I recently started building a movie/show collection again on my home NAS.
I know that generally H.265 files can be 25-50% less bitrate than H.264 and be the same or better quality. But what’s the golden zone for both types? 10 Mbps for a 1080p H.264 movie? And would it be like 5 Mbps for H.265 1080p to be on par with H.264? What about 4K?
For file size: would it be 25GB for a 2 hour 1080p movie to be near or at original Blu-Ray/digital quality?
I know that this is a non-answer, but the best thing to do is reencode a few files at multiple bitrates and see where the line is for you.
Try to get a few dark scenes, since that’s where compression artifacts tent to be most noticeable.
Also you’ll need to increase bitrate or adjust parameters depending on how much film grain there is. 70s Italian movies are some of the worst for that, lovely crisp and gritty grain but it gets absolutely obliterated when compressed incorrectly.