Re: RGB to Component video converter (SCART)

["Charlie" <charlieDOTd@verEYEzon.net>]

"Michael J. Mahon" <mjmahon@aol.com> wrote in message 
V5adnbcn4JDnGKLbnZ2dnUVZ_revnZ2d@comcast.com">news:V5adnbcn4JDnGKLbnZ2dnUVZ_revnZ2d@comcast.com...
> Charlie wrote:
>> "Michael J. Mahon" <mjmahon@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.
>

Thank you for the clarification.


>> 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.
>

Okay

>>  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,

Yes, it is a combination 1440x900 (19" wide screen) LCD monitor and HD TV 
with just about every type of video input.

> 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.
>


Yes, the pattern is constant and consistent over the width of the display. 
I do want to make clear that this pattern is not very bad (at least to my 
eye). Its better than the fuzziness of my failing IIgs monitor and the 
picture is a lot bigger which is better for my failing eyes.


>> 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.

I now understand your interest.

Charlie