Question / Help If I use this, does it get better?

Zidakuh

Zidakuh

Member
It's just grabbing the input from the monitor, and sending it to the CPU to be encoded.
Basically like running a desktop capture.
Even if it has H.264 encoding, it only compresses it for the CPU to reencode it anyways.
 
kiDix

kiDix

Member
But does this mean that for example, video capture cards like avermedia or elgato are junk for streaming?
 
koala

koala

Active Member
The product is intended to capture video output external to the PC you're streaming from. It is intended for capturing consoles like the Xbox or Playstation, for example. If you intend to generate the content on the same PC you're streaming from, i. e. some game you play on that PC, the game capture source of OBS is more efficient (lower CPU demand) than using that capture card.

Why game capture is more efficient:
Game capture is working within the GPU. It directly grabs the frame buffer of the game and sends it to the compositing process of OBS. No processing, no copying of data required. Essentially, the game's frame buffer is used for compositing. This is very low load.

Using the capture card, it is necessary to read the video data through USB bus into CPU memory, which consumes bus bandwidth and CPU resources, then the data is uploaded to the GPU for compositing, again using some CPU resources and a lot of pci-express bandwidth. Once uploaded to the GPU it occupies additional GPU memory (in contrast to the shared memory of game capture). This is somewhat heavy load.
 
kiDix

kiDix

Member
Okay, I just lost the idea of buying a video capture card. but what if it was an internal capture card? It would be the same thing, I suppose.
 
koala

koala

Active Member
An internal capture card is probably not so CPU-intensive as a USB capture card, but it still requires more resources than game capture. This is true at least if you intend to use OBS to record or stream.
There are capture cards that have an h.264 encoder onboard and are able to directly stream to some streaming provider, without OBS. In this case, the encoding is in fact offloaded to the capture card. But OBS isn't able to use this encoder. Before encoding, OBS composites the video data, i. e. it merges all its video sources with all their filters and rescaling. For this only uncompressed video data can be used. If you buy an expensive capture card with h.264 onboard encoder only to use it with OBS, you're using only half of the card.
 
kiDix

kiDix

Member
Thank you very much for all your information.

I remembered something stupid, because I do not know if it works, and if I use the Relive of AMD in conjunction with the OBS? Would that work for anything?
 
Zidakuh

Zidakuh

Member
Not more than asking double the work of the encoder, if you use AMD VCE. You can if you use x264 in OBS however.
 
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