def parse_vtt(filename):
    """parse .vtt file, return a list of (start, end, text)"""
    with open(filename) as f:
        events = []

        f.readline()
        f.readline()
        lines = [line.strip() for line in f.readlines()]
        i = 0
        while i < len(lines):
            idx = lines[i]
            i += 1

            start, _, end = lines[i].split()
            start = start.replace(',', '.')
            end = end.replace(',', '.')
            i += 1

            text = ''
            while i < len(lines) and lines[i]:
                text += lines[i]
                i += 1
            i += 1

            events.append((start, end, text))

        return events