Re: RGB to Component video converter (SCART)

[nyder <nyder.23@gmail.com>]

On May 7, 1:00 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:
> Charlie wrote:
> > "Michael J. Mahon" <mjma...@aol.com> wrote in message
> >5vSdnYkGg6mtYqPbnZ2dnUVZ_q2pnZ2d@comcast.com">news:5vSdnYkGg6mtYqPbnZ2dnUVZ_q2pnZ2d@comcast.com...
>
> >>mdj wrote:
>
> >>>On May 7, 8:38 am, "Michael J. Mahon" <mjma...@aol.com> wrote:
>
> >>>>I was thinking that the white RCA connector could also be a sync
> >>>>output...  But, IIRC, the SCART connector does have power, right?
>
> >>>Unfortunately, no. It provides stereo sound in/out, composite video in/
> >>>out, and RGB in/out. The later revisions of the standard allow the RGB
> >>>signal pins to carry either YUV or S-Video. IIRC, YUV isn't even a
> >>>part of the standard.
>
> >>>There's also pins for the D2B automation bus and a signalling pin for
> >>>16:9/4:3 source identification.
>
> >>>So that white connector could also be composite sync input. Perhaps
> >>>the power connection is obscured somehow.
>
> >>OK, my apologies...I thought all those RCA jacks were *outputs*!
> >>After all, it does say RGB *to* component, and SCART is RGB, right?
>
> >>And it also says:
>
> >>* BRAND NEW; Scart (male) to Component (female) Adapter.
> >>* For 'RGB' scart video signal to high quality 'Y/U/V' component video
> >>  signal.
> >>* Signal output from DVD players, Freeview, Sky or Sky+ set-top boxes
> >>  to Component Video.
>
> >>That sure *sounds* like it accepts an RGB signal on the SCART side
> >>and outputs a Component signal on the RCA side.
>
> >>I thought that SCART was also an *output* connector for AV equipment,
> >>and that it would supply RGB that this box would convert to component.
> >>(And with all those pins, not supplying a little power seems like an
> >>oversight...)
>
> >>Does anyone know what this $5 thing actually does?
> >>(I'm pretty sure that the $60 box does what I described.)
>
> >>In any event, this would be a straightforward way to drive a modern
> >>TV from a IIgs RGB signal, perhaps.
>
> > Michael,
>
> > Okay, I'm a little confused.  What is the difference between RGB component
> > video and Y/U/V component video?
>
> RGB is one thing, Component is another--and Y/U/V is another way of
> saying "component".
>
> "Component" is not commonly used to refer to RGB.
>
> RGB is three, high-bandwidth analog video signals, one per primary color
> of the display device.
>
> Component refers to three analog signals:  the high-bandwidth luminance
> signal (Y), and the (usually lower bandwidth) color difference signals
> called B-Y (or Pb or U) and R-Y (or Pr or V).  (These different names
> actually refer to different matrix factors used in forming the signals
> and their levels, so they are not *really* identical, though their
> usage is quite similar.)
>
> RGB is a standard native to tri-color displays and computer graphics
> systems, while component video is native to video recording and
> transmission systems.  Component video, with its typically reduced
> bandwidth chroma channels, is better suited to video transmission.
>
> > And more important to me, would either one
> > of the boxes (assuming they do what they advertise) give me a better screen
> > image than just running the IIgs output into my Monitor/TV with Roger
> > Johnstone's IIgs to SCART cable?
>
> No, direct analog RGB output to an RGB input is the best you can do.
>
> >  As it stands now I get a usable but not
> > perfect picture.  The only problem seems to be in the transition from one
> > color to another horizontally.  For instance, if you have a line of
> > horizontal black pixels which turn to white there will be one pixel at the
> > transition that is gray.  This creates a horizontal ghosting effect that can
> > be reduced by judicious adjusting of the contrast and sharpness, but some
> > color combinations are worse than others.  I had the impression from past
> > threads that this ghosting effect was caused by the monitor not being able
> > to sync with the IIgs signal frequency.
>
> I presume you are using a digital monitor, and you are correct, the
> "intermediate" value pixel is the result of the sampling clock of the
> monitor not being locked to the dot clock of the IIgs.  If the pattern
> of gray pixels is constant and consistent over the width of the display,
> then your monitor may have locked to a multiple of the dot clock.
>
> > My monitor/TV (Samsung SyncMaster 940mw) will accept several types of video
> > input including both SCART and component video but to further confuse me the
> > component video input is listed as Pr, Pb, Y.
>
> Those are the common names for the "components" of "component video".
>
> The reason for my interest in good, inexpensive RGB to component
> converters is that in the US, HD monitors typically do not have RGB
> inputs, but they often do have component inputs.  Since component
> signals can be created from RGB signals by analog matrixing (combination
> with specific weighting factors), such converters are, in principle,
> very simple.  Unfortunately, they also seem to be relatively low volume,
> so their simplicity often is not reflected in their price.
>
> -michael
>
> NadaNet file server for Apple II computers!
> Home page:  http://members.aol.com/MJMahon/
>
> "The wastebasket is our most important design
> tool--and it's seriously underused."



Does the IIGS output analog or digital RGB?