Devices & Routes

IAudioDevices lists the audio inputs and outputs the OS can see, reports which ones are in use, and raises Changed when the route changes, for example when a Bluetooth speaker connects or headphones are unplugged.

Available on iOS, Mac Catalyst, macOS, Android, Windows and Linux. IAudio.Devices throws PlatformNotSupportedException in the browser.

Showing where audio is going

Its most reliable use, on every platform, is showing the current route and updating it when the route changes, for example “Output: JBL Flip 5 · Bluetooth”:

using Shiny.Audio;

var devices = audio.Devices;

string input  = devices.CurrentInput?.Name  ?? "—";   // .Type: BuiltInMic, Bluetooth, ...
string output = devices.CurrentOutput?.Name ?? "—";   // .Type: BuiltInSpeaker, BluetoothA2dp, ...

devices.Changed += (_, _) => Refresh();               // route added, removed or switched

Member
GetInputs()	Capture devices: built-in mic, headset mics, USB mics, …
GetOutputs()	Render devices: speaker, headphones, Bluetooth, HDMI, …
CurrentInput / CurrentOutput	The route in use, or null
Changed	Raised when the input or output route changes. It can come from a platform thread
ShowOutputPicker()	Reserved for a system route picker. It does nothing today. See iOS

Each AudioDevice has an Id (a stable platform identifier), a Name (“JBL Flip 5”, “iPhone Microphone”), Io (Input or Output), a normalized Type and IsCurrent.

AudioDeviceType values: BuiltInMic, BuiltInSpeaker, BuiltInReceiver, WiredHeadset, WiredHeadphones, Bluetooth (HFP/SCO, can have a mic), BluetoothA2dp (stereo, output only), Usb, CarAudio, Hdmi, AirPlay and Unknown.

Wired, Bluetooth or built-in?

Rather than matching enum values by hand, use the classification helpers. Each one exists on both AudioDevice and AudioDeviceType:

var output = audio.Devices.CurrentOutput;

if (output?.IsWired() == true)      { /* 3.5mm jack, Lightning or USB-C */ }
if (output?.IsBluetooth() == true)  { /* HFP/SCO or A2DP */ }
if (output?.IsBuiltIn() == true)    { /* phone speaker or earpiece, nothing attached */ }

// Is the audio private to the user? For example, before reading a message aloud.
if (output?.IsHeadphones() == true)
    await audio.Player.PlayAsync(messageUrl);

// Will capture come from the accessory, or from the phone's own mic?
bool accessoryMic = output?.HasMicrophone() == true;

Helper	True for
IsWired()	WiredHeadphones, WiredHeadset, Usb
IsBluetooth()	Bluetooth (HFP/SCO), BluetoothA2dp
IsBuiltIn()	BuiltInMic, BuiltInSpeaker, BuiltInReceiver
IsHeadphones()	WiredHeadphones, WiredHeadset, Bluetooth, BluetoothA2dp
HasMicrophone()	WiredHeadset, Bluetooth

IsWired() deliberately includes USB

On phones without a 3.5mm jack, wired headphones are USB-C, and neither platform reports them as a Wired* type (Android reports UsbHeadset/UsbDevice, iOS reports PortUsbAudio). Including Usb is what makes “are wired headphones plugged in?” give the right answer on modern hardware. The downside is that a USB audio interface or DAC also counts. Use IsHeadphones() when you specifically mean something worn on the head, accepting that it misses USB-C earbuds.

HasMicrophone() leaves out Usb for the opposite reason: neither platform says whether a USB route has a mic based on the output device alone. Look in GetInputs() for a matching Usb entry instead.

Bluetooth can’t be narrowed further. A paired A2DP device could be earbuds or a room speaker, and no platform API tells them apart, so IsHeadphones() treats all Bluetooth as private.

Changed fires on plug and unplug on every supported platform, so you can combine it with these helpers. For example, you could pause playback when headphones are removed.

Selecting a route

Selecting a route is much more limited by platform than listing them.

Microphone: pass an input from GetInputs() to AudioCaptureOptions.InputDevice, AudioRecordingOptions.InputDevice, AudioDuplexOptions.InputDevice or IAudioMonitor.SetInputDevice. This works on every platform that has IAudioDevices.

Output: only the live monitor has an output selector:

await audio.Monitor.SetInputDevice(chosenInput);    // Android, iOS, Linux
await audio.Monitor.SetOutputDevice(chosenOutput);  // Android and Linux. iOS: built-in speaker toggle only

Platform	Lists inputs	Lists outputs	Choose the mic	Choose the output
Android	✅	✅	✅	✅ (monitor)
iOS / Mac Catalyst	✅	Current route only	✅ preferred input	Built-in speaker on/off
macOS	✅	❌	✅ capture, recorder, duplex	❌
Windows	✅	✅	✅ capture, recorder	❌
Linux	✅	✅	✅	✅ (monitor)

iOS: output routes belong to the system

Apple deliberately doesn’t let apps list or freely choose output routes. On iOS, GetOutputs() returns only the current output, and SetOutputDevice can only switch the built-in speaker on or off. AirPlay and Bluetooth output are chosen in the system route picker (AVRoutePickerView). There is no API for routing to a particular HomePod or speaker from code. The picker is a view, so host an AVRoutePickerView in your own UI. ShowOutputPicker() can’t display it on its own and does nothing.

Input can be chosen on iOS (AVAudioSession.SetPreferredInput).

Windows and Linux

Windows lists devices through the Windows device enumeration API and classifies them by name (Bluetooth, HDMI, USB, headset, headphones, otherwise built-in). The input Id it returns is what AudioGraph uses to open that mic for capture. Linux lists PulseAudio/PipeWire sources and sinks, or ALSA devices on the fallback. Changed fires on PulseAudio/PipeWire only, because ALSA has no change notification.