How can i create a function to get youtube video time

Tom J Nowell posted this code to help me retrieve the YouTube video time.

Functions

// function to parse the code from the URL
function parse_youtube_video_id_from_url( $video_url ) {
    $splited_data = explode( '=', $video_url );
    $video_unique_code = substr( $splited_data[1], 0, -strlen( strrchr( $splited_data[1], '&' ) ) );
    return $video_unique_code;
}

// use the youtube APIs to get a json string containing data about the video
function get_youtube_json_video_data( $video_code ) {
    $api_url = 'https://gdata.youtube.com/feeds/api/videos?v=2&alt=jsonc&q='.$video_code;
    $data = wp_remote_get( $api_url );
    return $data['body'];
}

Getting the data:

<?php $youtubecode = 'QiNIfGiNiOk';
$video_data = get_youtube_json_video_data($youtubecode);
$video_data = json_decode( $video_data ); 
echo '<pre>'.print_r($video_data,true).'</pre>';
?>

The data that the above code retrieves (e.g.):

stdClass Object
(
    [apiVersion] => 2.1
    [data] => stdClass Object
        (
            [updated] => 2013-02-27T18:29:22.395Z
            [totalItems] => 1
            [startIndex] => 1
            [itemsPerPage] => 25
            [items] => Array
                (
                    [0] => stdClass Object
                        (
                            [id] => QiNIfGiNiOk
                            [uploaded] => 2012-11-30T18:20:08.000Z
                            [updated] => 2013-02-26T22:33:56.000Z
                            [uploader] => ramonsteck
                            [category] => Entertainment
                            [title] => After Earth - Trailer 2013
                            [description] => Unete www.facebook.com/Cinemovs Historias Paranormales Reales, Películas de Terror Online y proximos estrenos de cine.
                            [thumbnail] => stdClass Object
                                (
                                    [sqDefault] => http://i.ytimg.com/vi/QiNIfGiNiOk/default.jpg
                                    [hqDefault] => http://i.ytimg.com/vi/QiNIfGiNiOk/hqdefault.jpg
                                )

                            [player] => stdClass Object
                                (
                                    [default] => https://www.youtube.com/watch?v=QiNIfGiNiOk&feature=youtube_gdata_player
                                    [mobile] => https://m.youtube.com/details?v=QiNIfGiNiOk
                                )

                            [content] => stdClass Object
                                (
                                    [5] => https://www.youtube.com/v/QiNIfGiNiOk?version=3&f=videos&app=youtube_gdata
                                    [1] => rtsp://v1.cache6.c.youtube.com/CiILENy73wIaGQnpiI1ofEgjQhMYDSANFEgGUgZ2aWRlb3MM/0/0/0/video.3gp
                                    [6] => rtsp://v1.cache6.c.youtube.com/CiILENy73wIaGQnpiI1ofEgjQhMYESARFEgGUgZ2aWRlb3MM/0/0/0/video.3gp
                                )

                            [duration] => 123
                            [aspectRatio] => widescreen
                            [rating] => 2.6722891
                            [likeCount] => 174
                            [ratingCount] => 415
                            [viewCount] => 247218
                            [favoriteCount] => 0
                            [commentCount] => 63
                            [accessControl] => stdClass Object
                                (
                                    [comment] => allowed
                                    [commentVote] => allowed
                                    [videoRespond] => moderated
                                    [rate] => allowed
                                     => allowed
                                    [list] => allowed
                                    [autoPlay] => allowed
                                    [syndicate] => allowed
                                )

                        )

                )

        )

)

How can I get the duration of the video (e.g. ‘1:23’).

He told me to:

create a function, hook that function into the ‘save_post’ and ‘publish_post’ actions, that updates the post meta/custom field based
on the above code

How can I create that function hook? And how can i put together:

Custom Field were I put the key:

<?php $key="trailer"; echo get_post_meta($post->ID, $key, true); ?>

To retrieve the video data, specify the YouTube URL code such as:

$youtubecode = 'QiNIfGiNiOk';

————————– UPDATE – The code that Works ————————-

<?php 
$key="trailer";
$youtubecode = get_post_meta($post->ID, $key, true);
$video_data = get_youtube_json_video_data($youtubecode);
$video_data = json_decode( $video_data ); 
foreach ( $video_data->data->items as $data ){
                echo brsfl_secondsToTime($data->duration);
    }
?>

——————————— Thanks to Brasofilo —————————-