write correct time_base

Originally committed as revision 10011 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/nutenc.c

@@ -343,7 +343,7 @@ static int write_header(AVFormatContext *s){
         }else
             return -1;
 
-        put_v(bc, 0); //FIXME
+        put_v(bc, (nut->stream[i].time_base - nut->time_base)/sizeof(AVRational));
         put_v(bc, nut->stream[i].msb_pts_shift);
         put_v(bc, nut->stream[i].max_pts_distance);
         put_v(bc, codec->has_b_frames);