[PD] synchronised video outputs

[simon wise]

On 25 Feb 2008, at 10:32 PM, altern wrote:

>
>>> I need to have several video outputs that run in sync. A friend who
>>> works in a art exhibition space told me there would be couple of
>>> solutions for this but both involve buying pretty expensive  
>>> equipment
>>> like special DVD players.
>>>
>>> I thought then that a solution for this issue could be to have  
>>> several
>>> computers on a local network playing video (with GEM) and  
>>> synchronise
>>> them via OSC. But I dont have any experience doing such a thing,  
>>> never
>>> used OSC for anything similar. Also I dont have a clue about how to
>>> synchronise together videos.
>>>
>>> Has anyone done anything similar? any experiences to share?
>>
>> yes.
>> we used a dual-head machine (actually it was a quad-head, so we had
>> plenty of space for editing...) running a single gemwin covering both
>> screens and 2 [pix_film]s that were controlled by the same counter.
>>
>> since Gem allows you frame-accurate access, the 2 videos were in  
>> perfect
>> synch.
>
> 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 it often, the basic principle for keeping the LAN machines  
in constant frame sync, allowing scrubbing etc, is each projector has  
a slave patch that uses [pix_film] to play by frame number rather  
auto, and receives those frame numbers (via [netreceive]) from a  
master patch which has a metro counting the frames and which plays  
any sound required. Works very cleanly and doesn't put much data  
through the network. Two [pix_film] Gem-chains in each slave will  
give you X-fades etc.


I could post the set of patches which add quite a bit more  
functionality than that if you like, I've built up a collection over  
several projects.


simon