dhirlinger

…and the answer is no. Use the gallery shortcode filter.

I should add that I’m using get_post_gallery(false) to display the gallery in question with the loop:

if ( get_post_gallery(false) ) :
        echo get_post_gallery(false);
endif;

Well if you stumble upon this question searching for the same or similar answer, here is what I ended up doing… The attachment post ID was indeed the issue. Since I’m using the img_caption_shortcode hook to display the value collected in the custom field the following will work inside my filter function :

$att_id = $attr['id'];
$att_id = str_replace('attachment_', '', $att_id);
$dpi = get_post_meta($att_id, '_custom1', true);

$dpi is what I ultimately wanted to display. I added inside an additional figcaption tag. With in the img caption shortcode function $attr[‘id’] gives you ‘attachment_{post-id}. This is why I had to use str_replace() before passing the ID along to get_post_meta().