php下载MP4视频

$filename="MP4/2mp4.mp4";//路径文件名
$file="https://vd2.bdstatic.com/mda-kahifai35xn97s75/v1-cae/sc/mda-kahifai35xn97s75.mp4";
 download_img($file, $filename);
   
function download_img($url, $filename){     
   // $cookie_file = dirname(__FILE__).'/cookie.txt';
  $ch = curl_init ();  
  curl_setopt ( $ch, CURLOPT_CUSTOMREQUEST, 'GET' );  
  curl_setopt ( $ch, CURLOPT_SSL_VERIFYPEER, false );  
  curl_setopt ( $ch, CURLOPT_URL, $url );  
  // curl_setopt($ch, CURLOPT_COOKIEFILE,$cookie_file);
  ob_start ();  
  curl_exec ( $ch );  
  $return_content = ob_get_contents ();  
  ob_end_clean ();  
     
  $return_code = curl_getinfo ( $ch, CURLINFO_HTTP_CODE );  
  $fp= @fopen($filename,"a"); 
  fwrite($fp,$return_content);  
  return true; 
}