Camera ohne Preview

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        _camera = Camera.open();
        Camera.Parameters p = _camera.getParameters();
        p.setPictureFormat(PixelFormat.JPEG);
        _camera.setParameters(p);

    }
    
    Camera.ShutterCallback _callbackShutter = new Camera.ShutterCallback() {
        public void onShutter() {
            Log.e(getClass().getSimpleName(), "SHUTTER CALLBACK");
        }
    };
    
    Camera.PictureCallback _callbackJpeg = new PictureCallback() {
        
        @Override
        public void onPictureTaken(byte[] data, Camera camera) {
            Log.d(TAG, "incoming stream (jpeg)");
            
        }
    };
    Camera.PictureCallback _callbackRaw = new Camera.PictureCallback() {
        public void onPictureTaken(byte[] data, Camera c) {
            Log.d(TAG, "incoming stream (raw)");
        }
    };
    
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
            _camera.takePicture(_callbackShutter, _callbackRaw, _callbackJpeg);
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

10-04 16:50:54.441: ERROR/QualcommCameraHardware(984): initRaw: clearing old mJpegHeap.
10-04 16:50:54.441: ERROR/QualcommCameraHardware(984): pmem pool /dev/pmem_adsp ioctl(PMEM_GET_SIZE) is 16384
10-04 16:50:54.441: ERROR/QualcommCameraHardware(984): TAKE PICTURE LOCK ACQUIRED
10-04 16:50:59.441: ERROR/QualcommCameraHardware(984): native_get_picture: MSM_CAM_IOCTL_GET_PICTURE failed... ioctl return value is -1 
10-04 16:50:59.441: ERROR/QualcommCameraHardware(984): main:2014 getPicture failed!
10-04 16:50:59.441: ERROR/QualcommCameraHardware(984): JPEG callback was cancelled--not encoding image.
10-04 16:50:59.441: ERROR/QualcommCameraHardware(984):  SIGNALLED QCS_IDLE in receivejpegpicture
10-04 16:50:59.441: ERROR/QualcommCameraHardware(984): receiveRawPicture: X