mpegvideo: fix position of bottom edge.

It was wrong in colorspaces where horizontal and vertical chroma
subsampling are not the same, e.g. 422.

libavcodec/mpegvideo.c

@@ -2313,12 +2313,15 @@ void ff_draw_horiz_band(MpegEncContext *s, int y, int h){
 
         edge_h= FFMIN(h, s->v_edge_pos - y);
 
-        s->dsp.draw_edges(s->current_picture_ptr->f.data[0] +  y         *s->linesize  , s->linesize,
-                          s->h_edge_pos        , edge_h        , EDGE_WIDTH        , EDGE_WIDTH        , sides);
-        s->dsp.draw_edges(s->current_picture_ptr->f.data[1] + (y>>vshift)*s->uvlinesize, s->uvlinesize,
-                          s->h_edge_pos>>hshift, edge_h>>hshift, EDGE_WIDTH>>hshift, EDGE_WIDTH>>vshift, sides);
-        s->dsp.draw_edges(s->current_picture_ptr->f.data[2] + (y>>vshift)*s->uvlinesize, s->uvlinesize,
-                          s->h_edge_pos>>hshift, edge_h>>hshift, EDGE_WIDTH>>hshift, EDGE_WIDTH>>vshift, sides);
+        s->dsp.draw_edges(s->current_picture_ptr->f.data[0] +  y         *s->linesize,
+                          s->linesize,           s->h_edge_pos,         edge_h,
+                          EDGE_WIDTH,            EDGE_WIDTH,            sides);
+        s->dsp.draw_edges(s->current_picture_ptr->f.data[1] + (y>>vshift)*s->uvlinesize,
+                          s->uvlinesize,         s->h_edge_pos>>hshift, edge_h>>vshift,
+                          EDGE_WIDTH>>hshift,    EDGE_WIDTH>>vshift,    sides);
+        s->dsp.draw_edges(s->current_picture_ptr->f.data[2] + (y>>vshift)*s->uvlinesize,
+                          s->uvlinesize,         s->h_edge_pos>>hshift, edge_h>>vshift,
+                          EDGE_WIDTH>>hshift,    EDGE_WIDTH>>vshift,    sides);
     }
 
     h= FFMIN(h, s->avctx->height - y);