[mythtv-users] vga to component converters

Erich Boleyn erich at uruk.org
Mon Sep 26 21:29:32 UTC 2005


Cory Papenfuss <papenfuss at juneau.me.vt.edu> wrote:

> On Mon, 26 Sep 2005, Erich Boleyn wrote:
...
> > Here's what I did:
> >  --  NVidia FX 5200 w/2 outputs, one DVI and one VGA.
> >  --  Tube TV is an AdventTV 32" HDTV model.
> >  --  Using NVidia proprietary drivers.
> >  --  1280x960 32-bit color buffer.
> >  --  One putting out 1280x960 @ 75 Hz.
> >  --  One putting out 1280x960 interlaced using this modeline:
> >        ModeLine "1280x960hdtv" 54.540 1280 1424 1480 1616 960 1016 1032 1124 
> interlace +hsync +vsync
> >
> > NOTE:  I first tried a 480p mode with no lasting success (it would glitch
> > regularly, looked like a sync issue), and only after some experimentation
> > got the 960 interlaced line above working stably.
> >
>  	Component is almost exactly the same as RGB on a VGA port.  The 
> only significant difference is that the color has been transformed into 
> YPbPr.  There are a number of schematics and howtos out there on how to 
> build your own transcoder.  If you are too lazy to do that, but one for 
> $100.
> 
>  	Also, resolutions on digital DV are not nearly as wishy-washy and 
> ill-defined as for analog NTSC/PAL.
> 
> 480p :=  720x480   @ 60Hz frame, 60Hz field rate, 31.5kHz Horiz
> 720p :=  1280x720  @ 60Hz frame, 60Hz field rate, 44.9kHz Horiz
> 1080i := 1920x1080 @ 30Hz frame, 60Hz field rate, 33.75kHz Horiz
> 
> (e.g. http://videosystems.com/mag/video_getting_tune_dtv/)
> 
>  	One can quibble about 1080p at 24, 480p at 59.9 Hz, etc, but the above 
> are the de-facto definitions.  Why would someone use a 1280x960 modeline 
> to output to a HDTV?  It's not a standard size and barely a standard 
> frequency.  The computer and/or the HDTV will be doing scaling.

It made it so I could use a single computer to output to both a high-end
presentation monitor (which could do 1280x960 @ 75 Hz) and the HDTV
at the same time with synched output.  Worked pretty well once I got
modelines that worked.

I then used some old Cybex KVM gear for distributing it throughout
my house to multiple locations.  The Presentation monitor, some LCD
monitors, and the tube HDTV.


>  	Do yourself a favor... read some of the HOWTOs on modeline 
> generation (e.g. the one in the mythtv wiki that someone copied from one 
> of my previous posts).  Random tweaking of numbers in a modeline is a good 
> way to destroy a monitor/tv.

I tried using exact timings to standard modes, and the TV was not very
cooperative.  I think the sync pulses coming out of the A960 are not what
it expects, or that the TV expects something somewhat different than the
standards officially call for.

In any case, I am no longer using the above setup.  I've gone all LCD
at 1080p or 720p.


--
    Erich Stefan Boleyn     <erich at uruk.org>     http://www.uruk.org/
"Reality is truly stranger than fiction; Probably why fiction is so popular"


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