Display Advanced Custom Fields (ACF) in an Envira Gallery. From http://www.jowaltham.com/display-advanced-custom-fields-envira-gallery/

single-portfolio.php

<?php
// Do NOT include the opening php tag above

add_action( 'genesis_entry_content', 'jmw_add_envira_gallery_after_content', 15 );
/*
 * Add the gallery after the end of the content
 */
function jmw_add_envira_gallery_after_content() {

	$gallery = get_post_meta( get_the_ID(), 'gallery' ); // 'gallery' is name of my ACF gallery field
	
	// If we have something output the gallery
	if( is_array( $gallery[0] )) {
		if( shortcode_exists( 'envira-gallery' )) {
			echo do_shortcode( '[envira-gallery id="107"]' );	
		}
		else { // Fall back to WordPress inbuilt gallery
			$image_ids = $gallery[0];
			$shortcode = '[gallery ids="' . implode( ',', $image_ids ) . '"]';
			echo do_shortcode( $shortcode );
		}
	}
	
}

add_filter( 'envira_gallery_pre_data', 'jmw_filter_envira_gallery_data', 10, 2);
/*
 * Filter the gallery $data and replace with the image data for our images in the ACF gallery field
 */
function jmw_filter_envira_gallery_data( $data, $gallery_id ) {
	
	$newdata = array();
	
	// Don't lose the original gallery id and configuration
	$newdata[ "id" ] = $data[ "id" ];
	$newdata[ "config" ] = $data[ "config" ];
	
	// Get list of images from our ACF gallery field
	$gallery = get_post_meta( get_the_ID(), 'gallery' );	
	$image_ids = $gallery[0]; // It's an array within an array

	// If we have some images loop around and populate a new data array
	if( is_array( $image_ids ) ) {
	
		foreach( $image_ids as $image_id ) {

			$newdata[ "gallery" ][ $image_id ][ "status" ] = 'active';	
			$newdata[ "gallery" ][ $image_id ][ "src" ] = esc_url( wp_get_attachment_url( $image_id ) );
			$newdata[ "gallery" ][ $image_id ][ "title" ] = esc_html( get_the_title( $image_id ) );
			$newdata[ "gallery" ][ $image_id ][ "link" ] = esc_url( wp_get_attachment_url( $image_id ) );
			$newdata[ "gallery" ][ $image_id ][ "alt" ] = trim(strip_tags( get_post_meta($image_id, '_wp_attachment_image_alt', true) ));
			$newdata[ "gallery" ][ $image_id ][ "thumb" ] = esc_url( wp_get_attachment_thumb_url( $image_id ) );
	
		}
	}
	
	return $newdata;
}