def segment(f, output, target_duration, mpegts):
    """Segment command."""
    try:
        target_duration = int(target_duration)
    except ValueError:
        exit('Error: Invalid target duration.')

    try:
        mpegts = int(mpegts)
    except ValueError:
        exit('Error: Invalid MPEGTS value.')

    WebVTTSegmenter().segment(f, output, target_duration, mpegts)