Streaming HTML5 large (>2GB) videos with PHP

Question

Ok, so basically I'm working on a project where I need to stream MP4 videos from a hidden source.

As most of people in this forum with this problem, I've used a solution derived from: http://mobiforge.com/developing/story/content-delivery-mobile-devices

function get_video($file){
    $fp = @fopen($file, 'rb');

    $size   = filesize($file); // File size
    $length = $size;           // Content length
    $start  = 0;               // Start byte
    $end    = $size - 1;       // End byte

    header('Content-type: video/mp4');
    header("Accept-Ranges: 0-$length");
    if (isset($_SERVER['HTTP_RANGE'])) {

        $c_start = $start;
        $c_end   = $end;

        list(, $range) = explode('=', $_SERVER['HTTP_RANGE'], 2);
        if (strpos($range, ',') !== false) {
            header('HTTP/1.1 416 Requested Range Not Satisfiable');
            header("Content-Range: bytes $start-$end/$size");
            exit;
        }
        if ($range == '-') {
            $c_start = $size - substr($range, 1);
        }else{
            $range  = explode('-', $range);
            $c_start = $range[0];
            $c_end   = (isset($range[1]) && is_numeric($range[1])) ? $range[1] : $size;
        }
        $c_end = ($c_end > $end) ? $end : $c_end;
        if ($c_start > $c_end || $c_start > $size - 1 || $c_end >= $size) {
            header('HTTP/1.1 416 Requested Range Not Satisfiable');
            header("Content-Range: bytes $start-$end/$size");
            exit;
        }
        $start  = $c_start;
        $end    = $c_end;
        $length = $end - $start + 1;
        fseek($fp, $start);
        header('HTTP/1.1 206 Partial Content');
    }
    header("Content-Range: bytes $start-$end/$size");
    header("Content-Length: ".$length);


    $buffer = 1024 * 8;
    while(!feof($fp) && ($p = ftell($fp)) <= $end) {

        if ($p + $buffer > $end) {
            $buffer = $end - $p + 1;
        }
        set_time_limit(0);
        echo fread($fp, $buffer);
        flush();
    }

    fclose($fp);
}

The problem appears when you are trying to process a video file bigger than 2GB (in a x86 machine).

The first problem I found was with the php filesize() function, which gives a negative value when the file is bigger than 2GB. For this issue I'm using a work around which is working correctly:

 function showsize($file) {
    if (strtoupper(substr(PHP_OS, 0, 3)) == 'WIN') {
      if (class_exists("COM")) {
        $fsobj = new COM('Scripting.FileSystemObject');
        $f = $fsobj->GetFile(realpath($file));
        $file = $f->Size;
      } else {
        $file = trim(exec("for %F in (\"" . $file . "\") do @echo %~zF"));
      }
    } elseif (PHP_OS == 'Darwin') {
      $file = trim(shell_exec("stat -f %z " . escapeshellarg($file)));
    } elseif ((PHP_OS == 'Linux') || (PHP_OS == 'FreeBSD') || (PHP_OS == 'Unix') || (PHP_OS == 'SunOS')) {
      $file = trim(shell_exec("stat -c%s " . escapeshellarg($file)));
    } else {
      $file = filesize($file);
    }
    return($file)
 }

The second one was that some parameters were being initialized like integers, and at some point, they failed... I worked around that by using floats instead.

The third one, was the php ftell() function (it is being called in the loop), which also returns an integer... so I have the same problem than with the filesize() function. As the value that ftell() would return when you enter to the loop would be the same value than the parameter $start has, I decided to play with a new parameter (let's call it $mm), which would enter to the loop with the same value than the parameter $start has, and then I would just add the value of the $buffer in every loop, so I wouldn't need to use the ftell() function.

It looks like this (clarify that $start is a float):

$mm = $start;
while(!feof($fp) && $p <= $end) {

    if ($p + $buffer > $end) {
        $buffer = $end - $p + 1;
    }
    set_time_limit(0);
    echo fread($fp, $buffer);
    $mm = $mm + $buffer;
    $p = $mm;
    flush();
}

$$mm and ftell() have the same value during all the loop, but for some reason, with this change it doesn't work even with <2GB files. As I thougth that maybe at some point they could have a different value, I placed a breakpoint inside the next condition:

if ($mm != $p){
  $dummy = 1; 
}

in:

$mm = $start;
while(!feof($fp) && ($p = ftell($fp)) <= $end) {
    if ($mm != $p){
      $dummy = 1; 
    }
    if ($p + $buffer > $end) {
        $buffer = $end - $p + 1;
    }
    set_time_limit(0);
    echo fread($fp, $buffer);
    $mm = $mm + $buffer;
    flush();
}

and it never stopped... So I'm a bit lost, do you know what can be wrong in the worked around loop? do you know any other work around that could work to avoid the ftell() function?