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Posted by Roy L. Fuchs on 01/03/06 03:38
On Tue, 03 Jan 2006 00:05:00 GMT, bv@wjv.com (Bill Vermillion) Gave
us:
>In article <9v7jr1dfk8irva1s907edn6ucq7bf828fs@4ax.com>,
>Roy L. Fuchs <roylfuchs@urfargingicehole.org> wrote:
>>On Mon, 02 Jan 2006 17:45:01 GMT, bv@wjv.com (Bill Vermillion) Gave
>>us:
>>
>>>but CAA is
>>>actually a series of CAV that change every few revolutions.
>>
>>
>> If one could not obtain a perfect frame still, it was not CAV.
>
>> It is one frame per revolution.
>
>CAV means 'constant angular velocity' - which means the number of
>degrees of rotation for a given time unit remains constant.
CAV discs are the ONLY discs which allowed perfect still to be
rendered on players that did not have a field memory.
There are 54000 frames, and each one consists of a single revolution
on the disc. THAT is why a "still" is the laser reading the same track
over and over.
>
>The orignal CAV disk did have one frame per revoltion.
There is only ONE CAV form factor. Your previous post declared that
there was a change to CLV disc. Here you are getting them confused,
AGAIN.
> But with
>CAA
Which was a variant of CLV, NOT CAV.
> - there would be several frame with the same angular
>accelleration then a lower angle for many frames, and then another
>lowering of the angle.
I say again, even on the newer CLV discs that were done in CAA, if
there is no still frame capacity without the player's assistance
through a field frame memory FIFO, it is NOT CAV.
>IOW it was made of many many bands of video with the same angular
>velocity. This meant you could get the same amount of time as the
>original CLV but without the adjacent frame interference.
>
>CLV uses a constantly changing disk speed, while CAA uses many
>segments of differing disk speeds all grouped together.
And the speed of the disc STILL slows as the head traverses to the
outer edge of the disc.
>And I can get a perfect still frame on one of my players :-)
Most newer players have a field frame memory FIFO in them now.
>It's a Pioneer 8000 - industrial unit - which actually buffers the
>frames to give perfect still
Which renders our entire argument moot.
> - that's why those units originally
>cost so much.
I have one of the first Pioneer HOME units that had it. It was
$1200.00 in 1985.
> But I think those may have been the only ones -
>except perhaps the Sony 2000 and Sony 3000 industrial players.
You THINK a lot, but you are having problems with remembering the
facts. A field frame memory eventually became the standard, and
nearly all players had it.
>The latter were pretty amazing as you'd never lose a picture when
>you were seeking a disk if it was recorded properly.
I don't need a primer. Also, my first player was an industrial unit
from an upright video game. It had a HeNe gas tube laser and full
optical bench inside it. It had a computer controlled frame access.
I know all about it. I worked on upright video games at the time.
> Those were
>rugged beasts - designed to be used in such places at military
>tanks.
Hahahahaha! So funny. They were used by TV broadcasters, satellite
uplink stations, upright video games, etc.
>THe best description of CAA is probably from Bob Niland's original
>FAQ - now maintained by others - but Bob and I corresponded in the
>early 1990s.
>
>Here's the segment on CAA
>
>========================================
> 5.6 What is CAA then?
>
> CAA stands for Constant Angular Acceleration.
>
> To be exact, the discs that nowadays are entitled CLV,
SEE? even HE says it was a change to the CLV disc. Just above, you
said it was CAV. Are you drinking?
> are actually
> CAA discs. In CAA the disc speed is not slowed down constantly, but it
> is kept constant for some time and then rapidly slowed down.
Yes, there are bands on the disc. The first third is at one rate,
the second at another, and the outermost band at another.
> The point
> in this system is to keep the horizontal sync signals aligned on
> adjacent disc tracks to keep crosstalk to a minimum. In Blaine Youngs
> (blam1@oz.net) words:
>
> "CLV: This format is dead.
Yet CAV never changed. It was ONE FRAME per revolution, constant
disc speed, and NO field memory was required for a perfect still
rendering.
> The name is still used for simplicity's
> sake, but 3M is the only manufacturer which uses it. In 1982/3, there
> was a shift to CAA. This is the only format used today. (Again, except
> for 3M which incorporates a minor variant on CLV to eliminate
> crosstalk). Regardless of which format is used (CLV or CAA) it is
> still required to have crosstalk rejection code built into the
> mastering software to prevent master crosstalk. Technidisc does not
> use such software and as a result, most of their CLV stuff looks like
> crap.
>
> CAA also offers something else, 5 different encoding routines. This
> will allow for variable playback times, depending on the program. What
> happens is that the initial CAV pattern at the beginning of the disc
> is altered (lengthened or shortened as necessary) and the track pitch
> is modified. The 5 formats are CAA45, CAA55, CAA60, CAA65 and CAA70.
> CAA45 has been used only once, that I know of. Any disc side running
> less than 55:05 uses CAA55 encoding. All other discs are CAA60. There
> are 2 known occurances of CAA65 and there has never been a CAA70 disc
> released in the US."
>
> From now on, CLV and CAA discs are just called CLV for simplicity, and
> because that's what's written on the disc sleeves.
>
>========================================
>
>And I first started working the laser disks when I was part of team
>writing what turned out to be the worlds first electronics parts
>catalog using Sony 1000 players [with a format incompatible with
>the Pioneer until the A model from Sony], and IBM PCs using
>DOS 2.0.
Oh boy. A database. Good job, I guess. I have a NASA disc with
images of the entire planet, including the first "google map" type
database of images from a lear jet at 40,000 feet.
> That was October 1983.
Yes, only five or so years after the advent of the CD (consumer
level). LD lasted a long time, despite what these dopes that want to
"sell their DVD collection" think about what "killed" what.
> I made so much money during that
>time frame I stopped being a recording engineer and moved into
>computers full-time.
And you still sport memory problems. :-] Or mild Disclexia.
>The local video production company used to make a lot of training
>LDs for both military and commercial, and had one of the few units
>in the South that could handle frame and chapter encoding.
General Motors uses them for training as well, though now, it is DVD.
>
>If they finished the tape and had it shipped by freight by 5PM
>then 3M would get check disk shipped back from Minneapolis by
>5PM the next day - so we could check disks in about 36 hours from
>shipping the tape.
>
>Things surely have gotten better and a hell of a lot cheaper since
>those days.
No more glue oozing out from the edges of the discs. Maybe that's
what affected you. :-] So far, you have transposed it twice. :-]
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