[linux-dvb] Re: Help with J2 RGB

[Emil Naepflein <Emil.Naepflein@philosys.de>]

On Fri, 30 Apr 2004 07:34:42 +1000, Michal Dobrzynski
<michal_dobrzynski@mac.com> wrote:

> In an email sent to me rather than the list you mentioned the 
> following. I hope you don't mind me forwarding this part to the list as 
> I wanted further opinions.

No, it is just the brain-dead setting of this mailing list which always
causes this problem. :(

> So I'd just like to know whether I have indeed been chasing an 
> impossible dream with the RGB output of J2. Is it true that in practice 
> the RGB  will not give a visibly better picture than the S-Video? 

The step from composite to s-video is really big. From s-video to RGB
the step is visable but much smaller if high quality s-video cable is
used. It is also dependend on the processing in the display device. 

> I 
> certainly know that on my STB and DVD players the RGB gives a 
> significantly better picture than S-Video. Is this impossible due to 
> the noise in the PC?

I don't expect much improvement.
 
> If it is impossible then why have so many on the list claimed that this 
> is the best way to go?

Do this people that claimed use RGB connection by themself?
What did they do exactly to tap the signals without much interference
from the environment?

Theoretically RGB is better than S-Video, but has really someone
practical experience?

> Furthermore is it significant that I am connecting the 75 Ohm resistors 
> to the J2 ground at the SCART end? Should I be connecting to the SCART 
> ground? 

This doesn't matter.

> Indeed is SCART from the TV delivering ground on pin 21? How 
> about all the other ground signals on the SCART? Would it be better to 
> connect the resistors to the SCART ground coming from the TV? Or would 
> it be better to connect them to the J2 ground at the J2 end?

It doesn't matter because all the ground signals *must* be connected
otherwise you would get floading signals which may fry electronic
components.

> But wait, there more! What about shielding? How can I effectively 
> shield the connectors at the SCART end? It's all essentially out in the 
> open INSIDE the PC case. I could take photos to help explain what I 
> mean.

You can use shielded cable and can put shielding around the connector.
It is important that everything is connected to ground.

> I have secondary reason for wanting to use RGB though and that is so 
> that I can use the pass through on my STB and DVD player to have 
> everything going through one AV input and therefore one channel on the 
> TV (for usability purposes associated with my parents). I have already 
> tested that with good SCART cables there is no visible reduction in 
> image quality. In order for this to work though all devices must be set 
> to RGB output as the AV input on the TV is manually set to RGB and 
> displays a black screen if the signal it gets is not RGB.

I understand your requirement and agree that you should go for it. But
you really need experience from someone who already has done this. As
the response in this list was not that great I would try it also in the
vdr list because not everyone reads both lists. You could als give
vdrportal a try in the hardware section. Someone must have provided this
filter circuit for a good reason.

Emil


-- 
Info:
To unsubscribe send a mail to ecartis@linuxtv.org with "unsubscribe linux-dvb" as subject.