下载远程文件并在客户端重命名文件和文件类型

I am working on a project where on the client-side it should start a download from a remote URL.

I currently got it to work with cURL, but the problem is that it downloads to the server, and not on the client's browser (asking where to save it).

The URL looks like this:

http://r13---sn-5hn7snee.googlevideo.com/videoplayback?expire=138181&mv=u&ipbits=0&clen=7511717&fexp=929447,913430,930802,916612,902546,937417,913434,936916,934022,936921,936923&ms=au&mt=1396164&itag=247&key=yt5&source=youtube&ip=2a00:7143:100:1:225:90ff:fe52:b3ad&sparams=clen,dur,gir,id,ip,ipbits,itag,lmt,source,upn,expire&signature=DBDCE9EFFC094C0FC653610C8FAAF367EA942CC4C6EF3971A186C&upn=0JQJ6yqyYPo&sver=3&gir=yes&lmt=13960601932&dur=130.133&id=17f0fd8b&size=1280x720,type=video/mp4

When downloading this just from the URL the filename will be 'videoplayback' without any file extension. So I need to have a custom file name and .mp4 as file type. (Which works on the cURL code below), but it writes to server instead of client-side download.

function download($file_source, $file_target) {
$rh = fopen($file_source, 'rb');
$wh = fopen($file_target, 'w+b');
if (!$rh || !$wh) {
    return false;
}

while (!feof($rh)) {
    if (fwrite($wh, fread($rh, 4096)) === FALSE) {
        return false;
    }
    echo ' ';
    flush();
}

fclose($rh);
fclose($wh);

return true;
}

$result = download('http://r13---sn-5hn7snee.googlevideo.com/videoplayback?expire=138181&mv=u&ipbits=0&clen=7511717&fexp=929447,913430,930802,916612,902546,937417,913434,936916,934022,936921,936923&ms=au&mt=1396164&itag=247&key=yt5&source=youtube&ip=2a00:7143:100:1:225:90ff:fe52:b3ad&sparams=clen,dur,gir,id,ip,ipbits,itag,lmt,source,upn,expire&signature=DBDCE9EFFC094C0FC653610C8FAAF367EA942CC4C6EF3971A186C&upn=0JQJ6yqyYPo&sver=3&gir=yes&lmt=13960601932&dur=130.133&id=17f0fd8b&size=1280x720,type=video/mp4');

if (!$result)
     throw new Exception('Download error...');

So my question is how I can turn this into so it renames the file and changes the extension to mp4, and then downloads the file on client-side.

Thanks

First output the correct headers to the client so it knows how to handle a file and then echo the file contents. So try this way:

<?php
// ... fetch the file using CURL and store it (in memory or on file system) ...

// Set the content type
header('Content-type: application/pdf');

// It will be called downloaded.pdf
header('Content-Disposition: attachment; filename="downloaded.pdf"');

// ... echo/output the file contents to the browser...
?>

Check out "Example #1 Download dialog" in the PHP documentation.

Also, you mention you are using CURL, I don't see that anywhere in your code.