Dieter wrote:
I noticed a strange thing while looking at DVD players (I guess Blu-Ray
players now). Most of them say that they will up-convert your old DVDs
to 1020 format. This strikes me as quite odd since my HD TV (as is the
case for all flat panels) has to contain its own scan converter to
display various formats. This would make this a very unnecessary
feature. It would appear even worse if you had a display with less than
1020 lines. There are a lot of 768 line displays especially in the
sizes less than 40 inches. If it really does this, you would first up
convert to 1020 and then down convert to 768. I doubt that that would
improve the picture quality compared with a single up convert to 768. :-)
IAC, we should avoid using a scan converter to convert the output to
match the screen -- we should simply be able to match the output format
to the screen being used. We would only need a scan converter when a
video image is going to fill part of the screen. Most chips have this
built in.
I assume you mean 1080 not 1020.
Hands haven't been cooperating lately. :-)
I've read that a lot of HDTVs have a poor quality scaler, so SD input
looks really bad. If the DVD player has a better scaler than the TV
it could be worthwhile.
That is an interesting theory, but since there are three vertical sizes,
a TV is going to have to do a lot of scaling even if it has a 1080 screen.
I agree that it would surely be better to scale it once to the actual
native resolution of the display than to scale it multiple times.
Even so there are scaling artifacts which can be annoying. :-(
Can you feed a 768 line picture to these TVs, or do they only accept
480i, 720p and 1080[ip]? For 720p I'd just letterbox it and avoid the
scaling artifacts. Having an option to not scale 480 would be nice to
have, although it would probably be rarely used.
I suppose that it depends on the TV, but most chips that have a scaler
that I have looked at are totally programmable but it would still depend
on the firmware in the set. Many TVs have a VGA or DVI plug and I don't
know how they handle but it would be nice if formats larger than
standard VGA could be displayed at full screen height.
The ethervideo box needs a scaler, since the input could be 1080i
and the output could be a 480i TV. Analog TVs don't have a scaler,
or any way to input 1080i.
Or the video might not be displayed as full screen.
Does anyone know what the horizontal resolution limit is for s-video?
Some analog TVs have surprisingly high horizontal resolution.
That is a good question. Clearly, there are limits on the frequency
response of, first, the connectors (HDMI has stripline connectors) and,
second, (possibly) the cable being used. There is no theoretical
limitations since the color channel has the standard NTSC (, PAL, or
SECAM) phase and amplitude (vector) modulated color signal but since it
is not modulated with the color subcarrier and combined with Y there is
no limit on the maximum frequency of the Y channel.
--
JRT
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