On Sat, 2 Dec 1995, Adrian Kennard wrote:

> you wrote:
>
> > I recall an article in Circuit Cellar, and source code on their server,
> > where a clever fellow used a PIC chip to read wind speed/dir, etc.
> > and simultaneously generate a simple character display video
> > stream.
>
> Anyone know the details of video time codes as used in production TV ?
> I think I have an application for an inexpensive timecode reader
> which could perhaps use a PIC and maybe a shift register and sync seperator.
>
> I don't have the spec on the time codes used though. It appears to be time
> or date/time as white wide dots in the top line(s) of the video (where
> teletext would go), but maybe a microsecond per dot.
>
There are currently two types of time code used in video.  The
traditional type is a serial stream that is recorded either on it's own
track or on an audio track.  It has some problems in that it can't really
be read when the deck is in pause and also reading it in reverse is
difficult (although it can be done, and is on high end decks).  The type
you are describing is VITC for vertical interval time code.  The name
tells you basically what's happening.  It solves the problems of
longitudinal time code.  A high clock speed Pic could probably pull it
off, but I don't know enough about the timing to say for sure.  Try a
search on SMPTE for more info.

morris beverly    avpres@world.std.com