Question / Help The best settings for an old PC recording 4 portable OBS ? Exists ?

Hello, fellows,
I finally configured my PC/OBS for recording 4 sources independently ( 4 cameras ), in order to edit later on Adobe Premiere.
That was made using the portable version. I created 4 independent OBS desktop shortcuts with their own settings.
It works like a charm, except for the fact that when recording 4 instances, the CPU goes to near 100%, although in iddle each
portable version consumes only about 2%. So, the problem is the computer which is too old for such a work, BUT...
There may be a reasonable codec setting thay I could use to improve.

My current PC and OBS recording settings:

i7 2600k ( 4 cores - 8 threads ), overclocked to 5Ghz, watercooler, 16GB RAM, SSDs, etc.
Recording disk: Seagate hard drive 8TB, 7200 rpm, sustained transfer rate around 220MB/s measured with crystal Diskmark.
OBS configured to 1080p canvas/1080p output, recording standard MP4 x264 CBR at 4000 on "veryfast" mode.

Although this is not the ideal recording for editing, if I raise from 4000kbps to let´s say, 6000, I can´t even run four instances at the same time,
My video card is old, an nVidia GTX 780, perhaps it doesn´t support the new NVENC that people talk so much about it, does it ?
So, after reading many posts on this foruns, I think there may be a reasonable CODEC settings for an optimal recording.
The recorded files are not big ( On this config, about 3GB/hour ), but I have plenty of space, I wouldn´t mind it the files were bigger but OBS don´t pound so much on compression. Should I use "ultrafast" instead of "veryfast" ? But that won´t have a worse video quality ?
Can´t I improve video quality by forcing a target video quality independently of the filesize without pounding on CPU ?
What about using VBR intead of CBR ?

I don´t know, but some of you may know, fellows.
Thank you for any ideas and suggestions.
 
Last edited:

Narcogen

Active Member
Don't use VBR or CBR rate control for recording. Use CQP and a quality setting. The lower the setting, the higher the quality and the larger the file. 0 is lossless, but honestly, never go below 14. 23 is good, but you may need to go higher to get good performance out of this machine while running 4 instances.

4-6000 are really, really low bitrates for recording. That's even the low side for streaming if you're trying 1080p60.

780 will use the new encoder and will make it more efficient, but that's about it-- you will not see a quality increase. You will not be able to run more than 2 encoding sessions with NVENC, but that might help take the load off your CPU.

Using ultrafast instead of veryfast (the default) will lower load at the cost of decreased image quality.

If you have trouble getting acceptable quality within your limits the easiest fix would probably be targeting 720p instead of 1080p. You didn't make mention of framerate.
 
Don't use VBR or CBR rate control for recording. Use CQP and a quality setting. The lower the setting, the higher the quality and the larger the file. 0 is lossless, but honestly, never go below 14. 23 is good, but you may need to go higher to get good performance out of this machine while running 4 instances.

4-6000 are really, really low bitrates for recording. That's even the low side for streaming if you're trying 1080p60.

780 will use the new encoder and will make it more efficient, but that's about it-- you will not see a quality increase. You will not be able to run more than 2 encoding sessions with NVENC, but that might help take the load off your CPU.

Using ultrafast instead of veryfast (the default) will lower load at the cost of decreased image quality.

If you have trouble getting acceptable quality within your limits the easiest fix would probably be targeting 720p instead of 1080p. You didn't make mention of framerate.

Narcogen, I only see CQP while choosing NVENC. It´s not available for my common x264, only CBR, VBR, ABR and CRF ( Which may be the same thing with other name ). NVENC really works, but only for two instances as you said. I intended 30fps. I tried to make different, instead of running 4 instances of 1920x1080 or 1280x720, I tried to create a preview of 3840x2160, which I could crop on the editor, but it hits the CPU even harder, and while using NVENC, I get stutters, so, I went back to 4 instances.
 

Dihelson

Member
CQP and CRF are functionally the same; CQP is for NVENC, CRF is for x264.

Thanks, Narcogen. Why I get only two instances running NVENC on a GTX 780 ? If I use a new powerful card like GTX 1660 would I get it to encode all 4 instances at 1080p without any glitch ? Even while encoding 1 instance at 1080 with my current card, the recording is choppy with NVENC. Even on preview I see the stutters while cpu usage is very low. The "good" codec is on the new cards is it that "NVENC new" that we often see on the posts ?
 

Dihelson

Member
Consumer cards are limited to 2 concurrent nvenc sessions by Nvidia. This is a hardcoded limitation in the chip.

Consumer cards ? But GTX 2080 is still limited to 2 ? When I purchased GTX 780 it was too as today a 2080 is top.
 

Dihelson

Member
These are consumer cards. Geforce is consumer and limited to 2 sessions, while Quadro is the professional line that is unlimited. See the compatibility matrix from Nvidia:


So, anyway, either with a 780 or a 2080ti I would be limited to 2 instances. People also "forget" about the cuda cores counts. Even in my old 780, if I'm not mistaken, there are 2300 cuda cores, while in some low entry modern cards like GTX 1660 there are less. So, sometimes I wonder about how the two cards would perform better on Adobe Premiere, preview and rendering.
 
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