This is a very interesting observation, thank you for sharing!
I’ve done some more testing this morning. I think this is going to be highly dependent upon the client being used to view the live TV stream. For example, I started recordings for 3 channels (being transcoded to HEVC with a quality of 25) and then attempted to view live TV with 2 different clients: Plex Web and Plex for Mac Desktop.
With Plex Web, it failed to start with a generic playback failed error. This is presumably because it needed to transcode MPEG2.
With the Plex for Mac app, it was able to play the same channel without issues. The app supports MPEG2, so no transcoding was required.
For what it’s worth, this Plex server is running on Ubuntu 22.04 LTS on a Jasper Lake-based Celeron (N5105). So, Gen11 Intel graphics. It’s pretty capable, but it’s no N100. Running intel_gpu_top showed ~30% utilization of the Video engine while doing these 3 recordings (though it did spike to around 50% occasionally).
