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INTRODUCTION
The
VP41S ~rVision
player
(ROM
disc
drive
) is
primarily
designed
for
use
in inleraclivc
oomputer-c:ontrolled
systems
rtu,1 exploit
the
capabiliticsofl.&strVisionas
a
vena1ile,high-quati1yst0111efrc1rieval
medium.
Communication between
the YP4tS
and
a
controllin&
COl'!IP'JICr is
via
s1andard
RS2J2-C or
SCSI
interfaoes,
bolh of
which
are
fitted to the player. The player
can
be
used with ordinary
Lz.erVision
discs containing
audiovisual
inrormacion.
or
LY-ROM
discs.
which contain
data a.swell
as
audiovisual information. This dala
lalr.nlheplaceoftheaudiochannelonsomeor
allsec;tiom;ofthcdisc.
1l>e VP415 can
of coum!
be
used for direct
playbxt of LascrVision
CAY ( Active
play) or CLV (Long
play)
discs.
In
1his
respect
it has
e111ensivc
program
control. wilh
search and memory
facilities.
conveniently operated from the remote
control h.andsc1.
THE
I.ASl-:RVISION
SYSl'EM
J...asnVisionis1he
on\yaudiovisualplayback
sys1emusing optical(laser
beam)
reai;lout.
The laser
beam, concentrated
10
an
almost
inconceivably
fine point (60
1imes
finer
Chan
a gramophone stylus).
reacts wry densely-packed
informalion under
lhe u amparcnt
surface
of
the
LascrVision
disc.
The:
ptdurc reproduced
is of high quality
wich
?-cha11ncl
mono or
slereowund.
There
is no wear to the disc
or 'pick-up·. and
the discs
are
uuesnely
resistant to scratches. dust
and
fingerprinls.
Typaef
1.aaerVilion
dbc
Thtte
1ypes
of
disc
arc
available and the player
will
operate
withanyofthese:
J.
NMaillCA. V(Active
play)di~spin
al
aoonscanl
speed of
1500
r.p.m.
They have
a
muimum
capaci1y of
54
000
pictures
per side
(36
minu1es played
at 25 pictures per $CC011d) and offer
special
LaserVision eUeclS such
as
still. slow-~
tOn.
reverse play. fast
forward. fMt reverse and
goco
picture
or
chap1er
number.
1.
CLV(Longplay)
discs
spin at
a speed
which g.rad1W11ly
decreases
as
11te
disc plays.
They
offer
conlinuous
forward
pby only. but
with
lime and
chapter search.
and
!he advantage of an increased
playing
lime
oflhourpcrsidc.
J.
LY-ROM.
ThisisatypeofCAV(Active
play)disc.withdata
replacing some
or
all
parts
of the
audio
tra,ck.
lbeir
maximum
u pacity
is
324
Mbytes of user data and
54 000
pim1res.
INU:RACllVI-:
USE
The VP41S
allows
all
the facilities
of
the
LaserViskin
system to
be
coratr~led
by
a
computer.
In
this
way.
the
computer can control
the
pK1ure, sound
and LV-ROM
data
.
Play
is
concrollcd
by
picrnre
numben. chapter number$.
autostops or
a compu1er
program.
The
program can be
activaced
by the Vf'41
S
remote control
h,mds.et.
or via
lbe computer
keyboard.
or
other
oomputer
peripheral.
Communication with the
VP4
15 is
achieved
u,ing
eilbc,
11
special
code
known u
F-wde.
or
L
V-DOS
commands (via
1he SCSI
interface).
1ltc
F-a>de
instruction
set
enables
commands 10
be
sen1 (as ASCII
characters) to
the
player;
some
of
these
commands c.aus.ing responses
10
be
relumed
to
the
computer.
Using F-code
oomm11ncb. a
VP415 can
participate in an
interactive program with
any computer system
that is
loaded wi1h the
necessary program.
LV-OOS commands
allow the
VP41S
10
be
used
as an LV-ROM
memory device in a compu1er system. Both data retrieval
from disc
andptayer control
are
possible.
FEAl'URES OF THE VP415
RGB o...,.1/PAl.,&GII dttoder
The VP41S
allows
the
best possible picture
quality 10
be
obtained from
a
LaserVisk>n disc. by emptoyina a built-in PAL-RGB decoder. Within
the Laser Vision
format.
video inform91ion
is
s1ored
on
the
disc-
in PAL
encoded
form.
Tlmcan
cause
problems when
the
dik:
is
played
in ·s1il\
frame·
or
'slow motton·.
or
any
other
non-standard playing
mode.
because lhe
PAL
8·riekl sequence becomes
destroyed. In
order 10
correct
lhis
sequenc.e
such that a monitor can understand ii and
reproduce
correct cofour.
many players incorporate
a 'PAL
Modifier'.
This piece
of
circuilry
corrects
the PAL
sequence.
but
in
doing
so.
reduces lhe
video
bandwidth. and
introduces other unwanted
effects.
e.g.echoes.
The
VP41S txkks this problem
by
employing a
fast-locking
PAL-
RGB
deooder.
Having 1his device built-in.
allows
its characteristics 10
be
fully
optimised
10
g;ve
1hc highest
possible
picture
quality
from the
disc.
even in non·Slandard
playing
modes.
The
resulc
is
an RCB
output giving the
full
S MHz video bandw:idlh
in
au playing modes. 1be benefit
is particularly
valuable
when
viewin&
videomaterialsuch
M
mapswith
fincteK
t.
RGB
output abo h:nds
it-1\tll to simpler miKing
with
computer
graphic
output
(al$o
RGB). in
uternal equipment
if required.
Sy11Cpalse1nent«
The VP41S
contains
a
n
internal sync pulse generator (SPG)
which may
either free-nm. or in
1he presence of
a
suitable reference signal.
lock
itself
to
the
u 1emal rererence
(Genlock).
The SPG
provides
fre~ly-generated line and field
sync
pulses
at
the
player·s
video
output
at
all times.
Followin1 the
decoclin&
process
rrom
PAL
to
RGB (sec above),
fresh
Jync
pulses
are
inserted into11te RGB
si1nal. which is
available
11
1he Euroconnector socket
.
Therefore
a
~table
output
rrom
1he
player is
guaranceed
at all
cimes
Gelllock
Genloc:k allo~ 1he field and
line
sync pulses
from
the
player
oulpul
to
be
synchronised wilh
an
external reference
signal. It
ensures
correct
overlay
of
video
signals and can
also prevent
picture
jump
or
roll.
The
reference
signal,
comprising
line
and
field syncs
(negalive•going)
should
be
applied to(i)
ei1herofthe
two SYNC IN soc:ketsor
(ii)
pin4
of the RGB (TTL) IN socket. A horizontal shift of the
overlay
picture
is achieved
by
adjusting
the H-SHIFT control situated
at
the
rear
of
1he
player.
Nou:
The
player
may
take up
to
2
seconds
inilially
to
effectively
lock
toarefcren<:esipl
The
VP415
eon1ains an
RG
B-PAL
encoder.
This 1akes
1he
RG
B
outpul from
lhe
player (prior to
the
video
mi
K ing
stage) and
encodes
it
into
a
C
VBS si1nal
using fresh
sync pulses
from the
internal SPG.
1be
signal
available at
the
CVBS output
is thus
totally
stable. It does
however have
a
reduced bandwidth in all
playing
modes
(approa 3
MHz).
A
C.C.D. (charge coupled device)
timebase
correclor is
employed
10
provide
correction
of
timing errors
always present
in the sign.al read
from
the
video
disc.
This
replaces
the more traditional tan&ential
mirror (mechanical
method)
allowing
for
a smaller. lighter optkal
syscem.
This
redlKtion
in
mass
allows
the
optical readou1 unit
co
uacl;
1he disc
fas1er
and
thus reduces
picture
access
lime.
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