Qt: Fix underrun stalling with Qt6

src/platform/qt/AudioDevice.cpp

@@ -62,3 +62,13 @@ qint64 AudioDevice::writeData(const char*, qint64) {
 	LOG(QT, WARN) << tr("Writing data to read-only audio device");
 	return 0;
 }
+
+bool AudioDevice::atEnd() const {
+	if (!m_context->core) {
+		return true;
+	}
+	mCoreSyncLockAudio(&m_context->impl->sync);
+	bool available = blip_samples_avail(m_context->core->getAudioChannel(m_context->core, 0)) == 0;
+	mCoreSyncUnlockAudio(&m_context->impl->sync);
+	return available;
+}

src/platform/qt/AudioDevice.h

@@ -20,6 +20,7 @@ public:
 
 	void setInput(mCoreThread* input);
 	void setFormat(const QAudioFormat& format);
+	bool atEnd() const override;
 
 protected:
 	virtual qint64 readData(char* data, qint64 maxSize) override;

src/platform/qt/AudioProcessorQt.cpp

@@ -21,6 +21,10 @@ using namespace QGBA;
 AudioProcessorQt::AudioProcessorQt(QObject* parent)
 	: AudioProcessor(parent)
 {
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+	m_recheckTimer.setInterval(1);
+	connect(&m_recheckTimer, &QTimer::timeout, this, &AudioProcessorQt::recheckUnderflow);
+#endif
 }
 
 void AudioProcessorQt::setInput(std::shared_ptr<CoreController> controller) {
@@ -34,6 +38,9 @@ void AudioProcessorQt::setInput(std::shared_ptr<CoreController> controller) {
 }
 
 void AudioProcessorQt::stop() {
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+	m_recheckTimer.stop();
+#endif
 	if (m_audioOutput) {
 		m_audioOutput->stop();
 		m_audioOutput.reset();
@@ -72,6 +79,12 @@ bool AudioProcessorQt::start() {
 		QAudioDevice device(QMediaDevices::defaultAudioOutput());
 		m_audioOutput = std::make_unique<QAudioSink>(device, format);
 		LOG(QT, INFO) << "Audio outputting to " << device.description();
+		connect(m_audioOutput.get(), &QAudioSink::stateChanged, this, [this](QAudio::State state) {
+			if (state != QAudio::IdleState) {
+				return;
+			}
+			m_recheckTimer.start();
+		});
 #endif
 	}
 
@@ -86,6 +99,9 @@ bool AudioProcessorQt::start() {
 }
 
 void AudioProcessorQt::pause() {
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+	m_recheckTimer.stop();
+#endif
 	if (m_audioOutput) {
 		m_audioOutput->suspend();
 	}
@@ -115,3 +131,16 @@ unsigned AudioProcessorQt::sampleRate() const {
 	}
 	return m_audioOutput->format().sampleRate();
 }
+
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+void AudioProcessorQt::recheckUnderflow() {
+	if (!m_device) {
+		m_recheckTimer.stop();
+		return;
+	}
+	if (!m_device->atEnd()) {
+		start();
+		m_recheckTimer.stop();
+	}
+}
+#endif

src/platform/qt/AudioProcessorQt.h

@@ -11,6 +11,7 @@
 #include <QAudioOutput>
 #else
 #include <QAudioSink>
+#include <QTimer>
 #endif
 
 class QAudioOutput;
@@ -38,10 +39,15 @@ public slots:
 
 	virtual void requestSampleRate(unsigned) override;
 
-private:
 #if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+private slots:
+	void recheckUnderflow();
+
+private:
+	QTimer m_recheckTimer;
 	std::unique_ptr<QAudioSink> m_audioOutput;
 #else
+private:
 	std::unique_ptr<QAudioOutput> m_audioOutput;
 #endif
 	std::unique_ptr<AudioDevice> m_device;