capturing elevator music udp mp3 data using python

capture elevator music data

# from the reddit post 
# https://www.reddit.com/r/programming/comments/4kdmmb/reverse_engineering_a_mysterious_udp_stream_in_my/

import socket
import struct

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind(('', 2046))

mreq = struct.pack("4sl", socket.inet_aton("234.0.0.2"), socket.INADDR_ANY)
s.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)

while True:
    data = s.recv(2048)
    print(data)
    

###############################
# write data with different offsets to separate files to find the format
data = s.recv(2048)
for i in range(25):
    open("test{}".format(i), "wb+").write(data[i:])
    
    


###############################
$ file test*
test0:    data
test1:    UNIF v-16624417 format NES ROM image
test10:   UNIF v-763093498 format NES ROM image
test11:   UNIF v-1093499874 format NES ROM image
test12:   data
test13:   TTComp archive, binary, 4K dictionary
test14:   data
test15:   data
test16:   UNIF v-1939734368 format NES ROM image
test17:   UNIF v-1198759424 format NES ROM image
test18:   UNIF v-256340894 format NES ROM image
test19:   UNIF v-839862132 format NES ROM image
test2:    UNIF v-67173804 format NES ROM image
test20:   data
test21:   data
test22:   data
test23:   DOS executable (COM, 0x8C-variant)
test24:   COM executable for DOS
test3:    UNIF v-1325662462 format NES ROM image
test4:    data
test5:    data
test6:    data
test7:    data
test8:    MPEG ADTS, layer III, v1, 192 kbps, 44.1 kHz, JntStereo
test9:    UNIF v-2078407168 format NES ROM image


##################################################
while True:
    data = s.recv(2048)
    sys.stdout.buffer.write(data[8:])
    

#################################################
$ python3 listen_2046.py > test.mp3
* wait a little to get a recording *
^C

$ mplayer test.mp3
MPlayer (C) 2000-2016 MPlayer Team
224 audio & 451 video codecs

Playing test.mp3.
libavformat version 57.25.100 (external)
Audio only file format detected.
=====
Starting playback...
A:   3.9 (03.8) of 13.0 (13.0)  0.7%