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Question on resolution with cable content and DLP

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Anonymous
September 4, 2004 12:01:09 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Here's my setup:

Samsung HLP-5063W
Motorola DCT6200
Adelphia Cable
Component

The Motorola STB is currently set on 1080i. I'm assuming that the TV
converts that signal to its native 720p (although the info box for each
station, including ABC-HD which outputs in 720p, indicates 1980x1080).

I can set the STB to 480i, 480p, but it won't let me set it to 720p. Why is
that? And, if the TV is converting to 720p anyway, why does the info box
indicate 1080i?

I also have the 4:3 override set to "None" which gives me a much better
picture for SDTV stations than 480p, and I don't have to reset the picture
size of the TV to 4:3 to prevent the stretching. This I understand, since
the outputting of SDTV in 1080i will automatically format with the black
side bars so it will present correctly in widescreen.

But could someone just give me a brief description of how and when
conversions are taking place with this setup?

Bruce
Anonymous
September 4, 2004 8:28:42 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

There are two places where scaling of the video can take place: in the STB
and in the DLP. There are a couple things to keep in mind to get the best
possible picture:

1) Fewer conversions of the picture will result in less numerical error and
better picture.
2) The DLP uses Faroudja scaling technology which is the best. Therefore
the DLP is better suited to doing the scaling than the STB.

That's odd that you can't get a 720p signal out of the box. It seems to me
I've heard something about this before. Maybe someone else will post
something. Maybe your box needs a firmware upgrade or something.

It may not be such a bad thing that you have it set to 1080i. At least for
all the 1080i HD material out there I believe you'll be getting the best
quality picture you could. I say that because then the STB outputs the
video in its native resolution and the DLP will use the Faroudja technology
to scale the image to 720p. Unfortunately for 720p material the STB will be
upscaling to 1080i and then the DLP will be down-scaling it to 720p again.
That's not very good for your signal quality (though it will probably still
look pretty darn good since it's HD). If there were a way to have the STB
just output the native format that would be best but it doesn't look like
that's an option.

For the 4:3 override I recommend that you try setting it to 480i. The
reason for that is that the STB will then output SDTV in its native format
and allow the Faroudja to upscale it to 720p. The reason it didn't look
very good when you set it to 480p is because then you have two conversions
taking place. The STB deinterlaces the picture to make it 480p and then the
DLP upscales it to 720p. It would be better to have the DLP do this all in
one shot.

Brad

"Bruiser" <noth@nks.com> wrote in message
news:b8GdndbQtN0hRaTcRVn-jw@giganews.com...
> Here's my setup:
>
> Samsung HLP-5063W
> Motorola DCT6200
> Adelphia Cable
> Component
>
> The Motorola STB is currently set on 1080i. I'm assuming that the TV
> converts that signal to its native 720p (although the info box for each
> station, including ABC-HD which outputs in 720p, indicates 1980x1080).
>
> I can set the STB to 480i, 480p, but it won't let me set it to 720p. Why
> is
> that? And, if the TV is converting to 720p anyway, why does the info box
> indicate 1080i?
>
> I also have the 4:3 override set to "None" which gives me a much better
> picture for SDTV stations than 480p, and I don't have to reset the picture
> size of the TV to 4:3 to prevent the stretching. This I understand, since
> the outputting of SDTV in 1080i will automatically format with the black
> side bars so it will present correctly in widescreen.
>
> But could someone just give me a brief description of how and when
> conversions are taking place with this setup?
>
> Bruce
>
>
Anonymous
September 4, 2004 8:28:43 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Brad Griffis wrote:
>> There are two places where scaling of the video can take place: in
>> the STB and in the DLP. There are a couple things to keep in mind
>> to get the best possible picture:
>>
>> 1) Fewer conversions of the picture will result in less numerical
>> error and better picture.
>> 2) The DLP uses Faroudja scaling technology which is the best.
>> Therefore the DLP is better suited to doing the scaling than the STB.

I understand those points. What exactly is the resolution as it comes from
the cable into the box? All SDTV channels are 480i and the HD ones 1080i,
with ABC and ESPN at 720p, correct?

>> That's odd that you can't get a 720p signal out of the box. It
>> seems to me I've heard something about this before. Maybe someone
>> else will post something. Maybe your box needs a firmware upgrade
>> or something.

The box was installed just a couple of weeks ago. My understanding is that
any firmware upgrades are done automatically through the cable, but I may be
misinformed about that.

When the two "kids" were installing, I mentioned to the one configuring the
box that the set's native was 720p, to which he replied, "Well, that's not
HiDef. Only 1080i is." I didn't say anything (I don't know alot about HD,
but I knew that was wrong) and let them finish. Afterwards, I experimented
with the box's menu and it can't switch over to 720p. It keeps trying but it
never finishes and gets back to the menu as it will with the others. I
figured this had to do with how Adelphia is transmitting, but I guess not.

>> It may not be such a bad thing that you have it set to 1080i. At
>> least for all the 1080i HD material out there I believe you'll be
>> getting the best quality picture you could. I say that because then
>> the STB outputs the video in its native resolution and the DLP will
>> use the Faroudja technology to scale the image to 720p.
>> Unfortunately for 720p material the STB will be upscaling to 1080i
>> and then the DLP will be down-scaling it to 720p again. That's not
>> very good for your signal quality (though it will probably still
>> look pretty darn good since it's HD). If there were a way to have
>> the STB just output the native format that would be best but it
>> doesn't look like that's an option.

Right, the only output options are 1080i, 720p (unavailable), 480p, 480i.
And I gather that the info box the DLP offers on each channel depicts the
resolution of the signal it is receiving (which is why it indicates
1980x1080i/60Hz for everything), not what is actually being seen on the
screen.

>> For the 4:3 override I recommend that you try setting it to 480i.
>> The reason for that is that the STB will then output SDTV in its
>> native format and allow the Faroudja to upscale it to 720p. The
>> reason it didn't look very good when you set it to 480p is because
>> then you have two conversions taking place. The STB deinterlaces
>> the picture to make it 480p and then the DLP upscales it to 720p.
>> It would be better to have the DLP do this all in one shot.

After I posted I went back and checked that myself, and I did see that
setting it to 480i was, indeed, better than 480p, but looked about the same
as setting it to "none" (even tho' there is that one extra conversion the
box is doing from 480i to 1080i). The trouble with the 480i setting, though,
is that every time I go to an SDTV channel I have to adjust the picture size
down from Wide to 4:3, then back again to Wide to view an HDTV channel. That
gets a little tedious, after a while.

Thanks for the clarifications, Brad.


>> "Bruiser" <noth@nks.com> wrote in message
>> news:b8GdndbQtN0hRaTcRVn-jw@giganews.com...
>>> Here's my setup:
>>>
>>> Samsung HLP-5063W
>>> Motorola DCT6200
>>> Adelphia Cable
>>> Component
>>>
>>> The Motorola STB is currently set on 1080i. I'm assuming that the TV
>>> converts that signal to its native 720p (although the info box for
>>> each station, including ABC-HD which outputs in 720p, indicates
>>> 1980x1080).
>>>
>>> I can set the STB to 480i, 480p, but it won't let me set it to
>>> 720p. Why is
>>> that? And, if the TV is converting to 720p anyway, why does the
>>> info box indicate 1080i?
>>>
>>> I also have the 4:3 override set to "None" which gives me a much
>>> better picture for SDTV stations than 480p, and I don't have to
>>> reset the picture size of the TV to 4:3 to prevent the stretching.
>>> This I understand, since the outputting of SDTV in 1080i will
>>> automatically format with the black side bars so it will present
>>> correctly in widescreen.
>>>
>>> But could someone just give me a brief description of how and when
>>> conversions are taking place with this setup?
>>>
>>> Bruce
Anonymous
September 4, 2004 8:28:44 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Bruiser wrote:
<SNIP>


>> The trouble with the 480i setting, though, is that every time I go to an
>> SDTV
>> channel I have to adjust the picture size down from Wide to 4:3,
>> then back again to Wide to view an HDTV channel. That gets a little
>> tedious, after a while.

Nope, I was wrong. With the override set to 480i, the picture size *will*
automatically go to 4:3 for SDTV and back to Wide for HDTV when changing
channels (I think it defaults to the last size selected, I'm not sure). And,
I also have the Zoom/Panorama sizes available if I want them, with the PQ
looking pretty darn good. I'll keep it on 480i then. Thanks for that tip.

Bruce
!