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I want to plot real time original audio signal and fft signal.

my code is,

socket_server.bind(server_address)

print "Listening...\n"

while(True):   
    packet, client = socket_server.recvfrom(buffer_size)
    count=count+1

    if packet=='stop':
        print "client stops to send packets"
        break

    #Convert packet to numpy array
    signal.append(np.fromstring(packet, dtype=np.int16))

print "First Here"

socket_server.close()


signal_f = np.fft.fft(signal)
**Time = np.linspace(0,(len(signal)*(buffer_size/2))/sample_rate, num=(buffer_size/2))**

f, ax = plt.subplots(2, sharex=True)
ax[0].plot(Time, signal)
ax[0].set_title('Original Signal')
ax[1].plot(Time, abs(signal_f), 'r')
ax[1].set_title('fft signal')
plt.show()

I receive packets(which are 16 bit pcm data) from android app. and minbuffersize is 3584 bytes. (buffer_size = 3584)

To get time vector, I should divide size of signal by frame rate.

So in bold line, i think size of signal is len(signal)(# of received packet) * buffer size/2(1792 bytes -> size of packet received). is it wrong?

after check, calculated time is exact! I used stopwatch and compared the result of [(len(signal)*(buffer_size/2))/sample_rate]. both are the same.

but above code results error in plotting.

ax[0].plot(Time, signal) error is " x and y must have same first dimension"

what should i do?,,

Hyunjung Park
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1 Answers1

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In the line where you call np.linespace(), try replacing num=(buffer_size/2), by num=len(signal)

The line becomes

Time = np.linspace(0,(len(signal)*(buffer_size/2))/sample_rate, num=len(signal) )
DrM
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