Connect with us

Convert Composite to S-Video

Discussion in 'Electronic Design' started by Ardent, Mar 8, 2006.

Scroll to continue with content
  1. Ardent

    Ardent Guest

    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.
  2. Guest

    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.
  3. 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...

  4. Ardent

    Ardent Guest

    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.
  5. 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

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

Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day