Re: Halide emulsion vs digital. Was RE: Warning of major NHS IT overspend

[Peter Fairbrother <[EMAIL PROTECTED]>]

Brian Beesley wrote:

> On Tuesday 02 November 2004 22:04, Alex Tibbles wrote:
 
>> AFAIK yes. You'd still struggle (ie more expensive
>> than film) to find hard drives that can muster 24 *
>> ~10MB frames per second, continually (mildly
>> compressed images of comparable quality to 35mm),

Star Wars 2 used ~2 megapixel HiDef cameras, at 24 frames per second and
1920x1080 pixels - a 35 mm movie frame is about half the size of a 35 mm
still frame - for 144 Meg per second raw rate. George Lucas said he couldn't
see the difference from 35 mm film (well he could, but he couldn't say that
one was better). 

That was in 2000 or so, and it started the digital feature industry, in
which HD 24p (there are different types and resolutions) is now the defacto
standard.

HD 24p averages about 50 MB/s near-losslessly compressed, and two fairly
ordinary striped drives can handle the ~80 MB/s peaks of that. In fact, some
single drives can handle the average rate, but with a few dropouts. In
practice they use RAID boxes professionally. They use 1GigE, or more often
now fibre channel, for transport to/from the RAID box, although dedicated
recorders are also available.

A compressed HD 24p movie is about 300 GB; a few TB are needed for a film
with outtakes. Figure on about £2k per terabyte if you're doing it on the
cheap, £6-25k if you want SCSI speed and reliability.

You can do it even cheaper - you can fit a terabyte or so in a large tower
case, along with the gubbins, for about £2500. Add another £2500 for
software, and whatever for a display and hardware encoder card, and you can
edit real-time for under £10k.

There is little point in paying more than £25k per terabyte for HiDef
storage, even if you're Speilberg - and have you seen the salaries of movie
stars? Or priced an Arriflex?

8 megapixel cameras are just becoming available, though afaik no-one has
made a movie with them. They tend to only have dedicated hard disk recorders
available for realtime full definition use (as did the early HiDef cameras).
They use about 200 MB/second compressed. They will probably end up using the
new 10-GigE standard for interconnection.

>> so for high-quality footage (eg. feature films) it is
>> still extensively used.

It is, but that may be partly "we already have the film equipment", partly
"this is the way we've always done it" and partly "the Unions will go on
strike".

35 mm film is used for the distribution of digital movies, where once a film
print was cheaper than digital media, and only a few cinemas have digital
projectors. 

At one time 70 mm film was used for premiere distributions of 35 mm films,
mostly for the better sound, but it hasn't been for ten or fifteen years
now.

> AFAIK feature films are usually shot on _70mm_ stock! They're then compressed
> horizontally for release on 35mm, there's a special "anamorphic" lens
> required to do the compression and decompression.

Feature films are mostly shot on 35 mm film nowadays, although HiDef digital
is growing in popularity. People haven't used 70 mm for years, with only a
very few exceptions (Tron comes to mind).

"Once Upon a Time in Mexico" is an example of a recent feature film shot
entirely digitally.



-- 
Peter Fairbrother