Big but old server, will it software transcode 4K?

[TheDreadPirate]

The problem is that video encoding does not scale linearly with core count. There is a point where adding more threads/cores will produce zero benefit. Which is why per core performance is important for encoding. This is even more true with lower resolution video as there are fewer "chunks" to spread around.

I can't say for certain how many transcodes your server will be able to handle. Just trying to manage your expectations. Direct play requires minimal resources, so try to encode your library with widely supported codecs (H264 + AAC) if you are able to. Of if you know that your playback devices support newer codecs.