vision mixing ( or switching - i think)

[duntokin]

Hey guys - being a total novice to video I could do with some pointing in the right direction.

 

I want be able to output video - visualisations / film clips from two PC's / laptops to a projector.

 

I want to be able to set up the source material on each of the PC /laptops and switch to that source when running so that I don't get all the tool-bars, setup menus, etc, projected - like DJ- ing I suppose

 

Before someone says it- I've trawled through all the topic, FAQ's, posts etc and am now totally confused by all the kit that is around that seems to be all Pro studio stuff, and way over the top for what I want to do - or am I being totally naive?

 

Preferably some gizmo that is really, really simple. - and not in the mega-bucks price bracket !

 

Thanks

[CPlater1]

http://www.amazon.co.uk/Port-Way-VGA-Monit...h/dp/B000J249JC

 

try that. It has a switch that may be useful for you.

[paulears]

The snag is that when you have lots of odd sources (as in more than 2) things get expensive quickly! mixing, or even just simple switching without frame rolls or total breakup needs synchronisers - essentially frame stores, where something coming in gets written to memory and then read out in sync with the others, essential for proper operation. A few cheap products are around and sometimes these have just one synchoniser, using the other input as a master. Once you move above two, the range of products reduces - with edirol and panasonic still being very popular. From time to time panasonics (mostly MX50s - 4 inputs, or MX12s) appear on ebay, but don't go cheap. Equate these products with proper dj audio mixers and you see the price problems. From time to time, ebay have older synchronised mixers - and these usually have huge and heavy processor racks making them not attractive price wise on ebay - so you can pick them up more resonably if you're willing to go and get them.

[Tomo]

http://www.amazon.co.uk/Port-Way-VGA-Monit...h/dp/B000J249JC

That is a "Crash-box"

Yes, it will work most of the time.

 

However, the transition between sources will be hideously ugly, and some monitors and projectors can't handle it.

What happens on change is that the monitor will break up, go black, scroll a bit and then (hopefully) come up with the new image.

 

For professional quality you need a proper video switcher that syncs the inputs.

[Toxopholist]

I'll second what Tomo is saying, about a crash switcher, like the one above, it'll do the job, and nine times out of ten you might get away with it, depending primarily on how similar the outputs are from the two laptops. At best, if you are using the VGA output of two identical laptops both set to the same resolution, refresh rate, colour depth etc then a crash switch will give you an effect rather like you just unplugged one laptop and plugged in another, the projector will then do its best to line up the source rapidly. If you are lucky it will try the last file it used, find it matches and lock up, if you are unlucky you will potentially get a glitching and best, at worst a blank screen while the projector sorts itself out, and it all just gets worse the more the outputs vary.

 

The way a professional switcher works is it provides its own reference signals, including refresh rates and resolutions so when you switch between sources the projector sees a continuous signal, and doesn't try and realign itself while the switcher sends the different combination of red, blue and green signal so that you see the different images. This sounds more like the effect you are trying to achieve. Unfortunately this is the bit that doesn't come cheap. you would need to look at seamless switchers offered by Extron, Analogue way, barco, folsom.

 

 

Be aware the mixers Paulears suggests, the panasonics, and the cheaper edirols are "video" as in from a camera/ video machine rather than VGA mixers/switchers. Your laptop may be capable of putting out s-video/ composite video and if you can live with the drop in quality this may be the cheapest way to go, but they will not cope with the standard VGA output of a laptop.

 

Unfortunately in this case it will always be a trade off between cost versus quality.

 

Can you tell us more about the projectors/screens and laptops you intend to use? and are you planning to use the VGA outputs?

 

Please feel free to get in touch if you need to know more.

 

Take care

 

Charlie

[MarkPAman]

The snag is that when you have lots of odd sources (as in more than 2) things get expensive quickly!

 

I've no idea if this would work, just thinking out loud :D

 

Use a two source mixer to feed the projector, bur put the crash type switches before it and only switch the "off line" side.

 

If I'm talking utter c### please say so!

[blackbird]

Sounds to me as if it would work ... but of course you've got to think very carefully about what you want to switch between, as if you end up with two sources on the same 'branch' needing to follow each other, then you're a bit stuck!

 

 

Edit:

 

On further refection, in this case you would actually be depending on what the decent mixer does when it loses its input briefly, as it would when you used the crash switcher on the "online" side.

[MarkPAman]

OK, so could one (or more) source be split and fed into both branches?

 

Edit: Just seen your edit. Now I'm in really unknown territory for me, but I hope that it would "catch up" after a short time so as long as the changes are not too rapid........ You would never switch the "online" side so the loss of signal would not be seen by the projector.

[Pete McCrea]

If you simply want to seamlessly switch two VGA sources, then thins can get quite expensive. Most manufacturers will have a mechanical 'Crash Switch' then something that does wth switch electronically, but is again a crash. VGA switchers with frame store which give the continuous sync.

 

It's only once you get to levels passing the analog way Octo type ranges and beyond that you start to see true seamless glitch free switching. Think over the £5000 mark for these.

[Toxopholist]

To follow MarkPAman's post I do do this from time to time, for shows with several show machines, and then the backups can be on a secondary crash switch, but then it is usuall with a primary switcher that deals with its own Sync signal totally independantly from the sources, you need to be aware that even some seamless switchers depend on the incoming sync signal to generate the outgoing sync, so if you start crash switching the source that is being used as a reference, again you will get glitching. I am not sure I would advise secondary switching for takes live to screen. There is also the obvious point that Blackbird makes about needing to switch from one source to another, both on the same input on the primary switcher.

 

The suggested solution about DAing the various sources and then going into secondary switchers up to a primary switcher could be handled I guess by introducing a x in 2 out VGA matrix upstream of your "decent" mixer, but could leave you facing a bit of a headache for each switch, and might end up being dearer than just buying a decent switcher/mixer with enough inputs. The Barco encore system uses this method to work around the limited number of inputs on each crate, although you are talking about top end switchers...

 

Unfortunately I think if you want true glitch free switching Pete is not far off for a minimum price for a unit and even then the Analogue way range is not really a favorite of mine, unless you go up to the eventix system. I tend to favour the Folsoms for their tweakability, but the Barco switchpro is fast becoming a favorite of mine as I like the encore alike interface.

 

Sorry for yet another rambling e-mail, and looking at the OP it may only be a case of switching between two sources... I wait to hear more.

 

Take care

 

Charlie

[duntokin]

thanks guys and here I was thinking this was going to be relatively easy and cheap.

 

equipment is Sanyo XP57 L 5500 lumen projector, Fujitsu - siemens amilo laptop ( a cheap one ) and a PC.

Projecting onto a white cyc. ( 6 meter throw ) Cable run is about 35 meters so I thought I would have to use VGA

 

I had seen these

 

http://www.pioneer.co.uk/uk/products/44/21...SW-1/index.html - doesn't have vga output - could I use the composite output over the distance ?

 

and

 

http://www.numark.com/productoverviews/AVM01_Overview.pdf

 

The Edirol stuff at Thomann looks ok but again it is all composite or component output, and as you all say, the prices are rocketing skywards

 

perhaps I'll just have to put up with the toolbars or wash the cyc with something bright whilst changing sources / clips

 

thanks

Tim

 

having just posted my last reply about s-vid and vga etc - and going back into the forum the very next topic seems to answer the query - more money !!!!

 

 

tim

[Andrew C]

If you have spent £ching on a projector, would £500ish be too much for a Kramer switcher? Available HERE from our friends at CPC. You may get better prices elsewhere...

[Toxopholist]

35m is technically a bit long for VGA but I go further quite regularly without significant loss and Composite will go several hundred meters. To use composite you would have to ensure both your PC and laptop have a Composite or component output to use the mixers you list, and there would be a noticeable drop in video quality. The two switchers/mixers you mention are both video only and can not cope with the direct output from a computer. You could scan convert the computer outputs down to a video type the mixer can manage, again a drop in picture quality.

 

I think the xp57 has 2 computer inputs, one on VGA 15pin sub D and one on a DVI-I which means you could use a dvi-vga adaptor on plug a second computer into the second input on the projector, and if you set up the inputs to load a specific file when you select an input rather than leave it on auto and do the switching on the projector, I cant remember how rough it is, but not as bad as a crash switch. You would also have the Composite/component inputs available. Do you have a couple of short VGA cables and a DVI adaptor to run a quick test? I think from memory it is a fade through black, like the kramer switcher listed above, or even better a straight cut. Turn the display option off on the projector so it doesn't show you the the text when you switch and you should have something usable. You can hard wire the remote using a long 3.5mm TRS jack, if you don't have a long one, snip the one they supply in the box in half and attach XLR connectors, one male one female and see if you cant beg a length of 3core XLR from the sound dept...

 

This last option is reasonably budget, though it means running 3 cables to the projector rather than 1.

 

HTH

 

Charlie

[slim_mcslim]

If this is for a theatre show then why not put all the clips on one machine in sequence, then you will eliminate the need for switching, add a second machine and a £10 crash box and then you have a live backup, again problem solved.

 

If this is for a live event where you want to play specific clips, then you need to look into video jocking stuff have a look at vj central which has articles on exactly what you want to achieve around the budget you want to spend.

 

P.

[duntokin]

thanks guys - will explore all this and get back to you all with result - my brain is beginning to boil.

 

tim