oEmbed.php

<?php

# Licensed under a CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
# http://creativecommons.org/publicdomain/zero/1.0/

function getEmbedCode($url="",$maxwidth=320) {

    $return = '';

	$providers = array(
		'dribbble.com'		=>	'https://api.embed.ly/v1/api/oembed',
		'flickr.com'		=>	'https://www.flickr.com/services/oembed/',
		'huffduffer.com'	=>	'https://huffduffer.com/oembed',
		'instagram.com'		=>	'https://api.instagram.com/oembed',
		'kickstarter.com'	=>	'https://www.kickstarter.com/services/oembed',
		'slideshare.net'	=>	'http://www.slideshare.net/api/oembed/2',
		'soundcloud.com'	=>	'https://soundcloud.com/oembed',
		'speakerdeck.com'	=>	'https://speakerdeck.com/oembed.json',
		'ted.com'		=>	'https://www.ted.com/talks/oembed.json',
		'ustream.tv'		=>	'http://www.ustream.tv/oembed',
		'vimeo.com'		=>	'https://vimeo.com/api/oembed.json',
		'youtube.com'		=>	'https://www.youtube.com/oembed'
	);

    $endpoint = false;

    foreach ($providers as $domain => $provider) {
        if (stristr($url, $domain)) {
            $endpoint = $provider;
        }
    }

    if (!$endpoint) {
        return $return;
    }

   $options = array(
        CURLOPT_URL => $endpoint.'?url='.urlencode($url).'&format=json&maxwidth='.$maxwidth,
        CURLOPT_USERAGENT => 'adactio.com',
        CURLOPT_TIMEOUT => 5,
        CURLOPT_RETURNTRANSFER => TRUE,
        CURLOPT_HEADER => FALSE
    );
 
    $curl = curl_init();
    curl_setopt_array($curl, $options);
    $result = curl_exec($curl);
    curl_close($curl);

    $response = json_decode($result,true);

    if (isset($response['type'])) {
        switch ($response['type']) {
            case 'photo':
                $return = '<img src="'.$response['url'].'" alt="'.$response['title'].'" />';
            break;
            default:
                $return = $response['html'];
            break;
        }
    }

    return $return;

}

?>

A function that checks a URL to see if it has an oEmbed endpoint and if it does, returns the embeddable content.

getEmbedCode('http://huffduffer.com/adactio/163894');