fix AudioOut pacing

Co-authored-by: Stefanos Costa <stefanos.costa1999@gmail.com>

src/libs/audio.cpp

@@ -82,6 +82,7 @@ public:
 	Id       AudioOutOpen(int type, uint32_t samples_num, uint32_t freq, Format format);
 	bool     AudioOutClose(Id handle);
 	bool     AudioOutValid(Id handle);
+	bool     AudioOutHasDevice(Id handle);
 	bool     AudioOutSetVolume(Id handle, uint32_t bitflag, const int* volume);
 	uint32_t AudioOutOutputs(OutputParam* params, uint32_t num, bool blocking = true);
 	bool     AudioOutGetStatus(Id handle, int* type, int* channels_num);
@@ -152,6 +153,10 @@ void AudioOutClose(int handle) {
 	}
 }
 
+bool AudioOutHasDevice(int handle) {
+	return g_audio != nullptr && handle > 0 && g_audio->AudioOutHasDevice(Audio::Id(handle));
+}
+
 uint32_t AudioOutOutputs(const OutputParam* params, uint32_t num, bool blocking) {
 	if (g_audio == nullptr || params == nullptr || num == 0) {
 		return 0;
@@ -451,6 +456,13 @@ bool Audio::AudioOutValid(Id handle) {
 	        m_out_ports[handle.GetId()].used);
 }
 
+bool Audio::AudioOutHasDevice(Id handle) {
+	Common::LockGuard lock(m_mutex);
+
+	return (handle.GetId() >= 0 && handle.GetId() < OUT_PORTS_MAX &&
+	        m_out_ports[handle.GetId()].used && m_out_ports[handle.GetId()].audio_device != 0);
+}
+
 bool Audio::AudioOutGetStatus(Id handle, int* type, int* channels_num) {
 	Common::LockGuard lock(m_mutex);
 
@@ -516,16 +528,18 @@ uint32_t Audio::AudioOutOutputs(OutputParam* params, uint32_t num, bool blocking
 		max_wait_time      = (wait_time > max_wait_time ? wait_time : max_wait_time);
 	}
 
-	bool all_ports_have_device = true;
+	bool any_port_has_device = false;
 	for (uint32_t i = 0; i < num; i++) {
-		if (m_out_ports[params[i].handle.GetId()].audio_device == 0) {
-			all_ports_have_device = false;
+		if (m_out_ports[params[i].handle.GetId()].audio_device != 0) {
+			any_port_has_device = true;
 			break;
 		}
 	}
 
-	// Device-backed ports are paced by the SDL queue above.
-	if (blocking && max_wait_time != 0 && !all_ports_have_device) {
+	// One real output device is enough to pace the whole synchronized batch. Applying the fallback
+	// when a vibration port is present would rate-limit the device-backed ports to exactly 1x and
+	// prevent their SDL queues from building an underrun cushion.
+	if (blocking && max_wait_time != 0 && !any_port_has_device) {
 		Common::Thread::SleepMicro(max_wait_time);
 	}
 

src/libs/audio_internal.h

@@ -26,6 +26,7 @@ static constexpr int OUT_PORTS_MAX = 32;
 
 int      AudioOutOpen(int type, uint32_t samples_num, uint32_t freq, Format format);
 void     AudioOutClose(int handle);
+bool     AudioOutHasDevice(int handle);
 uint32_t AudioOutOutputs(const OutputParam* params, uint32_t num, bool blocking = true);
 
 } // namespace Libs::Audio::AudioInternal

src/libs/libAudio2.cpp

@@ -336,6 +336,17 @@ static AudioOut2PortStateEntry* audioout2_find_port_locked(AudioOut2PortHandle p
 	return nullptr;
 }
 
+static bool audioout2_context_has_queueable_device(AudioOut2ContextHandle ctx) {
+	Common::LockGuard lock(g_audioout2_port_mutex);
+	for (const auto& state: g_audioout2_ports) {
+		if (state.used && state.context == ctx && state.audio_handle > 0 &&
+		    state.pcm_data != nullptr && AudioInternal::AudioOutHasDevice(state.audio_handle)) {
+			return true;
+		}
+	}
+	return false;
+}
+
 static void audioout2_queue_context_audio(AudioOut2ContextHandle ctx, bool blocking) {
 	std::vector<AudioInternal::OutputParam> params;
 	params.reserve(AudioInternal::OUT_PORTS_MAX);
@@ -493,15 +504,23 @@ int KYTY_SYSV_ABI AudioOut2ContextPush(AudioOut2ContextHandle ctx, uint32_t bloc
 	uint32_t sleep_micros = audioout2_grain_micros(512);
 
 	for (;;) {
+		// Only a synchronous submission carrying PCM to a real device can rely on the SDL queue for
+		// pacing. Async pushes must retain queue-depth backpressure, and a handle without PCM (or a
+		// vibration/failed-open handle) has no downstream operation that can block this call.
+		const bool use_device_clock =
+		    blocking != 0 && audioout2_context_has_queueable_device(ctx);
+
 		g_audioout2_context_mutex.Lock();
 		if (auto* state = audioout2_find_context_locked(ctx); state != nullptr) {
 			audioout2_update_context_locked(state);
 			sleep_micros = audioout2_grain_micros(state->num_grains);
-			if (state->queued < state->queue_depth) {
+			if (state->queued < state->queue_depth || use_device_clock) {
 				if (state->queued == 0) {
 					state->last_update = LibKernel::KernelGetProcessTime();
 				}
-				state->queued++;
+				if (state->queued < state->queue_depth) {
+					state->queued++;
+				}
 				g_audioout2_context_mutex.Unlock();
 				audioout2_queue_context_audio(ctx, blocking != 0);
 				return OK;