Hi Rings,
I'm assuming you're using a PI 4?
OpenMAX is deprecated on Bullseye, you will need to build the PiPlayer using AppGameKit Tier2 because the AppGameKit Player on the Pi builds against libopenmaxil.so
If you try the Linux command ldd on the PiPlayer:
linux-vdso.so.1 (0xbef91000)
/usr/lib/arm-linux-gnueabihf/libarmmem-${PLATFORM}.so => /usr/lib/arm-linux-gnueabihf/libarmmem-v7l.so (0xb6fa0000)
libGLESv2.so => /usr/lib/arm-linux-gnueabihf/libGLESv2.so (0xb6f5c000)
libEGL.so => /usr/lib/arm-linux-gnueabihf/libEGL.so (0xb6f3d000)
libopenmaxil.so => /opt/vc/lib/libopenmaxil.so (0xb6f27000)
libbcm_host.so => /opt/vc/lib/libbcm_host.so (0xb6f00000)
libXrandr.so.2 => /usr/lib/arm-linux-gnueabihf/libXrandr.so.2 (0xb6ee7000)
libpthread.so.0 => /lib/arm-linux-gnueabihf/libpthread.so.0 (0xb6ebd000)
libopenal.so.1 => /usr/lib/arm-linux-gnueabihf/libopenal.so.1 (0xb6dd6000)
libudev.so.1 => /lib/arm-linux-gnueabihf/libudev.so.1 (0xb6da6000)
librt.so.1 => /lib/arm-linux-gnueabihf/librt.so.1 (0xb6d8f000)
libXxf86vm.so.1 => /usr/lib/arm-linux-gnueabihf/libXxf86vm.so.1 (0xb6d7a000)
libXext.so.6 => /usr/lib/arm-linux-gnueabihf/libXext.so.6 (0xb6d5b000)
libX11.so.6 => /usr/lib/arm-linux-gnueabihf/libX11.so.6 (0xb6c39000)
libstdc++.so.6 => /usr/lib/arm-linux-gnueabihf/libstdc++.so.6 (0xb6af2000)
libm.so.6 => /lib/arm-linux-gnueabihf/libm.so.6 (0xb6a70000)
libgcc_s.so.1 => /lib/arm-linux-gnueabihf/libgcc_s.so.1 (0xb6a43000)
libc.so.6 => /lib/arm-linux-gnueabihf/libc.so.6 (0xb68f5000)
libGLdispatch.so.0 => /usr/lib/arm-linux-gnueabihf/libGLdispatch.so.0 (0xb6876000)
libdl.so.2 => /lib/arm-linux-gnueabihf/libdl.so.2 (0xb6863000)
/lib/ld-linux-armhf.so.3 (0xb6fb5000)
libbrcmGLESv2.so => /opt/vc/lib/libbrcmGLESv2.so (0xb683e000)
libbrcmEGL.so => /opt/vc/lib/libbrcmEGL.so (0xb6805000)
libvchiq_arm.so => /opt/vc/lib/libvchiq_arm.so (0xb67ef000)
libvcos.so => /opt/vc/lib/libvcos.so (0xb67d6000)
libXrender.so.1 => /usr/lib/arm-linux-gnueabihf/libXrender.so.1 (0xb67bd000)
libsndio.so.7.0 => /usr/lib/arm-linux-gnueabihf/libsndio.so.7.0 (0xb679e000)
libatomic.so.1 => /usr/lib/arm-linux-gnueabihf/libatomic.so.1 (0xb6785000)
libxcb.so.1 => /usr/lib/arm-linux-gnueabihf/libxcb.so.1 (0xb6756000)
libasound.so.2 => /usr/lib/arm-linux-gnueabihf/libasound.so.2 (0xb6675000)
libbsd.so.0 => /usr/lib/arm-linux-gnueabihf/libbsd.so.0 (0xb664d000)
libXau.so.6 => /usr/lib/arm-linux-gnueabihf/libXau.so.6 (0xb663a000)
libXdmcp.so.6 => /usr/lib/arm-linux-gnueabihf/libXdmcp.so.6 (0xb6625000)
If it's any help, I've attached a PiPlayer that I built using Tier2 to get it working on Buster.
Hopefully it works for you.