<?php
if (arg(0) == 'node' && is_numeric(arg(1))) {
$nid = arg(1);

$node = node_load($nid);
$field_name = 'field_video';
$invoked_video = field_get_items('node', $node, $field_name);

if ($format = 'url') {
$video_url = file_create_url($invoked_video[0]['uri']);

} else {
$video_url = $invoked_video[0][$format];
}

$ffprobe = "/opt/ffmpeg/ffprobe";
$options =" -show_entries format=duration -v quiet -of csv='p=0'";

$duration = shell_exec($ffprobe . " -i " . $video_url . $options);

return $duration;
}

?>