support downscaling frames for dynamic b frame decission

Originally committed as revision 4776 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/utils.c

@@ -708,6 +708,7 @@ static AVOption options[]={
 {"mb_lmax", NULL, OFFSET(mb_lmax), FF_OPT_TYPE_INT, DEFAULT, INT_MIN, INT_MAX, V|E},
 {"me_penalty_compensation", NULL, OFFSET(me_penalty_compensation), FF_OPT_TYPE_INT, DEFAULT, INT_MIN, INT_MAX, V|E},
 {"bidir_refine", NULL, OFFSET(bidir_refine), FF_OPT_TYPE_INT, DEFAULT, 0, 4, V|E},
+{"brd_scale", NULL, OFFSET(brd_scale), FF_OPT_TYPE_INT, DEFAULT, 0, 10, V|E},
 {NULL},
 };