On Sat, 02 Dec 2006 10:39:25 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Phil Allison wrote:
Hi to all,


ever wondered how Dolby Digital 5.1 sound is ACTUALLY carried by a 35mm
cinema film ?

Turns out the 320 kbit/s DD data stream is encoded onto square, optical
grids of about 60 x 60 bits & very cunningly fitted in * between* the
sprocket holes !!

http://upload.wikimedia.org/wikipedi...udio_macro.jpg

The embedded Dolby logo is cute dontcha think ?

A tiny CCD camera in the projector captures each 2.4mm square image, 96
of them per second, so it can be processed into 6 channels of audio.

The other tracks you see are Sony SDDS, L/R stereo analogue and timing
pulses for DTS so the CD can be synched with the movie.

Such a multi-format movie can be shown by any cinema in the world and
exact copies are made by ordinary, chemical film processing.

Betcha you ALL knew that already ....

Film offers all sorts of possibilities. One of its interesting properties
is a known long storage life - magnetic anything deteriorates sooner, and
optical media like the CD is also rather an unknown quantity - especially
the recordable type.

When ITV was a 'proper' organisation, their labs at Teddington Studios
were developing a system for storing digitally TV colour pics and stereo
sound on 16mm B&W film - which is a cheap material for archiving, with a
projected life if properly stored of over 100 years. ISTR it was capable
in theory of handling HDTV too.

Do you have any idea what the time ratio was - how many minutes of
digital they could store on how many minutes (when used normally) of
film?

d

--
Pearce Consulting
http://www.pearce.uk.com