Switching Video signals without projectors losing sync - Page 1
Forum section: electronics / projects

author: Hobgoblin612
author_rank: Contributor
timestamp: January 03, 2014, 04:27:23 am
content: I need to switch the signal going to some of the projectors in a venue between the signal coming from the computer (for presentations etc.) and the live output from a camera (so that the audience can see what is going on.)Currently most things we have are VGA, the computer output, cat5 extenders and projectors. The camera I currently have (an old camcorder) has a composite output although I would like to change that at some stage to a better camera with a higher quality signal. (I am using this camera because it provides a clean output and doesn't auto power down; and also it was lying around at home gathering dust)I tried using a cheap composite->VGA converter and a cheap VGA switch but every time I operate the switch the projectors lose sync and do the whole adjusting to source thing. (Obviously because the two sources are not in sync.)I am wondering if there is a product that will allow me to do this while still looking acceptable and clean, or if I can make a converter that will synchronize its conversion with the other VGA signal?I should also add that at the moment we have sort-of standardized on 1280*1024 60Hz VGA, so it would be nice if whatever solution I end up with fits that.Another thing on the wish list is to be able to fade through black while switching but that is not essential.We are on a tight budget so professional equipment is probably beyond our reach although I don't know much about it.Thanks in advance, Timothy.

author: Towger
author_rank: Super Contributor
timestamp: January 03, 2014, 06:56:03 am
content: Or run the inputs through a video mixer and then out to the projector(s).We use the software VMix to do this, you my get a way with running it on your existing PC and feeding the camera into a good capture card. Depends on what your presentations are. Else you will need to feed your presentation in to the mixer as well and what ever else you want! Logos, videos, photos etc etc. It supports PnP and a load of other options/effects.As a plus VMix in made on Oz!We have also in the past used Vidblaster, which is a resource hog and not as stable and a Panasonic hardware mixer, which while nice to use is nowhere as flexible.

author: Hobgoblin612
author_rank: Contributor
timestamp: January 03, 2014, 10:10:22 am
content: Does VMix support external controllers, ie can i have a hardware button on the desk to switch between the two outputs?

author: Towger
author_rank: Super Contributor
timestamp: January 03, 2014, 10:34:16 am
content: Not that I know of. It has a built in web interface so you can use a tablet/phone, but I have never tried it. There may be an API available if you wanted to create your own!Blackmagic and a few others have hardware control interfaces, but they are all an order of magnitude more expensive.

author: SeanB
author_rank: Super Contributor
timestamp: January 03, 2014, 10:37:24 am
content: USB keyboard and use keys as pushbutton inputs if the software supports keyboard switching?

author: Hobgoblin612
author_rank: Contributor
timestamp: January 03, 2014, 10:50:43 am
content: I might try VMix, the main problem is that the PC is already being used by another person for the presentations (words for songs and other info). This means that it always needs focus (i.e. keyboard and mouse input) so it will have to run in the background and be controlled from something else.

author: Towger
author_rank: Super Contributor
timestamp: January 03, 2014, 11:13:41 am
content: For words of songs and other non 'Dave' approved use, have a look at Easyworship. It can take a camera input, but it primary designed for displaying song words and displaying 'other' presentation material.

author: aargee
author_rank: Frequent Contributor
timestamp: January 03, 2014, 12:07:55 pm
content: Can you connect the camera to a video capture card in the PC you have driving the projectors and then flip to the camera via the PC and software?That way the projectors will be only getting one signal and the switching will be done by the PC.

author: Psi
author_rank: Super Contributor
timestamp: January 03, 2014, 12:12:58 pm
content: Running a shielded cable to the projectors composite input and using the projector remote to switch between inputs should make a clean transition between them.Otherwise, as said above, buy a cheap capture card and put it into the PC.You can create a simple shortcut on the desktop to launch VLC and automatically show the capture composited video fullscreen'ed. The presenter can easily right click and exit VLC when done. If you feed the composite audio into the PC line in it will mix with the PC audio and they wont need to switch any audio stuff over.You would also have the option of VLC set to "always on top" with all the controls set to minimal.That way they could have a small VLC window showing the composite video in a corner on top of powerpoint or whatever they're doing.

author: kolbep
author_rank: Frequent Contributor
timestamp: January 03, 2014, 12:55:15 pm
content: For a commercial unit,You willneed to look at a scaler/switcher.http://www.ebay.com/sch/i.html?_trksid=p2050601.m570.l1313.TR3.TRC2.A0.Xkramer+scaler&_nkw=kramer+scaler&_sacat=0&_from=R40they take any source, vga, composite, dvi , etc, and convert them all to conform with your projectors vga input resolution.the one I use at church vp724xl has about a quarter second blank when switching sources.

author: dannyf
author_rank: Super Contributor
timestamp: January 03, 2014, 01:01:16 pm
content: QuoteSynchronize all the sources - the easiest solution.

author: Hobgoblin612
author_rank: Contributor
timestamp: January 04, 2014, 01:01:34 am
content: We use EasyWorship now, the the problem is it doesn't support two outputs. When we have big services we setup another two extra projectors in an overflow room and the side chapel. We want to be able to still have the photos,words etc. on the main screen while switching the other projectors between that signal and and camera.I can see two options:VMix capturing the output from EasyWorship and the camera via a capture card, and outputting via the spare VGA on the motherboard.or a Scaler/Switcher.One other requirement that I probably should have mentioned is that it needs to be a very simple user interface (ie one button) because we have (quite elderly) volunteers operating the system.

author: Hobgoblin612
author_rank: Contributor
timestamp: January 04, 2014, 03:46:03 am
content: QuoteHow would i go about that?I have found that VMix has an API that uses simple HTTP commands to control things. An EtherTen with a button would be able to control it pretty easily.I have looked at Scaler/switchers and they are very nice but too expensive.

author: Towger
author_rank: Super Contributor
timestamp: January 04, 2014, 07:56:53 am
content: That's clearer now.Is there another person operating the camera? If you replace the camera with a ptz one, they can operate both the camera and vmix. We have 4 Sony Evi 30/70 cameras and a VGA to SVideo feeding in to a PC with vMix. This pc streams to the web via ustream, records and feeds back via a spliter to a 4x4 VGA matrix switch and another couple of TVs in other rooms. The matrix switch connects to two projectors in a hall, the vMix PC and a local monitor. The matrix switch is also feed by a PC with Easyworship and has another cable going to the front for the person giving the presentation, if they have their own laptop. This allows all the input and outs to be redirected as required.

author: Hobgoblin612
author_rank: Contributor
timestamp: January 04, 2014, 09:41:13 am
content: The camera is right beside the computer running EasyWorship.The goal is for one person to operate the camera and switch button and one person to operate EasyWorship. (for big services, for small ones we don't use the other projectors)Can you recommend a cheap capture card that works with VMix for composite video?

author: Towger
author_rank: Super Contributor
timestamp: January 04, 2014, 12:28:43 pm
content: Look for old Viewcast Osprey PCE/PCIE (watchout for the PCIX versions unless your mother board supports it!) cards on eBay, they have great drivers which just work without much messing around. I have 3 of these and two Hauppauge in the one PC. The Hauppauge cards work, but the drivers are not as good. Any old tv card, with video input should work once you can get modern drivers for it. Viewcast have win7/8 64bit etc drivers for even their the oldest cards. They they do not conflict if you have multiple cards in the PC. Keep away from OneHungLow (unless you have one to try in the junk box) cards and don't touch USB dongles...

author: Hobgoblin612
author_rank: Contributor
timestamp: January 04, 2014, 12:57:32 pm
content: Thanks for your help everyone. Lots of things to try.