Advanced Custom Field plugin uses get_field()
to retrieve values.
Your code should be something like:
$audio = get_field('audio_post_format_url', $post->ID);
var_dump( $audio ); # To make sure you're retrieving the right value
echo wp_oembed_get( $audio );
Note that get_field()
does not need a second parameter, it will take the current post ID if omitted.
If var_dump( $audio )
displays false
, then you should check your ACF key.