Which NAS for Jellyfin?

[Efficient_Good_5784]

1. What exactly is transcoding, like when people ask about streaming 4k? I rip my media, and run it through handbrake to reduce the file size. When someone talks about transcoding 4k, are they like ripping the file with mkv, keeping the file as in, and the machine is actaully converting the video on the fly as its streaming? I just want a better understanding since I hear about it so often.

Pretty much you're correct with your last statement, the server will convert the file as you stream it.

There are two main reasons why someone would need to transcode:

1. Their client is incompatible with the original source
   
2. Their network bandwidth is limited and they need to lower the bitrate to allow for smoother playback over the internet.
   

Try reading this post I made in the past that hopefully will explain what transcoding is in more detail.

2. I really like that on a tablet or a phone, you can download the original file though the jellyfin app, but I just want to confirm, that only downloads the file to the device right? At first I thought it would be like a way to access downloaded media though the jellyfin app/interface, but I cant open jellyfin if theres no connection to the server. It seems that its just downloading the file to the device, and thats it. Theres no way of having like an offlike library with jellyfin is there? The closest I've come is downloading the file on a tablet, and just moving it to my media directory for kodi on the tablet to recognize. Its still an improvement from what I used to do (transferring via micro sd) but just wanted to ask.

The Jellyfin Android app doesn't have an offline mode. The download option is indeed only to download the video onto your phone (so that you can use it with other apps to play it locally on the phone). There would need to be more work done to the app and the server to allow for the app to have in-app offline functionality.