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import struct
import pyaudio
from utils import *
# Receiver Class: Used to continuos listen for sound waves in the corresponding frequency range
# and decode the data being sent
class Recv:
def __init__(self, start_freq=18500):
# initialize frequency related variables with default values
self.start_freq = start_freq
self.freq_range = 500
self.sampling_rate = 44100
self.p = pyaudio.PyAudio()
self.bytes_per_transmit = 1
# initialize stream variables
self.CHUNK = 2048 * 2
self.FORMAT = pyaudio.paInt32
self.CHANNELS = 1
self.RATE = 44100
self.pause = False
# initialize stream object
self.p = pyaudio.PyAudio()
self.stream = self.p.open(
format=self.FORMAT,
channels=self.CHANNELS,
rate=self.RATE,
input=True,
output=True,
frames_per_buffer=self.CHUNK,
)
# reads and unpacks the incoming audio stream
def read_audio_stream(self):
data = self.stream.read(self.CHUNK)
data_int = struct.unpack(str(self.CHUNK) + 'i', data)
return data_int
# checks if the byte is safe to add to the data structure
def safe_check_byte(self, bytes_seen):
safe_byte = []
if len(bytes_seen) > 0:
for col in range(len(bytes_seen[0])):
count1s = 0
count0s = 0
for row in range(len(bytes_seen)):
bit = bytes_seen[row][col]
if bit == '1':
count1s += 1
else:
count0s += 1
if count1s > count0s:
safe_byte.append('1')
else:
safe_byte.append('0')
return safe_byte
# listens for incoming data
# uses two extra bits to handle data transmission protocol
def listen(self):
prev_is_data_flag = '0'
prev_is_new_byte_flag = '0'
bytes_seen = []
recv_buffer = []
while True:
data = self.read_audio_stream()
bits = wave_to_bits(data, self.start_freq, self.freq_range, self.bytes_per_transmit)
# handle the data flags
is_data_flag = bits[-1]
is_new_byte_flag = bits[-2]
if prev_is_data_flag == '0' and is_data_flag == '1':
prev_is_data_flag = is_data_flag
# just started receiving data
bytes_seen = []
recv_buffer = []
print("started receiving data!")
is_data_flag = bits[-1]
if prev_is_data_flag == '0' and is_data_flag == '0':
prev_is_data_flag = is_data_flag
# just waiting for new data
continue
if prev_is_data_flag == '1' and is_data_flag == '0':
prev_is_data_flag = is_data_flag
# just finished the last byte of data, add it to buffer, then write buffer to terminal
recv_buffer.append(self.safe_check_byte(bytes_seen))
# FIXME: what to do with buffer?
# for now print buffer as string
buffer_as_string = ''.join([receive_string(byte) for byte in recv_buffer])
print("data received: ", buffer_as_string)
# clear data structure & buffer
continue
# at this point, we know we are receiving data
if prev_is_new_byte_flag == is_new_byte_flag:
prev_is_new_byte_flag = is_new_byte_flag
# we are still receiving the same byte, store it in the data structure
byte = bits[:-2]
bytes_seen.append(byte)
continue
else:
prev_is_new_byte_flag = is_new_byte_flag
# we are receiving a new byte, so we need to write the old byte to the recv buffer
recv_buffer.append(self.safe_check_byte(bytes_seen))
# clear the data structure
bytes_seen = []
# append the new byte to the data structure
byte = bits[:-2]
bytes_seen.append(byte)
continue
def main():
recv = Recv()
recv.listen()
if __name__ == "__main__":
main()
|
