How to Capture Key Events from Bluetooth Headset with Android

Android: How to capture key events from Bluetooth headphones?

If anyone is facing the same issue, this is what worked for me now:

fun configureMediaSession(){
s_mediaSession = MediaSession(this, "MyMediaSession")
    s_mediaSession.setCallback(object : MediaSession.Callback() {
        override fun onMediaButtonEvent(mediaButtonIntent: Intent): Boolean {
            val ke: KeyEvent? = mediaButtonIntent.getParcelableExtra(Intent.EXTRA_KEY_EVENT)
            if (ke != null && ke.action == KeyEvent.ACTION_DOWN) {
                // Calling my method
                return true
            }
            return super.onMediaButtonEvent(mediaButtonIntent)
        }
    })
}

It would be great if anyone can share a better solution.

Handle bluetooth headset clicks (ACTION_VOICE_COMMAND and ACTION_WEB_SEARCH) on Android

I finally managed to detect the events. I didn't know about this class:

http://developer.android.com/reference/android/bluetooth/BluetoothHeadset.html

Using the classes BluetoothAdapter, BluetoothHeadset and BluetoothDevice I can register a receiver using IntentFilter BluetoothHeadset.ACTION_AUDIO_STATE_CHANGED and I'm able to detect clicks on my headset.

The problem with this is that the broadcast is non-ordered, so I can't abort it. I can close the VoiceDialer activity right after it opens, but that's not what I want.

I'll keep struggling with this.

Thank you @Toaster for your efforts :)

EDIT:

Code used to detect the events:

protected BluetoothAdapter mBluetoothAdapter;
protected BluetoothHeadset mBluetoothHeadset;
protected BluetoothDevice mConnectedHeadset;
protected AudioManager mAudioManager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

    if (mBluetoothAdapter != null)
    {

        mAudioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
        if (mAudioManager.isBluetoothScoAvailableOffCall())
        {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB)
            {
                mBluetoothAdapter.getProfileProxy(this, mHeadsetProfileListener, BluetoothProfile.HEADSET);
            }
        }
    }
}

 protected BluetoothProfile.ServiceListener mHeadsetProfileListener = new BluetoothProfile.ServiceListener()
{

    /**
     * This method is never called, even when we closeProfileProxy on onPause.
     * When or will it ever be called???
     */
    @Override
    public void onServiceDisconnected(int profile)
    {
        mBluetoothHeadset.stopVoiceRecognition(mConnectedHeadset);
        unregisterReceiver(mHeadsetBroadcastReceiver);
        mBluetoothHeadset = null;
    }

    @Override
    public void onServiceConnected(int profile, BluetoothProfile proxy)
    {
        // mBluetoothHeadset is just a head set profile, 
        // it does not represent a head set device.
        mBluetoothHeadset = (BluetoothHeadset) proxy;

        // If a head set is connected before this application starts,
        // ACTION_CONNECTION_STATE_CHANGED will not be broadcast. 
        // So we need to check for already connected head set.
        List<BluetoothDevice> devices = mBluetoothHeadset.getConnectedDevices();
        if (devices.size() > 0)
        {
            // Only one head set can be connected at a time, 
            // so the connected head set is at index 0.
            mConnectedHeadset = devices.get(0);

            String log;

            // The audio should not yet be connected at this stage.
            // But just to make sure we check.
            if (mBluetoothHeadset.isAudioConnected(mConnectedHeadset))
            {
                log = "Profile listener audio already connected"; //$NON-NLS-1$     
            }
            else
            {
                // The if statement is just for debug. So far startVoiceRecognition always 
                // returns true here. What can we do if it returns false? Perhaps the only
                // sensible thing is to inform the user.
                // Well actually, it only returns true if a call to stopVoiceRecognition is
                // call somewhere after a call to startVoiceRecognition. Otherwise, if 
                // stopVoiceRecognition is never called, then when the application is restarted
                // startVoiceRecognition always returns false whenever it is called.
                if (mBluetoothHeadset.startVoiceRecognition(mConnectedHeadset))
                {
                    log = "Profile listener startVoiceRecognition returns true"; //$NON-NLS-1$
                }
                else
                {
                    log = "Profile listener startVoiceRecognition returns false"; //$NON-NLS-1$
                }   
            }

            Log.d(TAG, log); 
        }

        // During the active life time of the app, a user may turn on and off the head set.
        // So register for broadcast of connection states.
        registerReceiver(mHeadsetBroadcastReceiver, 
                        new IntentFilter(BluetoothHeadset.ACTION_CONNECTION_STATE_CHANGED));

        // Calling startVoiceRecognition does not result in immediate audio connection.
        // So register for broadcast of audio connection states. This broadcast will
        // only be sent if startVoiceRecognition returns true.
        IntentFilter f = new IntentFilter(BluetoothHeadset.ACTION_AUDIO_STATE_CHANGED);
        f.setPriority(Integer.MAX_VALUE);
        registerReceiver(mHeadsetBroadcastReceiver, f);
    }
};

protected BroadcastReceiver mHeadsetBroadcastReceiver = new BroadcastReceiver()
{

    @Override
    public void onReceive(Context context, Intent intent)
    {           
        String action = intent.getAction();
        int state;
        int previousState = intent.getIntExtra(BluetoothHeadset.EXTRA_PREVIOUS_STATE, BluetoothHeadset.STATE_DISCONNECTED);
        String log = ""; 

        if (action.equals(BluetoothHeadset.ACTION_CONNECTION_STATE_CHANGED))
        {
            state = intent.getIntExtra(BluetoothHeadset.EXTRA_STATE, BluetoothHeadset.STATE_DISCONNECTED);
            if (state == BluetoothHeadset.STATE_CONNECTED)
            {
                mConnectedHeadset = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

                // Audio should not be connected yet but just to make sure.
                if (mBluetoothHeadset.isAudioConnected(mConnectedHeadset))
                {
                    log = "Headset connected audio already connected";
                }
                else
                {

                    // Calling startVoiceRecognition always returns false here, 
                    // that why a count down timer is implemented to call
                    // startVoiceRecognition in the onTick and onFinish.
                    if (mBluetoothHeadset.startVoiceRecognition(mConnectedHeadset))
                    {
                        log = "Headset connected startVoiceRecognition returns true"; $NON-NLS-1$
                    }
                    else
                    {
                        log = "Headset connected startVoiceRecognition returns false";
                    }
                }
            }
            else if (state == BluetoothHeadset.STATE_DISCONNECTED)
            {
                // Calling stopVoiceRecognition always returns false here
                // as it should since the headset is no longer connected.
                mConnectedHeadset = null;
            }
        }
        else // audio
        {
            state = intent.getIntExtra(BluetoothHeadset.EXTRA_STATE, BluetoothHeadset.STATE_AUDIO_DISCONNECTED);

            mBluetoothHeadset.stopVoiceRecognition(mConnectedHeadset);

            if (state == BluetoothHeadset.STATE_AUDIO_CONNECTED)
            {
                log = "Head set audio connected, cancel countdown timer";  
            }
            else if (state == BluetoothHeadset.STATE_AUDIO_DISCONNECTED)
            {
                // The headset audio is disconnected, but calling
                // stopVoiceRecognition always returns true here.
                boolean returnValue = mBluetoothHeadset.stopVoiceRecognition(mConnectedHeadset);
                log = "Audio disconnected stopVoiceRecognition return " + returnValue; 
            }
        }   

        log += "\nAction = " + action + "\nState = " + state 
                + " previous state = " + previousState; 
        Log.d(TAG, log);

    }
};

Like I said, I can detect the events, but I can't aboard the broadcast.

Capturing Bluetooth Headset longpress event in android

As per my understanding from bluedroid and bluetooth app(packages/apps/bluetooth) in android

Whenever bluetooth button in headset is pressed, it sends AT+BVRA command(check bluetooth hfp spec 1.5/1.6), this command expects phone to launch voice recognition

bluedroid source code
btif/src/btif_hf.c->BTA_AG_AT_BVRA_EVT calls BTHF_VR_STATE_STARTED

which gets translated to

/packages/apps/Bluetooth/+/android-4.4.2_r1/src/com/android/bluetooth/hfp/HeadsetStateMachine.java

processVrEvent->startActivity(sVoiceCommandIntent);
where sVoiceCommandIntent is ACTION_VOICE_COMMAND

so no intent is broadcasted for voice recognition .

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