Android App Freeze At Second Launch

[ffreality]

Issue Description

Hi, I built librealsense2.so for Android, integrated to UE5, packaged app as APK and installed to my Android device (Samsung Galaxy S23). I can open app for the first time and use it without problem. But after closing it, I can't open it again without restarting my Android device.

Unreal Engine just stuck at splash screen.

In order to test it, I set some delay before running actual C/C++ codes to get device list, device and stream.
I found out that RsContext initialization has problem. I am not Java programmer.
So, I could did some mistakes. I think I need somehow close or destruct RsContext at app close.

I call RealSense_Destruct with JNI at Event Destruct but it doesn't help at all.

This is my plugin and it's Java side.
https://github.com/FF-Plugins-Active/FF_RealSense/blob/main/Source/FF_RealSense/Private/Java/FF_RealSense.java

Do you have any suggestion ?

Required Info
Camera Model	D455
Firmware Version	5.16.0.1
Operating System & Version	Android
Platform	Android
SDK Version	v2.55.1
Language	C/C++ and Java
Segment	Smartphone / AR / VR

[MartyG-RealSense]

Hi @ffreality My research of the RealSense Android wrapper's Java source code indicates that when a Close void is used, the instruction nRelease (mHandle); is usually used. For example:

@Override
public void close() {
nRelease (mHandle);
}

Here is an example of using this mechanism in the Android wrapper's source code.

https://github.com/IntelRealSense/librealsense/blob/master/wrappers/android/librealsense/src/main/java/com/intel/realsense/librealsense/Frame.java#L62-L66

[ffreality]

librealsense/wrappers/android/librealsense/src/main/java/com/intel/realsense/librealsense/RsContext.java

Line 51 in ff8a9fb

public void close() {

But shouldn't this close RsContext ?

[MartyG-RealSense]

If an app is closed down then RsContext should be able to be initialized again on the next launch with RsContext.init like in the official RealSense Java example program.

https://github.com/IntelRealSense/librealsense/blob/master/wrappers/android/examples/java_example/readme.md#on-create

[ffreality]

Yes but it somehow affect whole engine's activity. I can't even start my app for second time after I use RealSense

[ffreality]

Okay something weird happened. Samsung Galaxy S23 Android 14 has this problem but on Oculus/Meta Quest Pro (Android 12) I can start app as much as I want. There is no freeze after first usages.

I think there is problem with Android 14. What do you think ?

[MartyG-RealSense]

There is precedent from 2021 for incompatibility between the RealSense Android wrapper and the chipset in some Samsung models, as described at #8442 (comment)

In the current latest 2.55.1 SDK, support for Android 12 was added. Official Android 13 and 14 support has not yet been implemented in the SDK. Please see #10965 for notes about the Android 12 support addition.

There have been a couple of past reports of unofficial Android 13 use. For one user it worked on their Android 13 device and for the other it did not work.

[ffreality]

I packaged for SDK API Level 30 and tried to run on Samsung Android 14.
I got second startup stuck problem. It's good to know that it can be Samsung or Android 14 related.

Btw. if I package project with API level 32, I got crash at when I try to run Rs_Context init function. But it can be related with Samsung, too.

When Meta release 5.4.1 version of their specialized branch, I will try to package a mixed reality project with API level 32 and look logs.

[MartyG-RealSense]

Thanks very much for the information!

[ffreality]

Okay, problem was about Samsung.
I packaged project with SDK API Level 32 and deployed to the Quest Pro. Works like a charm with multiple usage.

[MartyG-RealSense]

It's great to hear that you were successful. Thanks so much for your ongoing work on the UE5 plugin!