if(opts.frame_scale=='nocrop') {
                    frame_img_scale[i] = Math.min(opts.frame_height/img_h[i],opts.frame_width/img_w[i]);
                } else {
                    frame_img_scale[i] = Math.max(opts.frame_height/img_h[i],opts.frame_width/img_w[i]);
                }