Following is the function to change time format from 24 hours to 12 hours, please take a look at input and output examples before you use it

/*
 *  Return: 24 hours format to 12 hours format
 *  Input example: 1400, 730, 1205, 0
 *  Ouput example: 02:00PM, 07:30AM, 12:05PM, 12:00AM
 */
function timeformat_24to12($timeval){
    $hours    = substr($timeval, 0, -2);
    $mins     = substr($timeval, -2);
    $meridian = 'AM';

    if($hours>12) {
        $hours -= 12;
        $meridian = 'PM';
    }else if($hours == 12 AND $min>0) {
        $meridian = 'PM';
    }else if($hours == 0) {
        $hours = 12;
    }

    # Prepend zero to hours and mins less than 9
    $hours = str_pad($hours, 2, '0', STR_PAD_LEFT);
    $mins  = str_pad($mins, 2, '0', STR_PAD_LEFT);

    return $hours . ':' . $mins . $meridian; // you may say I added noise here but readability got higher priority in my coding rules :P
}