Samik R said:
Hello,
I have a old PC (Pentium II/488MHz/128MB RAM (Dell)) which I was
planning to use as a media player. The PC has a ATI 3D Rage Pro AGP 2X
(GT-C2U2) graphics card, which is supposedly capable of TV out. But when I
go to Display Properties->Settings->Advanced, there is no setting for TV
out. Can anybody help me out in getting this? Do I need to install new
driver? I went to the ATI website, and the closest I could see is this:
https://support.ati.com/ics/support/KBAnswer.asp?questionID=1298
This is the Windows XP Display Driver version 5.10.2600.6010 for RAGE
PRO. Is this the one I should try out?
Any other suggestions or pointers?
My basic aim is to use VGA to S-Video/RCA converters to get the display
on TV. All these converters (at ebay) mention that "It will work with VGA
cards that has TV-Out function capability through the VGA connector. Check
your Video Card manual or manufacturer to make sure that your VGA card has
TV-Out function capability."
In the past, I did see a reference to such a conversion method.
Basically, the VGA outputs from the video card are added together
with some weightings, to develop an electrical signal. The
claim is, that this adapter produces monochrome.
http://www.epanorama.net/circuits/vga2tv/composite_adapter.html
What you are trying to achieve, is color output. This document
explains how a color TV signal works. Basically, there is a
short burst of 3.579545 MHz sine waves at the beginning of a line
of dots, and the phase shift of the pixels determines their color.
The height of the electrical signal (amplitude) determine the
saturation of the color. Naturally, this is a lot more complicated
than the concepts used to make the monochrome adapter mentioned
above.
http://pdfserv.maxim-ic.com/en/an/AN734.pdf
If I am reading this thread correctly, a couple of people have
bought adapter cables like your Ebay one, and didn't manage to
get them working. Obviously, to generate the color burst signal,
the video card has to have some kind of hardware support for the
mode in question. My theory would be, that the video card
does most of the work here, and the cable is not as clever as
the design of the one in the first link above. After all, phase
shifting the pixels is something that only the video card can
do. So the cable is rather a sham in this case. It _might_
be doing something as simple, as taking one color gun output
and just routing that to an RCA connector.
http://www.meedio.com/forum/viewtopic.php?t=24140
Another device for converting VGA to some kind of video signal,
is a scan converter. Having seen one in action, it does seem
to do a better job than your average TV-out signal, and some
of these claim to handle quite high PC resolutions. Now, how
this is possible is a bit puzzling, as the composite video signal
has a limited bandwidth, and that bandwidth limit should limit
the sharpness of the pixels. A one pixel wide vertical line
on the screen should disappear, when viewed on the TV. (Maybe
edges get enhanced or something.) So, while the device may
accept a 1600x1200 signal, you cannot expect to read fine
text that way. There have to be some compromises.
http://www.aver.com/2005home/product/pc_to_tv/pc_to_tv.shtml
Your third option, is get a video card with a TV-out signal
on a separate jack (one of the many DIN connector variants
or an RCA output jack). The GPU on a video card, can have a
TV encoder internal to it, while cards a few years old, have a
separate chip on the card to do the encoding (some of them are
good, and some stink).
This web page had a collection of info about the older external
TV output chips. I don't know anything about the TVtool software
itself.
http://tvtool.info/index_e.htm
FAQ mentions CX25871 as the best external TV encoder chip:
http://tvtool.info/go.htm?http://tvtool.info/english/faq_hardware_e.htm
The video card database allows searching for that chip. My GF3
TI200 card, has one of the bad chips on it :-(
http://ssl.jbmedia.de/cardbase/cardbase_query.asp?lang=en
To summarize:
1) Conversion cable - a long shot. I'm still looking for an
account of a working combo, especially with comments about
the image quality. Still don't have a technical term for the
mode that the video card must be placed in. Manuals from that
era were likely paper-only, so the odds of finding PDF files
are limited.
2) Scan converter - at one time expensive, some now in the $99+
range.
3) Video card with TV output - lots of these around. Hard to get
info on image quality of very modern cards. Nothing I have
tested here, was really very good (chalk that up to a crappy
TV set I guess). A $50 video card new, maybe less used. Pick
AGP for best bus bandwidth - I don't know if a PCI version of
a card would really be smooth or not, especially on some older
chipsets. Resolution limit of 1024x768, and text is unreadable
most of the time.
To determine what kind of AGP video card upgrades might fit
in the machine, try this page. Your motherboard could be a
3.3V only one, which means a "Universal AGP Card" or
"Universal AGP 3.0 Card" would be the modern solution. In
some cases, you have to double check the info, as there
have been video card products that changed their declared
type, part way through the manufacturing cycle. See
"Matrox Parhelia" as an example of a dangerous manufacturing
transition.
http://www.playtool.com/pages/agpcompat/agp.html
HTH,
Paul
