There is a very interesting article on how this was produced. It shows that standardization to SMPTE VC-5 is not very usefull as it leaves out some vital information for decoding existing files. Probably explains why no one else has produced a CFHD codec.

https://medium.com/@kierank_/reverse-engineering-the-gopro-cineform-codec-7411312bfe1c

Gopro was the worst thing to happen to cineform.