Installing PyAudio on Raspberry Pi¶

Table of Contents¶

Setup
A note on the default audio device
Making pulesaudio an enabled service
Listing PyAudio devices

Setup¶

Using the raspian operating system. The required packages are

(sudo apt-get update && sudo-apt get upgrade)
sudo apt-get install portaudio19-dev pulseaudio

Pulseaudio seems to be required for translating the audio device indexes for PyAudio. Since we want it to run as a daemon, we must start it with

pulseaudio --start

Then, in the python environment we install

pip install pyaudio

and use a test script to ensure the behaviour is as desired, e.g. a minimal

import wave, pyaudio
testfile = "test.wav"

with wave.open(testfile, 'rb') as wf:
	prop = {}
	prop['rate'] = wf.getframerate()
    prop['format'] = self._p.get_format_from_width(wf.getsampwidth())
	prop['channels'] = wf.getnchannels()
    prop['output'] = True
    prop['output_device_index'] = None 	# change to desired, else None uses default

    pa = pyaudio.PyAudio()
    stream = pa.open(**prop)

    data = wf.readframes(1024)
    while len(data) > 0:
    	stream.write(data)
    	data = wf.readframes(1024)

    stream.stop_stream()
    stream.close()

    pa.terminate()

A note on the default audio device ¶

To view the default audio device used by PyAudio, use

import pyaudio
pa = pyaudio.PyAudio()
pa.get_default_output_device_info()

Making pulesaudio an enabled service ¶

We can make pulseaudio auto-start with systemd by creating a file in /etc/systemd/system/pulseaudio.service with contents

[Unit]
Description=Pulseaudio system daemon

[Service]
Type=notify
Exec=pulseaudio --system --realtime --daemonize=no

[Install]
WantedBy=multi-user.target

note that in this case we want to explicitly set daemonize=no for the program, else we cannot control it with systemctl. Additionally, in the manual pages, the --start flag implies daemonize, so cannot start it in the same way as we would on the command line. The --system flag enables the service across the whole system, instead of on a per user basis, and the --realtime flag helps synchronize the audio threads when running in system mode.

Enable and start the service

sudo systemctl --system enable pulseaudio.service
sudo systemctl --system start pulseaudio.service

Also note that interacting with this service using systemctl requires the --system flag, e.g. sudo systemctl --system status pulseaudio.

Listing PyAudio devices ¶

To list the audio devices PyAudio is able to interact with, use

import pyaudio
p = pyaudio.PyAudio()
for i in range(p.get_device_count()):
    print(p.get_device_info_by_index(i).get('name'))

notes

Installing PyAudio on Raspberry Pi

Contents