Snewer

force_download('101.mp3','Исполнитель - Композиция');

function tagSize($size_to_convert) {
    $result = 0;
    $mask = 0x7F;
    for ($i = 0; $i < 4; ++$i) {
        $temp = ($size_to_convert >> 7 * $i) & $mask;
        $result |= ($temp << 8 * $i);
    }
        
    return $result + 10;
}
 
 
function force_download($file, $name) {
    if (!file_exists($file)) die("Файл не найден!");
    if (fopen($file, 'r') && ob_get_level()) {
        ob_end_clean();
    }
    // $name должна быть в формате "Исполнитель - Композиция"
    list($artist, $title) = explode(' - ', $name);
    $comment = 'site.ru';
    
	$artist = mb_convert_encoding($artist, 'cp1251', 'utf-8');
	$title = mb_convert_encoding($title, 'cp1251', 'utf-8');
	$comment = mb_convert_encoding($comment, 'cp1251', 'utf-8');
	
    $tpe1 = pack('A4Nx3A*', 'TPE1', strlen($artist)+1, $artist);
    $tit2 = pack('A4Nx3A*', 'TIT2', strlen($title)+1, $title);
    $comm = pack('A4Nx7A*', 'COMM', strlen($comment)+5, $comment);
    
    $idlength = strlen($tpe1.$tit2.$comm."\0");
    $id3 = pack('A3vxN', 'ID3', 0x3, tagSize($idlength));
    $length = filesize($file) + $idlength + 10;
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename='.$name.'.mp3');
    header('Content-Length:'.$length);
    print $id3.$tit2.$tpe1.$comm."\0".file_get_contents($file);
    exit;
}

$num_one = rand(0,500);
$num_two = rand(0,500);
$num_three = rand(0,500);
$symbol = array('-','+');

for($i = 0; $i < 2; $i++){
   $sym_save[] = $symbol[rand(0, 1)];
}

$example = "$num_one $sym_save[0] $num_two $sym_save[1] $num_three";
$result = eval("return $example;");
echo $example, ' = ', $result;