Background Videorecording in Android: http://stackoverflow.com/questions/15049041/background-video-recording-in-android-4-0

BackgroundVideoRecorder.java

public class BackgroundVideoRecorder extends Service implements SurfaceHolder.Callback {

    private WindowManager windowManager;
    private SurfaceView surfaceView;
    private Camera camera = null;
    private MediaRecorder mediaRecorder = null;

    @Override
    public void onCreate() {

        // Start foreground service to avoid unexpected kill
        Notification notification = new Notification.Builder(this)
            .setContentTitle("Background Video Recorder")
            .setContentText("")
            .setSmallIcon(R.drawable.ic_launcher)
            .build();
        startForeground(1234, notification);

        // Create new SurfaceView, set its size to 1x1, move it to the top left corner and set this service as a callback
        windowManager = (WindowManager) this.getSystemService(Context.WINDOW_SERVICE);
        surfaceView = new SurfaceView(this);
        LayoutParams layoutParams = new WindowManager.LayoutParams(
            1, 1,
            WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY,
            WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH,
            PixelFormat.TRANSLUCENT
        );
        layoutParams.gravity = Gravity.LEFT | Gravity.TOP;
        windowManager.addView(surfaceView, layoutParams);
        surfaceView.getHolder().addCallback(this);

    }

    // Method called right after Surface created (initializing and starting MediaRecorder)
    @Override
    public void surfaceCreated(SurfaceHolder surfaceHolder) {

        camera = Camera.open();
        mediaRecorder = new MediaRecorder();
        camera.unlock();

        mediaRecorder.setPreviewDisplay(surfaceHolder.getSurface());
        mediaRecorder.setCamera(camera);
        mediaRecorder.setAudioSource(MediaRecorder.AudioSource.CAMCORDER);
        mediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
        mediaRecorder.setProfile(CamcorderProfile.get(CamcorderProfile.QUALITY_HIGH));

        mediaRecorder.setOutputFile(
                Environment.getExternalStorageDirectory()+"/"+
                DateFormat.format("yyyy-MM-dd_kk-mm-ss", new Date().getTime())+
                ".mp4"
        );

        try { mediaRecorder.prepare(); } catch (Exception e) {}
        mediaRecorder.start();

    }

    // Stop recording and remove SurfaceView
    @Override
    public void onDestroy() {

        mediaRecorder.stop();
        mediaRecorder.reset();
        mediaRecorder.release();

        camera.lock();
        camera.release();

        windowManager.removeView(surfaceView);

    }

    @Override
    public void surfaceChanged(SurfaceHolder surfaceHolder, int format, int width, int height) {}

    @Override
    public void surfaceDestroyed(SurfaceHolder surfaceHolder) {}

    @Override
    public IBinder onBind(Intent intent) { return null; }

}