Set first oembed in post to a global variable or function

Question

I have a function that gets the first oembed in the post. I got the code from this related post.

add_filter('embed_oembed_html', 'my_function',10,4);
function my_function( $cache, $url, $attr, $post_ID ) {
  global $my_previous_post_id;
  if ($my_previous_post_id != $post_ID) {
    // post ID changed, so this is the first oembed for the post
    // do something with $url
    $my_previous_post_id = $post_ID;
  }
  return $cache; // it's important that you return the $cache value as-is
}

How can I get the first oembed from a post and make it a global variable? If that is not possible can we make the oembed url as post meta in order to access the first oembed anywhere?

I need to be able to access the first oembed in a loop within my shortcode.

You can get the first image in in a post (featured image) through a function:

the_post_thumbnail();

You can get the first oembed in a post by:

???

@Otto wrote how to get the first oembed but how can we access it?

Answer 1

Since WordPress 3.6+

There is a function to print out all the media in the content.

get_media_embedded_in_content();