From: danrama@wam.umd.edu (Daniel Bloomfield Ramagem)
Subject: Re: LD Question: Why CAV ?
Organization: University of Maryland, College Park
Date: Mon, 11 Jan 1993 05:00:48 GMT

I received this reply as private mail, but the sender told me he made
a mistake and had intended to post it up, so as requested, here it
is:

Date: Mon, 11 Jan 93 13:14:37 +1100
From: quetzal@yoyo.cc.monash.edu.au (Quetzal)

In rec.arts.anime danrama@wam.umd.edu (Dan) wrote:

>Is there a point to having CAV LDs if you have an LD player that does
>special effects (i.e.: allows you to freeze frame and do slow motion on
>CLV LDs)?  

The arguments I have heard in either direction are:

CAV: As someone said, you can  freeze frame *perfectly* to the *exact*
frame you choose.  Some CAV discs are not encoded at 30 frames per
second like NTSC uses, but at the 24 fps that the original, cinematic,
release runs at (assuming we are talking films that come from the cinema
and not from video).  This is nice if you are running the film in slo-mo
(though benefits in animation are questionable since they're usually not
one-frame-per-cel [well, you know what I mean]); some people claim to be
able to tell the difference between 24 fps and 30 fps when they are
running in realtime (I can't; plus I'm used to the 25 fps of PAL).
Drawbacks are the way you have to get up after an hour to swap discs, or
every half an hour if you don't have a player that can play both sides.
For some of these reasons, CAV discs are considered collector's items by
some, and this, as well as the fact that more discs are needed to store
any given length of film, makes CAV discs more expensive.

CLV: If your laserdisc player is a pricey one and can play both sides of
the disc without you needing to get up to turn it over, then CLV is nice
in that you can watch the entire film (if it's under 2 hours long) in
one sitting.  If your player has a digital frame store, then you can
have some of the features that CAV discs have, such as freeze frame,
slo-mo, scan, and so on, but remember that NTSC, like all broadcast
standards, is interlaced, and so it's much easier for the player to get
just half of the frame (odd or even numbered lines) and send that to the
screen.  As a result the resolution is halved to a little over 200
lines, a figure very similar to video but without colour bleeding
problems inherent with videotape.  I know of no players that read both
half-frames of the interlaced signal (which would make CLV and CAV
freeze-frame identical).  With CLV, you can only search to the nearest
second, so freezing a particular frame is generally not possible.

The upshot of the matter is that you will have to decide how often you
are prepared to get up to watch a film (between every half-hour and
every two hours) and also whether you are prepared to have a perfect or
an almost-perfect still frame (no one in my family can tell the
difference, though naturally I can) or no still-frame at all if you go
for a cheaper LD player.  That of course is up to you, and that's why a
lot of films are in the two formats.  CLV is typically much more common
than CAV; quite a lot of films are only available on CLV (this goes for
live action; I don't know about anime).  My Personal Preference is CAV,
but every person's reasons on this differ; I'm no exception.

Hope I've brought some sort of balance to this argument - Now why is it
that I know so much about this when I've got just one LD so far, a -
gasp - *Disney* film!  Just goes to show that you can still have an
interest in one breed of animation though you loathe, despise and
detest it . . .

Tim Pickett