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Live video projecting

Discussion in 'Special Effects' started by theaterscout, Oct 5, 2006.

  1. theaterscout

    theaterscout Member

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    Ok heres what we have going on. In the play "1984" its is set in George Orwells idea of what the future may have been like from a 1940's viewpoint. In the set we have what is called the telesecreen. basically it is a TV that the Government uses to spew its propoganda and to spy on the citizens. the idea that we are kicking around is hooking up a projector to project onto our screen and having a live feed off stage in the wing. When they are done with whatever they have to broadcast onto the screen, it should fade back into a picture of "Big Brother Is Watching". Sound plausible?
     
  2. FxDrew

    FxDrew Member

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    It's how "plausable" it is depends on your budget. Let's talk about the components needed for the effect.
    Projector- Depending on the screen size and the ambient light, you need to determine how many lumens you need to make the screen seen. You may be able to snag a projector from media services at your school, great, but where will you put it? Unless you have an out of the way front of house position to put the projector that no one will cross in front of, it is usually done in theatre as a rear-projection. Which brings us to...
    Screen- A rear projection screen uses a special material to display the image onto the other side of the material. This stuff is not cheap. A perk to using rear projection is that it looks brighter because you are looking directly into the lamp of the projector and not looking at bounced light. A downside to read-projection screens is that any ambient light on the screen can wash out the image rather easily. One other thing to take in to consideration is the depth you have backstage to put the projector. This of course, depends on the amount of room you have backstage and whether there is enough room to make backstage crosses without having to walk in front of the projector. If you end up doing front projection, try to use an actual "projection screen", they bounce the light back better than a flat white wall. If you do use a white wall of some sort, I believe Rosco makes a "projection surface" paint that bounces more of the light back to the viewers eye. Next!
    Video Switcher- If you want to fade from one source to another ("Live feed fading to an image") you will need a switcher. Depending on how gracefull you want a switch to be, it can be a cheap multi-media switcher from Radio Shack to a couple thousand dollars for what the pros use. The "Fade" from one image to another is where it gets expensive. If you are using only composite signals (RCA style connection, Yellow) then you could just use a video switcher found common with most home entertainment systems that have a VCR Player, DVD Player and Cable Box.
    Video Generator- If you want an image of "Big Brother is Watching" you need to figure out where that image is coming from. You might immediately say, "well a computer of course!", but unless you have a composite video signal out of the computer (remember that little Yellow RCA connector?) to get into the Video switcher, how will you switch from one video source to another? Possible solution- The projector has several inputs. You plug your computer into the Projector which has the "Big Brother is Watching" image playing on it. Then in another one of the inputs, you plug your live video feed. Using the PROJECTOR, you would switch between your video sources. You would not be able to fade from one feed to another and a menu might pop up on the screen when you are changing sources.
    Live Video Feed- This depends on what kind of camera you have and how far away you are from the video input to the projector/switcher. You need a camera that would give you a constant output (most consumer video cameras will turn off if you haven't started recording any video after a while to save battery). The other thing is how you will get the video to the projector/switcher.

    The whole live video aspect of this project is what makes it messy on a low budget. If you need me to clarify or have any other questions to ask, always feel free to contact me. I too came from a dirt poor drama program and learned to make do with what I could get my hands on (several trips to media services). Right now I'm working on a musical production of "Chicago" using two rear-projection screens, lots of video/image playback, 3 live video "lipstick" cameras and a 3 camera set-up of live video input. Luckily, they have the budget to make this happen. Best of luck!
     
    Last edited: Dec 23, 2006
  3. JSFox

    JSFox Active Member

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    Andrew, you're thinking way to complicated. A DL2, a Catalyst, done deal. Righto!
     
  4. len

    len Well-Known Member

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    You really don't need catalyst if you have a dl2. Content resides within the unit. And I can get 4 for you, but you will need a Hog to control them (a DL2 burns 170 +/- dmx channels) and you'd need 2 of them. And Rockton isn't that far.

    But seriously, IMO your best bet is front projection, simply because you don't need a specific surface, and because RP tends to lose more output than FP. You could mount the projector from one of the electrics or something, and even dress it as a scenic element. If you want to get fancy, get an elevator.

    As for the mixer, camera, et al, I know a couple places in the Chicago area that could rent them to you, if you don't have them. You're going to have to fly it instead of ground support, since you'll want it away from the moving scenery (I mean actors).
     
  5. SHARYNF

    SHARYNF Well-Known Member

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    Yikes you guys are making it a bit overly complex
    Here are some thoughts, we do this sort of thing all the time

    Rear projection works far better, you can look on ebay under fastfold and see screens with rear surfaces or you can talk to your local av rental company, typically a place that did tradeshows or corporate work will have these especially from old slide projection systems. Video is 4:3 format typically and a lot of old slide screems are square, but you have a few options:

    One thing is to place the screen behind your wall a distance of say a foot, this will keep some of the spill light off the screen, and it also allows you to size hole for the image to what ever you want, not worrying about the screen being larger.

    If you use a projector of about 2000 lumens, and you project from the rear and you keep your image so to 4 feet by 3 feet you can have a pretty bright image, remember it is lumens distrubuted over the area.

    With modern projectors they have key stone correction, so you can mount the projector up higher, project down to the screen and correct the key stoning.

    It depends on the projector but for instance with Sharp Notevision 1700 lumen projector your would be looking at a distance of approximately 10 feet from projector to surface.


    You can get elaborate with live switching etc, but you also can pre record al your feed, edit this on any of the simple editing systems, and then use a dvd player to play back your program, this way you don't need live switching.

    If you want to be able to control the switch from the "feed" to the Big Brother is watching you can also use a slide projector that you turn the image on and off,

    The advantage of using pre recorded footage is that you can have the "watching" be even more worrysome, ie shots of you sleeping, in your car, walkinhg on the street etc, so it can give you more flexibility

    Re the distance from player to projector, the 10 foot distance is incorrect and is for audio not video. You can get S video cable and run it a 100 feet with no problem, if you use coax you can easily run it 300 feet. It is important to make sure that you plug the dvd player and the projector into the same power source if you can, and keep the cables away for a lot of power lines so that you don't get hum bars (rolling bars up the image) AV houses rent out filters that you can use if you are using coax cable that filter out this also.

    Sure you can do large scale concert production systems, but you also can use clever setups that can fit in your budget

    Sharyn
     
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  6. jbeutt

    jbeutt Active Member

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    Ha. For a verrry ad hoc production of Wizard, I devised a live projection of the wizard. I use "devised" very loosely and mean not to infer any sense of professionalism.

    A very creative friend of mine shot it in the booth on an old VHS camera, holding a glass color filter up to it, front projecting onto the curtain with fog.
    It looked fantastic. But of course I knew it would. ;)


    Sounds totally plausable. I'm not clear whether you have the screen already or if this is still in design phase. Makes no difference, I guess.

    You'll need a camera, projector and video mixer. Prrrrrobably a video amp as well, depending on your cable runs. One mixer channel can just be a DVD with a still of your image. that's the simplest method. The other, obviously, would be your camera.

    For the videography, keep in mind production value, i.e. camera type (3-chip), lighting and sound. I assume you want a certain look, which means a little knowledge of videography is neccessary just so you can control the look.

    The projection is a no brainer. You definitely want to rear project to ensure a TV screen look. If you're short on space, which is always a problem with rear projecting, you can venture into using a mirror. It doesn't have to really be any special kind, just flat. This only works if your projector or video mixer has the capability of flipping your video, though.

    Keep a lookout for problems with the video. Video is a tricky world and even on a small setup, you should be aware, if even laterally, of sampling issues, noise, and so on.
     
  7. SHARYNF

    SHARYNF Well-Known Member

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    If you go with a mirror system you need to be aware of a few issues

    First is that it is not correct that any mirror will work, if you use a standard mirror (REAR SURFACE) you will get shadowing so unless you want a poor quality image you need a front surface mirror

    Throw distance - You need to look at the required throw distance and how folding it with a mirror affects where the projector goes. This will affect the ou cmirror size as well, the closer in the projection path to the projector that you can use the mirror the smaller the mirror can be, but in this application physical constraints on where the projector and mirror can be located and mounted may be constrained.

    Projection Path - It need to be clear with no interference. Lights, structure, etc. need to be considered so that they do not block the projection or cast a shadow.

    Other Light Sources Depending on the lighting and location of the mirror it may be impossible to keep from having lights reflecting off the mirror, since you need to worry about reflections.

    Image Inversion - A single bounce mirror will invert the image. You can probably adjust for this in the projector setup or use a two mirror (double bounce) arrangement, but most projectors have inversion today

    Mirror Material - A mirror will have some light loss, the specifics depend upon the mirror. Mylar and glass mirrors are available. Glass tends to give less loss and a better image but mylar will be much lighter and may be a very viable option if this is hung overhead, and is typically front surface

    Mounting - Mounting of the projector and mirror is critical if they are overhead.

    I would say that if you could place the "tv" on the set so that you can have the projected distance you need without a mirror, you will have a lot less issues.

    In general, unless you NEED the video feed to be live, you are better off with a pre recorded version. Unless for instance you want to have video of your audience so that people can see themselves live as part of the effect, Again I would suggest going pre recorded.

    You can get a variety of video mixers, from the Videonics MX1 up to higher end Panasonic units. Keep in mind that you will need a monitor so that you can see what it is you are queing up etc. For Live feed mixing we have used a Panasonic MX50. It has the ability to store a still image and has 4 inputs, so what we have done is to have the "big Brother" title stored, or, we also use a TITLEMASTER 3000 so that we can run live titles etc.

    Personally I would say if you don't have an experienced live video crew, do it pre recorded. I have used video as a creative source of background scenes etc with projectors etc, quite effectively which can be fun and challenging but we have a whole video crew that gets into this sort of stuff.

    For instance in this production you can have the TV setup which is pretty standard for the BIG Brother monitoring effect, but you can also use projection to set the backgrounds for the scenes. I have done situations where the scene flats were infact rear projection screens and it was all projected

    Sharyn
     
  8. jbeutt

    jbeutt Active Member

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    No, it is correct that any mirror will work. Work well, well that's another story.

    I get the impression (and I apologize theaterscout if this is incorrect) that neither their show nor effect will suffer incredibly from the wrong mirror. Even large sets can be a pain to use rear projection in, so if they are a smaller space, they're going to have bounce project. Hmmm...have you thought about using a gigantic TV? :) Maybe one of those TV grids they have at best buy.

    With school shows that do their video live, it's usually because of some requirement of the directors that all the actors are in the live show. Which is totally appropriate for education shows. It's not really fair to pick one guy out, shoot his video piece, then send him home. But you're right Sharyn, it's not very practical. I'm not familiar with the show, but perhaps rather than worry about live video, pre-record your actor in silhouette. Run that as your video, but have the dialogue done live over the PA.

    As far as the projection goes, I suggest experimentation. without a dedicated and knowledgable video crew to do it, I'd see this as an opportunity to gain that skill and to be creative. From a strictly technical standpoint, though, there's only so much keystoning that will work. Using a mirror can give you shorter throw distance on the ground, but keep in mind, for this to be true, you have to have a decent sized mirror. I would certainly take the loss of quality for the reduction in required rear space and the lesser chance of intrusion by a set piece, light or actor into the projection path.

    Cheers
     
  9. SHARYNF

    SHARYNF Well-Known Member

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    Mayby I'm just used to higher production values when you use mirrors.
    Some things to keep in mind:

    You can project down from above and tilt the screen, this will allow you to use keystone and the screen to correct for angle, and it can also reduce the light spill

    Small front surface mirrors especially mylar are not all that expensive, also remember that you can use them to have the projector at right angles to the screen both from the side and from the bottom. If you look at the rear projection tv's like the old TOSHIBA'S this is an option, and you might find one that someone is getting rid of for their new flat panel tv, ALSO don't forget you MIGHT be able to borrow a flat panel, and use close up shots based on the smaller size. Most of these options are likel to be 50-60 inches diagonal

    Alot of the projectors schools are using like the Dells have lens setups that they work over shorter projection distances, and the DLP's are quite bright.

    I do a lot of work with projection of video and lasers, and rear surface mirrors definitely give you shadowing and a crap image :-(

    Sharyn
     
  10. jbeutt

    jbeutt Active Member

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    I'm with you on a front surface mirror. But using a small one won't really help them at all. To achieve this right angle projection and cut down rear clearance, the mirror would have to be fairly large. of course, this depends entirely on the size of the final projection surface. But still, the larger the mirror, the closer it can be placed to the projection surface and the smaller stage footprint the whole system will have. However, reducing the deck footprint will increase the verticle footprint and thusly the required height of the projection surface. And off you go! :D

    If you have the money, by all means go for a front surface. I honestly have have no price in my head to reference, but it seems Sharyn does, so go with him/her.
     
  11. SHARYNF

    SHARYNF Well-Known Member

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    here is a link for mylar for mirrors

    http://www.nielsensenterprises.com/snomo/mylar.htm

    You would want to get some of the thicker material, but as you can see the pricing is not all that expensive and it is safer than a glass mirror. You do need to be careful that someone does not poke a hole in it

    (its a she) ;-)

    Sharyn
     
  12. silvrwolf

    silvrwolf Member

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  13. SHARYNF

    SHARYNF Well-Known Member

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    There was a lot of misinformation in FXdrew's post
    First if you remove the tape from the camera, you will not get the shut down mode.

    Second is that your standard consumer camera IF you convert the output to quality rg59 cable you can easily run 100 feet, if you use rg6 you can easily run 200 plus feet. You can get an adaptor that will connect the rca jack from the camera to bnc . Many times I use a Fconnector (screw on) with an adaptor that converts the f male connection to a female rca so you just have to plug the conection it.

    If you take S video connection and get an adaptor that converts it over to Dual Coax run and you get some dual coax (rg6 is best) you can run s video several hundred feet also. The trick is to get this dual cable so that the length and cable is identical so you don't get any different delays on the signal. Dual rg6 coax is used for a lot of satellite dish installs so it is not all that expensive.

    One thing to watch out for is that some of the canon consumer camcorders will on default display on the video out the viewfinder overlay, so you need to have the remote to turn it off)

    Other than that it works quite well.

    Sharyn
     
  14. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Um, I would beg to differ to a degree. If you are using a "broadcast" camera and you and I define broadcast grade the same way, then the camera will run on triax... And the maximum cable length is about 2km, that would be what something around 6500 feet, which is somewhat more than 100 feet... Unless of course you and I are talking about different things.
     
  15. SHARYNF

    SHARYNF Well-Known Member

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    Think you will find that standard triax will allow for 600 meters and with a repeater 1500 m.
    Sharyn
     
  16. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Entirely possible that the information I was told was wrong, though the guy who told me knows quite a bit about broadcast grade vision. (Having worked in TV for 40 something years.) I am guessig that it may also depend on the individual cameras in question, as I imagine that different cameras transmit different strength signals and so have differing abilities to cover distance. The individual head end I imagine also plays a part. (And time for a slightly dumb question: when you say 1500 metres with a repeater, I assume that repeater is roughly half way along the cable?)
     
  17. SHARYNF

    SHARYNF Well-Known Member

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    Yes the repeator is placed mid point
    A lot also depends if you are running composite/component analog, if you are running SDI Digital, and also the CCU camera control unit. Most of the pro cameras have a multi cable, with supports intercom, audio, power, video, and other control signals. From a practical stand point I have rarely ever seen someone run over 300 feet on these systems. You also need to adjust the delay and signal when it gets to the OB truck etc so that you can match and sync the multiple cameras.

    Sharyn
     
  18. silvrwolf

    silvrwolf Member

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    Yes, I agree that triax can easily go further than 100 ft, but I was talking about pure video out of a broadcast camera via BNC.
     
  19. SHARYNF

    SHARYNF Well-Known Member

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    The spec for the signal coming out of a Broadcast OR consumer camera for composite video is from a distance stand point the same, and for all practical purposes the same in all respects, it is only when you get to component or sdi output that things differ. It is the cable used that makes the difference. IF you . as I said convert the cable over to quality coax rg6 for instance, you can get the long distances


    Sharyn
     
  20. Chris15

    Chris15 CBMod CB Mods Premium Member

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    I understand that most broadcast grade cameras run a multiplexed component video signal. Good quality coax makes all the difference as Sharyn has said. The other thing to consider is that this is all about reducing signal loss. For every connector in the line, you loose about 1 dB of signal. So a single uninterrupted cable is much better for signal strength than a series of shorter cables joined together. When your signal strength is problematic, reducing connectors could be the answer to your problems.
     

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