pre-transcoding library files?

[theguymadmax]

You can create multiple versions of a movie as outlined here, but Jellyfin doesn’t have a mechanism for clients to automatically select the most compatible version, the first version in the list will be played by default. To ensure compatibility, you would need to make the default version the most compatible one by naming the versions alphabetically and not including the resolution in the filename.

Movie (2000)
  Movie (2000) - A H264-8bit "compatibility" version - fallback / failsafe
  Movie (2000) - B H265-10bit or AV1-10bit - preferential for non-LAN streaming and remote connections
  Movie (2000) - C (whatever format) archival quality master version, appropriate for local network 4K TV streaming only