Homebuilt video digitiser MkII circuit description

Posted on Feb 4, 2014

A `video-digitiser` (also known as a `frame grabber`) captures still pictures frames from a TV set, video camera, or video recorder, etc. , and forwards them to a computer for display, storage, or general manipulation. This document describes the MarkII version of a home-built digitiser which interfaces to an EPP parallel port on IBM PCs. MkII supports colo

Homebuilt video digitiser MkII circuit description
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ur captures (PAL/NTSC decoding in software). Note: the Bt218 chip, around which this project is based, ceased to be manufactured during the year 2000. If you want to build this project as shown, ensure you can get some old stock! Alternatively, you could adapt the circuit to work with a different low-cost ADC, such as the TDA8703 from Philips. I have not done this myself yet, so cannot offer details. Any PC hardware capable of running the operating systems mentioned should run the software adequately, though as always, a faster PC will often result in better performance. In particular, colourisation will be very slow on anything sub-Pentium! An EPP-type parallel port is required (though with software modifications, a simple bi-directional port would be useable, with poorer speed) Still only captures one of the two interlace fields (though often the second one would lead to motion blur anyway. ). Limited by mere 256kB of buffer. Published design captures odd/even field at random, though by simple modification you could ensure one or the other is guaranteed. Digitisation clock arrangement shown is not fully phase-locked to the linesync. A proper line-locked sampling clock could quite easily be implemented as an extension to the project. In general, horizontal resolution is decreased in domestic video recording formats (and colour is really seriously degraded). Use off-air signals from a good aerial for best results! (This...

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