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Streaming - codecs encoding cpu/gpu/capture card

I just wanted some advice to get it clear in my own mind to make sure i'm not wasting money.

 

CPU encoding - Is the most wasteful as highest impact on the game played/other streaming processes

 

GPU encoding - how much impact does that have on CPU/GPU usage? NVENC...etc

 

Capture card - I find this most confusing, there seems to be a few different types, does this take load off the CPU if used in a single PC setup?

 

Is it still worth buying a completely seperate PC for streaming?

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1 minute ago, Kitsan said:

GPU encoding - how much impact does that have on CPU/GPU usage? NVENC...etc

Negligible.

 

1 minute ago, Kitsan said:

Is it still worth buying a completely seperate PC for streaming?

No, unless you have a very specific need that can't be achieved with a single-PC solution.

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Okay I thought so, I just had some bad advice which didn't make sense RE GPU encoding

 

How about capture cards, i'm confused as to what they actually do after looking at a few?

 

 

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3 minutes ago, Kitsan said:

Okay I thought so, I just had some bad advice which didn't make sense RE GPU encoding

 

How about capture cards, i'm confused as to what they actually do after looking at a few?

 

 

capture cards allow you to plug like a ps4 or switch or anything really into it then it will let you record/stream that using your PC. if you are streaming only PC games you do not need one.

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Just now, Woxolifo said:

capture cards allow you to plug like a ps4 or switch or anything really into it then it will let you record/stream that using your PC. if you are streaming only PC games you do not need one.

Do/can they do any of the encoding work or is that all on the CPU/GPU?

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Just now, Kitsan said:

Do/can they do any of the encoding work or is that all on the CPU/GPU?

I am pretty sure its all on the PC, unless stuff has changed in the last like 3-4 years, Thats when I last really looked into them. I have not needed any since so I never kept up to date. 

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No. They usually don't do the encoding work, unless they're the "external / standalone" type of capture device.

 

There's also two kinds of capture cards ... well there's more, but whatever.

 

1. the kind that captures the image and gives it to your pc in lossless format, without compression, so you get super quality, but basically the capture card produces tens to hundreds of MB of data per second, so you need good usb 3.0 ports or a pci-e x1 slot

 

2. the cheaper kind of capture cards(cheap usb capture card sticks, external usb powered capture devices). These usually have a cheap hardware encoder chip in them  which takes the raw high quality captured footage and compresses it to something like 10-60 mbps  and sends the compressed video to your pc. The driver of the capture card then uncompresses it and makes it available to applications like OBS, xsplit etc (advantage is because you're transferring only 10-50 mbps such devices work even with usb 2.0 ports, and because the encoding is done on the hardware codec chip, the card can be used with cheap old pcs, as long as the pcs can play back the encoded videos (but even ancient video cards have h264 hardware decoders these days)

 

For best quality you typically want the capture card to do as little messing about, no compression or anything to reduce the quality of the captured image.

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22 minutes ago, Kitsan said:

CPU encoding - Is the most wasteful as highest impact on the game played/other streaming processes

Yes, but keep in mind that CPU encoding also provides the best quality (depending on your settings).

 

Quote

GPU encoding - how much impact does that have on CPU/GPU usage? NVENC...etc

Almost none since it uses a special part of the GPU chip solely to do that. Worth noting that the final quality used to suck a lot and only got reasonably good with Turing's NVENC.

 

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Capture card - I find this most confusing, there seems to be a few different types, does this take load off the CPU if used in a single PC setup?

They only serve as a way to take the output of a console or any other device and present it as an input on your PC (pretty much like a webcam). Your PC still has to do all the encoding work.

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Capture cards can also be used to capture the hdmi output of a video camera / digital camera - some streamers use higher quality cameras / digital cameras instead of webcams and output the video through hdmi or sdi out and send it to a capture card

 

Yes, cpu encoding produces best quality, but nvenc on latest nvidia cards at good enough,at bitrates you typically have on twitch or youtube (6-20 mbps) the differences in quality are minimal.

 

Also Technically, you're still using the CPU to encode the audio portion of a stream, and mixing microphone with audio output of the game and so on....  the video portion is done in hardware but typically because mp3/aac compression uses so little cpu, nobody bothers doing hardware encoders for audio.

 

Note that it's also possible to use NDI to send the game image to a second PC which also has the capture card or capture cards and have that pc apply the overlays and effects in OBS and then have the assembled stuff encoded and sent to twitch/youtube etc

 

 

 

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  • 3 weeks later...

cpu encoding: not recommended if you use one pc for both gaming and streaming as it will KILL your performance.

gpu encoding: best performance, decent quality. little to no drop in fps.

capture card: is useless if you only have one pc as that pc is still going to be encoding. the way they're meant to be used is one pc for gaming (or a console) and one pc for streaming.

 

unless you absolutely need the super crisp lossless quality, buying a new pc just for streaming and recording is pointless. 

 

see: https://stream.twitch.tv/encoding/

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