WordPress at a glance
filter is not described

get_post_gallery filter-hook . WP 3.6.0

Filters the first-found post gallery.

Usage

add_filter( 'get_post_gallery', 'filter_function_name_1624', 10, 3 );
function filter_function_name_1624( $gallery, $post, $galleries ){
	// filter...

	return $gallery;
}
$gallery(array)
The first-found post gallery.
$post(int/WP_Post)
Post ID or object.
$galleries(array)
Associative array of all found post galleries.

Where the hook is called

get_post_gallery()
get_post_gallery
wp-includes/media.php 3842
return apply_filters( 'get_post_gallery', $gallery, $post, $galleries );

Where the hook is used (in WP core)

Does not used.