Thanks for reply 
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To be clear, I’m just wondering the following things:
When OpenCV officially releases the pre-built library (for Android in this case), does it potentially contain any other method which may use non-free patent? Because I haven’t found any clear statement about what patent risk that developer should be aware of, then we can’t even be sure what “backend” that the OpenCV 4.8 is using with respect to video, then we can’t even ask what patent is risky.
For example, how would we know if OpenCV official Android release internally uses GStreamer/FFMPEG for video capturing, or it actually uses system API like Android NDK for h264 decoding (Specifically, I mean this source code): https://github.com/opencv/opencv/blob/4.8.0/modules/videoio/src/cap_android_mediandk.cpp
So if the OpenCV official Android release really uses this Android NDK system API as backend, then the remaining question will just be “whether Android NDK system APIs uses h264 decode is free or not”.