ChooseAudioDevice.cs

[CanBeNull]
private static AudioDevice ChooseAudioDevice([CanBeNull] string name)
{
    var criterion = MediaDeviceCriteria.AudioDevice;
    var query = new MediaDeviceQuery(criterion);
    var useDefault = string.IsNullOrWhiteSpace(name);

    AudioDevice firstDevice = null;
    for (var i = 0; i < query.count; i++)
    {
        // Skip invalid devices
        if (!(query[i] is AudioDevice audioDevice))
            continue;

        // Keep track of the first valid device, in case we don't find anything better
        if (firstDevice == null)
            firstDevice = audioDevice;

        // If the default has been requested then use the default as soon as we find it
        if (useDefault && audioDevice.defaultForMediaType)
            return audioDevice;

        // Use the device if the name matches
        if (!useDefault && audioDevice.name.Equals(name, StringComparison.InvariantCultureIgnoreCase))
            return audioDevice;
    }

    // None of the device match the name, use the first available device
    return firstDevice;
}