# Q-Lab Tandem



## lighttechie5948 (Jan 4, 2014)

Hi everyone,

I want to run Q-Lab in tandem. I have one MacBook Pro which is the Master and I want an iMac as a backup slave running in tandem. How do I connect the two and how does the master trigger the slave? I was thinking I would connect the two via ethernet and figured the solution has something to do with MSC or something like that. But need the rest of the steps to get the master triggering the slave's cues.

Joe


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## carproelsofly (Jan 5, 2014)

Here's an older reply on the QLab discussion group:
https://groups.google.com/forum/#!searchin/qlab/slave/qlab/YndVGbSYeTc/4hANUW6HlmIJ

You can search there for other ideas if that's not what you're looking for!

http://figure53.com/qlab/help/

Jen


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## cpf (Jan 5, 2014)

General idea: 
- install ipMIDI from http://www.nerds.de/en/ipmidi_osx.html (free!)
- Make sure multicast packets can travel from the master to the slave - easiest way to guarantee this is to hook them directly together with a plain router (or, with appropriate configuration, you can do without)
- Unfortunately, I'm not too hip to the latest QLab 3 situation, so take a wander through the settings to see what MSC command you'll need to send to trigger a GO on the slave (make sure the appropriate ipMIDI device is selected for control)
- Add this as a MSC cue on the master


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## Pie4Weebl (Jan 5, 2014)

Qlab does a really great job with OSC, on your "master computer" for each of your cues add a linked cue that tells the other computer to fire a cue. Just make sure your ip adresses are correctly set and configure the OSC ports.

No extra software needed.


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## Drew Schmidt (Jan 6, 2014)

Are your machines doing two different tasks? Or are you trying to create a redundant system?

If you're trying to have a control machine execute different cues on the slave machine, then OSC is the winner. It's built into QLab and is insanely easy to use. Again, check cues prior. It's unlikely that your IP address will switch ... they should maintain their leases. But if they do switch, it's nice to know prior. I don't believe at this moment you can specify computer name instead. Holler if you need more help with this.

If you're doing a redundant system, most of the QLab forum would steer you away from networking options (ipMIDI, or OSC) as this just introduces another point of failure. Instead they would recommend a MIDI switch that passes itself to both computers. A single button then triggers both. There are then audio cards that handle switching when signal is lost. If this is your case, I would recommend spending time on that forum rather than here as the people that spend time there are specialized in this.


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## Drew Schmidt (Jan 6, 2014)

I recant, I believe you can specify a computer's network name (System Preferences > Sharing > Top of the screen)
I just did it and had to include ".local" at the end.


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## Joshualangman (Jan 6, 2014)

Having one computer trigger another is not redundant, because if the first computer fails, it will stop sending triggers to the second. The better way would be to use a hardware trigger box (http://www.ducksechosound.com or http://widgeteering.com) that connects to both machines, so one external button tells both machines to go. Then either run both sound cards into a switcher, or run both into your mixer and switch by means of unmuting the second set of channels.


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## jempage (Jan 31, 2014)

Can confirm that I recently ran double macbooks on Qlab 3 using the inbuilt OSC commands. Both computers hooked up with interfaces to the audio desk, and we set up a panic button on the console to crash fade to the backup if necessary.

The Qlab side is fairly graceful. Identical displays on both laptops with a nearly imperceptible delay in playback between the two.

A VGA (or appropriate codec) Switcher will help with your video backup in a one-to-one situation.

The Spark d-fuser is a somewhat more graceful (albeit rather more expensive) backup solution.


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