With devices like the WinTV-quadHD, on-the-fly transcoding of all tuners at once can be quite CPU taxing, even for pretty fast systems. But the disk space gain for H.264 is quite substantial versus the much older MPEG-2.
A feature that an old system I used to use, SageTV, offered was to transcode videos after recording completed, in a batch process with low CPU priority and limited number of parallel transcodes.
This would be very useful for Plex DVR. I would recommend running the transcodes at a maximum of 1 per every 2 CPU cores (not hyperthreads), of course could be configurable, and at the lowest CPU priority (“Idle” prio for Windows, nice +20 for Linux/Mac) so that they would stay out of the way of anything needing interactive response.
This wouldn’t be much different from the way Optimized Versions works, except that the transcoded video would replace the original MPEG2 stream. This would free up disk space using idle CPU time without chewing up nearly as much CPU at record time.
