S-vid vs. rf mod

[skim36]

I got a TV with s-video out to go in my cab.  It's a bit too wide but I have another TV with just rf out.  
 Would there be a big difference in picture if I ran it through an rf modulator?  I think I might test it later...and if it's workable I'll do it.  Just wanted some opinions....and sorry, I'm sure this question has come up before....

[Bgnome]

dont do it!
rf is the worst possible way to go and rf modulators vary in quality from liveably bad to worse.  if you must have a tv in your cab, i would not settle for anything less than s-vid, maybe composite if there was no other alternative.

[skim36]

Yup,

Looks like I'm tearing the TV apart to get it in there.  Not a major maming...just taking the speakers off the sides and see how it goes.  It will have to do til I get the monitor checked out

[MonitorGuru]

Video Quality from best to worse:

1) RGB [Pefrect]
2) YCrCb (Component) [near perfect]
3) Separate (S-Video) [acceptable]
4) Composite [poor]
5) RF [crap]

[anthonylitz]

Ok I am woundering vs this list where does my setup go in?  Ok I know that (at the bottom).

I bought at Radio Shack at s-video -> RCA adapter.  It is just that and about the size of a RCA jack itself.  Do you think this would output to be the same quality as an RF converter?  BTW- for those intrested in this device I described it was like $30(!!!)   But recently I saw them in bulk on e-bay for a few dollars each.

My set up is cpu -> s-video -> adapter -> RCA Cable -> RF converter ->co-ax-> VCR ->co-ax->tv

LOL but hey it works for my home theater/cpu setup.  I have $200 bucks to buy a TV for my cab though I am hopeing it has just plain ol s-video  

Anthony

[skim36]

I got my computer running thru the TV with s-video and it's workable....not as clear as a monitor..some colors...esp red bleed a little, but it's totally playable.  It'll work til

1. I get my old 25" Hantarex to work

2. I buy a new monitor to put in.

BTW...not to steal this thread...but are there any good hybrid 25" monitors out there?  Anyone own one?

[skim36]

oops..this is my thread...(smacks head)

I'll be alright really....

[MonitorGuru]

> "My set up is cpu -> s-video -> adapter -> RCA Cable -> RF converter ->co-ax-> VCR ->co-ax->tv"


OMG -- BARF!


First, each time you go through a connector, you loose, on average, 1db of signal strength.  I count a total of 8 CONNECTORS visible.  Additional components on each connector also lead to signal loss.

Second, each time you go through a CONVERTER, you also loose quality.  E.g. If I convert RGB to component then back to RGB (it's very a simple mathematical formula implemented by various resistors), the RGB out the back end is lower quality then the signal at the front end, even though both are RGB and they only steped down ONE conversion level to a still "very good" quality.    I see at least 11 conversions happening here (read below for the list)

Third each time you go back "up" the chain you don't ever gain quality (except  as a relative comparison in cases where one converter is better than another, e.g. converting SVideo to Component with a high priced converter outside the TV is better than the svideo to component converter in the TV set) but you never get more signal than what is there at the input of the converter.


Given that, here is what you're doing to that poor signal:

Computer outputs digital bits to the video card.
Inside the video card it converts it to analog RGB
The video card then downgrades it inside the chip to Svideo (2 steps down)
The video card then has a connector (signal loss)
You plug a wire into the connector and attach a SVideo -> Composite converter (1 more step down), plus 1 more connection point of signal loss
The other end of the connector gives another point of signal loss when you connect the next wire
The RF Converter then has yet another connector = more signal loss
The RF Converter drops the signal quality 1 more step down.
The RF Converter outputs through another connector, more signal loss
The Coax connects to your VCR, another connector, more signal loss

Here's where it gets even messier:
The VCR converts the RF signal into a channel read by a tuner
It then splits the RF signal into a composite video and audio signal and sends it to the signal processor (it "upded" the signal but can't add back what's already lost, plus is only as good as the tuner can lock it in, and is affected by other stray signals like real TV stations )
Inside the processor it sends it back out to a composite to RF video converter to connect to the coax output on the VCR (signal downgrade to lowest, a second time)
The connector adds another level of signal loss

Then you take a coax cable and run it to your TV.
The TV has a connector for the coax (signal loss)
Inside the TV it converts the RF into a channel in the tuner
It then takes the output of the tuner and converts it to a Composite signal + audio
It then takes the composite signal and produces Separate video from it (Luma + Chroma ---s video)
It then takes this and converts it to color differential video (component) and sends it to the guns on the TV that make pure RGB out of it.


WHEW!   What a process.

A PC VGA video card and an arcade monitor involve 2 connectors, 1 wire and NO signal conversion.   Seem like that would produce a better picture?  Yep!


In any case, you can at least improve your chances of bearable impage quality by doing one or more of these things:

1) Get a VCR that accepts LINE INPUTS instead of just coax.  Then your chain is this:
cpu -> s-video -> adapter -> RCA Cable -> VCR ->co-ax->tv

6 connectors, ~7 signal conversions.


2) Get a TV that accepts LINE INPUTS (Composite) instead of just coax. Then your chain is this:
cpu -> s-video -> adapter -> RCA Cable ->tv

4 connectors, ~5 signal conversions


3) Get a TV that accepts SVideo inputs instead of coax or composite:
cpu -> s-video -> RCA Cable ->tv
2 connectors, ~3 signal conversions

4) Get a TV that accepts Component inputs instead of coax or composite and buy or make  an RGB to Component converter:
cpu -> VGA connector -> wire -> Converter -> Wire -> TV component in

3 connectors, ~1 signal conversions

5) Buy an arcade monitor, use AdvanceMame and AdvanceMenu or Aracde OS -or- buy an arcade monitor and an ArcadeVGA card and use whatever Mame you want:
Cpu->VGA Connector -> wire->Arcade monitor

2 connectors, 0 signal conversions

[skim36]

Wow,

My head is spinning.....thanx monitor guru...you are the king.  Like I said....the picture is acceptable in s-vid til I get the monitor fixed...then I'll switch it out.

[anthonylitz]

Thanks Guru for making my setup feel lowly  No really thanks for the explination, you are very inforative.  

I have a question, I think I read a thread saying there is a component output vga card not, with this setup how is the text on windows, is it unusable like in s-video?

Thanks for the info everyone.

Anthony

[skim36]

I think it would depend on the amount of scanlines in your TV set.  I'm using S-vid and in windows it is hard to see some of the text.  But I have a cheapo TV also....I just use the extra large display properties for windows...it helps.

[Matt, GoC]

How do you make or where do you buy one of those RGB to component cables?  My TV in my cab has component inputs.

[MonitorGuru]

Converting between component and RGB is a simple mathematical formula.  You simply take the green signal, invert it, then produce color differential signals for Red and Blue, and QUARTER their bandwidth (since the human eye is not as sensitive to variations in Red and Blue colors as it is Green).

Therefore it takes 2 adders, 1 inverter and a handful of resistors to do it.

Here is a great site complete with schematic and pictures that show you how to convert RGB to component:
http://www.siliconchip.com.au/cms/A_102648/article.html

[Silver]

 (since the human eye is not as sensitive to variations in Red and Blue colors as it is Green).

This true? I though it was just sensitivity to colour i.e. Luminence (black and white) is given most bandwidth (both in component and S-Vid) and Chrominance (Colour) is dropped in bandwidth as you say. Same in TV signals (4:2:2 - much more Luminence info)

Just curious - apologies for slightly off-topic!