I've been searching for a way to make "Audio Player" (by Martin Laine) recognize the URL of an mp3 file in a custom field. There are a number of solutions for just one custom field in a post but I have ten custom fields that may or may not be populated (I'm forcing their creation, without a value, by a CSV import). I would like to be able to have Audio Player recognize custom fields that are populated but ignore the ones that are not (they will be populated at a later time).
I would imagine the php code would be in the loop and in the single.php template. That file will be in a child theme.
Any help is most appreciated.