Q:

Recording multiple microphones in python

I am having some trouble accessing more than two microphones usig pyaudio.  I have a Scarlett 18i20 mixing device to which I want to connect several microphones (up to 8) and then capture the audio stream through pyaudio.  After importing pyaudio I get the following standard input device:
In[34]:
s=pyaudio. PyAudio()
s.get_default_input_device_info()

Out[34]: 
{'defaultHighInputLatency': 0.18,
 'defaultHighOutputLatency': 0.18,
 'defaultLowInputLatency': 0.09,
 'defaultLowOutputLatency': 0.09,
 'defaultSampleRate': 44100.0,
 'hostApi': 0L,
 'index': 1L,
 'maxInputChannels': 18L,
 'maxOutputChannels': 0L,
 'name': u'Eingang (Scarlett 18i20 USB)',
 'structVersion': 2L}

I can easily access the first two microphones using the following code:
p = pyaudio. PyAudio()

stream = p.open(format=pyaudio.paInt16,
                channels=18,
                rate=44100,
                input=True,
                frames_per_buffer=1024,
                output_device_index=1)

for i in range(0, 1000):
    data = stream.read(CHUNK)
    frames.append(data)

stream.stop_stream()
stream.close()
p.terminate()

wf = wave.open('out.wav', 'wb')
wf.setnchannels(18)
wf.setsampwidth(p.get_sample_size(pyaudio.paInt16))
wf.setframerate(44100)
wf.writeframes(b''.join(frames))
wf.close()

I have tried to execute that code for all the different input devices available with 18 input channels.  The result is always the same, I get a wav file, that contains 18 channels, however only the first two of them contain signals.  The other channels are empty.  The Focusrite device works fine, I can see the microphone levels through an mixing application that came with the device. 
I would really appreciate any help... I am not a programming expert but I really need to get this thing to work. 
Thanks! 

A:

There is quite stupid error in my question.  In the code I posted I specify the output_device_index, while this should of course be the input_device_index for choosing the recording device.  Playing around with different input devices I found one, for which I can record all the plugged microphones.