[HELP] x265 encoding

[kento]

Hello everyone ,

I encode some UHD BR for some time now.
I usually use the -slow preset and --no-sao.
CRF on 18.

It works very fine with 2.35 movie when I crop the black strips.

But I find some weird results with 1.77 or 1.85 movie (aka full frame without crop).

Each time the bitrate is very high , sometimes higher than the original bitrate 

I can't explain this phenomena and it's bothering me.

So this is not a Hybrid issue , it's something I don't understand.

If someone's got a hint I would be happy

[Selur]

Personally I wouldn't disable sao unless I go below crf 10.
Why an encode can end up with a higher bit rate than the 'original', even when the compression settings of the reencode or better than those that were used to encode the original is simple:
Your decoded source contains more details than the source the 'original' was encoded from.
Through the encoding which created your 'original' additional compression artifacts were added which now count as details which the encoder will try to preserve.
This is why most folks typically at least use some mild degrain, deblocking, artifact removal filters during re-compression unless one is encoding lossless.

Cu Selur

[kento]

Personally I wouldn't disable sao unless I go below crf 10.
Why an encode can end up with a higher bit rate than the 'original', even when the compression settings of the reencode or better than those that were used to encode the original is simple:
Your decoded source contains more details than the source the 'original' was encoded from.
Through the encoding which created your 'original' additional compression artifacts were added which now count as details which the encoder will try to preserve.
This is why most folks typically at least use some mild degrain, deblocking, artifact removal filters during re-compression unless one is encoding lossless.

Cu Selur

Thank you for the explaination , this makes sense !