[mythtv-users] VGA to component cables

Stroller linux.luser at myrealbox.com
Fri Jan 5 06:05:42 UTC 2007


On 5 Jan 2007, at 05:01, Ow Mun Heng wrote:

> On Fri, 2007-01-05 at 15:55 +1100, Bill Williamson wrote:
>> On 1/5/07, Ow Mun Heng <Ow.Mun.Heng at wdc.com> wrote:
>>> Y not try some DIY 1st???
>>>
>>> http://www.myhometheater.homestead.com/vgacable.html
>>
>>
>> That will not do what he wants.  That takes component and then allows
>> it to be displayed on devices which have a "VGA" plug (HD15) which
>> ALSO accepts component (usually projectors).  It's a DIY version of
>> this: http://store.infocus.com/escalate/store/DetailPage? 
>> pls=infocus&bc=infocus&pc=SP-VESA-ADPT- 
>> R&tab=desc&clist=017080322b69:017080322b6b&ret=Accessories-Cables 
>> +and+Adapters&pls5catname=Accessories-Cables+and+Adapters
>>
>> It does NOT do the opposite (take a standard VGA signal and output it
>> in component)
>
> Woooo... My Bad.. I really thought it was doing the opposite.

Actually, it SAYS it is doing the opposite:

    Will I be able to use the VGA to component adapter to watch DVD's
    from my DVD player on my computer monitor?

    Probably not, the adapter just "adapts" it doesn't convert.  Nearly
    all computer monitors need an RGB signal, as compared to the  
component
    (Y, Pr, Pb) signal that a DVD player outputs.  To view a component
    signal on an RGB monitor requires a transcoder, which converts the
    component to an RGB signal.  Many projectors and some rare monitors
    will accept a compent signal via their HD-15 (VGA or RGB) port.
    This is the intended use for this adapter.   Bottom line:  For the
    adapter to work your display device must accept component inputs.

    Will I be able to use the VGA to component adapter to watch my
    computer on my big screen TV?

    You can connect your PC to your wide screen TV if either the TV has
    an RGB (HD-15 or 5 RCA) input or if your computer can output its
    signal in component.  Some video cards can do this natively (some
    ATI) or via a "dongle" (most Radeon cards), some NVIDIA cards have
    component output also.  Bottom line: you'll have to check the specs
    of your video card.  If there is no RGB input on the TC or component
    output from the video card, you'll need to get an RGB to Component
    transcoder, or scan converter (really two names for the same thing).

I think the cause of the confusion is that he talks about "component"  
and shows "YPbPr" in his diagram, yet VGA actually produces RGB (as I  
understand it)  ... and the author also refers to RGB in his VGA  
convertor article.

Component != RGB, although I appreciate this is better understood by  
home-theatre buffs in the UK & Europe than elsewhere.

I believe this kind of homebrew cable is better described in the  
articles at:
   <http://www.nexusuk.org/projects/vga2scart/circuit>
   <http://ryoandr.free.fr/english.html>
   <http://www.avforums.com/forums/showthread.php?t=136811&page=1>
   <http://www.mythtv.org/wiki/index.php/RGB_Scart>
Compare the pin-to-pin connections in these links to those in the  
diagram you linked to.

Stroller.


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