| Namespace | Windows.Devices.Midi2.Transports.Bluetooth |
|---|---|
| Type Name | MidiBluetoothTransportManager |
| Type | WinRT Runtime Class |
| IDL | MidiBluetoothTransportManager.idl |
Finds and connects Bluetooth MIDI devices, and publishes this PC as a Bluetooth MIDI peripheral.
| Static Property | Description |
|---|---|
IsTransportAvailable |
True if this transport is available in the service |
TransportId |
The GUID of this transport |
| Static Method | Description |
|---|---|
GetAvailableDevices() |
Returns a MidiBluetoothDeviceInformation for every Bluetooth MIDI device this PC has found, either by hearing it advertise or because it’s paired, whether or not it’s connected. A device the service is still trying to connect stays in the list while it’s switched off, so it can be disconnected. A device asked for by an address this PC has never found isn’t listed until it’s found |
GetDevice(bluetoothDeviceId) |
Returns the MidiBluetoothDeviceInformation for one device, or null if no device with that address has been found |
ConnectDeviceAsync(connectConfig) |
Connects to a device and creates a MIDI endpoint for it. Returns a MidiBluetoothDeviceConnectResponse |
DisconnectDeviceAsync(disconnectConfig) |
Disconnects a device and removes its MIDI endpoint. Returns a MidiBluetoothDeviceDisconnectResponse |
StartPeripheralAsync(peripheralConfig) |
Publishes this PC so other devices can connect to it. Returns a MidiBluetoothPeripheralResponse |
StopPeripheralAsync() |
Stops publishing this PC. Returns a MidiBluetoothPeripheralResponse |
GetPeripheralStatus() |
Returns the current MidiBluetoothPeripheralStatus |
GetPendingPeripheralClients() |
Returns the remote devices that have connected and are waiting for a decision, as MidiBluetoothPeripheralClient entries |
ApprovePeripheralClientAsync(bluetoothAddress, scope) |
Approves a waiting remote device for this MidiBluetoothApprovalScope. Returns a MidiBluetoothPeripheralClientDecisionResponse |
DenyPeripheralClientAsync(bluetoothAddress, scope) |
Denies a waiting remote device. Returns a MidiBluetoothPeripheralClientDecisionResponse |
ForgetPeripheralClientAsync(bluetoothAddress) |
Forgets a remembered allow or deny, so the device is asked about again next time. Returns a MidiBluetoothPeripheralClientDecisionResponse |
GetRadioInformation() |
Returns what this PC’s Bluetooth radio can do, as MidiBluetoothRadioInformation, or null with a service that’s too old to report it |
GetDefaultOfflineRetentionSeconds() |
Returns the transport-wide value that every device set to UseTransportDefault uses. It’s never UseTransportDefault itself |
GetSavedDevices() |
Returns a MidiBluetoothSavedDevice for every device saved in the configuration file, including ones saved as switched off. It reads what’s saved, so it works even when the service isn’t running |
One manager covers both Bluetooth Low Energy MIDI 1.0 and 2.0. The transport picks which protocol to use with each device, and prefers MIDI 2.0 whenever a device offers it.
Connecting and disconnecting are asynchronous because the radio has to find the device, open its GATT service, and subscribe to a characteristic. That takes a few seconds, and longer for a device that’s asleep.
Bluetooth doesn’t let Windows refuse an incoming connection. A remote device that connects while the policy is RequireApproval stays connected, but it has no MIDI endpoint, and no data moves until someone decides. So if your app never calls GetPendingPeripheralClients, the device just sits there, stuck and silent.
The address you pass to ApprovePeripheralClientAsync and DenyPeripheralClientAsync must be the one reported for the device that’s waiting. A decision made from an out-of-date list is rejected with ClientIdentityMismatch, instead of being applied to whoever connected since.
Passing a MidiBluetoothDeviceConnectConfig to ConnectDeviceAsync connects the device now, until the service restarts. Passing the same object to MidiServiceTransportPluginConfigManager.SaveUpdate saves it to the configuration, so it connects again after the service restarts.
auto config = MidiBluetoothDeviceConnectConfig(L"48B6201A719D");
auto response = co_await MidiBluetoothTransportManager::ConnectDeviceAsync(config);
if (response.Success())
{
// keep it across service restarts
MidiServiceTransportPluginConfigManager::SaveUpdate(config);
}
It works the other way too. Saving a MidiBluetoothDeviceDisconnectConfig stops the device from connecting on its own. If you create it with removeFromConfiguration set to true, saving removes the entry completely.
GetSavedDevices shows what’s saved. Use it to show devices that will connect when the service starts, including ones this PC hasn’t found yet.
A connection request is saved and carried out when it can be. So a request for a device that’s turned off succeeds, and the device connects later, when it shows up. MidiBluetoothDeviceConnectResponse.IsKnown and MidiBluetoothDeviceInformation.IsPresent tell “connecting now” apart from “waiting for it to show up,” which otherwise look the same.
Windows MIDI Services is an open source project with all source available on GitHub. We have a great community on Discord as well. Between GitHub and Discord, you should find the information you are looking for.
