def decode(self, bits):
bits = np.array(list(bits), dtype=int)
packets = []
flag = list(np.array(list(preamble), dtype=int))[-9:]
cur_b = []
num_packets = '0'
for n in range(0, bits.shape[0] - 7):
if list(bits[n:n+len(flag)-1]) == flag[1:]:
if len(cur_b): # end packet; do CRC and add to packets
cur = "".join([str(c) for c in cur_b[len(flag)-2:-1]])
cur = util.NRZI2NRZ(cur)
cur = util.bit_unstuff(cur)
cur = "".join(['1' if b else '0' for b in cur])
if len(cur) < self.packet + 48:
cur_b = []
continue
cur += '0' * (self.packet + 48 + self.ecc_p * 16 - len(cur))
try:
if self.ecc_p:
cur = util.ASCIIToBin(str(self.codec_p.decode(util.binToASCII(cur))))
except:
cur_b = []
continue
crc = cur[0:32]
idx = cur[32:40]
tot = cur[40:48]
payload = cur[48:]
if (zlib.crc32(util.binToASCII(idx + tot + payload)) % 2**32) == int("".join(crc), 2):
packets += [(int(idx, 2), payload)]
num_packets = tot
cur_b = []
else:
cur_b += [bits[n]]
return packets, int(num_packets, 2)
def receive(self, in_port, t = 75):
p = pyaudio.PyAudio()
Qin = Queue.Queue()
cQin = Queue.Queue()
t_rec = threading.Thread(target = util.record_audio, args = (Qin, cQin, p, 48000, in_port))
t_rec.start()
print "STARTED RECORDING..."
sys.stdout.flush()
time.sleep(t)
cQin.put('EOT')
p.terminate()
print "END RECORDING..."
data = np.array([])
while not Qin.empty():
data = np.concatenate((data, Qin.get()))
np.save("RECEIVED_LAST.npy", data)
print "START DECODE..."
rcv_bits = self.modem.demodulate_bits(data, pll_a = self.pll_a).astype(int)
print "received bits:", len(rcv_bits)
rcv_packets, n_p = self.packer.decode(rcv_bits)
print "received packets: ", len(rcv_packets), "\t total packets: ", n_p
payload = self.packer.decode_from_packets(rcv_packets, n_p)
decomp = zlib.decompress(util.binToASCII(payload[2]))
return util.ASCIIToBin(decomp)
def receive_saved(self, data):
print "START DECODE..."
rcv_bits = self.modem.demodulate_bits(data, pll_a = self.pll_a).astype(int)
print "received bits:", len(rcv_bits)
rcv_packets, n_p = self.packer.decode(rcv_bits)
print "received packets: ", len(rcv_packets), "\t total packets: ", n_p
payload = self.packer.decode_from_packets(rcv_packets, n_p)
decomp = zlib.decompress(util.binToASCII(payload[2]))
return util.ASCIIToBin(decomp)
def encode(self, bits, typ = 0):
bits = np.array(list(bits), dtype=int)
NUM_PACKETS = str(bin(int(math.ceil((2 + 24 + bits.shape[0]) / (0. + self.packet))) + 2 * self.ecc))[2:].zfill(8)
PAYLOAD_TYPE = str(bin(typ))[2:].zfill(2)
NUM_BITS = str(bin(bits.shape[0]))[2:].zfill(24)
bits = np.concatenate((np.array(list(PAYLOAD_TYPE), dtype=int), np.array(list(NUM_BITS), dtype=int), bits))
bits = np.array(list(bits), dtype=int)
z_pad = (self.packet - (bits.shape[0] % self.packet)) % self.packet
print "NUM BITS: ", bits.shape[0], "\t ZPAD: ", z_pad
bits = np.concatenate((bits, np.zeros(z_pad))).astype(int)
packets = np.reshape(bits, (-1, self.packet))
packets_ascii = [list(util.binToASCII("".join(packet))) for packet in packets.astype(str)]
packets_ecc = [self.codec.encode("".join(packet)) for packet in zip(*packets_ascii)]
encoded_packets = []
for packet_num in range(int(NUM_PACKETS, 2)):
packet_payload = "".join([chr(packets_ecc[i][packet_num]) for i in range(self.packet / 8)])
packet_nocrc = util.binToASCII(str(bin(packet_num))[2:].zfill(8)) + util.binToASCII(NUM_PACKETS) + packet_payload
packet_withcrc = util.binToASCII(str(bin(zlib.crc32(packet_nocrc) % 2**32))[2:].zfill(32)) + packet_nocrc
packet_ecc = str(self.codec_p.encode(packet_withcrc))
encoded_packets += [packet_ecc]
return encoded_packets
def dry_run(self, bits, typ = 0):
bits = np.array(list(bits), dtype=str)
if bits.shape[0] % 8 != 0:
raise Exception("Number of bits should be a multiple of 8")
bits_compressed = util.ASCIIToBin(min([zlib.compress(util.binToASCII("".join(bits)), i) for i in range(1,10)], key = lambda s: len(s)))
ENT_RATIO = len(bits_compressed) / float(len(bits))
bits_packets = self.packer.packets_to_bits(self.packer.encode(bits_compressed, typ))
PACKED_BYTES = len(bits_packets) / 8.
print "\nEntropy compressed ratio: ", ENT_RATIO
print "Final size (bytes): ", PACKED_BYTES
print "Channel efficiency ratio: ", len(bits_compressed) / 8. / PACKED_BYTES
self.audio_sig = self.modem.modulate(np.array(list(bits_packets), dtype=int))
print "Audio time is: ", len(self.audio_sig) / 48000.
if len(self.audio_sig) < 75 * 48000:
self.ready = True
print "ready to go! call dt.transmit()"
def decode_from_packets(self, packets, numpackets):
if len(packets) == 0 or len(packets) < numpackets - 2 * self.ecc:
raise Exception("Too many packets dropped!")
packets_order = ['0' * self.packet for _ in range(numpackets)]
for idx, payload in packets:
packets_order[idx] = payload
packets_order = np.array(packets_order)
packets_ascii = [list(util.binToASCII("".join(packet))) for packet in packets_order.astype(str)]
packets_corrected = [self.codec.decode("".join(packet)) for packet in zip(*packets_ascii)]
payload = ''
for packet_num in range(numpackets - 2 * self.ecc):
packet_payload = "".join([chr(packets_corrected[i][packet_num]) for i in range(self.packet / 8)])
payload += packet_payload
payload_bits = util.ASCIIToBin(payload)
payload_type = payload_bits[:2]
payload_size = payload_bits[2:26]
payload = payload_bits[26:26 + int(payload_size, 2)]
return int(payload_type, 2), int(payload_size, 2), payload
