Discord Baby Monitor 👾🤖🎤👶

A weekend project to test the feasibility of running a Discord bot on a Raspberry Pi that pipes microphone audio into a voice channel.

Conclusion: it works!

_{(Lugia best birb?)}

This bot has been tested to work on a Raspberry Pi 2 Model B running the latest Raspbian Stretch Lite (Build 2019-04-08). There's nothing obviously hardware-specific about this build, so it might even work on a Raspberry Pi Zero! I'm sure this setup would work adequately on an RPi 3, too.

_{The green ring indicates a live mic from the bot!}

I initially wrote this bot on a 2018 Macbook Pro running macOS Mojave (10.14.5), and so there's a bit of platform-specific code in getDefaultMicrophoneStream() in helpers/microphone.js. That said, the instructions below should work for both use cases with minimal modification. I'll try to be clear when a particular platform requires special consideration.

The bot is written in JavaScript using the latest stable release (v11.5.1) of the Discord.js API library.

CAVEAT: This was born as a weekend project, and thus everything is provided as-is. While I've taken strides to deliver a Pretty Robust™ collection of code, I can't guarantee you won't run into any issues when you attempt to stand this up yourself!

Requirements:

• Node v10.16.0
• USB microphone
  • An older Blue Snowball USB microphone was used on both platforms to great effect. I want to believe that whatever USB microphone you have on-hand will work as well.

On Raspbian Stretch Lite:

• FFMPEG

This can be installed via apt:

$> sudo apt install ffmpeg

On macOS:

• SoX v14.4.2
• FFMPEG v4.1.3

These can be installed via Homebrew:

$> brew install sox ffmpeg

Afterwards you'll need to set the USB microphone as the "device for sound import" from within the Sound preference panel to allow SoX' arecord utility (used under the hood) to use it.

Environment variables

The bot requires a .env file to be placed in the root project directory with the following variables:

• BOT_TOKEN: A Discord API access token for the bot
• BOT_PREFIX: The prefix character to require in front of the bot's commands.
  • This is typically something like an ! (BOT_PREFIX=!).
• ARECORD_DEVICE_ID (Raspbian only): A string in the following format: hw:<cardID>:<deviceID>.
  • The two ID's can be retrieved via ALSA's arecord -l command.
  • You may omit the :<deviceID> part of the string if the microphone displays a single device ID.
  • The bot will default to using the first available input device if this environment variable is not specified.

Running the bot

Install dependencies via NPM:

$> npm install

Then, start the bot:

$> npm run start:prod

You can also start the bot in "development" mode so that it restarts whenever changes are made to its source code:

$> npm start

Controlling the bot in Discord

1. Join the bot to your Discord guild with the following URL, replacing "BOT_CLIENT_ID_HERE" with a proper Discord Application Bot client ID:

https://discordapp.com/oauth2/authorize?&client_id=BOT_CLIENT_ID_HERE&scope=bot&permissions=3214592

The permissions query param specified in the URL above should request the following Discord guild permissions:

• Text Permissions
  • Read Messages
  • Read Message History
  • Send Messages
• Voice Permissions
  • View Channel
  • Connect
  • Speak
  • Priority Speaker

NOTE: In my testing, these were sufficient to enable all intended functionality. Additional testing may reveal the possibility of reducing this list of permissions even further.

2. From within your Discord guild, join a Voice Channel.
3. In a Text Channel the bot can access, type !bmonitor. The bot should join your Voice Channel and begin streaming audio from the microphone:
4. When you want to stop the monitor, type !bstop. The bot will stop streaming the microphone audio and then disconnect from the Voice Channel.
   • The bot has also been configured to automatically leave a Voice Channel when the user who invoked !bmonitor leaves that Voice Channel! This is intended to help fathers quickly stop streaming via a typical Discord user interaction.