Question / Help Minimum system requirement for 4 (four) 1080p60fps streams

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olafb

New Member
I have a 4K screen in front of me, which is split in 4 virtual FullHD displays and running off my intel i5-6400 internal GPU.

I max out at 100% CPU even on very low frame rates with x264 and Intel Quick Sync Video and I've read that common NVENC enabled GPUs only support two parallel encoding sessions.

What would be the recommended CPU or GPU to be able to stream all 4 parts close to realtime with 4 obs instances?

Thanks a lot,

Olaf
 
You can potentially upgrade to a Quadro card which does not have the 2-stream limitation, but they are quite expensive as they are workstation-grade cards.

Alternately, there are non-official patches available here and there to remove the limitation from a consumer-grade nVidia GPU, as they are purely a software limitation.
I'd probably grab a GTX 1660 and patch the drivers, if I were in your shoes; all the quality of the Turing NVENC core (which is generally on-par with x264 Slow compression quality, which is extremely good) at around a $200 price point. You can also grab a 1650 Super (NOT the non-super or Ti!) but they tend to have quite a bit less VRAM which may/will be a concern with a quad setup like you're intending.
As consumer-grade nVidia NVENC can handle two 4K60 streams at full speed, four 1080p60 (equivalent to one 4K60 stream) should be no sweat, once the drivers have been patched to remove the artificial limitation.

CPU software encoding for four 1080p60 streams isn't going to be feasible without spending several thousand dollars for an EXTREMELY beefy machine. And yeah, QSV is pretty poopy. It's a step up from AMD's AMF (which is complete garbage), but it's unsuitable for your needs.
 
Wow, that was a detailed answer @FerretBomb - exactly what I was looking for! Thank you so much.

I don't mind patching and removing the software limitation on a used 1660. A friend who was involved in mining might have one lying around and I could borrow it for further testing. The 4 screens I'm using are not games, but text based, auto updating excel sheets - so I might be able to drop the bitrate and still receive a good stream.

Good to know that I don't have to look further to CPUs, was thinking about an i3-9100F or a Ryzen 5 2600 as an upgrade.
 
olafb said:
Wow, that was a detailed answer @FerretBomb - exactly what I was looking for! Thank you so much.

I don't mind patching and removing the software limitation on a used 1660. A friend who was involved in mining might have one lying around and I could borrow it for further testing. The 4 screens I'm using are not games, but text based, auto updating excel sheets - so I might be able to drop the bitrate and still receive a good stream.

Good to know that I don't have to look further to CPUs, was thinking about an i3-9100F or a Ryzen 5 2600 as an upgrade.
Click to expand...
The Ryzen would be an option, just make sure the motherboard firmware is up to date. It contains CPU microcode updates, and early Ryzens had stability issues with OBS for reasons I don't know the details around.
I don't believe I'd ever go under an i5 on the Intel side. There is still other support work being performed by the CPU, and an i3 is solidly in the 'email machine' realm.

Interesting. In that case, you could probably get away with a used 10-series, or maybe even a 9-series card, with slow-updating, static-text content. I'd still likely go for the 1660 just for futureproofing if it was me, if the application changed later away from text.

I honestly can't help but think that there would have to be a better way to propagate four screens of text though, rather than sending full-rate RTMP streams. But yes, depending upon the speed of update, you could likely drop to 5fps and save... well. 11/12ths of the bitrate needs of 60fps video.
 
I really have to check the bitrate requirement with realtime tests. I imagine, if my excel sheet is updating at a rate of 1fps the picture stays in 59 frames exactly the same. If no changes are detected, any good video compression algorithm should not transfer any data.

Later I plan to have my camera on the lower right (at around 320x200) - so that part would need 60fps to look smooth.

Do the 4 screens have to be visible at all for the 1660s NVENC to do its work? If yes, would a dummy HDMI adapter help to move my 4 broadcast screens to the second (invisible) monitor?
 
I'd probably stick with 30fps; a facecam really doesn't need 60fps, just a nice-to-have. You could probably even cut to 20 or 15fps in some cases. 60fps in a CBR setting will need twice as much bitrate to maintain the same image quality as 30fps, three times as 20fps, and four times as 15fps. There's a reducing rate of returns so the multiplier isn't exact, but it's close-enough.

Unfortunately I believe Office is one of those that may not be able to be captured with a Window Capture properly. It'd be worth a shot. If it can, then you just need to make sure they aren't minimized and are on the screen somewhere, even if they're overlapped by other windows. A dummy plug would work to give you additional screenspace, yes. But that's more an issue with Windows and how it deals with the desktop compositor rather than NVENC. NVENC just takes the completed frame that OBS hands it, and compresses it.

Bitrate usage varies by target, and the target you can use depends on the service you're using.
For local recording, CQP/CRF quality-target based encoding will only use as much or little bitrate as needed to maintain a given quality level.
For livestreaming to a service like Twitch, Youtube, Facebook, etc... you'll be stuck with CBR. Constant bitrate. Which uses the same amount of bitrate every second no matter if a ton of stuff is going on, or if the same single frame is being sent for hours on end.

If you're using an internally-rolled service, that's a different story altogether and will vary based on the needs and requirements of your technical solution.

Speaking of which, hope you have a strong connection if this is going out somewhere. Each CBR 1080p60 stream will 'want' 12mbps upstream, but you can likely get away with less given the low-motion nature of your intended video.
 
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