x265 Settings for Fast Motion and Fine Detail

[creeve4]

I am trying to encode footage that I captured with my action camera (DJI Action 5 Pro), but the bitrate on the encodes is much higher than the original files. Are there settings/tweaks I can use with x265 to get my bitrates down to 15-25 MB/s while preserving most of the detail and avoiding heavy artifacts?

I am using Staxrip for encoding* and have tried CRF values from 18 to 26 and still get huge encodes, bigger than the original. At CRF 24 I am starting to notice quality degradation and the bitrate is higher than the source. I have also tried 2-pass, with ABR between 20 to 40 MB/s. Even at 40 MB/s there are noticeable artifacts and quality degradation.

Here is a short sample (https://filebin.net/ttawe20zj8ju7zvl#) of the footage I am trying to encode.

*I have been using Staxrip for years to re-encode HD and UHD Remuxes with great success.

[Cmptr]

What settings and preset are you using? Is the footage 60fps?

[Z2697]

The thing is this file is already at like avg QP 33-35, think it as being CRF 28 or higher

[creeve4]

I am encoding to 1080p, 10-bit, 30fps. The footage is 30 fps.

[Z2697]

The video is already low quality even at 50Mbps, you won't get any good compression even if you downscale it. (for the time being)

[rwill]

What Z2697 wrote.

Thank you for the very impressive sample, really high spatial/temporal complexity. Not random noise level spatial/temporal complexity but close. The amount of exploitable information redundancy that is needed for compression is very low.

Just keep the source file, its not going to get better than that.

[benwaggoner]

The video is already low quality even at 50Mbps, you won't get any good compression even if you downscale it. (for the time being)
For the time being?

[Z2697]

For the time being?

Maybe some future magical algorithm can get a nice compression? I'm being optimistic.
Or is there other problem?