fixed #712

rendering/exportthread.h

@@ -82,6 +82,8 @@ signals:
   void ProgressChanged(int value, qint64 remaining_ms);
 public slots:
   void Interrupt();
+
+  void play_wake();
 private:
   bool Encode(AVFormatContext* ofmt_ctx, AVCodecContext* codec_ctx, AVFrame* frame, AVPacket* packet, AVStream* stream);
   bool SetupVideo();
@@ -124,6 +126,8 @@ private:
   QWaitCondition waitCond;
 
   QString export_error;
+
+  bool waiting_for_audio_;
 private slots:
   void wake();
 };