CRF like constant quality mode for NVEnc?

agentusa · 16th July 2020, 04:48

I'm testing NVEnc HEVC on Turing with Staxrip and I'm trying to figure out what the optimal constant quality settings should be. I heard that CQP mode should be avoided because it's primitive compared to CRF. VBR mode apparently should be used instead with qp-min and qp-max set because it does a much better job. Is that correct?

Here's my NVEnc settings:

Code:

--vbr 0 --codec h265 --preset quality --profile main10 --output-depth 10 --qp-init 22 --qp-max 22 --qp-min 22 --vbr-quality 0 --aq --aq-temporal

Does that look right or is there something off? Thanks.

Sharc · 16th July 2020, 07:56

Where did you get this from?
The constant quality mode is set with
--vbr 0 --vbr-quality xx
with xx for example 22.0 Leave the --qp settings at their defaults.

See the doc
https://github.com/rigaya/NVEnc/blob..._Options.en.md

Quote:

Constant quality mode can be used by "--vbr 0 --vbr-quality <float>".

agentusa · 16th July 2020, 23:01

Thanks for pointing me in the right direction. I saw the --qp settings in a forum post on another site and a Github issue for Handbrake but questioned how accurate the info was.

easy2Bcheesy · 6th September 2020, 20:57

How does quality of NvEnc HEVC using this 'crf' mode compare to x265? The last time I looked into this, the best I could do with NvEnc HEVC was quality equivalent/filesize equivalent to x264 medium.

Sharc · 6th September 2020, 21:54

CRF ist not an absolute quality measure. Hence the same CRF value for different encoders does not mean the same quality.
There seems to be a consensus though that HW encoding is inferior to SW encodes. So your observation is probably about valid.

16th July 2020, 04:48	#1 \| Link
agentusa Registered User Join Date: Jan 2007 Posts: 10	CRF like constant quality mode for NVEnc? I'm testing NVEnc HEVC on Turing with Staxrip and I'm trying to figure out what the optimal constant quality settings should be. I heard that CQP mode should be avoided because it's primitive compared to CRF. VBR mode apparently should be used instead with qp-min and qp-max set because it does a much better job. Is that correct? Here's my NVEnc settings: Code: --vbr 0 --codec h265 --preset quality --profile main10 --output-depth 10 --qp-init 22 --qp-max 22 --qp-min 22 --vbr-quality 0 --aq --aq-temporal Does that look right or is there something off? Thanks. Last edited by agentusa; 16th July 2020 at 05:18.

16th July 2020, 23:01	#3 \| Link
agentusa Registered User Join Date: Jan 2007 Posts: 10	Thanks for pointing me in the right direction. I saw the --qp settings in a forum post on another site and a Github issue for Handbrake but questioned how accurate the info was.

6th September 2020, 20:57	#4 \| Link
easy2Bcheesy Moderator Join Date: Feb 2002 Posts: 643	How does quality of NvEnc HEVC using this 'crf' mode compare to x265? The last time I looked into this, the best I could do with NvEnc HEVC was quality equivalent/filesize equivalent to x264 medium.

6th September 2020, 21:54	#5 \| Link
Sharc Registered User Join Date: May 2006 Posts: 3,997	CRF ist not an absolute quality measure. Hence the same CRF value for different encoders does not mean the same quality. There seems to be a consensus though that HW encoding is inferior to SW encodes. So your observation is probably about valid.