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Jim Walton
05-21-1995, 03:36 PM
Roger and colleagues using the 50 Hz systems:

It just dawned on me that my remarks to Roger are now on the doorstep of
a large number of people using the other standards which operate at 50 Hz.
My original remarks were intended only for NTSC ("Never Twice the Same
Color" :-) ) or EIA RS-170 recordings made from film.

As I understand it, ALL other systems, (including PAL and SECAM, and other
more obscure broadcast standards) use a 50 Hz (field) or 25 Hz (frame)
refresh rate. Again, as I understand it, for a 50 Hz standard, the video
service bureaus produce two video fields for every frame of film.
Although this only produces 48 fields per second, it's considered "close
enough" for viewing purposes. However, for analysis purposes it means
that every image is duplicated. If you have an analysis system that
allows you to sub-sample the data, 1:2, you should have no problem.
However, if you don't have this option, you may also want to ask for a
"one-to-one transfer". otherwise you'll get uniformly spaced steps in
your data.

If anyone in the 50 Hz world has had experience with this, perhaps they
can confirm these observations.

Jim Walton

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On Sun, 21 May 1995, Rodger Kram wrote:

> Biomch-L Community:
>
> I have had a request from a collegue to borrow some of my high speed 16mm
> films. I no longer have a way to analyze them myself (moved to a new
> institution), nor does this collegue. We both have video analysis
> equipment.
>
> I am looking for suggestions as to how to transfer from 16mm film to VHS
> video in a frame by frame registered manner.
>
> The films in question are of kangaroos hopping and thus not easy to
> re-collect and of course over time chemical film decays to dust. (as we all
> do eventually)
>
> thanks for your two seconds of attention,
>
> Rodger Kram
> Assistant Professor
> Human Biodynamics Dept.
> 103 Harmon
> University of California
> Berkeley, CA 94720-4480
>
> phone 510 643-9370
> FAX 510 642-3355
> e-mail rkram@garnet.berkeley.edu
>