It looks like the closest you get is in the WP-Embed class:
autoembed( $content );
It says it extracts urls which are on distinct lines (like you’d put a url in for embedding it), but it then passes it to WP_Embed::shortcode().
Not quite what you want. You could dig into WP_Embed::shortcode() to see if you can figure out how to hack together your own script, but I don’t think there’s anything ready-made for you :/