Play HEVC raw video didn't use Hardware decoding

I use the VLCKit I compiled to play a HEVC raw file on IPAD 7th(software ver 13.1.1), it shows high cpu load like 80%.(The video can be played smoothly) I compiled the MobileVLCKit ver3.3.11 with flags -d, -f, -v on macOS Catalina(10.15.4). The compiling seems to be complete, it printed "[info] Build of static MobileVLCKit.framework completed".

How can I enable the hardware decoding? Or the compiling of VLCKit is not right?

I also found I cannot step into vlc c-files to debug with this MobileVLCKit framework. But for the old version of MobileVLCKit I compiled before, to play the HEVC raw file just cost less than 30% of cpu, and I can step into the vlc c-files to debug codes.

Can anybody help me? Many thanks!

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