Don,

If I can summarise what Mike is saying, he's saying that there is a "digital stream to picture" conversion taking place on the analog output of the nVi that bypasses the equivalent convertor in the projector. The digital output of the nVi doesn't have this "digital stream to picture" conversion and so it gets done in the projector. So using your earlier post it should have looked like this:


A: With compoment (analogue) cable connection:-

the N-vi; reads the dvd as a digital stream; uses its internal digital stream processor to convert this to a digital picture; uses its internal DAC to convert this to an analogue picture signal; passess the analogue picture signal to the component output and connected cable.

the screen; receives the incomming component analogue picture signals; uses its internal ADC to convert this to a digital picture stream; uses its internal scaler to convert this to 1080p; passess the 1080p picture stream to the plasma screen.


B: With DVI/HDMI (digital) cable connection:-

the N-vi; reads the dvd as a digital stream; passess the digital signal to the DVI output and connected DVI/HDMI cable.

the screen; receives the incomming DVI/HDMI digital signals; uses its internal digital stream processor to convert this to a digital picture; uses its internal scaler to convert this to 1080p; passess the 1080p picture stream to the plasma screen.


Mike, if I've misrepresented you or put words in your mouth please say. What I'm struggling to understand is what exactly this "digital stream to picture" converter is. At first I thought it might simply be a digital to analog converter, but that actually makes no sense as there is no digital to analog conversion step in the projector if it's being fed digitally (Mike - did you see Dave Dever's response to this?)

I thought it might be the picture control circuitry (i.e. for adjusting contrast, brightness, etc) but re-reading all this carefully I don't think you're referring to that at all. I'm going to make another guess here Mike; are you referring to the MPEG decoder (the bit that generates an uncompressed image based on the compressed image stored on the disc)? If so, regardless of whether you use digital or analog out, you will still be using the MPEG decoder built into the n-Vi, the projector doesn't have one. If I've still not got it, please can you describe what exactly this step is doing.

Don, I think if you delete the bits marked in bold above then you have the essentials of what is different between using the analog and digital outputs.

Gloop,

If you do the comparison and they look the same I'd suggest you go with HDMI. Why? because one day you may want to run a high definition source up to your projector. Analog component may look ok at 480p but will degrade at the higher frequencies required for HD.

I wouldn't bother with fancy expensive HDMI cables either. What you need is a good quality, well shielded 'studio' grade cable with tight fitting connectors and one that will work at the highest resolution+frequency you are likely to encounter. My recommendation is Molex. A 5m HDMI Molex cable will cost you about £30. I use a couple of 5m Molex cables here and even at 1080p60Hz they work perfectly.

The problem here is pretty straightforward.

One guy asks what cable he should use.

Another guy who's been down that road with the self same source component suggests a home dem of two options.

Nice & simple.

Folk start asking "why", and when "because I tried it, there was a difference, & I chose the best on performance" failed to satisfy the collective lust for knowledge, the guy making the recommendation made the horrendous mistake of trying to impart some technical details, but without making it so complex that folk got progressively (scanned!) more & more lost and confused.

I should have shut up at that point and just kept my fingers crossed that gloop took my suggestion and tried both cables.

Instead, I've embroiled myself in a situation where folk have been asking the same question again and again and again, and in an effort to simplify it I've then found myself on the sharp end from another fellow who questions the lack of precise technical detailing in my responses.

Yes I know what an MPEG decoder does, yes I know about colour space conversions, re-digitisation of analogue signals and all of that.
Allan... you're right that a display device doesn't necessarily have an MPEG decoder (although some which have SD memory card slots DO have them - so it's not an absolute). You're also right that not all display devices will do any more than upscale a digitally fed image... but SOME do.

It's this lack of absolutes in the destination component that absolutely warrants the necessity for the home dem.

Incidentally... I do agree with the future-proofing aspect of popping in an HDMI cable too... if gloop buys SKYHD or Virgin V+ his n-Vi will not video switch... and if the projector only has one HDMI or DVI socket then he will ABSOLUTELY need to use component to feed the n-Vi to it anyway.


Without going into another discussion Allan, I think you understand what I'm trying to get across, and I don't believe you're misrepresenting me. I've handed over (and freely, of my own will) too many hours of my life to this thread. I'm afraid I must bow out of this thread, safe in the knowledge that gloop will find what's right for him by home dem, but before the sheer frustration of having my words and help continually questioned leads me towards an ill-advised, frustrated, and un-gentlemanly response towards the next inquisitor.


All the best

Mike