From 90facf9e90ffb22cff7c81703eb1a06fd8256dcc Mon Sep 17 00:00:00 2001
From: Ghabry <gabriel+github@mastergk.de>
Date: Tue, 26 Mar 2024 03:00:56 +0100
Subject: [PATCH] Audio: Add Api to get the shared Midi Out Instance

Solves errors and lag in the audio settings when the device is opened multiple times
---
 src/audio.h                                | 10 ++++++++++
 src/audio_generic.cpp                      | 23 +++++++++++++---------
 src/audio_generic.h                        |  2 ++
 src/platform/linux/midiout_device_alsa.cpp |  3 ++-
 src/window_settings.cpp                    |  3 ++-
 5 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/src/audio.h b/src/audio.h
index 7449034abc..7a90137997 100644
--- a/src/audio.h
+++ b/src/audio.h
@@ -20,6 +20,7 @@
 
 // Headers
 #include <string>
+#include "audio_generic_midiout.h"
 #include "filesystem_stream.h"
 #include "audio_secache.h"
 #include "game_config.h"
@@ -39,6 +40,15 @@ struct AudioInterface {
 
 	virtual void vGetConfig(Game_ConfigAudio& cfg) const = 0;
 
+	/**
+	 * Instantiates and returns the Native Midi Out device.
+	 * The Midi Out device is usually an exclusive resource.
+	 * Implementing classes should only create one Midi Out and return the
+	 * shared instance.
+	 * @return Native Midi Out Device or nullptr on error
+	 */
+	virtual GenericAudioMidiOut* CreateAndGetMidiOut() { return nullptr; }
+
 	/**
 	 * Update audio. Must be called each frame.
 	 */
diff --git a/src/audio_generic.cpp b/src/audio_generic.cpp
index cd45e13dbe..0b46fc7c41 100644
--- a/src/audio_generic.cpp
+++ b/src/audio_generic.cpp
@@ -198,6 +198,19 @@ void GenericAudio::Update() {
 	// no-op, handled by the Decode function called through a thread
 }
 
+GenericAudioMidiOut* GenericAudio::CreateAndGetMidiOut() {
+	if (!midi_thread) {
+		midi_thread = std::make_unique<GenericAudioMidiOut>();
+		std::string status_message;
+		if (midi_thread->IsInitialized(status_message)) {
+			midi_thread->StartThread();
+		} else {
+			midi_thread.reset();
+		}
+	}
+	return midi_thread.get();
+}
+
 void GenericAudio::SetFormat(int frequency, AudioDecoder::Format format, int channels) {
 	output_format.frequency = frequency;
 	output_format.format = format;
@@ -222,15 +235,7 @@ bool GenericAudio::PlayOnChannel(BgmChannel& chan, Filesystem_Stream::InputStrea
 		bool wildmidi = Audio().GetWildMidiEnabled() && MidiDecoder::CreateWildMidi(true);
 
 		if (!fluidsynth && !wildmidi && Audio().GetNativeMidiEnabled()) {
-			if (!midi_thread) {
-				midi_thread = std::make_unique<GenericAudioMidiOut>();
-				std::string status_message;
-				if (midi_thread->IsInitialized(status_message)) {
-					midi_thread->StartThread();
-				} else {
-					midi_thread.reset();
-				}
-			}
+			CreateAndGetMidiOut();
 
 			if (midi_thread) {
 				midi_thread->LockMutex();
diff --git a/src/audio_generic.h b/src/audio_generic.h
index 04755a2c7d..ab1ab3cf5e 100644
--- a/src/audio_generic.h
+++ b/src/audio_generic.h
@@ -61,6 +61,8 @@ class GenericAudio : public AudioInterface {
 
 	void vGetConfig(Game_ConfigAudio&) const override {}
 
+	GenericAudioMidiOut* CreateAndGetMidiOut() override;
+
 	void SetFormat(int frequency, AudioDecoder::Format format, int channels);
 
 	virtual void LockMutex() const = 0;
diff --git a/src/platform/linux/midiout_device_alsa.cpp b/src/platform/linux/midiout_device_alsa.cpp
index 9ed75b590c..d17bae9da1 100644
--- a/src/platform/linux/midiout_device_alsa.cpp
+++ b/src/platform/linux/midiout_device_alsa.cpp
@@ -79,7 +79,8 @@ AlsaMidiOutDevice::AlsaMidiOutDevice(std::string& status_message) {
 		return;
 	}
 
-	Output::Debug("ALSA MIDI: Using client {}:{}:{}", dst_client, dst_port_name, dst_port);
+	status_message = fmt::format("ALSA MIDI: Using client {}:{}:{}", dst_client, dst_port_name, dst_port);
+	Output::DebugStr(status_message);
 
 	status = snd_seq_create_simple_port(midi_out, "Harmony",
 		SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE, SND_SEQ_PORT_TYPE_APPLICATION);
diff --git a/src/window_settings.cpp b/src/window_settings.cpp
index decf01f81c..e603f83b4a 100644
--- a/src/window_settings.cpp
+++ b/src/window_settings.cpp
@@ -327,7 +327,8 @@ void Window_Settings::RefreshAudioMidi() {
 
 	if (cfg.native_midi.IsOptionVisible()) {
 		AddOption(cfg.native_midi, []() { Audio().SetNativeMidiEnabled(Audio().GetConfig().native_midi.Toggle()); });
-		if (!GenericAudioMidiOut().IsInitialized(GetFrame().options.back().help2)) {
+		auto midi_out = Audio().CreateAndGetMidiOut();
+		if (!midi_out || !midi_out->IsInitialized(GetFrame().options.back().help2)) {
 			GetFrame().options.back().text += " [Not working]";
 			GetFrame().options.back().color = Font::ColorKnockout;
 		} else if (cfg.native_midi.Get() && !used) {