From 29c43c2bb66033bd44787b3207e70ce0d31c845d Mon Sep 17 00:00:00 2001
From: Michael Gregorius <michael.gregorius.git@arcor.de>
Date: Sat, 1 Jun 2024 20:25:10 +0200
Subject: [PATCH] Provide a setting for system default input

Provide the setting "[System Default]" which instructs the SDL driver to
use the default device of the system as the input device. In the
configuration file this option is represented as an empty string. This
should play well with the current existing configuration of the users.
---
 include/AudioSdl.h          |  2 ++
 src/core/audio/AudioSdl.cpp | 27 ++++++++++++++++++++++-----
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/include/AudioSdl.h b/include/AudioSdl.h
index 858e7abd0..d4f08733a 100644
--- a/include/AudioSdl.h
+++ b/include/AudioSdl.h
@@ -69,6 +69,8 @@ public:
 	private:
 		QLineEdit * m_device;
 		QComboBox* m_inputDeviceComboBox = nullptr;
+
+		static QString s_defaultInputDevice;
 	} ;
 
 
diff --git a/src/core/audio/AudioSdl.cpp b/src/core/audio/AudioSdl.cpp
index e29472f60..dedc7dc16 100644
--- a/src/core/audio/AudioSdl.cpp
+++ b/src/core/audio/AudioSdl.cpp
@@ -109,13 +109,14 @@ AudioSdl::AudioSdl( bool & _success_ful, AudioEngine*  _audioEngine ) :
 	m_inputAudioHandle.callback = sdlInputAudioCallback;
 
 	const QString inputDevice = ConfigManager::inst()->value("audiosdl", "inputdevice");
+	const bool isDefaultInput = inputDevice.isEmpty();
 
 	// Try with the configured device
-	const auto inputDeviceCStr = inputDevice.toLocal8Bit().data();
+	const auto inputDeviceCStr = isDefaultInput ? nullptr : inputDevice.toLocal8Bit().data();
 	m_inputDevice = SDL_OpenAudioDevice (inputDeviceCStr, 1, &m_inputAudioHandle, &actual, 0);
 
-	// If we did not get a device ID try again with the default device
-	if (m_inputDevice == 0)
+	// If we did not get a device ID try again with the default device if we did not try that before
+	if (m_inputDevice == 0 && !isDefaultInput)
 	{
 		m_inputDevice = SDL_OpenAudioDevice(nullptr, 1, &m_inputAudioHandle, &actual, 0);
 	}
@@ -290,6 +291,8 @@ void AudioSdl::sdlInputAudioCallback(Uint8 *_buf, int _len) {
 
 #endif
 
+QString AudioSdl::setupWidget::s_defaultInputDevice = QObject::tr("[System Default]");
+
 AudioSdl::setupWidget::setupWidget( QWidget * _parent ) :
 	AudioDeviceSetupWidget( AudioSdl::name(), _parent )
 {
@@ -303,6 +306,8 @@ AudioSdl::setupWidget::setupWidget( QWidget * _parent ) :
 	m_inputDeviceComboBox = new QComboBox(this);
 
 #ifdef LMMS_HAVE_SDL2
+	m_inputDeviceComboBox->addItem(s_defaultInputDevice);
+
 	const int numberOfInputDevices = SDL_GetNumAudioDevices(1);
 	for (int i = 0; i < numberOfInputDevices; ++i)
 	{
@@ -312,7 +317,14 @@ AudioSdl::setupWidget::setupWidget( QWidget * _parent ) :
 
 	// Set the current device to the one in the configuration
 	const auto inputDevice = ConfigManager::inst()->value("audiosdl", "inputdevice");
-	m_inputDeviceComboBox->setCurrentText(inputDevice);
+	if (inputDevice.isEmpty())
+	{
+		m_inputDeviceComboBox->setCurrentText(s_defaultInputDevice);
+	}
+	else
+	{
+		m_inputDeviceComboBox->setCurrentText(inputDevice);
+	}
 #endif
 
 	form->addRow(tr("Input device"), m_inputDeviceComboBox);
@@ -327,7 +339,12 @@ void AudioSdl::setupWidget::saveSettings()
 							m_device->text() );
 
 	const auto currentInputDevice = m_inputDeviceComboBox->currentText();
-	if (!currentInputDevice.isEmpty())
+	if (currentInputDevice == s_defaultInputDevice)
+	{
+		// Represent the default input device with an empty string
+		ConfigManager::inst()->setValue("audiosdl", "inputdevice", "");
+	}
+	else if (!currentInputDevice.isEmpty())
 	{
 		ConfigManager::inst()->setValue("audiosdl", "inputdevice", currentInputDevice);
 	}