Develop Reference

Audio Routing in tinyAlsa

We are working on Custom Board having Audio Codec, AM/FM Tuner, BT Headset, BT Classic all controlled by I2S peripheral. We wants to route audio from BT Classic to Audio Codec, BT Classic to BT headset and so on.
We were planning to have seperate threads for connecting 2 audio devices. In application space, we will provide seperate device IDs which will indicate what device should play the Audio.
I needs to know how we can create a thread interlinking 2 audio devices? Also, is there any other ways to route various audio devices output to another audio devices?

BluetoothAdapter.getDefaultAdapter().getProfileProxy(this, mScanCallback, BluetoothProfile.A2DP);
BluetoothProfile.ServiceListener mScanCallback = new BluetoothProfile.ServiceListener() {
#Override
public void onServiceConnected(int profile, BluetoothProfile proxy) {
if (profile == BluetoothProfile.A2DP) {
proxy.getConnectedDevices().forEach(device -> {
if (selectedDevice1 != null
&& selectedDevice1.getDeviceMAC().equalsIgnoreCase(device.getAddress())) {
try {
Class clazz = Class.forName("android.bluetooth.BluetoothA2dp");
Method method = clazz.getMethod("setActiveDevice", BluetoothDevice.class);
method.invoke(proxy, device);
} catch (Exception e) {
Log.e("TEST", "", e);
}
}
});
}
}
#Override
public void onServiceDisconnected(int i) {
}
};

BluetoothServerSocket hangs on accept

I've seen many other posts regarding this specific issue, all with results that did not help me or were relevant to my case.
Here is my problem, I'm trying to setup a bluetooth piconet, with one node as a server and 7 as clients, each given a number as a location representative starting from 0 ( the server) and going to 7 (the clients). Currently I'm trying to get this to work for just two devices, the server and one client. And I assume that they're already paired. In the following code uuid is
private UUID uuid=UUID.fromString("0000111f-0000-1000-8000-00805f9b34fb");
Here is my thread which accepts incoming connections, ad is just the bluetooth adapter
private class BTServerThread implements Runnable{
#Override
public void run() {
try {
if (ad != null) {
if (ad.isEnabled()) {
BluetoothServerSocket btss=ad.listenUsingInsecureRfcommWithServiceRecord("MyApp",uuid);
Location=0;
Integer loc=1;
Log.wtf("Server","Searching");
while(loc<=7){
Thread t=new Thread(new BTServerHandler(btss.accept(),loc));
t.start();
Log.wtf("BTS","Found");
loc++;
}
} else {
Log.e("error", "Bluetooth is disabled.");
}
}
}catch(Exception e){
e.printStackTrace();
}
}
}
And here is my client thread which attempts to connect
private class BTClientThread implements Runnable{
#Override
public void run() {
try {
if (ad != null) {
if (ad.isEnabled()) {
Set<BluetoothDevice> bondedDevices = ad.getBondedDevices();
if (bondedDevices.size() > 0) {
Iterator<BluetoothDevice> iter = bondedDevices.iterator();
BluetoothDevice device = iter.next();
Log.wtf("dev", device.getName());
BluetoothSocket clientsocket = device.createInsecureRfcommSocketToServiceRecord(uuid);
clientsocket.connect();
Log.wtf("Connected",device.getName());
}
Log.e("error", "No appropriate paired devices.");
} else {
Log.e("error", "Bluetooth is disabled.");
}
}
}catch(Exception e){
e.printStackTrace();
}
}
}
Hold your breath, here comes the weird part, the call btss.accept() hangs forever (Doesn't even return once), while at the same time, the client device connects somehow. When I call
BluetoothSocket clientsocket = device.createInsecureRfcommSocketToServiceRecord(uuid);
clientsocket.connect()
This pops the toast on the phone which is hanging on accept saying "DeviceName connected" then after a while it pops another toast saying "DeviceName disconnected" on its own, without me doing ANYTHING, and at the same time the serverphone is still hanging on accept.
Here are my questions, why is it hanging on accept when the toast popped saying connected? And how could it possibly connect when the other phone is still listening for a connection?
Thanks for the help.

As it turns out, using that specific UUID caused a problem from some reason I still don't understand? After trying many random things, I finally decided to try another random UUID and that magically caused it to work.
Here is my new UUID
private UUID uuid = UUID.fromString("56e8a14a-80b3-11e5-8bcf-feff819cdc9f");

Connection to specific HID profile bluetooth device

I connect bluetooth barcode scanner to my android tablet. barcode scanner is bonded with android device as a input device - HID profile. it shows as keyboard or mouse in system bluetooth manager. i discovered that bluetooth profile input device class exist but is hidden. class and btprofile constants have #hide annotaions in android docs.
hidden class:
http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/4.3.1_r1/android/bluetooth/BluetoothInputDevice.java
here they should be also 3 other constants
developer.android.com/reference/android/bluetooth/BluetoothProfile.html#HEADSET
just like
public static final int INPUT_DEVICE = 4;
public static final int PAN = 5;
public static final int PBAP = 6;
that constants are simple accessible by reflection.
What i need to achieve, is list of devices by hid profile(INPUT_DEVICE). it should be simple with small changes using method:
developer.android.com/reference/android/bluetooth/BluetoothA2dp.html#getConnectedDevices()
not for A2dp profile, but for hid profile accessed also by reflection methods.
sadly
Class c = Class.forName("android.bluetooth.BluetoothInputDevice")
won't work..
any ideas how i should approach to the problem ? i need only list of hid devices

I figured out how to solve my problem.
That was very helpful.
First of all I needed to prepare reflection method which return input_device hidden constants of hid profile:
public static int getInputDeviceHiddenConstant() {
Class<BluetoothProfile> clazz = BluetoothProfile.class;
for (Field f : clazz.getFields()) {
int mod = f.getModifiers();
if (Modifier.isStatic(mod) && Modifier.isPublic(mod) && Modifier.isFinal(mod)) {
try {
if (f.getName().equals("INPUT_DEVICE")) {
return f.getInt(null);
}
} catch (Exception e) {
Log.e(LOG_TAG, e.toString(), e);
}
}
}
return -1;
}
Instead of that function, I could use value 4, but i want to do it elegant.
Second step was to define listener of specific profile:
BluetoothProfile.ServiceListener mProfileListener = new BluetoothProfile.ServiceListener() {
#Override
public void onServiceConnected(int profile, BluetoothProfile proxy) {
Log.i("btclass", profile + "");
if (profile == ConnectToLastBluetoothBarcodeDeviceTask.getInputDeviceHiddenConstans()) {
List<BluetoothDevice> connectedDevices = proxy.getConnectedDevices();
if (connectedDevices.size() == 0) {
} else if (connectedDevices.size() == 1) {
BluetoothDevice bluetoothDevice = connectedDevices.get(0);
...
} else {
Log.i("btclass", "too many input devices");
}
}
}
#Override
public void onServiceDisconnected(int profile) {
}
};
In third step I invoked
mBluetoothAdapter.getProfileProxy(getActivity(), mProfileListener,
ConnectToLastBluetoothBarcodeDeviceTask.getInputDeviceHiddenConstant());
Everything clearly works and mProfileListener returns me list of specific profile bluetooth device/-es.
Most interesting thing takes place in onServiceConnected() method, which returs object of hidden class BluetoothInputDevice :)

Bluetooth SCO fails after incoming call

I am trying to send all the audio of an application via SCO.
I am able to successfully send the audio,
But when an incoming call comes I need to disconnect form SCO so that the application audio will not interfere with the call,
The problem is that, when I try to reroute the audio to SCO after the call, it does not work.
Here is the code I use to send the audio to SCO:
public class BluetoothManager {
// For Bluetooth connectvity
private static String TAG = "BluetoothManager";
private static BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
private static AudioManager aM;
/**
* Set the audio manager of the device.
* #param c: The context this method is called from
*/
public static void setAudioManager(Context c) {
aM = (android.media.AudioManager)c.getSystemService(Context.AUDIO_SERVICE);
}
/**
* Check if a Bluetooth headset is connected. If so, route audio to Bluetooth SCO.
*/
private static void initializeAudioMode(Context context) {
BluetoothProfile.ServiceListener mProfileListener = new BluetoothProfile.ServiceListener() {
public void onServiceConnected(int profile, BluetoothProfile proxy) {
if (profile == BluetoothProfile.HEADSET) {
BluetoothHeadset bh = (BluetoothHeadset) proxy;
List<BluetoothDevice> devices = bh.getConnectedDevices();
if (devices.size() > 0) {
enableBluetoothSCO();
}
}
mBluetoothAdapter.closeProfileProxy(profile, proxy);
}
public void onServiceDisconnected(int profile) {}
};
mBluetoothAdapter.getProfileProxy(context, mProfileListener, BluetoothProfile.HEADSET);
}
/**
* Bluetooth Connectvity
* The following methods are associated with enabling/disabling Bluetooth.
* In the future we may want to disable other sources of audio.
*/
private static void enableBluetoothSCO() {
aM.setMode(AudioManager.MODE_IN_CALL);
aM.startBluetoothSco();
aM.setBluetoothScoOn(true);
}
/** Right now, this simply enables Bluetooth */
#SuppressLint("NewApi")
public static boolean enableBluetooth(Context c) {
// If there is an adapter, enable it if not already enabled
if (mBluetoothAdapter != null) {
if (!mBluetoothAdapter.isEnabled()) {
mBluetoothAdapter.enable();
}
setAudioManager(c);
initializeAudioMode(c);
Log.e(TAG, "SCO: " + aM.isBluetoothScoOn());
Log.e(TAG, "A2DP: " + aM.isSpeakerphoneOn());
return true;
} else {
Log.v(TAG, "There is no bluetooth adapter");
return false;
}
}
/** Right now, this simply disables Bluetooth */
public static void disableBluetooth() {
// If there is an adapter, disabled it if not already disabled
if (mBluetoothAdapter != null) {
if (mBluetoothAdapter.isEnabled()) {
mBluetoothAdapter.disable();
}
} else {
Log.v(TAG, "There is no bluetooth adapter");
}
}
public static void restartBluetooth(){
aM.setMode(AudioManager.MODE_IN_CALL);
}
public static void stopBluetooth(){
aM.setMode(AudioManager.MODE_NORMAL);
}
}
When I call stopBluetooth() correctly the audio of the application is not sent to the headset anymore,
But when I call restartBluetooth() the audio plays NOT form the headset as intended, but from the phone speakers.

Is it possible that the SCO link was brought down after the call ended? If this is the case then the SCO link would also have to be brought up along with routing the audio.
Have you tried calling enableBluetoothSCO() within restartBluetooth()

You probably need to call:
aM.startBluetoothSco();
aM.setBluetoothScoOn(true);
after you set the mode.

inside your restart function initialize everything again, and see if it works. like so:
public static void restartBluetooth(){
enableBluetooth(getApplicationContext());
}
if this works then it means that when the call is ended the last initialization is lost for some reason.

Google Doc say's that
"Phone application always has the priority on the usage of the SCO connection for telephony. If this method is called while the phone is in call it will be ignored. Similarly, if a call is received or sent while an application is using the SCO connection, the connection will be lost for the application and NOT returned automatically when the call ends."
So when call is disconnected you must have to re-establish the connection by calling startBluetoothSco()

For anyone that is still having issues with this, there are a few things that need to be done. The first thing you need to do is to keep track of the phone state. You can see how to do that here:
How to know Phone call has ended?
When the state is idle that means the incoming call has ended. Now if you try to reconnect the bluetooth at this point you'll find it still does not work since it takes a while (roughly 2 seconds) for the call to "release" the bluetooth device.
So you have two option, wait a bit then try to reconnect, or you can add another listener to BluetoothHeadset.ACTION_AUDIO_STATE_CHANGED.
You can then add a global boolean value isIdle that is true when TelephonyManager.CALL_STATE_IDLE or false when TelephonyManager.CALL_STATE_OFFHOOK (Otherwise you'll reconnect to BlueTooth during the incoming call). At this point when BluetoothHeadset.STATE_DISCONNECTED and isIdle is true, then reconnect to Bluetooth.
#Override public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals((BluetoothHeadset.ACTION_AUDIO_STATE_CHANGED))){
int state = intent.getIntExtra(BluetoothHeadset.EXTRA_STATE, BluetoothHeadset.STATE_AUDIO_DISCONNECTED);
switch(state) {
case BluetoothHeadset.STATE_AUDIO_DISCONNECTED:
if (isIdle){
//reconnect bluetooth
}
break;
}
}
if(("OFFHOOK").equals(intent.getStringExtra(TelephonyManager.EXTRA_STATE))) {
isIdle = false;
// turn bluetooth off
}
if(("IDLE").equals(intent.getStringExtra(TelephonyManager.EXTRA_STATE))) {
isIdle = true;
}
}

How to programmatically pair a bluetooth device on Android

For my application I'm trying to programmatically pair a bluetooth device. I'm able to show the pairing dialog for the device I want to pair and I can enter a pincode. When I press "Pair" the dialog is removed and nothing happens.
I only need to support devices with Android 2.0 and newer.
Currently I am using the following code to start the pairing progress:
public void pairDevice(BluetoothDevice device) {
String ACTION_PAIRING_REQUEST = "android.bluetooth.device.action.PAIRING_REQUEST";
Intent intent = new Intent(ACTION_PAIRING_REQUEST);
String EXTRA_DEVICE = "android.bluetooth.device.extra.DEVICE";
intent.putExtra(EXTRA_DEVICE, device);
String EXTRA_PAIRING_VARIANT = "android.bluetooth.device.extra.PAIRING_VARIANT";
int PAIRING_VARIANT_PIN = 0;
intent.putExtra(EXTRA_PAIRING_VARIANT, PAIRING_VARIANT_PIN);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(intent);
}
Before starting a pairing request I stop scanning for new devices.
My application has the following bluetooth permissions:
android.permission.BLUETOOTH_ADMIN
android.permission.BLUETOOTH

I managed to auto request a pairing procedure with keyboard featured devices through an app working as a service checking the presence of a specific kind of device and a modified version of the Settings app.
I have to say that I was working on a custom device running Android 4.0.3 without external controls (no back/Home/confirm buttons): pairing a controller on boot complete without any interaction until PIN request was mandatory.
First I created a service starting an activity on boot (with android.intent.action.BOOT_COMPLETED and android.permission.RECEIVE_BOOT_COMPLETED) that checks periodically the presence of a 1344 class device (a keyboard, the only way to input data on request) on the onReceive callback:
public void onReceive(Context context, Intent intent)
...
BluetoothDevice dev = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
...
if(dev.getBluetoothClass().getDeviceClass() == 1344){...}
Once filtered I choose the first keyboard available and then I pass the BT address to the Settings app:
Intent btSettingsIntent = new Intent(Settings.ACTION_BLUETOOTH_SETTINGS);
btSettingsIntent.putExtra("btcontroller", dev.getAddress());
startActivityForResult(btSettingsIntent, 1);
The tricky part was looking for the best position to call the pairing process. Using only the
intent.putExtra(BluetoothDevice.EXTRA_PAIRING_VARIANT, PAIRING_VARIANT_PIN);
led me to a paring dialog that once closed left me with the device paired, but unusable.
Digging into the classes of com.Android.settings.Bluetooth I found my way through the
createDevicePreference(CachedBluetoothDevice cachedDevice)
in the DeviceListPreferenceFragment.
From there I did compare my previously selected BT address with those available coming up and once successfully matched I call
cachedDevice.startPairing();
I know, it's tricky and requires access to the Android source code, but in a custom environment it works.
I hope this could be helpful.

It's my answer:
in onCreate() write this:
registerReceiver(incomingPairRequestReceiver, new IntentFilter(BluetoothDevice.ACTION_PAIRING_REQUEST));
then create variable
private final BroadcastReceiver incomingPairRequestReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothDevice.ACTION_PAIRING_REQUEST.equals(action)) {
BluetoothDevice dev = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
//pair from device: dev.getName()
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
dev.setPairingConfirmation(true);
//successfull pairing
} else {
//impossible to automatically perform pairing,
//your Android version is below KITKAT
}
}
}
};

Unfortunately, I think the best that you are going to get is opening up Settings/Wireless & networks/Bluetooth Settings for the user like so:
Intent intent = new Intent(Settings.ACTION_BLUETOOTH_SETTINGS);
startActivityForResult(intent, REQUEST_PAIR_DEVICE);

Using reflection you can call the method createBond from the BluetoothDevice class.
See this post: How to unpair or delete paired bluetooth device programmatically on android?
There is also a solution for unpair.

Reflection is DODGY, different manufacturers can change these underlying methods as they wish! I have tested many different apps on our 10 devices here and these reflection method only works fully on roughly 75% of devices. If you want an app that works for everyone be very careful when using reflection - try some cloud testing to test your app on 100+ devices and check the failure rate.
In this case reflection is not needed at all since API 19 (KitKat 4.4)
BluetoothDevice has new method CreateBond.
private void pairDevice(BluetoothDevice device) {
device.createBond();
}
developer.android.com/reference/android/bluetooth/BluetoothDevice.html

May be you need to startActivityForResult instead of only startActivity?
Other option is to look into the BluetoothChat application sample and start an RFComm connection socket, as soon as you start the socket a pairing request will automatically appear without needing to send a separate intent for pairing. This way you won't need to handle pairing.
http://developer.android.com/resources/samples/BluetoothChat/index.html

I am using this class to do connection between my client smartphone and the server device:
private class ConnectThread extends Thread
{
private final BluetoothSocket mmSocket;
private final UUID WELL_KNOWN_UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
public ConnectThread(BluetoothDevice device)
{
// Use a temporary object that is later assigned to mmSocket,because
// mmSocket is final
BluetoothSocket tmp = null;
// Get a BluetoothSocket to connect with the given BluetoothDevice
try
{
tmp = device.createRfcommSocketToServiceRecord(WELL_KNOWN_UUID);
//This is the trick
Method m = device.getClass().getMethod("createRfcommSocket", new Class[] { int.class });
tmp = (BluetoothSocket) m.invoke(device, 1);
} catch (Exception e)
{
e.printStackTrace();
}
mmSocket = tmp;
}
public void run()
{
DebugLog.i(TAG, "Trying to connect...");
// Cancel discovery because it will slow down the connection
mBluetoothAdapter.cancelDiscovery();
try
{
// Connect the device through the socket. This will block
// until it succeeds or throws an exception
mmSocket.connect();
DebugLog.i(TAG, "Connection stablished");
} catch (IOException connectException)
{
// Unable to connect; close the socket and get out
DebugLog.e(TAG, "Fail to connect!", connectException);
try
{
mmSocket.close();
} catch (IOException closeException)
{
DebugLog.e(TAG, "Fail to close connection", closeException);
}
return;
}
}
/** Will cancel an in-progress connection, and close the socket */
public void cancel()
{
try
{
mmSocket.close();
} catch (IOException e)
{
}
}
}
First, get the BluetoothDevice object that you want to connect (listing paired devices or discoverying devices). Then do:
ConnectThread ct = new ConnectThread(device);
ct.start();
Because connect() is a blocking call, this connection procedure should always be performed in a thread separate from the main activity thread. See Android Developers for more detailed info.

I've found that using different values for PAIRING_VARIANT_PIN result in different pairing UI behaviours.
See this page:
http://code.google.com/p/backport-android-bluetooth/source/browse/trunk/backport-android-bluetooth201/src/backport/android/bluetooth/BluetoothDevice.java?spec=svn67&r=67
I suspect the problem you're having is that both devices are Bluetooth 2.1, in which case a pairing request should result in a 6 digit passkey being displayed on both devices.
The best result I was able to achieve was using PAIRING_VARIANT_PIN = 0. When prompted by my application, I entered pin 1234 and a 6 digit passkey appeared on my target device. The pairing UI finished and that was that.
Either you need to find out how to initiate a Bluetooth 2.1 pairing request, using some other pairing variant or pairing variant pin. Or, you're not catching the result of the activity that's running properly.
Given the amount of time I've been trying to do this, I've decided that my end users will just have to pair using the android settings before using my application.

This is how I get it:
Bluetooth device = mBtAdapter.getRemoteDevice(address);
//address:11:23:FF:cc:22
Method m = device.getClass()
.getMethod("createBond", (Class[]) null);
m.invoke(device, (Object[]) null); // send pairing dialog request
After pairing//
connectDevice(address);

in addition to my comment, by the way, even if these ACTION types did exist, that's not how you use them. here's an example:
Intent intent = new Intent(BluetoothDevice.ACTION_PAIRING_REQUEST);
intent.putExtra(EXTRA_DEVICE, device);
int PAIRING_VARIANT_PIN = 272;
intent.putExtra(BluetoothDevice.EXTRA_PAIRING_VARIANT, PAIRING_VARIANT_PIN);
sendBroadcast(intent);