetStatCounters();
 
 	static constexpr u32 GRANULE_SIZE = 256;
 
@@ -107,6 +110,7 @@ private:
 	int queuedSamplesTarget_ = 0;
 	float smoothedReadSize_ = 0.0f;
 	float frameTimeEstimate_ = 0.0f;
+	int outSampleRate_ = 0;
 
 	void Enqueue();
 	void Dequeue(Granule* granule);

UI/AudioCommon.cpp

@@ -47,12 +47,13 @@ void NativeMix(int16_t *outStereo, int numFrames, int sampleRateHz, void *userda
 void System_AudioGetDebugStats(char *buf, size_t bufSize) {
 	if (buf) {
 		if (g_Config.iAudioPlaybackMode == (int)AudioSyncMode::GRANULAR) {
-			snprintf(buf, bufSize, "(No stats available for granular yet)");
+			g_granular.GetAudioDebugStats(buf, bufSize);
 		} else {
 			g_resampler.GetAudioDebugStats(buf, bufSize);
 		}
 	} else {
 		g_resampler.ResetStatCounters();
+		g_granular.ResetStatCounters();
 	}
 }