Android 6.0: Load 32-bit OpenCV library on 64-bit arch

[jtkac]

Hello,

So I was trying to use:
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_0_0, this, mLoaderCallback);
and only include 32-bit libraries in my local jniLibs folder in hopes that my application would recognize that it is supposed to load on a 32-bit platform instead of a 64-bit platform. After a couple days of research I had the best fitting solution to only include 32-bit libraries but OpenCVLoader still tried to load a 64-bit framework and instead of gettings the error that this is a 32-bit library in a 64-bit application, I was getting the opposite figurehead.

I guess my issue/requested fix would be to allow the user to explicitly state whether they want to load a 64-bit platform or a 32-bit platform or to detect local jni files to load as necessary through OpenCVLoader's code.

Thank you for your time and consideration,

Koala

[alalek]

Please provide more details.
Where you get OpenCV? How did you build? What options are used? Do you have OpenCV manager?
How did you get both 32-bit and 64-bit versions?

Did you try this code for OpenCV loading?
https://github.com/Itseez/opencv/blob/231685133ead7a8b2a4777ff6fa1427d8acf4ba4/samples/android/tutorial-1-camerapreview/src/org/opencv/samples/tutorial1/Tutorial1Activity.java#L79-L85

[jtkac]

Pardon me

I am using OpenCV for Android
The steps I took to install OpenCV were:

1. download the library (3.0)
2. In Android Studio: File ->New -> Import Module -> OpenCV-3.0.0-android-sdk -> sdk -> java
3. Right click project -> Module Settings -> app -> Dependencies -> + -> Module Dependency -> OpenCV
4. Created Folder jniLibs under app -> src -> main
5. Took contents from OpenCV 3.0's sdk -> native -> libs and pasted there
6. Implemented a BaseLoaderCallback
7. Called OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_0_0, this, mLoaderCallback);
8. Ensured the gradle.build targets, build tools, and minimum were the same in the OpenCV lib

I want to use another library that is only 32 bit. Android 6 searches the abi for 64-bit libraries first and if the device finds a 64-bit library, it loads that library and cannot also load 32-bit libraries.

Android 6 can load 32-bit libraries so long as that is all the device loads. They cannot mix.
So without a way to mix libraries (which is just not possible) I must have the originally loaded OpenCV libraries as 32-bit libraries.

What I am asking is if a feature could be implemented to allow developers the explicit statement of what bit format OpenCV loads. It automatically detects and searches for 64-bit when both formats are possible but if it is desired to omit 64 bit libraries, I should be able to specify to OpenCVLoader's Abi to only load from armeabi or armeabi-v7a.

Thank you again and hopefully that will clarify what I am asking,

Koala

[alalek]

Thanks! Problem is more clear now.

Did you try to remove/ignore "invalid" 64-bit library folders from native/libs (OpenCV for Android)? Does it work?

[jtkac]

Thank you for the quick reply,

So far I have just tried removing them but it results in the following error:
java.lang.UnsatisfiedLinkError: dlopen failed: "/data/app/org.opencv.engine-1/lib/arm64/libopencv_java3.so" is 64-bit instead of 32-bit

so having removed them is detecting that a 32-bit version should be loaded but the loader is looking in a folder that I haven't even got included

[jtkac]

the folders I have included from the native -> libs are:
armeabi
armeabi-v7a
mips
x86

I have also tried cleaning and rerunning my application

[alalek]

1. Remove "OpenCV manager" application from your device. Received path is from this app.
2. Check this loading scheme:
   https://github.com/Itseez/opencv/blob/231685133ead7a8b2a4777ff6fa1427d8acf4ba4/samples/android/tutorial-1-camerapreview/src/org/opencv/samples/tutorial1/Tutorial1Activity.java#L79-L85
   This scheme will try to use libopencv_java3.so from your "libs".

[jtkac]

Well although this is progress, it is for some reason not searching for libopencv_java3.so but instead libopencv_java.so and throwing a different unsatisfiedlinkerror

[jtkac]

There we go
I edited statichelper to contain opencv_java3 opposed to opencv_java

[alalek]

It is already fixed in OpenCV 3.1.0: 83b2621

[jtkac]

:/ must have missed it by a couple days... I'll update to the new version

Pardon the waste of time

[jtkac]

Everything is compiling correctly and updating to the new version just made it so I wasn't manually altering the files!

To you I say Kudos and thank you.

This issue is resolved.

[alalek]

Thanks for update.

There are no plans to add this feature into OpenCV Manager (because problem is very specific and can be resolved in other way).

[gaochunchun]

Thanks. @alalek