Spatial jitters with PJ and Sky....




I emailed PACE asking them if they knew why I get a flickery/shaky image when watching Sky+ through my InFocus 5700 PJ.

They replied with:

Your projector will invariably have a straightforward line doubling circuit to allow 625 line video signals to be displayed on computer monitors, LCD devices, plasmas displays or any other VGA display devices.

What is happening is that the interlaced set top box video is being doubledin line frequency by simply doubling the number of lines on each field of video. This doubling mechanism effectively over samples the signal without any subsequent anti alias filtering, leading to spatial jitters on the displayed image for picture detail with a vertical content of high frequency. This effect is particularly noticeable on graphics information and any picture content with high contrast between horizontal boundaries.

The solution is to invest in a higher quality de-interlacer that produces a VGA progressive scan with both fields combined and filtered correctly. Or turn the contrast down so the jitteriness is less noticeable.

I would have thought the onboard Faroudja (sp?) processor would combat this - is that not right?

Anyone know how I can stop this effect?



Novice Member
PJ are you getting the same artifacts on both film and video material from Sky+?



Well basically the whole image kinda shudders and flickers a bit, most noticably with say the TV Guide or onscreen graphics/banners. It does still do it when viewing TV, but is barely visible.

Watching DVDs or playing on the PS2 gives no such effect, so it is not the PJ itself, yet watching Sky+ by connecting the digibox to a CRT TV via RGB also removes the issue, so it is definitely the interaction between PJ and digibox.

I have the PJ connected to digibox via D5 component, but S-Video-S-Video gives the same result.

Any ideas?

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