Possible to iterate/process NAL units?

[rundexz]

Hi. I have a TS video with HEVC encoding where the keyframes NAL units are encrypted on which I need to iterate over those specific NAL units and decrypt them. Then, finally output the new TS video file with those decrypted NAL units without doing any reencoding. I know how to iterate over frames though I am not sure how to iterate over the NAL units. Is it possible to use this project to accomplish what I need?

Thank you.