Introduction

Control the routing of audio using a Raspberry Pi. This software runs on a Raspberry Pi and communicates with an ITEC audio controller (ITEC MultiMix) using the serial port. It provides a webinterface to easily connect an audio input source to multiple audio destinations.

Further, it can read audio from an url, and send it to a configurable input of the ITEC. And the other way around: it is possible to send audio from an configurable ITEC output to an Icecast mountpoint.

The userinferface is created in the Dutch language. It consists of 2 pages; Control and Settings:

Control screen

Settings screen

Howto deploy on raspberry pi

This is tested on Raspberry Pi version 3. OS: Raspberry Pi OS version 2020-08-20.

1. Update OS and packages

1.1 Enable ssh

Option 1: Before inserting the sd card to the Pi, add a file named 'ssh' to the boot partition. Option 2: Use Desktop environment to enable ssh

Add ssh key

PI_IP=192.168.1.96
ssh-copy-id -i ~/.ssh/id_ecdsa pi@${PI_IP}

Update

ssh pi@${PI_IP}
sudo apt update
sudo apt full-upgrade

Change default password

sudo raspi-config

2. Install Python and dependencies

2.1 Install python 3.7

Python 3.7+ is preinstalled on the OS. Also ffmpeg is preinstalled. Check this by running:

python3 --version
ffmpeg -version

2.2 Create a virtual environment

mkdir ~/AudioController
cd ~/AudioController
python3 -m venv pyenv

2.3 Install dependencies

source ./pyenv/bin/activate
python -m pip install --upgrade pip
python -m pip install pyserial
python -m pip install tornado
python -m pip install python-socketio
python -m pip install python-decouple

Optional:

sudo apt update
sudo apt install python3-gpiozero
python -m pip install gpiozero
python -m pip install rpi.gpio

3. Copy audio_controller project/package to pi

Check if ./audio_controller/audio_controller/static/js/main.js exists. If not, first compile python code from ./transcrypt/python to generate main.js

Copy from local to pi (use correct ip-address):

scp -r ./audio_controller pi@${PI_IP}:~/AudioController
scp ./run_audio_controller.sh pi@${PI_IP}:~/AudioController
scp ./audio_controller.service pi@${PI_IP}:~/AudioController
scp ./audio_controller.html pi@${PI_IP}:~/Desktop

To install an update of the software it is usually enough to run the first command from above. Tip: instead of using the scp command, use rsync, and manually exclude files which were not updated.

First test with dry-run and check rsync-result.txt:

rsync --dry-run -r -v --exclude="fontawesome*" --exclude="bootstrap*" --exclude="*.pyc" ./audio_controller pi-test:~/AudioController > rsync-result.txt

And then for real by removing --dry-run

4. Create auto startup

Copy on pi, from home dir to /etc/systemd/system/

ssh pi@${PI_IP}
cd /home/pi/
sudo cp ./AudioController/audio_controller.service /etc/systemd/system/audio_controller.service
sudo chmod 777 ./AudioController/run_audio_controller.sh
sudo systemctl enable audio_controller.service

Some commands to start and stop service:

sudo systemctl status audio_controller.service
sudo systemctl start audio_controller.service
sudo systemctl stop audio_controller.service
sudo systemctl restart audio_controller.service
sudo systemctl enable audio_controller.service
sudo systemctl disable audio_controller.service

For a automatic daily restart of the service (at 4 o'clock):

sudo crontab -e
0 4 * * * systemctl restart audio_controller.service

To start the browser in kiosk mode, add the following lines to /etc/xdg/lxsession/LXDE-pi/autostart:

@xset s off
@xset -dpms
@xset s noblank
@chromium-browser --kiosk http://localhost:5000/

If it does not work, the last line should (maybe) be:

@chromium --kiosk http://localhost:5000/

For example the full file content becomes:

@lxpanel --profile LXDE-pi
@pcmanfm --desktop --profile LXDE-pi
@xscreensaver -no-splash
@xset s off
@xset -dpms
@xset s noblank
@chromium-browser --kiosk http://localhost:5000/

5. Use external USB sound card

Check if card 1 is indeed installed and can play and record:

aplay -l
arecord -l 

BELOW IS DEPRECATED (probably):

Change number of default card from 0 to 1 in alsa.conf:

sudo nano /usr/share/alsa/alsa.conf

Change lines to match:

defaults.ctl.card 1
defaults.pcm.card 1

And play test sound (connect headphone to external device):

speaker-test -c2

6. Enable remote login

ssh pi@${PI_IP}
cd ~/AudioController/audio_controller/audio_controller/
sudo -s
python3
import utils
utils.add_user("<username>", "<password>")
assert utils.check_user("<username>", "<password>"), "Configuration failed"
exit()

Extras

Disable updates

Enable NTP to have time updated

timedatectl status
sudo timedatectl set-ntp True

Remarks

Make sure to place user file and settings file in home of root, not in home or pi user. AudioController runs as root user.

How to contribute

User Linux as host. Windows is also possible, but not covered by this manual.

To read or write audio from/to an url, install ffmpeg.

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