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tv wall and home made video matrix

Discussion in 'Multimedia, Projection, and Show Control' started by AberNStein, Dec 16, 2007.

  1. AberNStein

    AberNStein Member

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    i'm doing tech for a school production of macbeth, and the director wants a 'tv wall' as well as two projected screens on stage.
    i've pretty much figured out what i want to do, but i found this forum and thought i may as well post my plan and see if anyone has any suggestions.

    so, to get one image split up into ten pieces for the pyramid of tvs she wants, i'm going really lo-fi, and am going to point cameras at different parts of one tv. we're using little security cameras, which won't turn off when idle, and will be easy to attach to some sort of frame. we're gonna use rg6 coaxial cable with f-type to rca adapters on the ends to get the video from the booth to sidestage, where the tv-and-video-cameras contraption will be.
    (got the idea from http://maybevideodoes.de/sites/mosaic.html and we've tested it out on a small scale. the scan lines look really cool and the refresh rate wasn't an issue.)

    to project onto a screen at the back of the stage, we're going to mount a projector on the proscenium bar, using a projector mount made for mounting on trusses. again, coaxial with rca ends to get the video from the booth to the projector.

    the other projector is to be rear-projected. i've never done it, but apparently wax paper works well for a screen. the guys making the set pieces and the pyramid to hold the tvs are making the screen and all that.

    i'm going to be making my own video matrix, because i want to be able to output video from any of three dvd players to any of the three screens (treating the tv wall as a single screen). to make the video matrix i'll be using one three-way video splitter, one rca y-adapter, and three three-way input selectors (leaving one input blank).
    [​IMG]
    with that setup, i'll be able to have one image on each screen, the same image on all screens, or any combination of two on one and one on the other.
    i.e.
    111
    121
    123
    211
    113

    the only thing i haven't figured out yet is how to send a blank signal to the projectors, so that they won't go to a 'no input' message or something. i think i heard once that you can send audio into the video input and it will just give a blank image. is this true? is there a better way to send a dummy blank signal?

    any suggestions anyone has would be great
    thanks

    p.s. we're pretty settled on the cameras-and-tv method for the video wall. everything else was too expensive (though we were close to using a linux cluster; big tvs are easier to find than computer monitors).
     
  2. Footer

    Footer Senior Team Senior Team Premium Member

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    I would spend some cash and rent a video mixer, doing an ABC switch for switching live video is going to drive you up a tree, and the projectors/TV as well. Each time you switch video the projecter will have to re-sync to that source, you WILL get video jumps, and possible blue screens. Remember, ABC switches are just simple contact closures. I am also concerned that you are going to lose your video signal with all that splitting and cable runs, might want to look into some composite amplifiers. I would also take a long and hard look at the wax paper screen thing, paper products have high and low spots, I don't think its going to look the best for an RP screen.

    You might also want to attempt to go to PC based content instead of DVD, I think you might be much happier. You can get 3 pc's, link them together using a program called synergy, http://synergy2.sourceforge.net/, and be able to cue them all at the same time. Either that, or put the same content on all 3 DVD players, and only cue the one you need at the time. So, DVD 2 and 3 would have the content that would be played from DVD 1 when you want the same content on all 3. That would take out a lot of the difficulty.

    Just a side note, real world you would use a watchout system to do this, this is what that technology was made for. I would also be interested in seeing what the video wall thing turns out looking like. Also, keep in mind "video black", no matter what you send those TV's and projectors, they will still be spitting out light, so blackouts will not be possible in this production without dousers on everything.
     
  3. AberNStein

    AberNStein Member

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    thanks
    re: the switcher and the projectors, we may well have to rent a video mixer. good point.
    re: signal loss, my plan is to try it out and if necessary buy a couple signal boosters. i know for the projectors if the signal's not strong enough they won't display anything.
    re:wax paper, i'm skeptical too, but it's not my job to make that happen. i just know right now they're looking at stuff that's cheaper than buying/renting a proper RP screen.
    re:video black, I think we'll be ok; as far as I know, there aren't any blackouts called for, and the transitions will be videos.

    thanks again
     
  4. Van

    Van CBMod CB Mods Premium Member

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    My only input on this will be on the screen, there are much more qualified Vidiots < no offense intended, it's like "crescent wrench", a trade name> I have extolled, on many occasions, the virtues of Tricot < Tree-coh>. It's a stretch fabric, great for front or rear projection. It's cheap, available in many colors, and widths. You might really want to suggest this to the carps building your screen. It can usually be found in the Wedding, or Undergarments department of any decent fabric store.
    I'd say it sounds like you've put a lot of thought in on this project, I'd love to see a ground plan of the set and a little more in-depth explanation as to how the video will be used in this production of the "Scottish Play".

    Make a post in the new members Forum and tell us a bit more about yourself and your theatre.
     
  5. AberNStein

    AberNStein Member

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    thanks
    i've passed on your suggestion about Tricot

    the idea behind our production is that the witches represent the Media (specifically, their influence on Mac == the everpresent influence of the Media upon youth in today's society)
    the play will begin with a 'video overture' (war footage, tv commercials, etc.), and the video screens will be used throughout the play as backgrounds and to set up the atmosphere of each scene.
    Banquo's ghost will appear on screen, and the witches will be doing scary stuff on the tv wall (as well as appearing on stage)
    I think a couple deaths are happening on screen, and possibly a fight scene.
     
  6. Van

    Van CBMod CB Mods Premium Member

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    Very cool concept.
     
  7. museav

    museav CBMod CB Mods Departed Member

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    Given the intended use I would be very wary of the screens and their locations. Not only do you want to be sure that the screens and projectors have appropriate physical relationships for throw distance and angles and are of the correct size for the audience area, but it sounds as though light on the screens and maintaining a usable contrast ratio may be a concern.

    This is one area where the wax paper screens really concerns me. Other concerns on that include how fragile the screen material is, how well it prevents hot spotting, what kind of viewing angles you get and what it does to the light output from the projector. The overall issue is making sure that the entire audience can see what is on the screens and not have it washed out or impossible to tell what it is.

    The video 'wall' idea is interesting. I looked at the link you provided for the concept and it sounds like it is not actually a video wall where you split an image across multiple screens as much as it is ten different shots of the same image; different angles, portions of the image, etc. If this is wrong and the idea really is a video wall with a single image across multiple displays, then there may be some problems with the proposed approach.

    Another consideration is that the application shown in the link provided was for a single person viewing from a short distance from the displays. Not knowing anything about your venue, you may want to consider how that translates to a larger audience. It is possible that some audience member further away may not be able to discern much from the images, they may just be a blur of color and brightness. It is even possible that this could become more of a distraction for some, not really being able to discern the images but drawing them away from other activities on stage. This is very venue and application dependent so it may not be an issue for you, but sometimes things that work wonderfully in smaller settings simply do not translate well for larger venues.

    As noted, you will have some resyncing occurring at the projectors when you switch between sources. Using switcher/scalers or seamless switchers could prevent this but would also be more expensive and require running RGBHV/VGA to the projectors. The concept of putting the same files on each DVD is interesting, but unless the DVD players are synchronized you would have differences between them.

    Which goes to an important point for your particular application, that you may not care about many of these aspects. In fact, having images poorly registered, delays between different images, hot spots, etc. may actually be a desired 'effect' for this use. And you may not care if the effects differs over the audience area. The one area that may be of concern is making sure that the images are easily visible over the audience area so you might need to verify the screen material, projector brightness and locations and how lighting and set pieces impact the projected images.
     
  8. AberNStein

    AberNStein Member

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    as i understand it, they'll be experimenting with the rear projection screen until they get something useable and cheap. i've never built a rear projection screen (let alone set one up), but we'll be able to control the light hitting it, so contrast should hopefully be OK

    the image quality and definition on the 'tv wall' is not an issue. figures and faces will be discernible, and the 'grungy' look of a video camera filming a tv is exactly what we want

    the only thing i'm really concerned about right now is the input switching for the three screens. i may well have to get just one continuously playing dvd for each screen, and then put them all in identical dvd players and press play with a remote to synchronize.
    i feel like i'd need to rent three video mixers to do what I need
     
  9. Footer

    Footer Senior Team Senior Team Premium Member

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    Give the DVD players a try, its worth it. You can even cover up the IR reciever on one if you need to play two, it works...
     
  10. museav

    museav CBMod CB Mods Departed Member

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    Perhaps I misunderstood, but is a continuous signal from the DVDs practical? Is the show timing such that everything else can match to the DVDs? It would seem to be potentially awkward during rehearsals or if something happened during a show.

    Speaking of which, if you have to stop or pause the DVD players, will they stay in pause indefinitely or do they stop after a short time, causing you to recue them all? How would you cue and control the DVD players? This may be planning for "what ifs" but it is one area where a real matrix router would be beneficial as you could have one local monitor that could be fed from any DVD player for cueing and monitoring.

    You also did not mention how you are addressing audio related to the DVD sources, are the three switchers handling that or are you running each DVD output directly to the mixer? With the DVDs continuously running the latter approach might mean muting different DVDs at different times (you don't want three sources of the same audio active) or maybe putting all the related audio on one disc.
     
  11. AberNStein

    AberNStein Member

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    you're right. i'll be cueing up chapters and then playing them when needed i suppose. i know that i won't be using all three screens at once for the whole show; there will be times when i'll need 'black' on a given screen. rather than have that black as part of the dvd, i'd like to use a switcher. i think some projectors can be set to display black rather than blue for no input. using a physical switch (as opposed to a mixer) could well work for switching between an input and none, but as has been discussed, not for switching between inputs.
    i'm still not convinced we need a real matrix router. the switch that selects input to the tv wall can be a physical switcher, as the output is analog.
    what if I ran the input into each projector through a time base corrector? would that solve my resync issues when changing sources?
    alternately, what if I just have one dvd per output destination (ie tv wall, proj's) with everything on it that will need to be displayed on that screen, and have cues for button-pushing underlings ('rookies') to cue, play and pause the dvd player, and an A-B switch for 'blacking' the projector? for the times when we need a synchronized image on two screens, two dvds will have the same content, and then we can press play on both at once (or try a remote)
    i was going to have each dvd player in a stereo channel on the mixer. muting/unmuting channels is not a problem.
     
  12. SHARYNF

    SHARYNF Well-Known Member

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    I think you are going to go nuts trying to rube goldberg this this way.
    First: Rear projection, wax paper on a stage with lights is asking for trouble, you can get lycra or tricot and stretch it and the material can actually come in 10 foot widths, and unlimited lengths, and runs about 40 dollars a yard (3feet by 10 feet). The problem with paper or other methods is getting it stretched, and joined. IF you insist on a make it your self in the early days, people got a sheet of clear or near clear plastic and used chalk dust to coat it, but as I say, the materials are not all that hard to find and the advantage of a stetch material is that it can be held in place easily.

    Here is the link for the material called trapeze
    http://www.iweiss.com/stage/fabric/specialty.html


    Trying to do all the mixing and switching and creating a video wall is just going to drive you crazy. If you are looking at timebase correctors for each input with a sync source to sync all the three feeds you are already out of the home brew setup.

    The simplest way to do it, without spending a fortune,is to decide the production in advance, and edit three dvd's that have the three feeds already created in advance. you then get three dvd players, use the ir remote and pause and play them. Not perfect, using three synced pc's is better but more elaborate. IF you use something like Vegas you can produce three different video tracks each of which will be the individual feed for each projector, you can create these tracks with parts of the image image over the three projectors etc.

    Your other option is to get a package like Arkaos midi and use this for the visuals and use pc's
    http://www.arkaos.net/

    Sharyn
     
  13. icewolf08

    icewolf08 CBMod CB Mods

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    I agree with Sharyn, it sounds like you are really overcomplicating things. This is one of those situations where a synchronized cue list (as Sharyn mentioned) would probably be the best way to get the job done. Set up one DVD or computer to drive each output (the two projectors and the TV wall) and then create a DVD for each. Each DVD should have some track for every video cue even if that means a few minutes of black when an output is not being used. Then all you have to do is take the IR remote (assuming all the DVD players are the same model) and push play and pause. All the Machines will go and stop together. Simple.

    If you have to go to a live video on your screens you need to have a switcher. You are in school right? Do you have an A/V department? My high school did, and I bet if you asked nicely they might have a video switcher you can borrow for the show. You could also try asking at your local TV stations, especially if you have a local cable access channel, they often like to help out the community.

    As others have mentioned, a physical A/B switch will probably just create a headache for you. If you need to go to real black and not "video black" on your projectors you can get a device like City Theatrical's Projector Dowser or you can go the low tech way and put a piece of cardboard on a hinge with some tieline attached that a crew person can pull open and then let gravity pull closed.

    I am not going to get in on the screen material debate because I don't know enough about it, but I will say that you could look into Screen Goo which is a paint on projection surface. They make rear screen paint, but I don't know what they recommend for a rear screen surface.
     
  14. AberNStein

    AberNStein Member

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    back from a holiday. looking over the production now, you guys are probably right about having everything pre-timed on the DVD. that certainly takes a load off of me, and the director will just have to work with the people making the dvds a lot. (and the lesser workload is much needed, as i'm SMing a one-act that's being performed in the first week of February)
    thanks everyone for their input; i'll keep you all posted as things develop. we should be setting the TVs up in the first week or two back to school. i'll take pictures when it's up.
     
  15. kwotipka

    kwotipka Active Member

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    I had to reread this thread a couple of times just for the heck of it. It sounds as though you know what you want to do. Now while some of your concepts are not "real world", I think that they will work out fine for the grungy effect you are going for.

    I have had this similar argument with artists for their multimedia shows and lost every time. In the end, most of them looked great for what they were trying to do despite all my telling them "that's not the way that you do it".

    So, here are a few things. If you are going the CCD camera route at a monitor, remember that TV screens refresh at the same rate as the cameras. Computer monitors don't always. Composite video is not the same as RF so make sure what kind of distribution amp you are getting. Also, you cannot split composite video like you can RF. You will see your signal getting darker and darker (in serious steps) every time you try to split it.

    If you are looking for a black source, get another CCD camera and keep the lens cap on.

    If you are looking to go wild and you don't mind all of the sync issues that were presented to you, look into something like an Extron matrix router. They can be had for cheap on ebay or a local station might be junking one because they are upgrading. Look for one with a serial port. Extron still provides the software to create preset "looks" that will make even the smallest 8x8 router switch around pretty fast.

    Lastly, be prepared to have one monitor go to gray instead of black. It's the nature of the beast.

    Again, those before me have presented you with some pretty strong issues for you to consider. Read them and test, test, test.

    kw
     
  16. AberNStein

    AberNStein Member

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    thought i might post an update, as things have actually happened

    1. the main screen. we purchased and mounted a 4000 lumen hitachi projector (the zoom and focus are controllable by remote, which made things really easy to set up) which projects onto the back wall of the stage. the projector is hung from our proscenium lighting bar using a truss mount made for projectors. the image is bright enough with a reasonable amount of light on it, and the 'video black' is black enough.

    2. the rear projection screen. it was made out of interwoven wax paper and the frame is made of 2x4s. (not my doing; i think it was mentioned in another thread on here.) it actually works quite well. we ran into issues with actors needing to come on and off stage behind it while it's being used, and after experimenting with lenses (no luck in reducing the focal length so that actors could walk behind the projector) we've decided to build a wall mount and let the actors walk under it. there is a "hot spot", but it's not awful, and the viewing angle is fine.

    3. the TV wall. it works! we've got tiny little X10 security cameras mounted on a vertical piece of plywood about a foot away from a tv, and each camera is connected to a tv in the wall. picture attached shows the wall while we were still setting it up (only three cameras going. the picture's actually not very representative of how good it looks right now.). i'll take a photo tomorrow of it fully working. it's really awesome.

    just thought i'd let you guys [i.e. the other people who've posted in this thread] know how it's working out. if anybody has questions on mounting a projector to a lighting bar, building a dirt cheap rear projection screen, or making a really ghetto tv wall that looks really cool, i'm now qualified to answer. [no offense intended to anyone who actually lives in a ghetto, but the tvs are all old, used, and free, and it's a really macgyver'd way of doing it.]
     

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  17. kwotipka

    kwotipka Active Member

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    Glad to hear that it is working out for you. Never be afraid to experiment (as long as you are safe).

    kw
     

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