Download issue in php - php

Question

I have a php script for downloading mp4 videp files . It is working properly now for files having small size (upto 60 MB is tested) . When i try for a big one (300 MB) it displays an error related with "memory limit" . So that done some edits in ini file for increasing the memory limit upto 400 MB (memory_limit = 400M) . Then i try to run my script , But the download box is displaying a content size of 189 bytes. I tried it with an another mp4 file (small size) , its working well . I dont understand the reason for it . So please kindly direct me . My script is as follows..
$file = $_SERVER['DOCUMENT_ROOT']."/folder_name/filename.mp4";
$filesize = filesize($file);
$fileName=$file;
$offset = 0;
$length = $filesize;
if ( isset($_SERVER['HTTP_RANGE']) ) {
$partialContent = true;
preg_match('/bytes=(\d+)-?/', $_SERVER['HTTP_RANGE'], $matches);
$offset = intval($matches[1]);
$length = $filesize - $offset;
}else {
$partialContent = false;
}
$file = fopen($file, 'r');
fseek($file, $offset);
$data = fread($file, $length);
fclose($file);
if ( $partialContent ) {
header('HTTP/1.1 206 Partial Content');
header('Content-Range: bytes ' . $offset . '-' . ($offset + $length) . '/' . $filesize);
}
header("Content-type: video/mp4");
header('Content-Length: ' . $filesize);
header('Content-Disposition: attachment; filename="' . $fileName . '"');
header('Accept-Ranges: bytes');
print($data);
The download box displaying is..

Answer 1

Please check with your server sometime your server not support this many memory allocation to your script.
Please add following line on top of script.
ini_set('memory_limit', '-1');
ini_set('max_execution_time', '0');
then let me know if that not working.

Answer 2

It isnt good to change all directives without a good reason, so the first step is to know what specific problem you have.
When you run a script for downloading files, like in this case, mp4 video files, and the download box is displaying a content size much smaller than the actual file, its easy to get a clue about what was wrong:
You just need to download that file and, no matter it looks like a video, open it with a text editor.
Right click > open with... and then select any text editor.
You will find that the actual content of the file is the information about the error occurred in the server. With this you will have better information about what happened, so you can figure out for example, if it is related to the memory_limit, to the max_execution_time, or to any other reason.
Now you can decide to change one or more of the directives, or probably change your script to get a better performance.
Note: if the file you downloaded is empty, or doesnt contain any error information, probably you have the error reporting disabled. To enable it you can add this two lines at the begining of the script:
ini_set("display_errors","1");
error_reporting(E_ALL);