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Video Projection Formating questions

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Hal SloaneVideo Projection Formating questions
by on Apr 18, 2006 at 10:56:34 pm


I've got a number of corporate projects coming up that will be played back via projector onto a large screen. I've done this before using DVcam, mini DV, QTDV files from a laptop. Anyway, I've always had pretty good results but the other day we did a review screening for the client with a cheapo projector they had on site and ran into some aliasing issues with the graphics. This version was played back from a G4 laptop and the source was a Quictime file in the DV codec. For the events I will be playing back from DVcam master tape. My question (sorry it has taken me so long to get to it) is do I need to deinterlace the project to avoid having pixelized graphics or will playback from a tape source take care of this aliasing issue? Maybe it was just the crappy projector?

Thanks much

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Thomas LeongRe: Video Projection Formating questions
by on Apr 20, 2006 at 6:27:12 pm

I'll venture a guess.

When you playback from a computer, the output is non-interlaced and you are connected to the projector's RGB input. Moreover, if the computer is set to output a resolution that is not native to the projector, then the projector's own internal electronics has to both de-interlace AND rescale the resolution to its native (if it has a de-interlacer built-in). With a low-end projector, the quality of the parts (de-interlacer and scaler) probably failed to process the input within the micro milliseconds allowed before outputting to screen.

When you playback from tape, you are connected to the projector's video input. There is no de-interlacing required. A low-end projector probably has SVGA resolution as its native res (800x600). That's close enough to SD video resolution so the re-scaling is minimal and the projector should be able to handle that. Heck, it is probably built to handle video from tape than from computer, i.e. more for home movies. The only real problem you may have is the color from low end projectors. I've seen one output blue as a horrible purple.

Your best bet is to get hold of the projector for a day or two and test with your tape well before showday.

Thomas Leong

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