Merge "BluetoothMidiService: Subtract header from MTU" into main (68eda146) · Commits · e / os / android_frameworks_base

media/packages/BluetoothMidiService/src/com/android/bluetoothmidiservice/BluetoothMidiDevice.java

+21 −6

Original line number	Diff line number	Diff line
		@@ -50,8 +50,16 @@ public final class BluetoothMidiDevice {
		private static final String TAG = "BluetoothMidiDevice";
		private static final boolean DEBUG = false;

		private static final int DEFAULT_PACKET_SIZE = 20;
		private static final int MAX_PACKET_SIZE = 512;
		// Bluetooth services should subtract 5 bytes from the MTU for headers.
		private static final int HEADER_SIZE = 5;
		// Min MTU size for BLE
		private static final int MIN_L2CAP_MTU = 23;
		// 23 (min L2CAP MTU) - 5 (header size)
		private static final int DEFAULT_PACKET_SIZE = MIN_L2CAP_MTU - HEADER_SIZE;
		// Max MTU size on Android
		private static final int MAX_ANDROID_MTU = 517;
		// 517 (max Android MTU) - 5 (header size)
		private static final int MAX_PACKET_SIZE = MAX_ANDROID_MTU - HEADER_SIZE;

		// Bluetooth MIDI Gatt service UUID
		private static final UUID MIDI_SERVICE = UUID.fromString(
		@@ -135,8 +143,8 @@ public final class BluetoothMidiDevice {
		// switch to receiving notifications
		mBluetoothGatt.readCharacteristic(characteristic);

		// Request higher MTU size
		if (!gatt.requestMtu(MAX_PACKET_SIZE)) {
		// Request max MTU size
		if (!gatt.requestMtu(MAX_ANDROID_MTU)) {
		Log.e(TAG, "request mtu failed");
		mPacketEncoder.setMaxPacketSize(DEFAULT_PACKET_SIZE);
		mPacketDecoder.setMaxPacketSize(DEFAULT_PACKET_SIZE);
		@@ -204,8 +212,15 @@ public final class BluetoothMidiDevice {
		public void onMtuChanged(BluetoothGatt gatt, int mtu, int status) {
		Log.d(TAG, "onMtuChanged callback received. mtu: " + mtu + ", status: " + status);
		if (status == BluetoothGatt.GATT_SUCCESS) {
		mPacketEncoder.setMaxPacketSize(Math.min(mtu, MAX_PACKET_SIZE));
		mPacketDecoder.setMaxPacketSize(Math.min(mtu, MAX_PACKET_SIZE));
		int packetSize = Math.min(mtu - HEADER_SIZE, MAX_PACKET_SIZE);
		if (packetSize <= 0) {
		Log.e(TAG, "onMtuChanged non-positive packet size: " + packetSize);
		packetSize = DEFAULT_PACKET_SIZE;
		} else if (packetSize < DEFAULT_PACKET_SIZE) {
		Log.w(TAG, "onMtuChanged small packet size: " + packetSize);
		}
		mPacketEncoder.setMaxPacketSize(packetSize);
		mPacketDecoder.setMaxPacketSize(packetSize);
		} else {
		mPacketEncoder.setMaxPacketSize(DEFAULT_PACKET_SIZE);
		mPacketDecoder.setMaxPacketSize(DEFAULT_PACKET_SIZE);