returned to AVFilter solution

main.cpp

@@ -3,12 +3,14 @@
 
 extern "C" {
 	#include <libavformat/avformat.h>
+	#include <libavfilter/avfilter.h>
 }
 
 int main(int argc, char *argv[])
 {
 	// init ffmpeg subsystem
 	av_register_all();
+	avfilter_register_all();
 
     QApplication a(argc, argv);
 	MainWindow w;