Recommended bit rates for various resolutions?

[Reaper4578]

When ripping blurays, I don't know what bit rates to use for optimal quality vs file size. For 4K HDR blu rays, what bit rates are acceptable? And for 1080p SDR blurays? These are movies, obviously, so I'm looking at 1.5-2.5 hours, and I'd like the files to be a max of 10-15GB (although up to 20 is fine for the 4K HDR ones). Thank you so much for any advice you can give!

Edit: I'm encoding them all in x265 with 10 bit color

[jagabo]

There's no simple answer for that because different videos require different bitrates. The best way to approach this is to use an encoder that supports constant quality encoding (for example CRF mode in x264 and x265). That way you always get the right bitrate for the quality you specify.

[Anonymous5394]

No easy answer to that as every source is different. It was said that 0.2 pixel ratio for the older avi format gave good quality and then we moved on to h264 so 0.1 was acceptable, ergo 0.5 for h265 as they say if offers twice the compression benefits at lower bit rates though the quality evens at higher ones.

What this is as bit rate is anyone's guess? Using a bit rate counter might help. I recently did a blu ray to 2400kbps bit rate and couldn't see any difference from the source though peak signal noise tests would determine that better. Mostly depends on the source and I don't believe in doing these use huge encodes of 5gb plus or even 10gb plus as you might as well place the original source in an mkv container untouched.

[fornit]

Different sources require different bitrates.

That's why constant visual quality (cfr = constant rate factor) has been introduced.

There's a point where encodes start to become "transparent". I.e.: You won't notice a difference between the original and the encode. Maybe that point is subjective. For me that's crf 18 (with x265).

With that setting bitrate can vary much. For full hd blu rays it can range from as less as 1050k until 6500k or more.