@Cornstick said:
I don’t think it’s quite this complicated. It’s just a cable TV tuner card. All it does is de modulate QAM RF signal and convert it to IP. All Plex does it tell it what channel to tune and the card tunes it providing the video via IP.
You might be right, as I said I don’t know for sure but somehow I think it isn’t as simple as that either.
What your saying assumes there is a “standard” interface but I suspect they are all different at the device level which is probably what’s presented via the device file that would become available by loading the kernel module.
But, again, I could be wrong, that happens all the time, 
All of the live TV and DVR function is existing in PMS already.
You don’t know that for sure, only the Plex DVR developers know how they interface to tuners and that’s not available to community members, AFAIK.
So adding support for “any” tuner probably isn’t doable by community members.
I have a dvblogic supported tuner and a licence for the dvblogic software which is available as a QNAP qpkg (and installs the needed kernel modules at boot time).
But based on the fact that it isn’t included in the supported Plex tuners list I’m not even going to try it.
I’m pretty much certain it won’t be recognised by Plex.
As far as any licensing? It appears Ceton has published everything they have and said “have fun!”
So maybe that part isn’t a problem but that sentiment would need to be stated clearly in writing in the source distribution for it to be usable. From a business POV licensing is very important and from a personal POV no-one should be willing to risk using software that is not provided with an appropriate licence.
In any case there’s still no way to write the needed Plex interface code for it to recognize and use the card.
Like I said, I’m pretty sure this can’t be done, at least by community members alone.