It’s not that difficult to be honest. VLC / ffmpeg can do most of the heavy lifting. And there’s no shortage of libraries for rendering in a UI.
There used to be dozens of options to choose from. Multiple different XBMC forks. Multiples different Subsonic forks. Multiple different DNLA servers. Multitudes of web-based servers. CLI MP3 servers. Independent media centres for a variety of different consoles.
Maybe that’s still available and just not indexed on that site. But I noticed the choices had shrank significantly last year when I was looking for Plex alternatives compared with when I last built a media centre approximately 15 years ago.
Maybe smart TVs have reduced people’s desire here?
I would love to see an Open Source media center that supports streaming services. I wouldn't care if the services say "we only support 1080p for browsers / open source, anything more needs a locked-down device". (Perhaps the project could have some add-on you can buy that's a physical hardware dongle for doing 4k HDR and emitting HDCPed HDMI.) I already live with that for watching on my laptop. Just having watchable basic-resolution streaming would make it a one-stop-shop.
I think I understand how to use about 20 of the command line options for ffmpeg and the companion utilities like ffprobe. Which is to say; I understand about 0.5% of the total options they provide and am likely a world leading expert in it. I'm mostly joking -- as in, overstating how many of them I understand.
Understanding ffmpeg borders on a specialization in itself. No big surprise that so many of the alternatives have fallen away over the years as people realize the absolute scope of that piece of software.
> It’s not that difficult to be honest.
Sounds easy if all you have to do is write a short comment about it. People who actually did it, like the recently retired lead of the Jellyfin project, didn't make it sound like it's "not that difficult" [1].
If you want ot vibe code a project for yourself it's probably reasonable amount of effort. But if you want to build a product, something with polish, something not held together by spit and scotch tape, something reliable, it won't be easy.
[1] https://forum.jellyfin.org/t-project-leadership-changes