Question / Help NVenc Indistinguishable Quality Settings for 3440x1440

Hi, I know that at 1080p the CQP should be 15 for indistinguishable quality but could someone tell me what it should be for 3400x1440? I saw a calculation somewhere to determine this but I didn't understand it at all.

Also could I get the CQP setting at 3440x1440p for lossless quality if it's different please.

Thanks
 

Suslik V

Active Member
If you are about this thread: Quicksync Output Settings
then:
...
IndistinguishableQ
crf=16 - truncate_to_integer_{ {1 - the_smaller_of_[ 2000; square_root_of_(output_size_X * output_size_X + output_size_Y * output_size_X)] / 2000 } * 10}
...
...=16-trunc{{1-min[2000; sqrt(3400*3400+1440*1440)]/2000}*10}=16
Answer: 16.

Edit: B-frames behaviour changed in Studio for NVENC, wait for new release.
https://github.com/jp9000/obs-studio/commit/1e0d5e7b3e68ca3ca67df8bc3cae4d5d141a1036
 
Last edited:
Thank you. Just two questions remain.

If indistinguishable at 1080 is 15, and at 3440x1440 is 16, is it stupid to assume that since high quality at 1080 is 23, that high quality at 3440x1440 is 24?

Also, is there a page somewhere that details all of OBS's settings that it uses for all recording methods in simple mode?
 

Suslik V

Active Member
My calculations gives to me crf=16 for 1920x1080 Indistinguishable (see link above), thus High is crf=23.

Mathematical expression and settigs from source code: https://github.com/jp9000/obs-studio (window-basic-main-outputs.cpp file).
Streaming settings from services.json file of the source code (depend on web service type).
You can look into log-file to see the most settings for the encoder (for x264, it is: crf; veryfast; high; key interval 250).
 
Sorry, that was a typo. Where I wrote 15 I meant 16, and where I wrote 16 I meant 17.

For 3440x1440p I will just add 1 to the 1080 quality settings.

Edit: Are these calculation all handled automatically when using simple mode?
 

Suslik V

Active Member
PC applications always calculate something. Yes, values automatically apply (try to record with any preset and post a log or look at log-file - you'll find all settings).
 
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