parses timecode string frames '00:00:00:00' or '00:00:00;00' or
        milliseconds '00:00:00:000'

def parse_timecode(cls, timecode):
        """parses timecode string frames '00:00:00:00' or '00:00:00;00' or
        milliseconds '00:00:00:000'
        """
        bfr = timecode.replace(';', ':').replace('.', ':').split(':')
        hrs = int(bfr[0])
        mins = int(bfr[1])
        secs = int(bfr[2])
        frs = int(bfr[3])
        return hrs, mins, secs, frs