Generate MPEG-TS stream with TDT info

tdt.py

from binascii import hexlify
from struct import pack
from time import sleep
from datetime import datetime
import socket

ts_header = 0x47401410
table_id = 0x70
pointer_field = 0x00
flags_plus_length= 0x7005

def datetime_to_tdt(d):
	temp_year = d.year - 1900
	l = 1 if d.month <=2 else 0
	mjd = 14956 + d.day + int((temp_year - l)*365.25) + int((d.month+1+l*12)*30.6001)

	bcd_hour = ((d.hour/10) << 4) | (d.hour % 10)
	bcd_minute = ((d.minute/10) << 4) | (d.minute % 10)
	bcd_second = ((d.second/10) << 4) | (d.second % 10)

	return pack('>H3B', mjd, bcd_hour, bcd_minute, bcd_second)

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 20)

counter = 0
send = True
padding = '\xff' * 175

while send:
	try:
		current_header = ts_header|counter
		tdt_date = datetime_to_tdt(datetime.now())
		packet = pack('>IBBH%ss%ss' % (len(tdt_date),len(padding)), current_header,  pointer_field, table_id, flags_plus_length, tdt_date, padding)
		print "Sending %s" % (hexlify(packet))
		s.sendto(packet, ("239.1.82.238", 1234))
		sleep(30)

		if counter == 127:
			counter = 0
		else:
			counter+=1
	except KeyboardInterrupt:
		send = False

s.close()