使用php下载jpg，doc，ppt文件已损坏

我正在尝试使用 php 下载一些文件以隐藏文件路径，但某些文件类型总是损坏。像pdf和mp3这样的文件类型效果很好。像doc，ppt，jpg这样的文件类型总是下载损坏。

我使用这些哑剧类型

if (file_exists($file_real)){ 
$extension = strtolower(substr(strrchr($file, "."), 1)); 
switch($extension){ 
case "ppt": $type = "application/vnd.ms-powerpoint"; break; 
case "pdf": $type = "application/pdf"; break; //------ok
case "doc": $type = "application/msword"; break; 
case "mp3": $type = "audio/mpeg"; break;//------ok
case "jpg": $type = "image/jpg"; break;  
default: $type = "application/force-download"; break; 
} 

和这些标头

header("Pragma: public"); 
header("Expires: 0"); 
header("Cache-Control: must-revalidate, post-check=0, pre-check=0"); 
header("Cache-Control: public", false); 
header("Content-Description: File Transfer"); 
header("Content-Type: " . $type); 
header("Accept-Ranges: bytes"); 
header("Content-Disposition: attachment; filename='"" . $header_file . "'";"); 
header("Content-Transfer-Encoding: binary"); 
header("Content-Length: " . filesize($file_real));
if ($stream = fopen($file_real, 'rb')){
            while(!feof($stream) && connection_status() == 0){
                set_time_limit(0);
                print(fread($stream,1024*8));
                flush();
            }
            fclose($stream);
        }