Being able to stream the internal audio of your Mac computer can make for a powerful addition to your broadcast. Whether you're playing local video or audio files, showing content on a browser, or working inside a DAW (digital audio workstation), being able to harness your computer's audio on stream opens up the variety of content you can bring to your audience.
MacOS does not come natively with internal audio routing; you will need to download a third party application in order to accomplish this. These programs allow you to capture the computer's internal audio stream and use it in applications like OBS. For computers running 10.9 (Mavericks) to 11 (Big Sur), we recommend using BlackHole from Existential Audio. If you are using a different audio routing application, the process of connecting it to your computer's internal audio stream will be similar.
In this guide:
Installing BlackHole
You can download BlackHole and find complete installation instructions here.
Note: As a safety measure, always download software from the developer's website or from verified sources.
With more recent versions of MacOS, you may need to take some extra steps to download BlackHole successfully.
If you are on Mac OS Catalina, you can install BlackHole successfully by opening the download folder, right-clicking on ‘BlackHole2ch.pkg’, and select "Open With > Installer" as depicted below.
Setting Up A Multi-Output Device with BlackHole
Now that BlackHole has been installed, it needs to be paired with an audio output. We do this with a Multi-Output Device.
Launch the Audio MIDI Setup utility by typing the name into Spotlight Search (CMD+Space) or from the Utilities folder in Applications (The file pathway is Finder->Applications->Utilities->Audio MIDI Setup). The utility appears as follows:
Note: The window we are using is the 'Audio Devices' window in the Audio MIDI Setup utility. If you do not see the Audio Devices while the utility is open, press Command + 1 or select Window in the Menu Bar to find it.
Once on the Audio MIDI Setup screen, click the plus sign in the bottom left corner as shown by the orange arrow below. Click ‘Create Multi-Output Device’.
Double click the title of the Multi-Output Device to rename it.
You should see your renamed device appear as the header of the section. Make sure your master device and sample rate are properly configured. Note about Sample Rate: make sure the sample rate you choose is the same across all your applications (e.g. DAW, OBS)
In the next section below, choose which audio device(s) to attach to the BlackHole 2ch. In this example, we've selected the Built-in Output. Choose the BlackHole 2ch for Drift Correction.
Note: Apply Drift Correction to all used devices that are not the Master Device
You now have a Multi-Output Device that will allow you to stream your computer's audio. Let's complete the process by adding BlackHole as an input in OBS.
Setting up OBS with BlackHole
Open up OBS and add a new Audio Input source to your scene by clicking the plus sign, '+', and selecting 'Audio Input Capture' (We are assuming you have a stream setup in OBS. If you'd like help setting one up, check out our guide).
Naming the source can be useful to organizing your sources, but it is not necessary. We have named this source 'Computer Audio'.
Choose Blackhole 2ch from the dropdown menu that is presented. Choose OK at the bottom of the window to add the source to your scene.
You should see the source populate in your Sources Section and Audio Mixer.
Playing some audio on your computer, either locally or on the internet; and view the meter in the OBS Audio Mixer. You should see levels in the audio mixer.
We have successfully routed our computer audio into our stream.
Aggregate Device Creation and Setup
Aggregate Devices can be used in place of a Multi-Output device when configuring I/O settings in a DAW that only allows one I/O Device. Aggregate Devices are also used when combining the I/O of multiple interfaces.
Create an Aggregate Device from the Audio Devices window of the Audio MIDI Setup.
You can change the name the device if you desire by double clicking on the name.
Beneath the Device Name, choose your Clock Source and Sample Rate
Below this section, choose the Audio Devices you would like to use by checking the box in the Use Column. You will see the device(s) populate in the Subdevices section above. For every device besides your clock source, also check the box in the Drift Correction column.
Note: If you don't see the Input/Output Channels, increase the size of the window.
In order for your Aggregate Device to properly feed audio to OBS, BlackHole must be set as Output Channels 1 & 2. If it is not, select the BlackHole item beneath the Subdevices header and drag it to the leftmost position.
Play audio through the device and check OBS to confirm that your Aggregate Device is functioning correctly.
Note: If you have already set up your Multi-Output Device to work in OBS, since it uses BlackHole as its source, you should see the signal come through the same source.
Further Resources