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Posted by MassiveProng on 01/30/07 01:11
On Mon, 29 Jan 2007 18:05:00 GMT, bv@wjv.com (Bill Vermillion) Gave
us:
>In article <vhobr2l80sqbamu9n4ugug28cm1vh4setq@4ax.com>,
>MassiveProng <MasiveProng@yourhiney.org> wrote:
>>On Mon, 22 Jan 2007 19:10:45 -0500, "Joshua Zyber"
>><joshzyber@comcast.net> Gave us:
>>
>>>"Bill Vermillion" <bv@wjv.com> wrote in message
>>>news:JCA6wC.1tJx@wjv.com...
>>>> And just this morning I got the latest CED digest
>>>
>>>The latest CED digest?
>
>> Read what his take on LD and CAV is. He is out in left field.
>
>In what way. CAV - constant angular velocity. The disk rotates
>at one speed. CLV - constant linear velocity - the disk changes
>speeds to keep the data stream under the pickup constant.
>
>With the first CLV releases, such as Blazing Saddles, there was
>in many players a noticeable herringbone pattern, so a
>method call CAA - constant angular accelleration was developed -
>though the name CLV was retained.
>
>CAA is best described as banded CAV - where there are bands
>that all rotate as the same speed, channging speeds as the pickup
>moves from the center to the outside. This prevented the
>herringbone pattern that was caused by each adjacent track field
>being slightly offset from the previous one.
>
>Where am I in left field on that?
>
CLV is a single "worm" type track from center to edge. The pit
pitch is constant, so as the laser head progresses toward the edge of
the disc, the rotational speed slows to keep the same pit rate (bit
rate) passing under the laser head.
CAV is comprised of distinct numbered tracks that tally 54000
exactly, which is 30 minutes at 30 fps, for each full disc side.
It is not recorded in worm fashion, there are separate cylindrical
tracks for each frame of film. The pit pitch the laser records at
varied, and the disc rotational speed remains constant. This means
that "pits" at the outer edges of the disc are stretched, as are the
"lands", to make the resulting bit rate (pit rate) pass the laser head
as at the hub of the disc. The adjacent track on an optical disc does
not affect the track being read.
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