チューナーから標準入力されたストリームを読み込んで時刻情報パケット(TDT)から時刻を取得し、GUIの時計を表示します

isdbt_clock.py

#!/usr/bin/env python3
#coding:utf-8

import json
import random
import time
try:
    from gi import pygtkcompat
except ImportError:
    pygtkcompat = None

if pygtkcompat is not None:
    pygtkcompat.enable() 
    pygtkcompat.enable_gtk(version='3.0')
import gtk
import gobject
import math

import bitstring
import sys
import io
import datetime

packet_length = 188
#packet_length = 204
syncbyte = 0x47

count = 0
failcount = 0
readpos = 0

bio = io.BytesIO()

#quoted from https://gist.github.com/jiffyclub/1294443
def mjd_to_date(mjd):
    jd = mjd + 2400000.5
    jd = jd + 0.5
    F, I = math.modf(jd)
    I = int(I)
    A = math.trunc((I - 1867216.25)/36524.25)
    if I > 2299160:
        B = I + 1 + A - math.trunc(A / 4.)
    else:
        B = I
    C = B + 1524
    D = math.trunc((C - 122.1) / 365.25)
    E = math.trunc(365.25 * D)
    G = math.trunc((C - E) / 30.6001)
    day = int(C - E + F - math.trunc(30.6001 * G))
    if G < 13.5:
        month = G - 1
    else:
        month = G - 13
    if month > 2.5:
        year = D - 4716
    else:
        year = D - 4715

    return year, month, day

class TS:
    def __init__(self, packet):
        self.packet = packet
    
    def unpack(self):
        if packet_length == 188:
            #188-5(header+pointer)-4(CRC)=179, 179*8=1432bits
            self.sync, self.error, self.pid, self.scramble, self.counter, self.pointer, self.payload, self.crc = \
                self.packet.unpack('uint:8, bool, pad:2, uint:13, bits:2, pad:2, uint:4, uint:8, bits:1432, bytes:4')
        else:
            #204(16がリードソロモン)
            self.sync, self.error, self.pid, self.scramble, self.counter, self.pointer, self.payload, self.crc, self.reedsolomon = \
                self.packet.unpack('uint:8, bool, pad:2, uint:13, bits:2, pad:2, uint:4, uint:8, bits:1432, bytes:4, bytes:16')
        
        #find sync
        if self.sync != syncbyte:
            found = self.packet.find('0x47', bytealigned=True) #findには文字列で渡す…
            return True
        
        return False    

    def tdt_unpack(self):
        table_id, mjd16, h1, h2, m1, m2, s1, s2 = \
            self.payload.unpack('uint:8, pad:16, uint:16, uint:4, uint:4, uint:4, uint:4, uint:4, uint:4')
        year, month, day = mjd_to_date(mjd16)
        hour = int(str(h1)+str(h2))
        minute = int(str(m1)+str(m2))
        sec = int(str(s1)+str(s2))
        print('TIME {}-{}-{} {}:{}:{} JST'.format(year, month, day, hour, minute, sec))
        return datetime.datetime(year, month, day, hour, minute, sec)
        

while True:
    #新規パケットをwriteする前に終端にseek(seek位置から書くから)
    bio.seek(0, io.SEEK_END)
    bio.write(sys.stdin.buffer.read(packet_length*2))
    #読むので前回位置にseek
    bio.seek(readpos)
    read_data = bio.read(packet_length)
    #前回seek位置を次のに合わせる
    if count%10000 != 0:
        readpos += packet_length*2 #一つ飛ばし
    else:
        #10000ごとにバッファクリア
        bio = io.BytesIO()
        readpos = 0
    
    packet = bitstring.ConstBitStream(bytes=read_data)
        
    ts = TS(packet)
    if ts.unpack():
        #syncできなかったら戻る
        if ts.packet.bytepos != 0: #このパケット内にsyncがあったら
            if readpos > packet_length*2:
                readpos = readpos - packet_length*2 + ts.packet.bytepos #一つ飛ばし考慮
            else:
                readpos = ts.packet.bytepos
        failcount += 1
    
    else:
        #TDT
        if ts.pid == 0x14 and not ts.error:
            nowtime = ts.tdt_unpack()
            break
        
    count += 1


#マシン時計の標準時に対する遅延を返す
def delayer(nowtime):
    unixtime_isdb = nowtime.timestamp()
    unixtime_machine = time.time()
    unixtime_delay = unixtime_isdb-unixtime_machine
    return unixtime_delay

delay = delayer(nowtime)
print('delay:', delay)

class gui:
    def __init__(self):
        #Window
        self.window = gtk.Window()
        self.window.set_title('ISDB-T Clock')
        self.window.connect('destroy_event',self.end_app)
        self.window.connect('delete_event',self.end_app)
        #self.window.set_icon_from_file("icon.ico")
        self.window.set_default_size(200,50)

        time_str, wait_msecs = self.make_time(delay)

        if 0<wait_msecs:
            time.sleep(wait_msecs)
        else:
            #正に修正
            time.sleep(1+wait_msecs) 

        #Label
        self.label_clock = gtk.Label()
        self.label_clock.set_markup(time_str)

        #Button
        #self.adjust_button = gtk.Button()
        #self.adjust_button.set_label("再校正")
        #self.adjust_button.connect("clicked",self.redelayer)

        self.vbox = gtk.VBox()
        self.vbox.add(self.label_clock)
        #self.vbox.add(self.adjust_button)
        self.window.add(self.vbox)

        self.window.show_all()
        
        gobject.timeout_add(1000,self.on_timeout)
        
    def make_time(self, delay):
        nowunixtime = time.time() + delay
        nowtime_str = time.ctime(nowunixtime)
        #小数点以下を出1- 
        wait_msecs = 1-math.modf(nowunixtime)[0]
        return '<b>'+nowtime_str + '</b>', wait_msecs

    def end_app(self,widget,data=None):
        #gtk.main_quit()
        exit()
        return False
       
    def on_timeout(self,*args):
        wait_sec = self.make_time(delay)[1]
        #誤差修正
        if 0<wait_sec:
            time.sleep(wait_sec)
        #多少の誤差は許容
        elif 0>wait_sec+0.05:
            time.sleep(1+wait_msec)
        time_str = self.make_time(delay)[0]
        self.label_clock.set_markup(time_str)
        return True

    def redelayer(self,widget,data=None):
        delayer(uri)

gobject.threads_init()
gui_instance = gui()
gtk.main()