What You Need
This guide focuses on a macOS setup. So if you have a Windows or Linux machine then contact support for advice.
BlackHole is a macOS application that allows you to pass audio to other applications. It essentially grabs your computer's audio and sends it elsewhere.
LineIn is another macOS application that enables play thru of audio from physical input devices, such as a microphones or mixers. You can also hear the sound coming in through the input device to make adjustments.
UPDATE: LineIn no longer works on newer versions of macOS. As an alternative, try Audio Hijack.
BUTT (Broadcast Using This Tool)
BUTT is an application for macOS, Windows, and Linux machines. It can encode and stream live audio from your computer and out to your online radio station.
How to Get Setup
Sending audio from your computer and to your station can be broken into 4 steps.
Your setup will send audio using BlackHole and LineIn, through the BUTT encoder, and out to your online radio station with Radio.co.
1. Setup BlackHole
Download Soundflower - Once installed restart your Mac. Open up Audio MIDI Setup by searching for it in spotlight (command + spacebar).
Audio devices will be opened, showing your current devices you can use like a built-in microphone and built-in output. Click the + button and select Create Multi-Output Device. The master device should be set to Built-in Output, sample rate should be 441000.0 Hz, and select Built-in Output and BlackHole (2ch) for your audio devices.
Now open up your sound settings in System Preferences -> Sound. In Output select the new output device you created; the default name is Multi-Output Device.
Your computer's audio is now bundled together. Anything you play, whether that's in a media player, browser, or any other application, is grabbed and pushed out to where you want it. Audio isn't controlled by a master channel, instead, you need to adjust audio from within the applications you're using.
If you want to talk over your music through a microphone then go to the LineIn section, if not skip over to the BUTT section.
2. Setup LineIn
Note: The information in this section is out of date, see how you can use Audio Hijack as an alternative.
Download LineIn - Open up the application. In the input dropdown select your microphone, in this case we're using the Built-in Microphone: External Microphone. In the output dropdown select Soundflower (2ch). Click Play Thru, LineIn will send your input device's audio to Soundflower, which is grouped together in your multichannel output.
Open up your sound settings like before by going to System Preferences -> Sound. In Input select External Microphone or the input device you're using to talk. Use the Input Volume to control your input device's volume level; far right to talk, far left if you don't want to talk.
3. Setup BUTT
Download BUTT - Open up the application. Choose Settings, in Main, click Add. Enter your radio station's details, they can be found in your Radio.co Dashboard - Make sure you have a live event scheduled when attempting to broadcast.
In the Audio tab, click the Audio Device drop-down and select BlackHole (2ch). Leave all other settings as default.
Test your connection by clicking the play button.
Once connected it will state the stream time and your station's details.
4. Broadcast Online
By now you should have your setup ready to go. Check that your volume levels are correct and music/microphone audio is being accepted.
As audio is grabbed from multiple channels the metadata isn't sent correctly. Update the metadata in BUTT within the Stream tab under Update Song Name Manually, then click OK.