S-Video hack for DTV converter box?

In alt.engineering.electrical Bill R wrote:
| DaveC wrote:
| I like the programmable feature of the DTV Pal (Dish Network) converter box.
| The one drawback is that it doesn't output S-Video.
|
| I haven't received it yet, so I can't crack it open and give component
| specifics but are the video chips that are common in these boxes capable of
| both composite and S-Video output? Is it likely that only a connector and a
| bit of wire is all that is needed for a slightly better signal output?
|
| Thanks,
|
| It would be much simpler to buy a composite to s-video adapter. Places
| like MCM Electronics sell them for $4.99 (part number 33-0001 for the
| "S" male to RCA female version).

The whole point of S-video is to avoid ever combining the Y and C signals in
the first place, because it is so hard to separate them. You might as well
let the TV's composite input separate them, unless the composite to S-video
converter you get is a "perfect" design (and this would be very expensive).

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| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

So, it's time to
peel off the lid and tell us what chips are actually in the box.

When it arrives, I'll do that.

Thanks,
--
DaveC

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Please reply in the news group

Greegor writes:

On Feb 19, 3:27*pm, "Joel Koltner"
wrote:
"Bill R" wrote in message

...

It would be much simpler to buy a composite to s-video adapter.

Yeah, but then the image quality is no better than the original composite
signal. *For a larger TV set, this difference is noticeable.

Is/was S-video ever really better quality signals than Composite
video?

Yes S-video is technically better and in real life usually noticeable
better than composite video. Especially when the the video source
and/or receiver side are not up to be best "professional video"
quality, the composite video picture quality is often not the
best possible and S-video is considerably sharper especialy on
demandign material (for example computer screen graphics to TV).
Very good professional video equipment can work with composite
video signal from cameras so well that it is hard to tell if
composite video or S-video interface is used.

My impression is that converting between the two was only a
matter of routing the right pin.

It is more than that.
Converting from S-video to composite video is just matter of
combining signals from two pins on S-video connector to
one signal pin on composite video connector. Simplest
as simple as this
http://www.epanorama.net/circuits/svideo2cvideo.html

Y-ground------------------+
+---------- RCA/composite ground
C-ground------------------+

Y-------------------------+
+--------- RCA/composite video
C------------||-----------+
470pF

The opposite direction, from composite video to S-video, with
good image quality is much much more complicated.
It can be done with some passive filtering circuitry with
not very optimal picture quality (needs different component
values for PAL and NTSC video standards). Very good quality
will need pretty complicated signal processing circuitry.

Was the alleged higher quality (S-Video over composite)
by virtue of the type of cabling as opposed to the
signal sent through it?

http://www.mcmelectronics.com/produc...-322G-/33-0001

$7.89

Features:
This high quality adaptor converts composite video to S video and S
video to composite video. With a male S VHS connector on one end and a
female RCA type connector on the other (#33-0001), only a standard RCA
type video cable is required for connection or you can match the S-
video adaptor to your cables. The adaptor measures only 13/4" long and
1/2" in diameter allowing it to plug directly into the equipment and
solves the problems associated with mixing composite and S–video
inputs and outputs.
Note: This unit is a passive device and although it will allow
composite video signals to be used in S video inputs the signal will
remain the quality of composite video.

I have my doubts on the quality it can do the composite video to S video
conversion. With such passivode converter the result could
be anything from not so good to useable, but never "crystal clear".
With good quality equipment that has composite video input
and S-video inputs, wiring the composite vidoe signal to composite
video input will give you better image quality than with passive
composite video to S-video converter to S-video input.
The best image quality would be available if you can get S-video
from your signal source to S-video input on display device
(or some even better video interface if you have such option).

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/

On Thu, 19 Feb 2009 13:10:00 -0800, DaveC wrote:

I like the programmable feature of the DTV Pal (Dish Network) converter box.
The one drawback is that it doesn't output S-Video.

I haven't received it yet, so I can't crack it open and give component
specifics but are the video chips that are common in these boxes capable of
both composite and S-Video output? Is it likely that only a connector and a
bit of wire is all that is needed for a slightly better signal output?

Thanks,

There is a list of converters with S-video he
http://www.ezdigitaltv.com/Additiona...es_Matrix.html

John