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9800 Pro AIW SVHS capture from VCR: colour flicker

Discussion in 'ATI' started by mglover, Nov 13, 2003.

  1. mglover

    mglover Guest

    I have come across a weird problem in capturing SVHS material from
    VCR, which produces colour flicker, whereas SVHS capture from my DV
    camcorder produces completely clean analogue capture. Let me try to
    explain the problem as clearly as possible:

    1. All of the following refers to MPEG2 capture at DVD quality, but
    the problem is independent of the recording format selected. Also,
    the SVHS tapes to which I'm referring are non-commercial and do not
    have Macrovision etc.

    2. If I capture in the analogue domain from my DV camcorder via the
    SVHS connection, the Radeon will produce a good quality image with no
    significant artefacts.

    3. However, capturing in SVHS from my Panasonic SVHS edit deck
    produces an image that flickers from frame to frame between
    red-saturated and green-saturated. If I play the same tape but
    connect via the composite connector, there is no such problem: the
    image itself is of lower resolution (of course) but there is no colour
    instability. This Panasonic deck has a switchable TBC and the problem
    occurs independently of the setting of the TBC. It is also
    independent of the setting of other 'picture enhancement' features.
    Turning down the colour confirms that this is a problem of colour
    flicker only: there is no flicker in brightness or other instability,
    as the b&w image looks rock solid.

    4. I have just borrowed a friend's JVC SVHS VCR as a check. This is
    producing exactly the same result: a tape played via the SVHS
    connector will produce the colour flickering (red to green, from frame
    to frame) whereas the same tape in composite will be fine.

    5. As an ultimate check (to make sure that the results were
    independent of any one tape), I brought up the on-screen menu in the
    new JVC deck, which displays white and black text against a blue
    background. A similar result occurs: the menu is displayed without
    problem when the JVC is connected via the composite cable, but there
    is a lot of red/green flickering in and around the white text when it
    is connected via the SVHS cable.

    This is not some monitor-only type problem, as a DVD burned from
    material captured via SVHS shows just the same problems when played
    via my standalone DVD player and TV set (whereas the same material
    captured via composite is fine). Both VCRs play SVHS tapes fine via
    my TV set.

    Does any of this make the least bit of sense? I would have assumed
    the problem was due to time base errors if the Panasonic deck didn't
    include a TBC. And why should such errors only occur in SVHS and not
    composite VHS?

    Any help would be appreciated!


    mglover, Nov 13, 2003
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