Question / Help Game Capture less performance when preview is on

S

Schauerland

Member
Hey there.

I had noticed mini lags (looks like heavy motion blur) while moving fast ingame for a long time now, but could not figure out what the problem was.
i tested many thing but now i found out what's the cause of these lags.

It seems that the preview is causing these lags. if i switch off the preview i have no more lags in my recordings.

That's fine and great because this problem racked by brain for a long time.

So let me show a Video to proof (it's not listed and not monetized, so i don't soak u guys :) i just want to show the difference):

https://youtu.be/fNjbQdykeIk (YouTube maybe takes some time for HD/60FPS)

Now i can have smooth recordings yay <3

BUT... the great advantage for me was the preview.
I have two monitors: 1080p samsung 60 hz on displayport (left monitor) and 1440p dell 60 hz as my primary monitor.
im playing games on the dell and recording in 1440p

obs is on the second (samsung 1080p) screen.

My card is a GTX970 i have a xeon e3-1231v3 and 32 gb ram.
OBS was using ~8% of CPU while recording (encoding with nvenc but same problem when using x264)
oh and i did see the difference between ingame and preview even when i was not recording.
So something in the preview is causing the lag.

I think there is no difference in performance running obs on the same screen where the game is running. i've testes it before (but had no idea i could switch preview off) so the only way it gets better is switchin preview off.

Any chance to keep the performance while preview is on?

if not, a hotkey for switching preview on/off would be awsome so if a have the need for checking my recording i could switch on preview and off when im done while recording.
Becaus i also do streams and it's very handy to see the preview with twitch alerts etc

So i hope you guys understand what i was trying to say, because my english is not so good :) sorry for that

I LOVE OBS and your work and hope you could investigate or fix that or provide a hotkey for toggeling preview
 
S

Schauerland

Member
But let me ask a question: i witch way can preview influence the rendering for recording.
is the pipe renderScene -> preview -> output
or
renderScene -> output
-> preview
 
S

Schauerland

Member
Here are the log (Upload didnt work here, so sorry for pastebin)
preview is on: http://pastebin.com/ZRFXpS2h

preview is off: http://pastebin.com/N8Mx2B2s

as far as i understand the log, when preview is on, a lot of frames are skipped:
20:09:22.817: Output 'adv_file_output': Number of skipped frames due to encoding lag: 40 (2.3%)
20:09:22.817: Output 'adv_file_output': Number of lagged frames due to rendering lag/stalls: 92 (5.2%)

when preview is off, only one frame i skipped
20:10:26.951: Output 'adv_file_output': Number of skipped frames due to encoding lag: 1 (0.0%)
20:10:26.952: Output 'adv_file_output': Number of lagged frames due to rendering lag/stalls: 1 (0.0%)
 

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  • preview-on.txt
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S

Schauerland

Member
Hey just want to give you an updtate.

In the Nvidia Control panel i switched Multi-Display to compatibility performance mode
also i tested Single Display Mode and both causing less rendering lags

i always though this setting is for opengl only but seems to work (better)
 
S

Schauerland

Member
So.. why does this setting fix my problem?
Nvidia says its only for openGL and obs is usign dx11 right?

so is this a bug in obs or nvidia driver?
 
S

Schauerland

Member
so the compatibility mode doese not fix it at all.
there are less frames dropped, but still dropped.
no frames are dropped when preview is off.

i would say this is a bug or a design feature, because the preview should not be processed before it is passed to the encoder.

this should be totally independently an preview should not influence the recording.
 
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