PHP inside Wordpress shortcode

Question

I've done a ton of searching and I'm pulling out what's left of my hair. The PHP code on its own is:

<?php echo wp_get_attachment_url($file->ID) ?>

...the shortcode is: [embed][/embed]

I've tried all sorts of variations of 'do shortcode' but can't get things working. Can you suggest the correct code?

Answer 1

WordPress (3.6 or higher) has an audio shortcode, the following should work:

$mp3 = wp_get_attachment_url( $file->ID );
echo do_shortcode( '[audio src="' . $mp3 . '"]' );