diff --git a/ffmpeg.c b/ffmpeg.c
index 7e2d82afd8..08a50d541b 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -3274,6 +3274,8 @@ static void opt_input_file(const char *filename)
                 dec->flags |= CODEC_FLAG_EMU_EDGE;
                 frame_height >>= dec->lowres;
                 frame_width  >>= dec->lowres;
+                dec->height = frame_height;
+                dec->width  = frame_width;
             }
             if(me_threshold)
                 dec->debug |= FF_DEBUG_MV;