The question is related to this discussion ([link][1]).


Your answer helps a lot. Thanks. My use case is the following: Upon an event on my Python script running on my PC, I need to send a command to the RPi to record 5 seconds from a USB microphone plugged to my RPi.

The Python script (I lost credit to ; sorry about that) runs well on RPi when I run it manually from PuTTY windows.

import pyaudio
import wave

form_1 = pyaudio.paInt16 # 16-bit resolution
chans = 1 # 1 channel
#samp_rate = 44100 # 44.1kHz sampling rate
samp_rate = 16000 # 16kHz sampling rate

chunk = 4096 # 2^12 samples for buffer
record_secs = 3 # seconds to record
dev_index = 2 # device index found by p.get_device_info_by_index(ii)
wav_output_filename = 'test1.wav' # name of .wav file

audio = pyaudio.PyAudio() # create pyaudio instantiation

# create pyaudio stream
stream = audio.open(format = form_1,rate = samp_rate,channels = chans, \
                    input_device_index = dev_index,input = True, \
frames = []

# loop through stream and append audio chunks to frame array
for ii in range(0,int((samp_rate/chunk)*record_secs)):
    data = stream.read(chunk)

print("finished recording")

# stop the stream, close it, and terminate the pyaudio instantiation

# save the audio frames as .wav file
wavefile = wave.open(wav_output_filename,'wb')

On my PC I have the following script thanks to you @chris :

from paramiko import SSHClient, AutoAddPolicy

def Connect(ip, username='pi', pw='raspberry'): 
    '''ssh into the pi'''
    print('connecting to {}@{}...'.format(username, ip))
    ssh = SSHClient()
    ssh.connect(ip, username=username, password=pw)
    print('connection status =', ssh.get_transport().is_active())
    return ssh

def SendCommand(ssh, command, pw='password'):
    '''send a terminal/bash command to the ssh'ed-into machine '''
    print('sending a command... ', command)
    stdin, stdout, stderr = ssh.exec_command( command )

    if "sudo" in command:


    out = stdout.read()
    print(f'stout =  {out}')
    print(f'sterr = {stderr.read()}')

myssh = Connect(ip='192.168.x.y') #replace x and y by right value
SendCommand(myssh, command='sudo python ~/TestDirectory/TestAudio1.py')

But when I run it on my PC from Spyder I have the following output:

connecting to [email protected]... connection status = True sending a command... sudo python ~/TestDirectory/TestAudio1.py stout = b'recording\nfinished recording\n' sterr = b"ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition 'cards.bcm2835.pcm.front.0:CARD=0'\n [etc etc] No such file or directory\nALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM bluealsa\nconnect(2) call to /tmp/jack-0/default/jack_0 failed (err=No such file or directory)\nattempt to connect to server failed\n"

So the script starts well since I see "stout = b'recording\nfinished recording\n'" but then I have the sterr. Any clue where this issue is coming from? Thanks in advance for your help

EDIT April 16th 2019 Eventually I found out that, despite the big error message, the audio file was actually correctly created. So no worries anymore

  • How do I "close" the question? Apr 16, 2019 at 20:11
  • You can finish the question by making an answer. Then after two days you can accept it yourself.
    – Ingo
    Apr 17, 2019 at 19:31

1 Answer 1


Eventually I found out that, despite the big error message, the audio file was actually correctly created. So no worries anymore

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