Input Device Selection

Unreal does not provide an easy method to switch input devices (like a microphone) when using the default Audio Capture, even though most players would expect this feature in a game with Voice Chat. Let's take a look at how we handle this in the ODIN plugin.

By David Liebemann at SciCode Studio.

Creating an Odin Audio Capture

To change input devices, instead of using the default Create Audio Capture method, we'll use the Create Odin Audio Capture function call. This will create an extended Audio Capture object that allows us to change the audio capture device using either Blueprints or C++.

Your logic for joining an Odin room should now look something like this:

Please note that we store a reference to the Odin Audio Capture object as a variable—we're going to use it in the next sections to display the available devices in the UI.

UI Creation

You'll probably have to adjust the next steps to fit your UI implementation, but in general it's easy to adapt the necessary UI elements.

We'll create a new Blueprint Widget that gets displayed when the player presses Tab. This Widget should show the available capture devices in a drop-down box and change the active device on selection.

1. Create a new Widget Blueprint in your project—we'll call it BPW_SelectInputDevice.
2. In the widget's event graph, create a new Custom Event called UpdateAudioCapture with an input parameter of type Odin Audio Capture. We'll use this event in the next section, so simply leave it unconnected for now.

3. In your player controller's Begin Play, add a Create Widget call, select the class BP_SelectInputDevice, connect the Self property to the Owning Player input, and save the resulting widget object in a variable.

4. The final step in the player controller is to add logic for toggling the "Select Input Device" UI, as shown below. Please note the call to Update Audio Capture when making the UI visible. This will supply the Audio Capture object to the widget blueprint, which we'll use to request the available capture devices.

tip

If you can't create the InputAction ToggleDeviceSelection event, make sure to add an Action in Project Settings > Input > Action Mappings and bind it to a keyboard input—we're using Tab for testing.

Widget implementation

Currently, the widget does not contain any visible UI elements, so let's change this. We'll add a simple see-through background and a dropdown box, in which we'll list all available capture devices. Changing the selection in the dropdown box will change the capture device used for Odin. Additionally, we'll preselect the currently active capture device in the dropdown box.

1. In the widget's Designer mode, add a Canvas Panel as the root element and a Border and ComboBox (String) as direct children. Set the Border element's Brush Color to (0,0,0,0.5) to make it darken the gameplay, but still keep it see-through. Additionally, let's give the ComboBox a meaningful name—e.g. "SelectionDropBox".

2. Let's now switch to the Graph mode and start extending our Custom Event UpdateAudioCapture. We'll store the Odin Audio Capture object as a variable and call Async Get Capture Devices Available. This will return the available capture devices and the current device as outputs in the connected event.

warning

The Odin Audio Capture object also contains synchronous function calls to access and change capture device data. During testing, we've noticed that these synchronous calls can take quite a while to run: more than 100ms on average, in some cases more than a second. This lag is due to Unreal's internal implementation for changing capture devices. We, therefore, strongly recommend using the async function calls.

3. Let's name the connected event OnReceivedDevices. We'll store a reference to the available devices, as well as retrieve and store the current device name from the Current Device info structures.

4. Because OnReceivedDevices will be called each time we open up the UI, we'll need to reset the current options by calling Clear Options on the Selection Drop Box.

5. Now we need to add the available capture device names as options in the dropdown box. We iterate over our Available Devices array, retrieve the Device Name from the device info structures, and add that as an option to the Selection Drop Box.

6. Afterwards, we'll preselect the currently active device by calling Set Selected Option with our Current Option. Your blueprint logic should look something like this:

7. Finally, we'll change the capture device when the user selects an item from the dropdown box. Add the event On Selection Changed (SelectionDropBox) to your Event Graph. The Selected Item will contain the name of the input device that should become the active capture device. Let's do a quick check for whether the Selected Item is empty or equal to the currently selected option. If the item passes the checks, we call Async Change Capture Device by Name with the Selected Item as input. The On Change Completed callback will let us know whether the given device was activated successfully. Your blueprint should look something like this:

Now anytime a user chooses a new option, the Odin Audio Capture object will change the capture device and restart the input stream automatically.

What's next?

This is a very simple implementation with minimal UI, which you'll be able to easily adapt to your project's needs. For more information on Unreal with Odin Voice Chat, check out our Discord and take a look at the following guides we've prepared for you:

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