Question / Help CPU VS CPU+GPU for recording only, could a CPU suffice?

[Roy777]

Hello friends,

I'm looking to build a new PC for the purpose of capturing my desktop together with a camera input overlaid over it (like streamers do) for the purpose of making video tutorials. I'm not intending to stream ever :)

I'm looking at the Ryzen 3700x CPU and also at the Nvidia RTX2060 Super graphics card.

I'm intending to record videos locally of 1080p 30fps in good quality.

The software that I'll be running besides OBS uses the CPU mostly but very lightly, it could use a more only under strain as when completing a task for a few seconds. (think of running an effect in photoshop for example) they will also use some of the GPU for some tasks, very lightly again, usually the cheapest graphics card does the job. I will not be recording any game play.

I'll also use a camera with an HDMI capture card like Camlink, would that take some CPU decoding the video? i'll also have OBS chroma keying the green screen behind me if it matters for the CPU usage.

My question is, would you think that in anyway that CPU (or even a better one like 3900x) could suffice? or I'll have to purchase a good graphics card as well? I'm asking because of the price difference, I could get the PC first and run tests (as it would be a custom build) and then purchase the graphics card later on and add it, but I might just get it all at once if the probability of using only a CPU successfully is very low.

I've also read that the CPU gives the best x264 quality or the same quality and smaller file size? Is that true? I am interested of getting the smallest files possible while keeping the quality very very good.

I've also learned that the new Nvidia RTX series cards have a dedicated NVENC encoder which could be helpful taking the strain off the CPU? but I'm not sure it won't be an overkill and if the CPU wont be enough to handle everything by itself, That's why I'll appreciate your advice!

Many thanks in advance,

Roy.

 

[FerretBomb]

OBS requires a DX11 hardware compliant GPU to operate properly, due to the housekeeping processes it runs (scaling, color conversion, etc).

x264 CAN provide better compression quality than NVENC, but with the advances made by nVidia with the Turing encoder core (on the 20-series, 1660, and 1650 Super but NOT the 1650 normal or Ti) it requires an EXTREMELY powerful machine to run at a preset slow enough to generate better compression quality in a realtime encode.
Turing NVENC is roughly the equivalent of x264 Medium, or Slow in some cases. To be able to run at x264 Slow, Slower or Placebo, you're looking at building a $5000+ machine for a very minor compression quality improvement.

Generally though, if you are only recording and not livestreaming, using a quality target based encoding method (CQP or CRF) is going to get you the same quality regardless of if you're recording on a Turing NVENC card, x264 Slowest/Placebo, an old nVidia 700-series card with first-gen awful NVENC, or even AMF or QSV which are pretty awful... the only thing that will change is the file-size. Which you can always go back and re-encode later in non-realtime with something like Handbrake to bring the filesizes down, using x264 Slowest to make them as small as you like.

Yes, the Camlink will use CPU for video decode. It's generally pretty minor on a modern CPU. Same with applying filters... it's negligible. The real heavy lifting is in the video encoder stack, which NVENC alleviates entirely.

 

[Roy777]

@FerretBomb Thanks so so much again, let me see if I got it right.. if I'm only recording (which I am) I can go in two routes:

1. Use the CPU and a Turing NVENC Nvidia card to encode in real-time and get a quality "equivalent of x264 Medium, or Slow in some cases." Using the NVENC encoder in OBS.

or

2. Use only the CPU with a decent inexpensive graphics card to record using the CPU to Encode in real time in a very good quality like x264 Slow/Slowest/Placebo and just get a really big file size and later re-encode the files? I wouldn't get any lags in this way?
Thanks so much for the Handbrake app tip, I didn't know about it before.

Do you think I should get the PC and use the very low-end GT710 (2GB) I got and see if it works before I invest in an RTX graphics card? or get a better card which is not an expensive RTX card for that purpose?

I would definitely wont mind re-encoding the files after recording if eventually I'll get a better quality AND wont have to invest in an RTX card.

Thank you so much for helping! I really appreciate it.

Roy.

 

[FerretBomb]

2. Use only the CPU with a decent inexpensive graphics card to record using the CPU to Encode in real time in a very good quality like x264 Slow/Slowest/Placebo and just get a really big file size and later re-encode the files? I wouldn't get any lags in this way?
Thanks so much for the Handbrake app tip, I didn't know about it before.

Do you think I should get the PC and use the very low-end GT710 (2GB) I got and see if it works before I invest in an RTX graphics card? or get a better card which is not an expensive RTX card for that purpose?

I would definitely wont mind re-encoding the files after recording if eventually I'll get a better quality AND wont have to invest in an RTX card.

If you buy a $5000 machine with a cheap GPU, then the CPU would be able to record x264 Slow with a quality target (CQP/CRF) in realtime during the recording. Generally this isn't cost-effective or worth it. This would result in relatively small filesizes though.

You can just record with x264 Ultrafast with a quality target though and a poor CPU/GPU, and end up with the same quality video, just larger initial file sizes until re-encoded with Handbrake in non-realtime later. Essentially throwing a ton of bitrate (so big files) so the CPU doesn't have to work hard in real-time to get the initial recording.
When livestreaming, that isn't a viable option as you can't re-encode it later. If you're just recording, all you need is to get the recording itself in real-time... you have the luxury of being able to re-compress it later with better encoding, even if it takes a few hours for the computer to chew on it.

 

[Roy777]

@FerretBomb I got you now, sorry, I was confusing "very slow" and "very fast" for my intended use..

so you think Ryzen 3700x could do handle it? or I should opt for a better CPU like the 3800x or 3900x?

I think I'll get the PC first and run tests, if it will work out it would be great and if not i'll get an RTX card.

Thank you so much for advising me!

 

[koala]

Even if you encode with CPU (x264), OBS needs a minimum amount of GPU power to do the video compositing. A GT 710 isn't suited for OBS operation at all. You will get rendering lag with it. Even iGPUs might become overloaded, if you compose your scenes with more than 1 or 2 sources. If you add filters, you need even more GPU power, because OBS's filters run as shaders on the GPU.

You should build a PC with balanced CPU+GPU power. Pushing one of these too much makes the PC too expensive on the pushed part and too weak on the other part. If you plan a machine for video capturing, i. e. OBS, I would buy a Nvidia GPU for sure because of the Nvenc encoder. If I will actually use it or not doesn't matter - it's an option that enables you to change plans.

If you don't game, a GTX 1650 SUPER is not that expensive and has the high quality Turing Nvenc encoder (be sure to get the SUPER, the non-SUPER don't have Turing Nvenc). It's what I'd recommend as GPU for OBS usage. It's also strong enough to do any video processing within OBS. If you game, get some Nvidia RTX.

As CPU, I consider a AMD Threadripper overkill for this usage. Their huge number of cores cannot be used efficiently enough by OBS and by most other apps. If you have something massively parallel computing stuff, yes, but for single apps, no. Use some Ryzen 7 CPU, they are quite price/performance efficient. Look at this https://www.cpubenchmark.net/cpu_value_available.html for price/performance comparison and pick the cheapest CPU that has the desired performance. It's probably the Ryzen 7 3700x or Ryzen 9 3700x - depending on your budget. (according to the chart the Threadripper 1920x seems the best choice, but it is actually not a good pick, because it is quite old - 1st Ryzen generation with its flaws and with its NUMA architecture. The actual performance you get will be less than with the modern 3th generation Ryzen. It also needs special mainboards no other type of CPU can be put in)

 

[Roy777]

Even if you encode with CPU (x264), OBS needs a minimum amount of GPU power to do the video compositing. A GT 710 isn't suited for OBS operation at all. You will get rendering lag with it. Even iGPUs might become overloaded, if you compose your scenes with more than 1 or 2 sources. If you add filters, you need even more GPU power, because OBS's filters run as shaders on the GPU.

You should build a PC with balanced CPU+GPU power. Pushing one of these too much makes the PC too expensive on the pushed part and too weak on the other part. If you plan a machine for video capturing, i. e. OBS, I would buy a Nvidia GPU for sure because of the Nvenc encoder. If I will actually use it or not doesn't matter - it's an option that enables you to change plans.

If you don't game, a GTX 1650 SUPER is not that expensive and has the high quality Turing Nvenc encoder (be sure to get the SUPER, the non-SUPER don't have Turing Nvenc). It's what I'd recommend as GPU for OBS usage. It's also strong enough to do any video processing within OBS. If you game, get some Nvidia RTX.

As CPU, I consider a AMD Threadripper overkill for this usage. Their huge number of cores cannot be used efficiently enough by OBS and by most other apps. If you have something massively parallel computing stuff, yes, but for single apps, no. Use some Ryzen 7 CPU, they are quite price/performance efficient. Look at this https://www.cpubenchmark.net/cpu_value_available.html for price/performance comparison and pick the cheapest CPU that has the desired performance. It's probably the Ryzen 7 3700x or Ryzen 9 3700x - depending on your budget. (according to the chart the Threadripper 1920x seems the best choice, but it is actually not a good pick, because it is quite old - 1st Ryzen generation with its flaws and with its NUMA architecture. The actual performance you get will be less than with the modern 3th generation Ryzen. It also needs special mainboards no other type of CPU can be put in)

@koala Thank you so much for your advice! yeah.. I've figured I'll need a better graphics card but when you put it this way, I'm sure of it now..

I am thinking about getting the Ryzen7 3700x, and thank you very much for the GTX 1650 SUPER recommendation. I'll look into it, I just don't want to get a card that I'll need to replace later on with an RTX one, even though I don't game.. but I'll think about what I'll do :)

Thanks a lot again.

 

[Roy777]

@FerretBomb @koala One last question I have before I'm done deciding what hardware I'm going to get, if I may :)

as it seems, the system I'll be building will look like this:

CPU- Ryzen 7 3700x
GPU- GTX 1650 SUPER or RTX 2060 SUPER(?)
MB- ASUS TUF B450-PLUS GAMING
RAM- Corsair Vengeance LPX 32GB (2 x 16GB) DDR4 DRAM 3000MHz C16
HD- 2 drives of 480GB Corsair SSD
PSU- Corsair RM550x (I've checked it to be sufficient for all components and the RTX206 SUPER if i'll go for it).
With the:
Camera- Canon SL3 (maybe with the EF-S 24mm prime lens)
Capture Card- Blackmagic Design Intensity Pro 4K

again just to mention, this system is only for recording and not for streaming. so my main question is:

Do you think I should go with the GTX 1650 SUPER or be on the safe side and already get the RTX 2060 SUPER?

as for the Motherboard, I chose the B450 chipset as it's half the price of the x570 chipset where I buy it, could anything in that x570 chipset provide any advantage for my use that it would be worth investing in?

If you have any comments about this setup, I would really really appreciate your input.. Thank you so much for helping me!

Roy.

 

[koala]

To be honest, I don't like giving any "go" to some specific hardware setup. If I say it's ok, and you spend your money to find it's actually not fit after all for your purpose, you might blame me for giving bad advice.

I cannot say anything at all about camera and capture card.

The PC components, well, I don't know. They seem ok. If this were my PC and I design it, I would check the shop's or vendor's website for a feature comparison between mainboards of both chipsets. Then I'd choose the cheapest mainboard that matches all my essential feature requests, whatever they might be (my demands are probably different to yours). Then I'd search and check reviews of that mainboard for show-stoppers and choose another, if there is any show-stopper. After finding the mainboard, I would consult that mainboard's memory compatibility list from the manufacturer's website and choose only RAM that is listed on that list and is available from my favorite vendor as well. There is more to do, for example choosing a CPU cooler that is powerful enough for the CPU's TDP as well as silent enough for my sensitive ears. Please understand that I will not do this kind of research for some PC someone on some forum intends to build. This takes some evenings to do right. At least how I do it. I do this once every 4-5 years when I get myself a new PC. My current PC is 3.5 years old, so the next is due probably after the Corona crisis early next year.
About choosing a GTX 1650 SUPER or RTX 2060 SUPER: the price difference is 170 Euro versus 420 Euro (this was the only research I will do for you), so choose well. To only be on the safe side this is a too high difference, so you need valid arguments to choose the 2060 over the 1650. Just for recording and without intent to do some gaming on that machine, I'd choose the 1650.

Regarding recording versus streaming: both use cases require the same CPU and GPU resources. If a machine is fit for one purpose, it's fit for the other as well. Streaming needs upload network bandwidth with your internet provider in addition, but no different PC.

 

[Roy777]

To be honest, I don't like giving any "go" to some specific hardware setup. If I say it's ok, and you spend your money to find it's actually not fit after all for your purpose, you might blame me for giving bad advice.

I cannot say anything at all about camera and capture card.

The PC components, well, I don't know. They seem ok. If this were my PC and I design it, I would check the shop's or vendor's website for a feature comparison between mainboards of both chipsets. Then I'd choose the cheapest mainboard that matches all my essential feature requests, whatever they might be (my demands are probably different to yours). Then I'd search and check reviews of that mainboard for show-stoppers and choose another, if there is any show-stopper. After finding the mainboard, I would consult that mainboard's memory compatibility list from the manufacturer's website and choose only RAM that is listed on that list and is available from my favorite vendor as well. There is more to do, for example choosing a CPU cooler that is powerful enough for the CPU's TDP as well as silent enough for my sensitive ears. Please understand that I will not do this kind of research for some PC someone on some forum intends to build. This takes some evenings to do right. At least how I do it. I do this once every 4-5 years when I get myself a new PC. My current PC is 3.5 years old, so the next is due probably after the Corona crisis early next year.
About choosing a GTX 1650 SUPER or RTX 2060 SUPER: the price difference is 170 Euro versus 420 Euro (this was the only research I will do for you), so choose well. To only be on the safe side this is a too high difference, so you need valid arguments to choose the 2060 over the 1650. Just for recording and without intent to do some gaming on that machine, I'd choose the 1650.

Regarding recording versus streaming: both use cases require the same CPU and GPU resources. If a machine is fit for one purpose, it's fit for the other as well. Streaming needs upload network bandwidth with your internet provider in addition, but no different PC.

@koala Thank you so much for your reply, of course, I would never blame anyone for my decisions, I just wanted to know that I'm on the right track as I'm so not knowledgeable on these matters like you people here :) and of course, I didn't ask or expect anyone to do any research for me as I would never want to bother anyone and I'm also doing so much of it myself, it's for my work as an independent.. so in these crazy times, I literally spend my whole work days on this since the corona crisis began (as no one works), I'm investigating all the components as I aim to build something that will work for my purpose rather than finding out I got the wrong specs.
So thanks for all your tips, these are all things I'm taking into consideration.
I'll go with the B450 chip and the 1650 Super GPU, Thank you so much again :)

 

[DanielL]

Hi, I read through this thread, it's very helpful to me. Thank you very much. But I have some further question about this topic, would like to have your suggestion.

I have exactly the same need for recording the live stream clip, which is provided by some website. I'm not gaming, now or in the future.
I'm following koala's suggestion to search for GTX 1650 SUPER, but it's hard to find good one. Instead, I found some MSI GTX 1660 SUPER.

My question is: Is this MSI GTX 1660 SUPER good, even better as 1550 SUPER, have the TURING NVENC?
koala said in previous posting: "(be sure to get the SUPER, the non-SUPER don't have Turing Nvenc)", So this is why I wanna to confirm.
Thank you very much.

 

[FerretBomb]

Hi, I read through this thread, it's very helpful to me. Thank you very much. But I have some further question about this topic, would like to have your suggestion.

I have exactly the same need for recording the live stream clip, which is provided by some website. I'm not gaming, now or in the future.
I'm following koala's suggestion to search for GTX 1650 SUPER, but it's hard to find good one. Instead, I found some MSI GTX 1660 SUPER.

My question is: Is this MSI GTX 1660 SUPER good, even better as 1550 SUPER, have the TURING NVENC?
koala said in previous posting: "(be sure to get the SUPER, the non-SUPER don't have Turing Nvenc)", So this is why I wanna to confirm.
Thank you very much.

All 1660s have Turing NVENC. It's just the 1650s where some do and some do not.

 

[DanielL]

@FerretBomb:
Thank you so much for confirming on this.