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Live Chroma Key software

Discussion in 'Camcorders, Action Cams & Video Making Forum' started by AgeOwns, Oct 26, 2004.

  1. AgeOwns

    AgeOwns
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    A relative noobie to video editing. My experience is limited to creating light sabre effects in Adobe premiere and photoshop. I am looking for some some 'live' chroma key effects. Adobe premiere will do it, but only on pre-recorded video. I am looking to set a display up where i work where people can step in front of the camera and appear on a large video screen with a different background.

    Is this possible with a PC? If so what software can do it?

    Many thanks...
     
  2. Roy Mallard

    Roy Mallard
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    The only way i've ever done it live was to use a panasonic MX50 video mixer (or similar) with a chroma key function on it.

    You would need a blue or green screen behind your subject and fairly specialist lighting (doing it live you have far less error margin/latitude).

    You would need even set (flooded) lights on your blue/green screen a fill (soft flooded) 2 backlights (usually spotted across subjects head and shoulders, but out of camera shot) and 1 key (spotted) down opposite side of face from fill, all on your subject and they would not be able to wear blue or green (depending on the screen you've used) and sometimes even black causes problems).

    If you wanted to record the live rig up you would also need a video deck or second camera with analogue in.

    I far prefer to do it in post where practical as you can include and exclude areas, garbage matte, and very accutely control the chroma and luma of the subject you wish to to key out, the tolerance can be varied to a greater degree as well. However, live, theres no easy way.
     
  3. Mr.D

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    Most pro live bluescreen applications use a hardware Ultimatte type rig (Ultimatte make the best colour difference keying algorythms...they practically invented the process and I have to say they are still the best). You can cook up an ultimatte type keyer in any decent image manipulation package using the algorythmns on their website but replicating the tweaking tools is a little more difficult.

    Doing it live shouldn't be a problem . Just tweak your tolerances and lighting to get the best results but don't expect photorealistic comps.

    If you are doing it with a domestic video format use a greenscreen rather than blue but bear in mind green produces more spill for the same amount of light you put on the screen as blue . Don't over or under expose the screen and keep it as evenly lit as possible (eveness is more important than brighness).

    Don't put filters on the camera other than ND. Gels to balance the lights are fine as long as its consistent across the scene.

    Personally I'd still use green ( blue will give very noisy edges on video , I normally even specify green on 35mm film shoots unless subject matter suggests blue will be more applicable)

    Also if you can take a shot of the screen without your subject matter in front of it and use it to pull an additional difference matte to help reinforce your key.
    Softening the image you key from prior to keying may also help however only use this image for the matte don't comp it.

    Obviously how much of this you can actually do will depend on what sort of kit you have and whether or not it will work live.
     
  4. AgeOwns

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    Setting up the screen, seems tricky, but i'll give it ago. Are you suggesting that their is no PC software that can do chroma key live? and that i need a hardware board?

    Does anyone know of PC software that can do this?
    What type of hardware board am i after?

    Cheers in advance.
     
  5. Mr.D

    Mr.D
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    google for live chroma key doesn't bring up much . A couple of sotware packages that claim to do it but only run at 640x400 at 15fps with hellish compression , very poor.

    It should be possible on nominal PC hardware with a single incoming video stream and a still or possibly a pre-rendered background but I doubt a PCI bus will handle capturing two video streams , process ,comp and display them at anything approaching decent quality.
     
  6. Roy Mallard

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    I seem to recall using a corel draw as a titling package on an old linear suite i used to hire years ago, it took the form of placing your text on a computer generated blue screen, then using a genlock to key out the blue, so that your captions appeared over your video footage.

    This genlock was routed in to the mixer on its permanant bus, and so could be faded in and out as you mastered your tape (this means it was effectively live).

    Now it goes without saying that you would need a genlock to synch up the output from yout cam and the background video source, but if you can find real-time software you should be able to use a second genlock to output with the source and camera output in synch.

    I still think an mx50 would be your best bet.
     
  7. AgeOwns

    AgeOwns
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    I'll have to go back to work and beg for the money for a MX50 video mixer then.
    might happen.

    Many thanks for all the help. :smashin:
     
  8. zedo

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    It's been a few years now, is there any new Windows software to do live chroma keying and outputting live like it appears like a webcam or something.
     
  9. shwhjw

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    i've been looking for software to do this for a few days now... not found nowt
     
  10. DigiStuff

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    Guys,

    Check this dealer out, they list Chroma keying products from around £900 to whatever you want to pay!!! http://www.planetdv.net/Content/Chroma_Keying.asp

    I used to deal with this dealer loads some years ago and they were very good...

    Hope this helps

    Digistuff
     
  11. shwhjw

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    ok its not exactly live, but it's a start... i do now know how to play a movie over webcam (providing you have a camcorder)...

    1) record your movie onto your camcorder tape

    2) link your camcorder to your computer and put it in 'playback' mode

    3) set up your webcam options so you have your camcorder selected as the active webcam

    4) invite someone to view your webcam, press play on the camcorder and they can watch your movie, without having to download it first!:smashin:
     
  12. DigiStuff

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    Hi shwhjw,

    Not meaning to be rude, but is this in the correct thread as what does this have to do with Chroma Keying !?!?!

    Read the other posts to learn more about Chroma keying....

    Your instructions would only work how you state if your camcorder is able to be used as a web cam as all are not.
     
  13. Andrew O.

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    Live/real-time chroma keying in software is possible via one of our SDKs:

    Live Chroma Key SDK - MediaLooks

    Of course, you need a good CPU for HD content, but... its possible.
     
    Last edited: Jul 7, 2009

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