Serial control of a dvi/hdmi kvm switch into a blackmagic intensity

jrs's picture

Hi All,

I'm building an information kiosk and I need to pipe in video feeds from a few different sources and control the switching of them via QC. I've got a single source of video feeding in fine but the blackmagic intensity I'm using to do the capture is pretty finicky about resolutions and frame rates.

I'd like to add a kvm into the mix and have QC control the switching via the serial port and I'm just wondering if anyone has had any experience with this before?

My concerns are:

1) Do I need something like EDID Management (which makes things much more expensive) to make sure the input computers are always outputting at the right resolution for the blackmagic? I'm worried that when I switch displays the input computer will loose display sync and start outputting at a different resolution and I won't see anything on the blackmagic when I switch back.

Read more about EDID here -

2) Kineme's serial controller won't work with a specific KVM

Some different KVM options

1) Name: Gefen 4x1 Switcher for HDMI 1.3 Link: Price: $199 Pros: Cheap, supports serial control Cons: Doesn't Doesn't have physical buttons (although it does have an ir remote), Doesn't support usb switching (this isn't needed but would be nice)

2) Name: Gefen 4x1 DVI KVM Switcher Link: Price: $899 Pros: supports serial control, supports EDID Cons: Expensive

3) Name: Rose Vista AV 4 port Link: Price: $695 Pros: Cons: Not sure if it supports EDID

4) Name: Any gear from ATEN Link: Price: Pros: Supports EDID (video datasync) Cons: No Serial control although they mention being able to switch via hotkeys - it requires the scroll lock though which I couldn't get working via lookitscook's key event emulator patch (

Any thoughts/lessons learned would be much appreciated - Cheers James

P.S - my other option is to try and get an IR emitter hooked up to QC - thoughts?

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conanp's picture
Re: Serial control of a dvi/hdmi kvm switch into a ...


In the thoughts/lessons learned category:

What I've gathered about the intensity card: it advertises 720p50/60 just fine but for 1080 it's limited to 24/25/30Hz progressive or 50/60 interlaced, but I haven't been able to get interlaced video to show properly in QC, it shows the fields on top of one another... and of course, it doesn't do HDCP.

If you don't have more than 2-3 sources it would be interesting to see how QC handles more than one Intensity card. If it does, then you could handle immediate switching with an image multiplexer patch, or even "crossfade" with a dissolve patch. The intensity card's EDID would keep each source signal active so there'd be no HDMI handshaking lag and no need for EDID injection hardware.

If you do end up using hardware for EDID management, I recommend Gefen's HDMI detective.

If your kiosk will run Quartz Composer or a Quartz Builder app for long periods of time unattended I'd recommend something to monitor a) if QC/App is running, and b) how much free RAM you have... I use a simple Applescript that checks both every 60 seconds and restarts things if they've crashed or free RAM is getting <1GB (evidently I have a leaky composition).

CrashReporterPrefs is an app that used to be bundled with Apple's Developer Tools before the App store came along. You can use that to set your kiosk to "Server" mode and it will keep the "your app crashed" messages from showing up.

If your kiosk has repetitive content, I would recommend setting up some white-screen time on your display to reduce burn-in. My kiosks run a simple patch to enable a white sprite for two hours after closing time, then the monitors are turned off via serial.

I do QC-based kiosks and am interested in what you're working on. Free to email me, kineme user name at's picture
Re: Serial control of a dvi/hdmi kvm switch into a ...

CAn you guys state which particular Blackmagic Intensity devices you are referring to, there's at least four now and another pricier TB one on the way… and I might be getting one so it's good to know the gritty details as they relate to actual devices as opposed to the product class. Sounds like you have the PCI card, conanp?'s picture
Re: Serial control of a dvi/hdmi kvm switch into a ...

A client of mine is using the Blackmagic ATEM Television Studio to switch video sources and overlay QC based graphics over the top of live video. THey're really happy with it so far as I have heard. It has it's own VIsion Mixing app that is included I gather. Not sure if serial control is included but being Blackmagic product I wouldn't be surprised if you can run a command line controller or something.

jrs's picture
Re: Serial control of a dvi/hdmi kvm switch into a ...

Thanks for the replies conanp and alistair.

I'm using the intensity pro (card) which I'm pretty sure you can have only one of - at one point two cards did work but I'm pretty sure the current state of play is that it doesn't work (there are a few threads here on kineme about this). I also need to do it with one capture card as I'm going to be moving the kiosk to a mac mini instead of a mac pro and use the intensity shuttle which I'm assuming you can only run one of. I'd also considered the decink quad but its sdi not hdmi and then there is the switching issues - I couldn't see any command line tools but they do have a software api but when you take into account the time to code this up, the connection converters etc I think a kvm is the cheaper/quicker way to go.

Here is a video of a kiosk I've done

Its using a pc running valves source engine and seeing machines face api to track the users face and mimic their expressions on the virtual character. That image gets green screened in QC which also receives the users head position via osc enabling the 3d parallax effect you can see.

conanp's picture
Re: Serial control of a dvi/hdmi kvm switch into a ...

Indeed, I'm using the Intensity Pro PCIe card in a 2009 Mac Pro, it works inconsistently at best with QC.

jrs's picture
Re: Serial control of a dvi/hdmi kvm switch into a ...

Once you get the resolutions and frame rate running ok I've found it to be really reliable - both under 10.6 and 10.7 using a 2011 mac pro

Do you find it crashes or just looses sync?