Goal

Add support for detecting and selecting USB audio input devices (microphones) that are not recognized by Twilio AudioSwitch.

Problem: USB microphones that are input-only (e.g., Rode Wireless Go II) are not detected by AudioSwitch because it uses ACTION_HEADSET_PLUG broadcast which only fires for devices with both input AND output capabilities. This causes professional USB microphones to be invisible to the SDK.

Reported issue: Live streaming feature on Patreon doesn't detect Rode Wireless Go II mics on OnePlus Nord 4, while the same mics work fine with the native Camera app.

Implementation

Use Android's native AudioDeviceCallback API (API 23+) to detect USB input devices, then route audio via JavaAudioDeviceModule.setPreferredInputDevice().

Changes:

1. New UsbAudioInputDevice class - Wraps AudioDeviceInfo for USB input devices

2. MicrophoneManager additions:

   • usbInputDevices: StateFlow<List<UsbAudioInputDevice>> - detected USB devices
   • selectedUsbDevice: StateFlow<UsbAudioInputDevice?> - current selection
   • listUsbDevices() - get available USB input devices
   • selectUsbDevice(device) - route audio to specific USB device
   • clearUsbDeviceSelection() - restore default routing
   • Auto-selects first USB device when detected (if none selected)

3. StreamPeerConnectionFactory additions:

   • setPreferredAudioInputDevice(AudioDeviceInfo?) - expose WebRTC device routing

Usage:

// USB detection is automatic on API 23+
// List USB microphones
call.microphone.listUsbDevices().collect { devices ->
    Log.d("USB", "Found USB mics: $devices")
}

// Select a specific USB microphone
val rodeMic = call.microphone.usbInputDevices.value
    .firstOrNull { "Rode" in it.name }
rodeMic?.let { call.microphone.selectUsbDevice(it) }

// Clear selection (restore default)
call.microphone.clearUsbDeviceSelection()

Testing

• Test with other USB microphones
• Test USB device hotplug (connect/disconnect during call)
• Verify audio quality and latency
• Test on different Android versions