Fix WAV exporting on Windows

include/AudioFileDevice.h

@@ -56,6 +56,10 @@ protected:
 		return m_outputFile.isOpen();
 	}
 
+	inline int outputFileHandle() const
+	{
+		return m_outputFile.handle();
+	}
 
 private:
 	QFile m_outputFile;

src/core/audio/AudioFileWave.cpp

@@ -27,6 +27,9 @@
 #include "endian_handling.h"
 #include "Mixer.h"
 
+#include <QFile>
+#include <QDebug>
+
 
 AudioFileWave::AudioFileWave( OutputSettings const & outputSettings,
 				const ch_cnt_t channels, bool & successful,
@@ -72,13 +75,15 @@ bool AudioFileWave::startEncoding()
 		m_si.format |= SF_FORMAT_PCM_16;
 		break;
 	}
-	m_sf = sf_open(
-#ifdef LMMS_BUILD_WIN32
-					outputFile().toLocal8Bit().constData(),
-#else
-					outputFile().toUtf8().constData(),
-#endif
-					SFM_WRITE, &m_si );
+
+	// Use file handle to handle unicode file name on Windows
+	m_sf = sf_open_fd( outputFileHandle(), SFM_WRITE, &m_si, false );
+
+	if (!m_sf)
+	{
+		qWarning("Error: AudioFileWave::startEncoding: %s", sf_strerror(nullptr));
+		return false;
+	}
 
 	// Prevent fold overs when encountering clipped data
 	sf_command(m_sf, SFC_SET_CLIPPING, NULL, SF_TRUE);