我有这个smartReadFile()php函数，它允许从文件播放音频流。你将如何修改此函数，以便查询mysql数据库BLOB而不是读取特定文件？

function smartReadFile($location, $filename, $mimeType = 'audio/octet-stream')

{

if (!file_exists($location))

{

header ("HTTP/1.1 404 Not Found");

return;

}

$size = filesize($location);

$time = date('r', filemtime($location));

$fm = @fopen($location, 'rb');

if (!$fm)

{

header ("HTTP/1.1 505 Internal server error");

return;

}

$begin = 0;

$end = $size - 1;

if (isset($_SERVER['HTTP_RANGE']))

{

if (preg_match('/bytes=\h*(\d+)-(\d*)[\D.*]?/i', $_SERVER['HTTP_RANGE'], $matches))

{

$begin = intval($matches[1]);

if (!empty($matches[2]))

{

$end = intval($matches[2]);

}

}

}

if (isset($_SERVER['HTTP_RANGE']))

{

header('HTTP/1.1 206 Partial Content');

}

else

{

header('HTTP/1.1 200 OK');

}

header("Content-Type: $mimeType");

header('Cache-Control: public, must-revalidate, max-age=0');

header('Pragma: no-cache');

header('Accept-Ranges: bytes');

header('Content-Length:' . (($end - $begin) + 1));

if (isset($_SERVER['HTTP_RANGE']))

{

header("Content-Range: bytes $begin-$end/$size");

}

header("Content-Disposition: inline; filename=$filename");

header("Content-Transfer-Encoding: binary");

header("Last-Modified: $time");

$cur = $begin;

fseek($fm, $begin, 0);

while(!feof($fm) && $cur <= $end && (connection_status() == 0))

{

print fread($fm, min(1024 * 16, ($end - $cur) + 1));

$cur += 1024 * 16;

}

}