-EXTERN char *Output_Picture_Filename;
-EXTERN char *Substitute_Picture_Filename;
-EXTERN char *Main_Bitstream_Filename;
-EXTERN char *Enhancement_Layer_Bitstream_Filename;
+EXTERN const char *Output_Picture_Filename;
+EXTERN const char *Substitute_Picture_Filename;
+EXTERN const char *Main_Bitstream_Filename;
+EXTERN const char *Enhancement_Layer_Bitstream_Filename;