vp3: correctly clip vp3_draw_horiz_band call

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@22377 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/vp3.c

@@ -1565,7 +1565,7 @@ static void render_slice(Vp3DecodeContext *s, int slice)
       *     dispatch (slice - 1);
       */
 
-    vp3_draw_horiz_band(s, 64*slice + 64-16);
+    vp3_draw_horiz_band(s, FFMIN(64*slice + 64-16, s->height-16));
 }
 
 /*