MMD > Archives > September 1999 > 1999.09.26 > 06Prev  Next


Sound Movies on TV
By Jeffrey Borinsky

Jody, you are right.  In 50-Hz countries (which use PAL and SECAM)
we scan film at 25 frames per second and accept the 4% shortening and
pitch raising.  (What would Ralph Nader say about the short measure! :)
It is possible to correct the pitch with modern DSP [digital signal
processing], or perhaps with one of those rotating head beasties that
were a previous strand.

In 60 Hz (59.94 Hz strictly) countries the usual method is a dreadful
thing called 3:2 pulldown which gives peculiar motion artifacts.  This
is (was) somewhat disguised because US telecine usually uses (used)
camera tubes with their attendant lag effects.  Elsewhere telecine is
usually flying spot which has no lag.

 [ The Vidicon camera had a phosphor coating which preserved the image
 [ for a few fields, thus 'blending' the individual movie frames.
 [ -- Robbie

Modern techniques scan the film at 24 fps sequentially and electronic-
ally convert to 30 fps interlaced. This can give much better results
than 3:2 pulldown.

Best regards

Jeffrey Borinsky


(Message sent Wed 22 Sep 1999, 14:47:20 GMT, from time zone GMT+0100.)

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