UNKNOWN_ERROR in librealsense on Android

Hello,

I've got a D435i RealSense camera and I'm trying to explore its capabilities using an Android 6 device (rooted).

I've downloaded the librealsense Android library from GitHub:

   https://github.com/IntelRealSense/librealsense.git

Then I opened the standalone java_example in Android Studio and deployed it to my Android device over ADB.

It deployed but the app says 'Wait for camera...' continuously and in the logs I get this kind of thing:

07-05 14:15:14.020 6589-6639/com.example.realsense_java_example I/librs: Found UVC Device vid: id-
vid- 8086
pid- ad6
mi- 0
unique_id- /dev/bus/usb/001/005
path- /dev/bus/usb/001/005
susb specification- 210
07-05 14:15:14.037 6589-6644/com.example.realsense_java_example D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: false
07-05 14:15:14.112 6589-6644/com.example.realsense_java_example I/OpenGLRenderer: Initialized EGL, version 1.4
07-05 14:15:14.120 6589-6644/com.example.realsense_java_example D/mali_winsys: EGLint new_window_surface(egl_winsys_display*, void*, EGLSurface, EGLConfig, egl_winsys_surface**, egl_color_buffer_format*, EGLBoolean) returns 0x3000
07-05 14:15:14.167 6589-6589/com.example.realsense_java_example W/art: Before Android 4.1, method int android.support.v7.widget.DropDownListView.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
07-05 14:15:19.036 6589-6639/com.example.realsense_java_example W/System.err: java.lang.RuntimeException: UNKNOWN_ERROR
07-05 14:15:19.037 6589-6639/com.example.realsense_java_example W/System.err: at com.intel.realsense.librealsense.Pipeline.nWaitForFrames(Native Method)
07-05 14:15:19.038 6589-6639/com.example.realsense_java_example W/System.err: at com.intel.realsense.librealsense.Pipeline.waitForFrames(Pipeline.java:29)
07-05 14:15:19.038 6589-6639/com.example.realsense_java_example W/System.err: at com.intel.realsense.librealsense.Pipeline.waitForFrames(Pipeline.java:25)
07-05 14:15:19.038 6589-6639/com.example.realsense_java_example W/System.err: at com.example.realsense_java_example.MainActivity.stream(MainActivity.java:95)
07-05 14:15:19.039 6589-6639/com.example.realsense_java_example W/System.err: at com.example.realsense_java_example.MainActivity.access$100(MainActivity.java:20)
07-05 14:15:19.039 6589-6639/com.example.realsense_java_example W/System.err: at com.example.realsense_java_example.MainActivity$2.run(MainActivity.java:80)
07-05 14:15:19.039 6589-6639/com.example.realsense_java_example W/System.err: at java.lang.Thread.run(Thread.java:818)

So the 'UNKNOWN_ERROR' sounds a bit worrying, and doesn't give me much to go on.

On another occasion I got some different error messages:

7-05 14:35:13.263 6228-6279/com.example.realsense_java_example I/OpenGLRenderer: Initialized EGL, version 1.4
07-05 14:35:13.271 6228-6279/com.example.realsense_java_example D/mali_winsys: EGLint new_window_surface(egl_winsys_display*, void*, EGLSurface, EGLConfig, egl_winsys_surface**, egl_color_buffer_format*, EGLBoolean) returns 0x3000
07-05 14:35:13.317 6228-6228/com.example.realsense_java_example W/art: Before Android 4.1, method int android.support.v7.widget.DropDownListView.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
07-05 14:35:14.171 6228-6276/com.example.realsense_java_example W/LIBRS_ANDROID_BACKEND: Timeout reached waiting for response!
07-05 14:35:14.225 6228-6276/com.example.realsense_java_example E/LIBRS_ANDROID_BACKEND: SetXU result:-1
07-05 14:35:14.234 6228-6276/com.example.realsense_java_example E/LIBRS_ANDROID_BACKEND: Cannot queue request: Device or resource busy
07-05 14:35:15.234 6228-6276/com.example.realsense_java_example W/LIBRS_ANDROID_BACKEND: Timeout reached waiting for response!

I've done some Googling but can find nothing on these errors.

Any ideas what might be wrong please?

Thanks,

G.