Convert Composite to S-Video

[Ardent]

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Hi Gurus over there !

Using Tomi Engdahl's solution (470 pf cap connecting C to Y) to
connect the RCA output of my VidCam to the S-Video socket in my
Capture Card I get the video ok but the picture shows wavy lines like
serrations across the screen - a search in Google indicates this is
common with such simple solution.

Anyway I am looking for a circuit to split the composite video so that
I can have the pleasure to build one. I would rather not go for chips
like AD725 but require a circuit that uses basic components.

If one of you know of such a circuit or have the link for one, will
you please let me have it?

Thanks in advance for your time and attention.

 

[[email protected]]

Using Tomi Engdahl's solution (470 pf cap connecting C to Y) to
connect the RCA output of my VidCam to the S-Video socket in my
Capture Card I get the video ok but the picture shows wavy lines like
serrations across the screen - a search in Google indicates this is
common with such simple solution.

What happens if you

1) build it in a small shielded enclosure using shielded cables

2) try it without the cap, so that you are driving only the luma? Does
this at least get rid of the interference?

For common consumer Brooktree/Conexant/Fusion/whatever type chip video
capture cards, the luma half of the S video in (if it is implemented)
is connected to a pin (multiplexer input actually) that is also able to
receive composite video, while the chroma is fed into a seperate pin.
So if your card has one of these, all you might need to do is set the
approriate option to the driver.

 

[martin griffith]

X-No-Archive: yes

Hi Gurus over there !

Using Tomi Engdahl's solution (470 pf cap connecting C to Y) to
connect the RCA output of my VidCam to the S-Video socket in my
Capture Card I get the video ok but the picture shows wavy lines like
serrations across the screen - a search in Google indicates this is
common with such simple solution.

Anyway I am looking for a circuit to split the composite video so that
I can have the pleasure to build one. I would rather not go for chips
like AD725 but require a circuit that uses basic components.

If one of you know of such a circuit or have the link for one, will
you please let me have it?

Thanks in advance for your time and attention.

You need to remove the chroma from the composite feed . You have
chroma info on both C and Y, so I suggest that they are being mixed,
so you get patterning. Maybe a lump of 75 ohm coax, on the Y sig,
unterminated, will notch out your subcarrier. Cant remember the
correct length... http://www.kyes.com/antenna/coaxfilter.html


martin

 

[Ardent]

X-No-Archive: yes

You need to remove the chroma from the composite feed . You have
chroma info on both C and Y, so I suggest that they are being mixed,
so you get patterning. Maybe a lump of 75 ohm coax, on the Y sig,
unterminated, will notch out your subcarrier. Cant remember the
correct length... http://www.kyes.com/antenna/coaxfilter.html

Yes, that seems to be obvious route. I have seen the above page and
will try to work out a filter.

And thank you very much for the lead. Thanks to the others also who
tried to help me.

 

[Glenn Gundlach]

X-No-Archive: yes



Yes, that seems to be obvious route. I have seen the above page and
will try to work out a filter.

And thank you very much for the lead. Thanks to the others also who
tried to help me.

Whatever for? Simply filtering the video to separate chroma/luma is a
'trap'. This is what is already in the cheapest TV sets. To do it right
(as in it actually looks better) requires a 3 line adaptive comb
filter. These are already in the better grade TV sets. So again, what
for?

I think Motorola had a digital 3 line comb IC 10+ years ago. I believe
it needed sync and 4x subcarrier to work.

GG