For those keeping an eye, the Blackmagic Decklink Quad HDMI capture card is finally shipping!
While it can handle up to 4 HDMI captures (up to 4K resolution) I will be at 1080p60 for Pinball - but it will be nice to mix in some 4K cameras as they come down in price. 
Really excited to put this piece in my broadcast computer!
I will be sure to give it extensive testing and report back! Please let me know if you all would like me to test any specific stuff as well.
Need some help with audio from Elgato Cam Link, please. I have my Sony cameras plugged in, and they show up in OBS, but I am not getting any sound at all registering in the Mixer. I have tried these settings https://obsproject.com/forum/resources/cam-link-optimized-settings-for-obs-studio.549/, and I am getting nothing. What basic thing am I missing? Thanks in advance. Really trying to fix this ASAP today.
Which camera are you using? Unfortunately the Sony HDR CX-405 etc. cameras do not transmit audio over HDMI. Youāll need an external microphone hooked into your PC.
Well, you are dead right! I just lost an hour of my life and a lot of unnecessary stress. Thank you, MWelsh! I will work around this with an external mic.
Can you get 4 cameras all the same and point it at a clock with as much accuracy as possible (ideally tenths if seconds) or use a stop watch with tenths and hundreds and stop and start it?
Cheers
Neil
I see where you are going with this! Yeah totally! I will add it to the list of tests.
I hope to do some testing tomorrow. I sadly had a minor failure with my CPU cooler and Iām waiting for my replacement to show up before putting the card through its paces.
To MWelsh (and other streamers), a follow-up question from yesterday. After discovering that the HDR CX-405 cameras do not feed HDMI audio to Elgato Cam Link, I tried making my personal Sony Handycam the playfield camera (Itās about 4 years old - Iāll get the model if you are curious). Success! I was able to feed both HDMI audio and video from it, and I did not have any audio synchronization issues that I see plaguing some people.
One problem though: my personal Handycam will not do USB power like a CX-405. I did not have enough time to test every scenario ā I was just happy to get picture and sound off AC power. (It has a little USB cable stuck in the handleās pocket like a CX-405, but I think that might be to help charge a portable battery. If so, I think the camera has to be off. Portable batteries wonāt work for my long streams.)
So, is anyone using a portable camera in a mobile rig that can run off USB power and does not have audio sync problems that seem to affect some of the lower-end web cams?
Thank you again for the awesome, helpful replies I have been getting!
I use a cx-455. It has a mic input, which I use to plug in a shotgun mic. The shotgun mic audio gets added to the hdmi signal and is perfectly synced with the video.
Hmmā¦ I see in this tutorial video that with the CX-455 you cannot run off USB power. (Go to 1:07) On a mobile rig I would still have to run a power cable. I was hoping for a truly mobile solution where I could have a USB-powered camera like the CX-405 send HDMI video and audio wirelessly to the Elgato Cam Link. Any ideas?
USB power works on mineā¦unless the stock battery is some kind of miracle battery. I ran it for 12+ hours at TPF on my mobile rig, plugged into a monoprice battery pack
You should be able to run them from USB power, most of us run them that way. But sometimes itās finicky.
If youāre having trouble with a certain battery pack, try another one (the manual says 5V 500mA). Make sure the camera is off when you plug in the battery. The power LED on the outside of the case should light up after a second. Occasionally Iāve had to reseat all the cables once or twice to get it charging.
When using the battery packs, should we make sure the cameras themselves are fully charged then use the battery packs?
Iāve ran some tests and the suggested battery packs seem to be draining quicker than I expected.
Which battery packs are you using?
I purchased my cx455 used and when I first got it, had a very hard time getting it to charge via usb. I ended up buying a new battery for it and after that, it worked fine. I think I concluded that the original battery was bad.
I just have the camera plugged into this. The battery in the cx405s I assume is stock. One is used, two are new. So whatever came with the camera.
Reading is fundamental. I thought I bought the right ones and I bought the 10,000mah ones. I need the bigger ones. The ones that are like 37 bucks a piece.
Doh. Yeah you need 27000mah
Yeah I see the mistake now. I was clicking too fast when you first sent me the link and I didnāt read you say the larger size. I was wondering why they were so cheap! Haha.
Well no worries. Got spares for cell phones and whatnot.
I run 3 of these cameras on stream with usb battery charger. You have to remove the lithium battery for it to work.
I use a 26800 mAh battery charger
Initial tests are successful! This card is awesome!!
Using 4 Sony CX-405 Cameras, running at 1080p59.94, being all captured at the same time and my computer barely breaks a sweat on it! Using XSplit - but this is supported in Wirecast, OBS and many others.
Expect a full thorough review after the Northwest Pinball show!
Great news! Thanks for reporting in on the tests. Time to spend more money on fun fancy equipment 
Imperceptible for our purposes.