Question / Help Why a capture card?

[Maelas]

Hello,

I have been searching on forums as to why people use capture cards and am having a hard time finding a definitive answer. As far as i know, using something like OBS is just fine for 1080 streaming. What benefit does a capture card have over using OBS or something else that uses CPU to encode? I had a discussion with a fellow streamer who said that a capture card is the best way to go when 1080 streaming. But i couldnt understand why...OBS can stream at 1080 as well so why spend money on a capture card? Is there some sort of bandwidth difference between the two?

Thanks

Blake

 

[Lain]

For a single computer setup, it is a detriment, not a befit. Capture cards have poorer color quality, require CPU usage to convert the image, and then require bus bandwidth to upload its video for compositing. The built-in capture methods are superior because they are full RGB, can capture as fast as you want at whatever resolution you want, most don't require CPU usage, and thus also don't require bus bandwidth.

They are however great for capturing consoles, and great for multi-computer streaming setups (where you stream/encode with one PC and game with another)

 

[dodgepong]

Jim is correct. THe idea that capture cards give performance improvements is a bit of misinformation that has spread around a lot due to marketing from certain capture card manufacturers, and the fact that with certain other streaming programs, a capture card actually does improve performance because their other capture options perform so poorly.

 

[Maelas]

Ahh, ok that makes sense. Thanks for helping me get some closure. So what i should take away from all this is that OBS on a single computer setup is all i need.

Now to find out what I need to do 1080p streaming on twitch. I personally dont think the recommended 3500 kb/s bitrate max is enough. (Though when they suggested that bitrate it was for 720, not 1080)

Twitch recommends that we not exceed 720 3500 kb/s, im assuming to reduce strain on their servers. But now a days 1080 is all i see people streaming. I have a max upload of 5000 kb/s. I guess i could just run some tests but i wonder if 3500 bitrate really is enough or even if my max is enough.

 

[dodgepong]

There is no recommendation from Twitch that suggests to not exceed 720p. They once tweeted that 720p at 2000kbps is a good middle-of-the-road setting for maximum viewership for non-partners, but it was not more than that. You can stream at 1080p just fine within Twitch's recommendations.

3500kbps for 1080p is a judgment call. If the video content is low or medium movement (SC2, LoL, retro games in emulators), then it can be alright. If the content is high motion (some FPSes and most 3rd person MMOs), or has fine details that don't compress well (such as the grass in DayZ) then 3500kbps is probably not enough, and better relegated to 720p.

But that's from my own experience. You can do whatever you want to do. Just don't try 1080p60 (since it kills Flash and is extremely difficult for viewers to decode) and don't go over the 3500kbps max that Twitch requests.