List audio devices · oneaudio cookbook

List the playback and recording devices in C#, find the system defaults, and open a particular device by its id, with the RecursiveAI.OneAudio.Devices package.

Terminal

dotnet add package RecursiveAI.OneAudio --version 1.2.1
dotnet add package RecursiveAI.OneAudio.Devices --version 1.2.1

using OneAudio.Devices;
 
// The operating system's audio API: WASAPI, Core Audio or ALSA.
Console.WriteLine($"backend: {AudioDevices.Backend.Name}, " +
                  $"available: {AudioDevices.IsAvailable}");
 
DeviceDirection[] directions = [DeviceDirection.Output, DeviceDirection.Input];
foreach (DeviceDirection direction in directions)
{
    IReadOnlyList<AudioDeviceInfo> devices = AudioDevices.List(direction);
    AudioDeviceInfo? def = AudioDevices.Default(direction);
    Console.WriteLine($"{direction}: {devices.Count} devices, " +
                      $"default: {def?.Id ?? "none"}");
}
 
// Pick a device by part of its name. Id is what DeviceStreamOptions.DeviceId takes;
// it is backend specific, so match on Name and pass Id through untouched:
// new DeviceStreamOptions { DeviceId = d.Id }.
string wanted = args.Length > 0 ? args[0] : "USB Audio";
foreach (AudioDeviceInfo d in AudioDevices.List(DeviceDirection.Output))
{
    if (!d.Name.Contains(wanted, StringComparison.OrdinalIgnoreCase))
        continue;
    Console.WriteLine($"first output matching \"{wanted}\": {d.Id}");
    Console.WriteLine($"  {d.Name.Replace('\n', ' ')}");
    break;
}

Text

backend: alsa, available: True
Output: 90 devices, default: default
Input: 45 devices, default: default
first output matching "USB Audio": hw:CARD=Audio,DEV=0
  USB Audio, USB Audio Direct hardware device without any conversions

This ran on a Linux desktop with PipeWire, a USB audio interface, a webcam and HDMI outputs. ALSA lists every PCM name it knows, plug-ins included, which is why the counts are high. On Windows and macOS the list is the endpoints you see in the system’s sound settings.

AudioDevices.List(direction) returns an AudioDeviceInfo per device: Id, Name, IsDefault, and, where the backend can tell, DefaultSampleRate, MaxChannels and MinLatencyFrames. Call it from a control thread, never from an audio callback.
Id is backend specific. On ALSA it’s a PCM name such as default or hw:CARD=Audio,DEV=0; on Windows it’s the endpoint id. Don’t parse it; pass it to DeviceStreamOptions.DeviceId.
With no DeviceId, a stream uses the system default and follows it when it changes. SelectDevice(id) moves an open output or input to another device; SelectDevice(null) goes back to the default.
AudioDevices.DevicesChanged fires when devices are plugged in or removed, on WASAPI and Core Audio. ALSA has no hot-plug events, so on Linux read the list again when you need it.
IsAvailable is false when the system’s audio library isn’t there, such as libasound on a server. Outputs then render silently and inputs deliver nothing.

Choosing a device and playing to it: Play audio in C#.