Using the Simple HTML DOM Library:

<?php
    include('lib/simple_html_dom.php');

    $string = '<object height="81" width="100%"> <param name="movie" value="http://player.soundcloud.com/player.swf?url=http%3A%2F%2Fapi.soundcloud.com%2Ftracks%2F17181143"></param> <param name="allowscriptaccess" value="always"></param> <embed allowscriptaccess="always" height="81" src="http://player.soundcloud.com/player.swf?url=http%3A%2F%2Fapi.soundcloud.com%2Ftracks%2F17181143" type="application/x-shockwave-flash" width="100%"></embed> </object>  <span><a href="http://soundcloud.com/kiwinest/linkin-park-iridescent">Linkin Park - Iridescent</a> by <a href="http://soundcloud.com/kiwinest">KiwiNest</a></span>';

    $html = str_get_html($string);
    //$html = file_get_html('http://www.mysite.com/');

    if ($html) {
        foreach ($html->find('object') as $obj) {
            foreach ($obj->find('param') as $par) {
                if ($par->name == 'movie') {
                    $embed = parse_url($par->value);
                    parse_str(urldecode($embed['query']), $val);
                    if (array_key_exists('url', $val)) {
                        $url = parse_url($val['url']);
                        $path = explode('/', $url['path']);
                        $code = array_pop($path);
                        if (is_numeric($code)) {
                            echo 'CODE: ' . $code . PHP_EOL;
                        }
                    }
                }
            }
        }
    }
?>

Output:

CODE: 17181143

Notes:

• Requires external library (DOMDocument doesn't like that fragment)
• Works with multiple embeds (should, anyways.. only tested with sample embed)
• Uses PHP's URL parser (rather than RegEx)

您可以使用 PHP 和 REGEX 将数字提取到数组中，从而丢弃其他所有内容。

$my_string = '<object height="81" width="100%"> <param name="movie" 
value="http://player.soundcloud.com/player.swf?url=http%3A%2F 
%2Fapi.soundcloud.com%2Ftracks%2F17181143"></param> 
<param name="allowscriptaccess" value="always"></param> <embed allowscriptaccess="always" 
height="81" src="http://player.soundcloud.com/player.swf?url=http%3A%2F  
%2Fapi.soundcloud.com%2Ftracks%2F17181143" type="application/x-shockwave-flash" width="100%">
</embed> </object>  <span><a href="http://soundcloud.com/kiwinest/linkin-park-iridescent">Linkin 
Park - Iridescent</a> by <a href="http://soundcloud.com/kiwinest">KiwiNest</a></span>';

// Assuming all the numbers are going to be 8 characters long, if they are not, then just change
// the regex.
// look for all numbers that are 8 characters long.
preg_match_all('/[0-9]{8}/', $my_string, $ids);