Fix occasional audio interface deadlock (#4450)

include/AudioJack.h

@@ -37,7 +37,6 @@
 #include <QtCore/QVector>
 #include <QtCore/QList>
 #include <QtCore/QMap>
-#include <QMutexLocker>
 
 #include "AudioDevice.h"
 #include "AudioDeviceSetupWidget.h"
@@ -108,7 +107,6 @@ private:
 
 	bool m_active;
 	bool m_stopped;
-	QMutex m_processingMutex;
 
 	MidiJack *m_midiClient;
 	QVector<jack_port_t *> m_outputPorts;

include/AudioPortAudio.h

@@ -145,7 +145,6 @@ private:
 	int m_outBufSize;
 
 	bool m_stopped;
-	QSemaphore m_stopSemaphore;
 
 } ;
 

include/AudioSoundIo.h

@@ -109,6 +109,8 @@ private:
 	fpp_t m_outBufFramesTotal;
 	fpp_t m_outBufFrameIndex;
 
+	bool m_stopped;
+
 	int m_disconnectErr;
 	void onBackendDisconnect(int err);
 

include/fifo_buffer.h

@@ -66,6 +66,12 @@ public:
 		return( element );
 	}
 
+	void waitUntilRead()
+	{
+		m_writer_sem.acquire( m_size );
+		m_writer_sem.release( m_size );
+	}
+
 	bool available()
 	{
 		return( m_reader_sem.available() );