Question / Help What's the point of most capture cards for PC if CPU usage doesn't go down?

[samfisher]

Me having never used one, always read about capture cards and how those with a built-in h.264 encoder takes the encoding load off of your CPU with a quality/FPS/bandwidth drawback. I seem to see now that even with capture cards, CPU usage remains high, so I guess my question is, what's the point of an integrated h.264 encoder if streaming still puts the load on the CPU?

It doesn't for ShadowPlay, but just browsing the elgato forums and xsplit forums (was helping someone on the Linus Tech Tips forum on a capture card issue) shows that it doesn't really do anything except for inputting console video.

 

[dping]

Me having never used one, always read about capture cards and how those with a built-in h.264 encoder takes the encoding load off of your CPU with a quality/FPS/bandwidth drawback. I seem to see now that even with capture cards, CPU usage remains high, so I guess my question is, what's the point of an integrated h.264 encoder if streaming still puts the load on the CPU?

It doesn't for ShadowPlay, but just browsing the elgato forums and xsplit forums (was helping someone on the Linus Tech Tips forum on a capture card issue) shows that it doesn't really do anything except for inputting console video.

the point of a capture card is to capture, not encode. the capture part takes audio and video from the streaming PC and transfers the video to a dedicated stream/recording PC. in this case the capture card will take the load off the gaming CPU.

capture cards are not for single PC setups. If you are capturing the feed, the placing that feed back on the same computer, obs still needs to encode that stream to be sent out.

 

[Harold]

The cards are used primarily for 2 reasons:
1> Console Capture
2> Dual-Computer streaming setups.

Encoding is still done on a cpu if you're using the x264 encoder. Using a capture card in the same system can actually INCREASE cpu usage depending on the card and configuration.

The dual-computer setup allows you to offload the entire encoding portion of cpu use onto a second computer.

 

[samfisher]

I totally understand the dual-PC streaming option, but then that would only require a capture card with passthrough capabilities. Why include a H.264 encoder if the 2nd PC will still need to encode the stream anyway? From what I know about the AverMedia Live Gamer Portable, it does the encoding on the fly as it receives the stream data.

Or does this only work with their own streaming software (Elgato's Stream Command and AverMedia's icantremember.exe)?

 

[Harold]

Even if it can work with other streaming programs, it introduces a quality loss vs x264 that could potentially make the video unsuitable for streaming.

 

[samfisher]

Even if it can work with other streaming programs, it introduces a quality loss vs x264 that could potentially make the video unsuitable for streaming.

Definitely, I know the quality loss as well, but it kind of defeats the purpose of having a built in H.264 encoder in the first place if everyone only uses the passthrough function and end up using X.264 to encode anyway.

 

[dping]

I totally understand the dual-PC streaming option, but then that would only require a capture card with passthrough capabilities. Why include a H.264 encoder if the 2nd PC will still need to encode the stream anyway? From what I know about the AverMedia Live Gamer Portable, it does the encoding on the fly as it receives the stream data.

Or does this only work with their own streaming software (Elgato's Stream Command and AverMedia's icantremember.exe)?

enocding does happen to fit that 1080p@60fps capture to fit on a USB bandwidth. this encoding is lite and is the reason for the capture card's delay. at that point, OBS's video capture device source takes that source and inputs it on an overlay which is then rescaled on the GPU to be processed by the CPU in x264. After that, it is encapsulated and transferred using rtmp to twitch (or where-ever).

 

[Boildown]

CPU usage goes down because with a capture card, the encoding is done on an entirely separate computer. The gaming computer only has to run the game, not encode the video.

If you're using the capture card in the same computer you're playing the game on, you're doing it wrong.

OBS doesn't use the embedded H.264 encoder that is sometimes included on Avermedia devices.