php 文件下载 处理中文文件名

$file_name = iconv('utf-8' , 'gb2312' , '歌.mp3');

$down_name = iconv('utf-8' , 'gb2312' , '吼吼.mp3');
$file_size = filesize($file_name);
header('content-type:application/octec-stream');
header('Accept-Ranges:bytes');
header('Accept-Length:' . $file_size);
header('Content-Disposition:attachment;filename=' . $down_name);
readfile($file_name);