Question / Help Hardware requierment for capturing multiple video sources

[Kuebrich]

Hello Forum,

I'm currently trying to record 4 Gigabit Ethernet cameras with a resolution of 1920x1080 by 50FPS.
All of these cameras have a seperate network connection to the PC, so none of them have to share the same bandwith.
Recording two of these at the same time is no problem at all but after adding the 3rd/4th one the framerate starts dropping hard.
The output file has to be in 1920x1080 with at least 50 FPS and also the quality of the input source cant be lowered.
While recording with these settings I saw that the CPU was at 100% all the time and OBS said that the CPU was to slow for encoding.

Therefore I am pretty convinced that my current Hardware setup has to be changend.
Right now this is built in:
4 Core CPU with 2.3 GHz
4GB RAM
No graphics card
256GB SSD

Can you guys please give me some advice to how I should configure the new system?
My first action would be, of course, to upgrade the CPU to at least a 16 Core. (32 w/ Hyperthreading, Intel® Core™ i9-9960X X-series Processor or maybe a Xeon)
Then I would get 16GB of RAM since there needs to be some headroom for the main application to run.
I guess I should also get some more SSD space because the video-files could get pretty large.
But I also dont really know if a graphics card is really needed and would improve the performance.
Btw, there is no game or graphic heavy application running on the PC.

I hope somebody can help me here.
Thank you in advance!

 

[R1CH]

What kind of video format is the input data in? If it's for example 1080p50 H264, this could add significant decoding overhead. If possible, set the camera to run at 720p so you aren't feeding in 1080p only to scale it down, or set the output format to something more decoder friendly like MPEG. A basic NVIDIA graphics card that supports DXVA would help ease the decoding load when combined with the upcoming OBS v24 which supports hardware acceleration.

 

[Kuebrich]

Thanks for the answer! Unfortunately I cant scale the resolution down, I need 1080p as a quality minimum. I will try setting the output format to mpeg.
Thank you for the tip with the graphics card, so I guess I should definitely buy one for the new setup.
Should I also use a 16 core CPU or will a 8 core do the job?

 

[Kuebrich]

So to specify my question a bit more, I dont really know if I should get a CPU with 8 cores that uses hyperthreading or a CPU that already has 16 cores.
Maybe you could tell me if OBS is more of a single thread application, that would really help me.

 

[R1CH]

It really depends on the video format as to whether the decoder is multi-threaded, but each video source is decoded in its own thread. Assuming a single-threaded decoder, then only 4 cores would be used for 4 sources.

OBS itself uses multiple cores for rendering and encoding so it will scale well with cores.