Resizing from 4K to 2K with maximum PQ

[Tenaka]

Hi !


I'm asking for advice concerning my settings.

I would like to resize the source file  from 4K to 2K and passthrough everything, while ensuring maximum picture quality and encoding speed.

Source file :
Resolution : 3840 x 2160
Codec : HVEC
Profile : Main 10@L5.1@High
Color primaries : BT.2020

Target file :
Resolution : 1920x1080
Codec : HVEC

I don't mind a file size around 30Go to 70Go for 2 hours of video content.
My video player can downscale 4K to 2K using SSIM in live, so it should be quick once the streams are extracted no ? (i5 3570K 4 thread @ 4.41Ghz)


Here are my settings :

Base tab

• Video : x265
  
• Audio : passthrough all
  

x265 -> Base  tab

• Constant quantizer (1 pass), strengh at 0, lossless box ticked
  
• Profile/Level/Tier : Main 10@L5.1@High
  

x265 -> Signaling tab

• Primaries box ticked
  
• Matrix box ticked
  

Crop/Risize tab

• Picture resize : bicubic-spline
  
• Auto adjust to mod 2
  
• 1920x1080
  

Everything else by default.

x265 --input --output-depth 10 --y4m --qg-size 8 --limit-modes --no-open-gop --keyint 24 --min-keyint 1 --lookahead-slices 0 --lossless --aud --no-deblock --repeat-headers --colorprim bt709 --transfer bt709 --colormatrix bt2020nc

Am I doing something wrong ?

Do you have any recommendation concerning my settings ?

I would be happy to provide more informations.