How much grunt do I need to run 2-3 simultaneous high bitrate 4k streams?

[AceTheUsurper]

Trying to figure out what my best option is, and set myself a saving target. I need something gutsy enough to run 2-3 high bitrate 4k streams, maybe 4 just to be safe, without struggling, and without needing to leave my gaming PC on all the time. But also half thinking I'd like to have my storage running separate. Is that a good idea? Like can I have a NAS and a media server running side by side or will that hurt performance? Am I better off building an all in one solution?

* How much am I gonna be looking to pay up front? How much total?
* Can I delay some of that up front cost by just building a NAS first, and running JF from my PC? then buying a media server later?
* Can I delay some of the costs. Say put in 4 hard drives initially, then put in another 4 later in later?
* Do I need transcoding?
* Should I get something rack mounted? Or is old cases n stuff fine? I half like the idea of having a mini rack, having like a NAS/Media Server/file server/Game Server/security system all running out of the garage or whatever.
* Should I just take a swing on an old second hand server/NAS or build/buy new?
* If I build a raid array, with some level of redundancy, can I say for example have like 4 16gb iron wolf pros, with 1 of them as redundancy? Can I add in hard drives to that array later on to expand it?
* What sort of minimum specs do I want? What are the recommended specs I want?
* Is it clear I have a very minimal idea what I'm talking about? lol.
* any other questions I forgot about? lol.

plz, explain like I'm 5. lol.

[TheDreadPirate]

* How much am I gonna be looking to pay up front? How much total?

Depends on where you live and what you end up choosing.  But what you're specing for does not require a lot.

* Can I delay some of that up front cost by just building a NAS first, and running JF from my PC? then buying a media server later?

A NAS is just a PC in a specialized chassis.  IMO, using a NAS just for storage is overused and adds complexity that a lot of beginners have trouble navigating, especially when it comes to file permissions.  You do not need one, especially if you are just using it for Jellyfin.

* Can I delay some of the costs. Say put in 4 hard drives initially, then put in another 4 later in later?

100%.  Gradually expanding storage is possible.

* Do I need transcoding?

Aim for direct play, but plan for transcoding.

* Should I get something rack mounted? Or is old cases n stuff fine? I half like the idea of having a mini rack, having like a NAS/Media Server/file server/Game Server/security system all running out of the garage or whatever.

You DO NOT need rack mounted anything.  Rack mounting just helps with density and organization if you have multiple PCs/servers.

* Should I just take a swing on an old second hand server/NAS or build/buy new?

Depends on your budget.  One thing you will need for your expected use case is a dedicated GPU.  Luckily Intel Arc GPUs are both cheap and extremely fast for transcoding at good quality.  You could buy a surplus office PC, making sure the chassis can accommodate a GPU (both power connectors and height), and just throw in an Intel Arc GPU.  Or if you happen to have parts lying around, as long as they aren't ancient and it has an available PCIe 16x slot you could use that.

What is your budget, BTW?

* If I build a raid array, with some level of redundancy, can I say for example have like 4 16gb iron wolf pros, with 1 of them as redundancy? Can I add in hard drives to that array later on to expand it?

If you use ZFS and configure as a RAIDZ1, you can just keeping add hard drives to the pool and it will accommodate them.

* What sort of minimum specs do I want? What are the recommended specs I want?

A not too old CPU.  At least 4GB of RAM if you are running a headless Linux server OS.  8GB of RAM if Windows or a desktop Linux OS.  The OS and Jellyfin's data directory should be on a SSD.  A SATA SSD is fine.  Just to clarify, this is only the Jellyfin app data.  Your movies/shows are ok to be on a HDD.

* any other questions I forgot about? lol.

Just need to know what your budget is.

[Efficient_Good_5784]

* If I build a raid array, with some level of redundancy, can I say for example have like 4 16gb iron wolf pros, with 1 of them as redundancy? Can I add in hard drives to that array later on to expand it?

If you use ZFS and configure as a RAIDZ1, you can just keeping add hard drives to the pool and it will accommodate them.

Responding more-so to OP's question here since you brought up ZFS.

Talking specifically about OpenZFS, RAIDZ expansion is supposed to be supported starting with OpenZFS v2.3.
If you're using an older version than that, you can't expand any RAIDZ array. Those remain permanent with the amount of drives they contain once they're created in older versions.

You can always add another VDEV to a storage pool in ZFS. RAID is not at the pool level, but at the VDEV level in ZFS.

The minimum drive count for RAIDZ1 is 3 drives (2 usable, 1 parity). That means, if you want to expand a pool that already has a RAIDZ1 VDEV, you'll need a minimum of 3 drives to add another RAIDZ1 VDEV. Though with two RAIDZ1 VDEVs, you'll lose 2 drive's worth of space to parity.

I don't know when OpenZFS v2.3 is set to release, but until then, this is a limitation of ZFS's RAIDZ.