Device Selection

Kodio allows you to enumerate audio devices and direct recording or playback to specific hardware.

List available devices

Kodio.listInputDevices() and Kodio.listOutputDevices() are suspend functions. Call them from a coroutine:

suspend fun listDevices() {
    // Input devices (microphones)
    val inputs = Kodio.listInputDevices()
    inputs.forEach { device ->
        println("Input: ${device.name} (${device.id})")
    }

    // Output devices (speakers, headphones)
    val outputs = Kodio.listOutputDevices()
    outputs.forEach { device ->
        println("Output: ${device.name} (${device.id})")
    }
}

Each device has:

id: Unique identifier
name: Human-readable name (for example "Built-in Microphone", "AirPods Pro")

Record from a specific device

Use an external microphone or other input device:

suspend fun recordFromDevice() {
    val inputs = Kodio.listInputDevices()
    val externalMic = inputs.find { it.name.contains("USB") }

    val recording = Kodio.record(
        duration = 5.seconds,
        device = externalMic  // null uses system default
    )
}

Play to a specific device

Route audio to headphones, speakers, or other output devices:

suspend fun playToDevice(recording: AudioRecording) {
    val outputs = Kodio.listOutputDevices()
    val headphones = outputs.find { it.name.contains("Headphones") }

    Kodio.play(recording, device = headphones)
}

In Compose

Load devices in a coroutine and pass the selected device to rememberRecorderState:

@Composable
fun DeviceSelector() {
    var selectedDevice by remember { mutableStateOf<AudioDevice.Input?>(null) }
    var devices by remember { mutableStateOf<List<AudioDevice.Input>>(emptyList()) }

    LaunchedEffect(Unit) {
        devices = Kodio.listInputDevices()
    }

    DropdownMenu(/* ... */) {
        devices.forEach { device ->
            DropdownMenuItem(
                text = { Text(device.name) },
                onClick = { selectedDevice = device }
            )
        }
    }

    val recorderState = rememberRecorderState(device = selectedDevice)
    // ...
}

Platform support

Device selection support varies by platform:

Platform	Input selection	Output selection	Notes
JVM	Full	Full	Complete device enumeration via `javax.sound.sampled`
macOS	Full	Full	Resolves to a real CoreAudio device UID
iOS	Full	Full	Routed via `AVAudioSession` ports
Android	Limited	Limited	Honoured via `AudioRecord.preferredDevice`/`AudioTrack.preferredDevice`; final routing decided by the system
Web	Not supported	Not supported	Throws `AudioError.DeviceSelectionUnsupported` when a non-null device is passed

On web, output device selection via setSinkId is not implemented. Passing a non-null output device yields AudioError.DeviceSelectionUnsupported.

Error handling

If a specified device is unavailable:

try {
    val recording = Kodio.record(
        duration = 5.seconds,
        device = specificMic
    )
} catch (e: AudioError.DeviceNotFound) {
    // Device was disconnected or unavailable
    showError("Microphone not found. Using default.")
    val recording = Kodio.record(duration = 5.seconds)
} catch (e: AudioError.DeviceSelectionUnsupported) {
    // Platform cannot pin a specific device (for example browser output selection).
    showError("Device selection isn't supported here. Using default.")
    val recording = Kodio.record(duration = 5.seconds)
}

Last modified: 03 July 2026