Quote:
Originally Posted by britdiver /forum/post/14326769
...if I get really close to the screen (50 inch plasma) it looks a little "snowy" but of course it may always look like that and I never look that closely. I guess I'm now paranoid that the quality has dropped whereas it probably hasn't.
It depends somewhat on what you mean by "snowy." Many images will look mottled at fine detail in solid color areas, simply because the source material is like that. For example, motion picture film often has a sort of dye-cloud effect in dark areas which is part of the nature of the film; if you're viewing this in close detail it might seem "snowy" in a way.
Pixel-dropout sparkle with a failing HDMI cable is pretty obvious. Usually the dropout pixels will either render as white or as a solid primary color (for some reason I see them in green fairly often), and usually they'll all be the same color. Accordingly, if you see lots of green or white one-pixel sized dots all over your screen, that's probably HDMI pixel dropouts. If, instead, you feel that you're seeing a bit of crawly, cloudy, random color in solid color areas that's probably simply what the source material looks like. Sometimes you'll see the latter for the first time when you view material at higher resolution than before, simply because lower-resolution gear tends to smear out these dye-cloud kinds of effects. At the extreme, standard VHS tape, for example, will pretty well obliterate that effect because it simply can't provide enough color definition or resolution to distinguish small areas from horizontally-adjacent areas sharply.
Quote:
Originally Posted by britdiver /forum/post/14326769
...does an analog source upscaled by Tivo to 1080i generate the same data as if it came from a 1080i channel? If that's the case any differences between channels must be from my source (cable provider) rather than "interference". Does that make sense?
I'm not quite sure what you're asking here but will give it a whirl.
An analog source upscaled by your HD Tivo is NTSC standard-def. The source itself being analog, and being by the nature of NTSC rather low-quality, it will differ from a native 1080i digital broadcast or cable (ATSC or QAM) signal considerably. If you are seeing a lot of noise in it, it is fairly likely that that's because the signal coming into your home has a lot of noise in it; this is quite common as most cable companies do an absolutely wretched job of keeping signal quality clean. I have Comcast here in Seattle and the analog channels have always looked atrocious.
I am not sure how the TiVo handles these internally but my guess would be that it encodes the NTSC broadcast in MPEG-2 and sticks that on the drive; then, at playback, it upscales it, and delivers that upscaled image through the HDMI port. The datastream it sends through the HDMI port will have the same basic characteristics as it would if the original source had been an ATSC or QAM channel, but of course the quality of the picture that datastream represents may be considerably different.
Quote:
Originally Posted by britdiver /forum/post/14326769
Finally I have seen "pixelation" on digital or HD channels sometimes, how does that differ in appearance from "interference sparks" or HDMI signal quality issues?
If by pixellation you mean that areas of the screen become consolidated into multi-pixel rectangular blocks of the same color (which is also called "macro-blocking") then this will look completely different from HDMI signal quality issues. HDMI is run uncompressed and cannot cause macroblocking; if you see macroblocking, that's in the source.
If I've misunderstood any of what you've asked or you need some further explanation, let me know...
Kurt
Blue Jeans Cable