TimeFunctions.php

<?php

function HHMMSStoSeconds($time) {
    return strtotime("1970-01-01 $time UTC");
}

function secondsToHHMMSS($seconds) {
    return sprintf("%02d%s%02d%s%02d", floor($seconds / 3600), ':', ($seconds / 60) % 60, ':', $seconds % 60);
}

// Time to decimal converter
function timeToDecimal($time) {
    $timeArr = explode(':', $time);
    $decTime = ($timeArr[0] * 60) + ($timeArr[1]) + ($timeArr[2] / 60);
    return $decTime;
}