Are you looking for how to convert HEVC to something else?
First of all, what is HEVC: High-Efficiency Video Coding (HEVC), also known as H.265 and MPEG-H Part 2.
Its a video compression standard, designed as a successor to the widely used Advanced Video Coding (AVC, H.264, or MPEG-4 Part 10).
In comparison to AVC, HEVC offers from 25% to 50% better data compression at the same level of video quality,
you can read more about here.
Do you have iPhone or iPad and its storing image in this format and you do not want that you can change it.
You can read more about it here.
It has been hard to find any free application that can do this convert at the moment. Rumors says that iMac och Macbook might have some build-in function that can help you with this for free but has not verified it yet
In my search, I came across Wondershare UniConverter and it can do the convert so, for example, a Synology that not support HEVC can play does move, the same quality but without HEVC encoded.
You try this application on your own risk, and to do full converts it will cost.
If you were looking for HEIC and not HEVC check this post out
Hope this information could be too some good for you and can help you with what you are looking for.