Question / Help Good sucess with x264 on 1440p60. Please help me understand why!

[DamageInc]

Please note: this is local recording only

So i got a bit down when i couldnt get lag free 1440p60 using nvenc and any combo of settings

I went back to x264 experimentation and last night stumbled upon a combi that worked shockingly well.
CBR
Custom buffer off
Bitrate 100,000
Cpu preset: ultrafast
Rest of settings pretty standard

The output file viewed in premiere is pretty flawless and dialing the bitrate back to 80,000 is still very very nice. Obs log reporting 0 dropped frames and 99.7% within 2% of 16.7ms

Battlefield 4 runs at about 40% cpu usage without obs and rises to a steady 85-90% mark when at ultrafast and 100,000. I deliberately want to leave headroom on my cpu.

What i dont understand is if i change cpu preset to superfast i can barely set the bitrate above 20,000 without maxing cpu to 100% and the output file looks fairly blocky and blurry.

So, in a non-bitrate constrained environment (cos im not streaming) is the ultrafast cpu preset the only sensible choice when shooting for quality without killing your cpu?

My rig is a i7 4790k and a gtx980

 

[Suslik V]

Ultrafast preset disables B-frames support at encoding. This is major difference between ultrafast and other presets.
For local recording people usually use CRF instead of CBR.

 

[DamageInc]

Ok. I will google b-frames support. Not knowing what it is i dont know if thats bad or not. From the way you said it, its probably bad.

 

[DamageInc]

So b frames support seems to be about how compressible a file is. If i dont care about compression (and i dont - im writing to a dedicated 500gb SSD) then does this affect me?

I intend to compress using handbrake after editing in premiere. I just care about getting high quality data onto my ssd from the game. If not adding in bframes means i can do that great.

Im worried i am over simplifing this tho?

 

[Suslik V]

In general you are right (b-frames can save bandwidth while keep video at the same quality, important thing if you are using CBR).

 

[Schauerland]

bframes are very expensive
se the images here why:
https://en.wikipedia.org/wiki/Video_compression_picture_types

with a gtx980 you could try nvenc for encoding

 

[DamageInc]

NVENC was the first thing i tried. Compated to shadowplay, obs's nvenc implementation is grim - lots of dropped frames or lagged frames. Ive had lots more sucess with x264 recently.

Im all ears for good nvenc settings. I was hoping the update might fix the issues i was having.

In shadowplay i can record 1440p60 at 50mbps butter smooth with no dropped frames. In obs i can barely get past 25mbps without dropping frames galore. In x264 with cpu preset on ultrafast i can do 80-100mbps with no dropped frames. Looks great.

 

[Osiris]

FYI, there is no obs nvenc implementations, it's ffmpeg's implementation.

You also didn't post any logs.

 

[DamageInc]

Logs were in an initial thread i posted a few weeks ago. Ive learned a lot since then, but im enjoying just tinkering in obs as i can see the massive potentisl it has as a one stop shop for those who split multiple audio tracks.

i will do some more nvenc logs tonight for ya