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diff --git a/20210919-raspberry-pi-white-noise-machine.md b/20210919-raspberry-pi-white-noise-machine.md new file mode 100644 index 0000000..666157e --- /dev/null +++ b/20210919-raspberry-pi-white-noise-machine.md @@ -0,0 +1,56 @@ +# Raspberry Pi white noise machine + +September 19, 2021 + +A white noise machine can help find sleep or mask ambient noise or even tinnitus. It can also be used to muffle conversation from potential eavesdroppers. I wanted to experiment with a white noise machine for sleep purposes so I decided to build one with a Raspberry Pi I had lying around. + +For this you will need: + +* A Raspberry Pi equipped with a jack port and an OS installed (I used a Pi 3B with Raspbian OS) +* Speakers connected to the Pi + +Actually a Pi 3 is a bit overkill for this. I have a Pi Zero lying around that could fit the bill except it needs a USB dongle to connect speakers and I don't have such a dongle. + +## Preparing the white noise + +First you need to find a white noise sample, preferably a long one. I chose to extract the sound from a 3 hour long YouTube video of a waterfall. Of course, choose what suits you. If you want to extract the sound from a YouTube video, you could use one of the many online tools but I won't recommend that to you. Instead, you can use [youtube-dl](https://github.com/ytdl-org/youtube-dl): + + $ youtube-dl -x --audio-format mp3 https://www.youtube.com/watch?v=dQw4w9WgXcQ + +Some explanations for the options used: + +* `-x` asks youtube-dl to extract the audio from the video. As stated in youtube-dl's help, ffmpeg or avconv is required for this +* `--audio-format` should be self-explanatory + +## Creating a white noise service + +Next we are going to create a service to play the white noise automatically at system startup. My Raspberry Pi is running raspbian so systemd is used to manage services. Create a `/etc/systemd/system/whitenoise.service` file with the following contents: + + [Unit] + Description=White noise machine + StartLimitIntervalSec=0 + + [Service] + Type=simple + Restart=never + User=pi + ExecStart=mpg123 --loop /home/pi/whitenoise.mp3 + + [Install] + WantedBy=multi-user.target + +You should adjust your username and path to the file. I used [mpg123](https://mpg123.org/) because it's the simplest and lightest audio player I could find. Its loop option is handy to keep playing infinitely. It needs to be installed: + + # apt install mpg123 + +## Auto start, auto stop + +To start automatically the service on system startup, you just need to enable the service on startup: + + # systemctl enable whitenoise + +To stop it, you can use a cron job set at the time you want it to stop: + + 55 6 * * * sudo systemctl stop whitenoise + +This will stop the white noise at 6:55am. And that's it! Enjoy your homemade white noise machine! |