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I did a quick test with Open Broadcaster Studio. I used two cameras and one HDMI capture device recording the output of the "Test-Compo-Machine". For a quick test it worked out pretty well but I only had a 720p60 capture input. Since 1080p50 or 1080p60 is not really a video standard, most of the capture devices do not capture this. I own a matrox mini which is also limited to 1080p30.

How would you solve this problem? (Tricaster is far to expensive for small parties)

What's the capture device? The good ones should be able to do 1080p60 just fine.

Not that it's any help, but FYI they're standardised in SMPTE 424M.

So there is no "we just send compo-pc-nvidia-1080s-nv-encoded-stream over network" to OBS trick? Seems I have to invest in a game-capture device.

...huh?

maybe its worth looking into NDI, which is video over ip/ethernet basically and afaik OBS can handle it either out of the box or with a plugin. Its not completely free and open source but they have a free toolbox and stuff on their site.

1080p60 is ~3Gbit uncompressed. Bandwidth is often the limiting factor with video ;)

For that reason it's common to use a "visually lossless" (but ultimately lossy) intra-frame format.

Yeah. But then there’s the problem of compressing while the demo is running. No easy answers ;)

Even if we don't assume a dedicated computer for capture, intra-frame compression is very light-weight compared to inter-frame. Even if it wasn't, I don't think most demos are CPU constrained or make effective use of multiple threads, so there are potentially several idle CPU cores available while the demo is running.

There are many valid solutions to this problem, each with their pros and cons. Assuming you're fine with a 720p stream, you can for instance put a scaler in-between; the LKV391N is tried, trusted, crappy, cheap and works. :-) Just be aware that in its default settings, it darkens the picture a bit (did I mention the crappy part?).

@wysiwtf: NDI isn't open source, FWIW.

Sorry, I missed the “not” :-)

i would just have the compo machine with 2 outputs, and run obs on the second screen capturing what's happening on the main display.

might have problems if you plan to change stuff in obs while playing the things though O_o windows losing focus and such...

I have Blackmagic capture cards (3 cards 1 hdmi input for each, Decklink)
we use Scaler(Kramer) to connect different devices with different resolutions etc..
The biggest problem was to convert HDMI to VGA because my Scaler has no HDMI inputs
After first expirience I bought on ebay 2 more Blackmagic cards with SDI/HDMI inputs (BlackMagic DeckLink HD Extreme 3D) where you have 2 SDI in and + 1 HDMI in and 2/1 outs..
I put those two cards into Sonnet Echo Express SE II Thunderbolt 2 and I can connect this box with thunderbolt2to3 adapter to my laptop.
Also there are a lot of HDMI2SDI and vice versa adapters which allow you to deliver your cameras or outputs(for instance you have 2 big screens or big monitors) to any location of your partyplace.

All those cards allow to have 1080p60, with scaler you can connect different inputs like PC/ZX/Amiga etc..

Now I think about cheap way to capture screen from several PC's..

And of course, frame rate. (I.e. this is a terrible idea, don't do it.)

Ok I see... this means we have to invest some more than just purchasing a decent capture card. Thank you for advices. I'll do some additional research...

Rewinding to the original post, it sounds like you already have a working setup, and that the only problem is that you can't capture more than 720p60 or 1080p30. Why do you need more than a 1080p60 capture card to solve that?

mhm HD60Pro looks very promising since one can passthrough HDMI. So we would not spend money for an additional HDMI splitter. Thank you.

We use a HD60 at Evoke, works fine, but you can only use one Elgato USB Capture Device, if you want more than one you need to go PCIE, so HD60Pro keeps that option open.

@dirtie: Be aware, there are devices (especially projectors) that get confused when you have more than two devices on the HDMI bus, as you have when you use HDMI passthrough. Usually it's fine in steady-state, but you could see things like the projector blinking if you have to start and stop capture. That won't typically differ between passthrough and a splitter, though.

@faxe and gargaj I ordered an hd60pro

@sesse is windows desktop/screen cloning an option to duplicate the output?

A bit too late but whatever These cards can do 1920x1080 @60Hz and all sorts of tweakmodes in full RGB space, very good from stuff like amiga RGB capture/MSDOS crap to clear 1080p60 capture.
Normally cost closer to 1k but this guys seems to have a huge supply of them. A lot of RGB gaming fetishists have been buying these and I'm using an e2s. Really great card and can recommend.

FYI, it doesn't do audio at all, just framegrabbing either with digital or analog video.
There are cheap solutions for audio grabbing tho.

oasiz: how does that E1s handle frame rate changes on the fly and weird rates, and is there a working software+video format combination that can handle such stuff? I'm thinking about things like Amiga demos which switch between interlaced and non-interlaced modes, C64 which isn't exactly 50 Hz, and weirdo self-made PC graphics modes.