code: def convert_timestamp(timestamp):
      
      timestamp = timestamp.strip()
      chunk, millis = timestamp.split(',')
      hours, minutes, seconds = chunk.split(':')
      hours = int(hours)
      minutes = int(minutes)
      seconds = int(seconds)
      seconds = seconds + hours * 60 * 60 + minutes * 60 + float(millis) / 1000
      return seconds
docs: Convert an srt timestamp into seconds.