[QLab] Triggering other computers in a network

[Christopher Ashworth]

On Apr 17, 2007, at 4:58 PM, Jarrett Krauss wrote:

> If I wanted Qlab to control let's say 5 separate video projections,  
> can I do
> that with one Qlab computer or do I need to network 5 different  
> computers
> together?

Hi Jarrett,

All of Marc's advice is great; I'll just point you at one more  
example, which describes an installation that uses separate computers  
networked using MIDI over ethernet.  Tom wrote a nice description of  
it here:

http://figure53.com/qlab/showcases/video-cue-at-detheaterschool/

One drawback to using MIDI over ethernet is that you may get delays  
from the packet transport.  I haven't built my own test rigs to  
explore this in detail, but Tom reported that with his particular  
networked setup he was seeing delays in MIDI delivery over ethernet  
that could introduce sync problems between the separate computers.   
Since I wasn't able to inspect his setup in person, I can't say  
whether that was a fixable problem or not, but it's something to be  
aware of.

Clearly, running video from a single machine can avoid the sync  
problem, but as Marc said you need a pretty beefy machine to drive a  
lot of projectors at once.  Presumably running over traditional MIDI  
channels (instead of going through TCP and an ethernet switch) would  
also help.

Best,
Chris