static AVInputFormat *file_iformat;
static AVOutputFormat *file_oformat;
static AVImageFormat *image_format;
-static int frame_width = 160;
-static int frame_height = 128;
+static int frame_width = 0;
+static int frame_height = 0;
static float frame_aspect_ratio = 0;
static enum PixelFormat frame_pix_fmt = PIX_FMT_YUV420P;
static int frame_padtop = 0;