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Dual PAL video input -> cropped, split output

Discussion in 'Electronic Design' started by Quack, Jan 3, 2005.

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  1. Quack

    Quack Guest


    I am trying to find (or make if i can find the right chips to make it simple
    enough) a device that will take 2 out of sync PAL video inputs and create a
    single PAL output comprised of both signals split horizontally (in a cropped
    fashion, not squashed).

    Without going into too much detail, there is no way around it, vertical
    splitting or 'squashed video' is not an option. This is for a very specific

    I have tried googling around but i cant find what im looking for, but i
    could be using the wrong terminology. Perhaps its a simple normal thing to
    want to do.

    Any hints anyone ?

  2. I read in that Quack <>
    To make a horizontal split, you need a video switch, toggled at twice
    the field rate, i.e. at 100 Hz for PAL. This is not very difficult. But
    if the video streams are out of sync, you need a genlock as well, and
    that is more ambitious.
  3. Quack

    Quack Guest

    Yes i considered this, but i cant guarantee the cameras will be insync.
    I have all parts for this already and could knock it out quickly.
    The 'genlock' you mention, this would be a function of the cameras as i
    understand it, and not of the 'device in the middle' ?
    As a compromise we could have the cameras in-sync as a requirement, but this
    is not the ideal solution :(

  4. Tim Wescott

    Tim Wescott Guest

    It sounds like what you really want is to be able to read the video
    streams into a pair of frame buffers so you can sync them up, then read
    them out as described -- the nice thing about using the frame buffers is
    you no longer need to be genlocked, but you can get into some serious
    work to make it happen.

    If you haven't already try searching for "video effects".
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