[PD] synchronised video outputs

[Damian Stewart]

altern wrote:

> but we might need up to 6 to 8 video outputs, thats too much for the 
> same machine. Thats why I thought about having a machine per video 
> output connected to a LAN and synchronised via OSC.

i've done this in the past, though not using PD/Gem. the tricky part is the 
robustness of the networking system, not the actual synchronisation (as 
local-area networking has a typical latency of 1-2ms, even over wireless). 
to sync more than one pc together you need a client/server architecture, 
basically, with one pc acting as the master timekeeper and all the others 
being slave. but then what happens if your master goes down? the others 
just sit there dormantly...

to solve this issue of robustness, which was a big deal (it was for 
synchronising three cpus in a travelling roadshow built into a truck 
trailer: http://www.frey.co.nz/projects/futurefarming which spent most of 
its time a long way away from me), i built a system where each cpu had the 
ability to be either server or client. when the first cpu came up it would 
listen for server pings for a couple of seconds, and if it didn't find one 
it would assume that it was to be the server so started up and sent out a 
ping every few hundred ms. then when the next ones came online they'd hear 
a server ping and so would connect to it as a client. this way if one 
machine was down the network could reorganise itself.

.. this kind of thing is probably overkill for your situation, but it's 
something to be aware of, perhaps.


-- 
damian stewart | +351 967 797 263 | damian at frey.co.nz
frey | live art with machines | http://www.frey.co.nz