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Video Systems Inc.
Carlton
ompany
digital disk recorder A60 64
A60 64
Preliminary
igital Video
nterface
Manual
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PRELIMINARY
A60jA64 Dig i t a l
Video
In te r face
Manual
Rev 1 .2
21-AUG-87
Copyright C) 1987
Abekas Video Systems,
Inc .
This manual
desc r ibe s
t h e formats for
both
the
CCIR
601 4:2 :2 d i g i t a l
component
video i n t e r f a c e and the
Small
Computer
Systems
In te r face
SCSI).
t
covers
both 525 and 625 l i n e ve rs ions o f t he A60
and
A64.
The SCSI
i n t e r f a c e
al lows t he
A60jA64 D ig i t a l Disk
Recorders to be t r e a t e d as computer per iphera l s
us ing
the same i n t e r f a c e
and
command
s e t as
computer
mass
s to rage devices such as di sks o r t ape
dr ives .
The A64 SCSI
i n t e r face i s
con ta ined
in an
opt iona l i n t e r f a c e un i t
in
t he A60 it i s i n t e g ra l .
The SCSI
i n t e r f a c e a l so
provides
an l t e r ~ t i v e
method
o f
remote con t ro l
s ince a l l
the s e r i a l
pro toco l
commands can be i s sued
through
t h e SCSI
por t .
Some of the
da ta
formats descr ibed in t h i s
manual
are
a l s o
used fo r t r a ns f e r s t o the A60 v i a the
Etherne t
por t .
Abekas Video Systems,
Inc .
101 Galveston
Drive
Redwood
Ci ty
C
94063
415)
369-5111
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1
2
3
4
ONTENTS
Component Video Appl ica t ion Notes
1 1 Lines Fie lds and Frames
1 2
1 3
1 4
1 5
1 6
1 7
1 8
SCSI
2 1
2 2
2 3
2 4
2 5
2 6
2 7
CCIR
Color
Encoding
Rendering i n to
t he Framestore
Component sampling
Framestore dimensions
Example
Component Data
Blanking
In t e rpo la t ion
Fi l t e r ing
Gamma Correc t ion
I l l ega l
Colors
Pixe l
Aspect Ratio
Appl ica t ion Notes
Dif fe ren t l eve l s of implementation
SCSI IDs
Mult ip le
I n i t i a t o r s
Disconnect ion
Single I n i t i a t o r
opt ion
SCSI Po in te r s
Linked Commands
Synchronous
Transfers
Physical
s pec i f i ca t i ons
Drive capab i l i t y
Terminat ion
Dif f e r en t i a l
dr i ve r s
Remote te rminator power
Bus Signals
Bus Phases
Error condi t ions
In t e r f a c i ng
to
t he Abekas
Disk Recorders
Example SCSI Transfer
601 Reference
Matr ices
4:2 :2 Sampling
Data
Blanking
Addi t ional Notes
A60/A64 SCSI Data
Format
4
5
9
9
9
10
10
11
12
13
14
16
17
18
18
19
19
19
19
19
20
20
20
20
21
21
21
22
22
22
23
25
25
25
26
27
27
8
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5 .
6 .
7 .
8 .
9 .
10.
11.
SCSI
5.1
5.2
Reference Manual.
Logical
blocks .
SCSI
Commands
Tes t un i t
Ready
Request Sense .
Rezero un i t . .
Read Direct)
wri t e
Direct)
Seek
.
Read
Direct Extended)
wr i t e Direct
Extended)
Seek Extended) .
Rewind
. . .
Read
Block Limits
.
Read
sequent ia l )
wri te
sequential)
Space
Mode Se lec t
Mode Sense
Transpor t Commands.
A60/A64
Off l ine Storage
Data
Format . . . . . .
I M PC
In te r face .
Microsystems In te r face
.
SCSI Bus
Addresses .
Sun
8 .1
8 .2
8 .3
8.4
8 .5
8 .6
Disk
Labels
. .
Machine
Control . .
Reconf igur ing
the
kernel .
Configur ing
t he Abekas
SCSI
Example
program
in te r face .
A60/A64
SCSI
In te r face
Hardware .
9.1
External Connections.
9 .2
Terminat ion . .
9.3
SCSI Connector assignment.
9 .4 SCSI
Address
Se t t ings
. . .
9.5
A64
SCSI Adapter Layout .
9.6
A6
Computer Layout
. . .
9.7
Kennedy
SCSI
Control le r
Layout
. .
Example
Conversion
Program.
SCSI
format program .
ii
31
33
33
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
56
57
57
59
61
6
6
63
63
64
66
67
68
69
73
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12 I 3 J L } ) J L l . ( ) ~ ~ C l l ? l l l
78
l l l
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1.
Component Video Appl ica t ion
Notes
In t roduct ion
This s ec t i o n
gives a
b r i e f background descr ip t ion o f 4:2:2
Component Dig i t a l
sampling. t i s aimed
a t
programmers
in tending
to
render
mater ia l i n to the na t ive format of Abekas Dig i t a l
Disk
Recorders .
Although t h i s
s ec t i o n
does not
go i n to
any
l eng thy mathemat ical
explana t ions
no
a t t empt i s made to expla in words
l i ke
phase o r
modula t ion and bandwidth
any
reade r unfami l i a r with these
terms
i s advised to read the f i r s t few
chapte rs
o f
a
book
on
TV
theory .
This document i s
not d i rec t l y
concerned with the
NTS
and
PAL
s tandards as
these a re t he coding schemes used
to genera te
the
composite video s i g n a l s . The d i g i t a l format
and
sampl ing
fo r
both
TV s tandards i s
the
same, they
d i f f e r
only in
the
number
o f
l i ne s
and
t h e
f i e l d r a t e .
The d i f f e r e n t ve rs ions of the d i g i t a l
s tandard
a r e
r e f e r r e d t o
here as
525/60
and
625/50 being t h e
number of l i ne s in
a
frame and the f i e l d
frequency.
Dig i t a l
video
i s
s to red
in
component
format
in both t h e Abekas
A64
and A60.
Note however
t h a t
the Abekas
A62 i s a
composi te
NTS
machine which s to r e s the video
as a
s ing le
channel
o f composite
video
r a the r
than the
component
machines which
e f f e c t ive ly s tore
video
as
t h ree separa te channels o f component video.
Abekas cur ren t ly
of fe r s
the fol lowing d i g i t a l i n t e r f a c e s on t h e i r
d isk
recorde r
product s
A6
A64 (A62)
CCIR
601 Dig i t a l Video
X X
Framestore Pa ra l l e l
po r t
X X
Bui l t i n SCSI
X
op t iona l
SCSI in te r face
X
X
Off l ine s to rage
opt ion
X
X X
Etherne t
TCP/IP
X
The Off l ine s to rage
opt ion
i s
a
high speed
SCSI
s t reaming
t ape
d r iv e
t h a t permi ts t r ans fe r by t ape from
any computer t h a t can
PRELIMINARY
Component
Video
Appl ica t ion Notes
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Dig i t a l Video In te r face
Manual
wri t e 9 Track Magtape in
the
requ i red format.
The fol lowing methods o f Remote con t ro l a re
av a i l ab l e
Se r i a l Por t s :
RS422
o r RS232
Abekas Keyboard
Protocol
Edi to r Protocols : Sony Ampex CMX
Pa ra l l e l
Por t
A64)
SCSI
Etherne t
A60)
Timecode
Trigger
GPI Contact Closure)
Rela t ive
speed
o f
t r a n s f e r
3
Etherne t :
raw
YUV frames t r ans fe r in l e s s than 5
seconds ,
conver t ing
from
RGB
and
f i l t e r i n g
w i l l t ake about 10 t imes
longer .
SCSI can achieve
t r a n s f e r
r a t e s of 1 .1 MBytes but
the
da ta has to
be in
YUV format with syncs and ex t ra
l i ne
number informat ion in
t he da ta stream. The A64 Pa ra l l e l p o r t
should
al low t r a n s f e r
ra t e s
up to MHz
but
the handshake r equ i res custom
hardware.
Etherne t
Data Formats
At
t ime of wr i t ing two da ta f i l e formats
w i l l
be of fe red YUV and
RGB.
YUV
i s t he n a t iv e
format
of the Disk Recorder, t r a ns f e r s
w i l l
be
much
f a s t e r
and
the da ta
w i l l
not
be
changed between
w r i t i n g
and
reading.
YUV s to r e s 16 b i t s
p e r
p ixe l non YUV images o f grea te r reso lu t ion
eg
24 b i t RGB samples) are
conver ted as they
are wri t t en to
and
read
form
t h e
d i sk
and
in
so doing t he re i s
an
i nev i t ab le loss of
in fo rmat ion . So
fo r example RGB
da ta wri t t en to
the
A60 and then
read
back w i l l
not
neccesa r i ly have the
same va lues
t ge t s
rounded to the neares t value in
YUV
space and f i l t e r e d to
l i m i t
ts bandwidth.
The d isk Recorders can
be used
fo r s to rage o f Non YUV
image
da ta
fo r ins tance t emporar i ly buffer ing
RGB
images while
composi t ing
severa l
l aye rs .
The
only
r e s t r i c t i o n
i s
t h a t
the da ta
passed
through
t h e
SCSI
por t
should not conta in the
va lues
00
and
FF
s ince these a re
rese rved
fo r
syncs.
PRELIMINARY
Component Video
Appl ica t ion
Notes
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1.1 Lines Fie lds
and
Frames
The fol lowing t a b l e
shows the
fundamental t imings fo r the
two
TV
s t anda rds .
525/60 NTSC)
Line Rate
15.735264
KHz 2Fsc/455
)
Lines
per F ie ld
262.5
Fie ld Rate
59.94 Hz
2/525 H
625/50
PAL)
Line Rate
15.625
KHz
4Fsc/ 1135+4/625
Lines
per
F ie ld
312.5
Fie ld Rate
50 Hz
2/625 H
Fie lds and Frames
The 525 l i ne p i c t u re
i s
scanned
as
two i n t e r l aced f i e lds o f 262.5
l i ne s
each
The
f i r s t
e igh t
and
a
ha l f l i ne s
in
the
f i e l d
a r e
t aken
up with
v e r t i c a l
sync and the nex t s ix teen l i ne s are blanked
car ry
no video
information)
to al low fo r the
v e r t i c a l re t race
per iod . This
l eaves
243 l i ne s per
f i e l d
fo r the ac t ive p ic tu r e .
The 625 l i ne p ic tu r e has 312.5 l i ne s per f i e l d o f which 288
are
ac t ive .
spa t i a l
separa t ion o f
f i e lds
t
i s
poss ib le to
render
the
same informat ion i n to
both f i e lds
o f
a frame but
t h i s
e f f e c t ive ly
halves the
ver t i ca l
reso lu t ion of the
image.
Temporal
separa t ion o f
f i e lds
Beware t h a t
if two
f i e lds are f rozen
eg
t he re was some motion of
the sub jec t
between
them) This
movement
appears
as
an
annoying
frame
r a t e f l i cke r .
PRELIMINARY
Lines Fie lds and Frames
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In te r face Manual
5
Animation
Sequences are
b e t t e r
rendered
as
separa te f i e lds t o
give
a
smoother motion. Indeed
to
t ake
t h i s
one
s t ep fu r the r
note
t h a t
the t op
l i ne
o f a f i e l d i s ac tua l ly sampled and
displayed a t
a
d i f fe ren t
t ime to the bottom
one.
Although
the
f i e l d
ra t e s
fo r the
two s tandards
are
d i f fe ren t
so
i s
the
v e r t i c a l reso lu t ion the reduc t ion in
p e r cep t i b l e
f l i cke r
in the 60Hz system
i s t raded of f
aga ins t number
of ver t i ca l l i nes .
The l i n e
r a t e s fo r
both s tandards
are
almost
the
same giv ing a
l i ne pe r iod of
64 uS.
The
d i f fe ren t
q u a l i t y o f
NTSC
video r e l a t i v e to PAL can be
a t t r i bu t ed
to t h e
s impler
co lo r encoding scheme o f NTSC coupled
with
t he
narrower
broadcas t
channel bandwidth.
In
terms of the
CCIR 601
spec the
bandwidth
and
da ta r a t e o f
both
systems
a r e
the same.
1.2 Color
Encoding
In
orde r to
encode
a
composi te video s igna l fo r
t ransmiss ion
the
Red Green and Blue s igna l s
from
a
co lo r camera are conver ted
i n to
a luminance Y
s igna l
and
two
co lo r
d i f f e rence
s igna l s
R-Y
and
B-Y.
The
luminance
s igna l
i s
in tended to
r e t a i n
compat ib i l i ty with t he
e a r l i e r
monochrome
s tandard
and i s
t r ansmi t ted
as
an
ampli tude
modulated s igna l . The
two
co lo r
d i f f e rence
s igna l s
are
superimposed
on
t h e luminance s igna l in the
form
o f a quadra tu re
phase encoded sub ca r r i e r .
Sampling frequency
The
4:2:2 d i g i t a l
component video s t anda rd t akes
these
Y B-Y and
R-Y
components and
d i g i t i ze s them. The luminance
channel
i s
sampled
a t
13.5 MHz and the two co lo r d i f f e rence channels
are
sampled a t 6.75MHz. This i s the or ig in of the 4:2:2 r a t i o which
expresses
the
r e l a t i ve bandwidth of
h e YUV
components
fo r every
two
luminance
samples t he re i s only one
p a i r
of co lo r
d i f f e r en ce
samples.
Luminance Satu ra t ion
and
Hue
RG co lo r space can be viewed
as a
cube
s tanding
on one of i t s
PRELIMINARY
Color Encoding
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Video
Interface
Manual
6
corners the bottom corner i s black the top corner diagonally
opposi te
t i s
white.
The
red green and
blue points are a t the
end
of the
edges
direc t ly
connected
to
the
black corner
and
the
secondary
colors
are
a t the
remaining
three points , Yellow between
Red and gree n Cyan between
Green
.and Blue and magenta between Blue
and
Red.
t
RGB
Cube
diagram
LSH
Lozenge
diagram
I f the colored corners of the cube are
t rans la ted
ver t ica l ly so
t ha t
t he i r
perceived
luminance
value on
the black
to white scale
i s
equal
to the i r ver t ica l
posi t ion
the
cube
becomes
dis tor ted
in to
a lozenge- l ike shape
where
a l l
of the faces are
paral lelograms.
The equation for the luminance component of an RGB color i s based
on
the
luminosity coeff ic ients (or the
observed
re la t ive
brightness) of
Red Green and
Blue.
Y
=
0.299
R
+
0.587
G
+
0.114
B
Viewed from above th i s cube
forms a
hexagonal
shape s imi lar
to the
vector scope display of
a composite video s ignal
The
center of
the hexagon i s the l ine jo in ing the white and black corners viewed
PRELIMIN RY
Color Encoding
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end on.
From
th i s
view we
can express hue and saturat ion in polar
coordinates
where hue
i s
the
angle
and
saturat ion i s
the distance
from
the center of the hexagon to the color.
c ~ '
vector
Scope
Diagram
The composite
video s ignal consis ts of the
luminance s ignal
with
subcarr ier
modulated
on top
of
i t The amplitude
of
the color
subcarr ier
i s
equal to the
sa tura t ion and
the phase of the
subcarr ier
re la t ive to
reference
i s
the hue.
R-Y B-Y
Color
Difference
Signals
Algebraic
juggling of the luminance equation above can
yie ld
the
following two equations
R-Y)
= 0.701 R -
0.587
G - 0.114 B
B-Y)
= -
0.299
R -
0.587
G
0.886
B
These two differences are adjusted
as follows.
PRELIMIN RY
Color Encoding
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A60/A64 Digi t a l Video
In t e r face
Manual
Cb
=
0.564
B-Y)
Cr
= 0.713
R-Y)
8
The
weight ing normal ises the color d i f f e rence s igna l s
to
the range
-0 .5 to +0.5
when
t he
luminance
s igna l i s i n t he range 0.0 to 1.0
and so a l lows maximum use of the dynamic range ava i l ab l e .
Note
the weight ing
coe f f i c i en t s
a re
d i f f e ren t
to
those
used for PAL and
NTSC
coding
where they
a re
used t o l imi t
the
maximum
excurs ions
of
t he modulated s igna l .
Two color d i f fe rences
and
a luminance value
provide
s u f f i c i e n t
informat ion to
r egenera t e t he RG
informat ion
a t t he rece ive r .
The
human
eye i s
more
s ens i t i ve
to
changes
in
luminance
than
changes
in
chrominance. In
order
to
reduce t he
bandwidth
o f t he
video
in format ion
to a manageable l eve l
the
amount o f chrominance
informat ion i s halved.
Once t he RGB-YUV conversion
has
been performed once
to
round
the
RG
values to
t he
nea res t YUV value t
should
be poss ib l e to
reverse and r epea t the convers ion wi thout any progress ive
degradat ion
of the video . The only obs tac le in t h i s
process i s
t ha t when t he conversion
i s
done
the
components have to be
f i l t e r e d
to l i m i t t he i r bandwidth to ha l f
the
sampl ing
frequency,
unless t h i s
i s
a
p e r f e c t
f i l t e r the in format ion wi l l
become
smeared
by success ive
passes
through the f i l t e r .
Put t ing a l l t h i s in to one
matr ix
we ge t :
Y =
0.299
Cb
= -0 .1686
Cr
=
0.4998
PRELIMINARY
r 0.587
r - 0.3311
r - 0.4185
g 0.114 i
g 0.4997 i
g - 0.0813
i
Color
Encoding
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1.3 Rendering i n to
the Framestore
Component
sampling
The samples
are in a
sequence
o f four bytes : Cb Y
Cr
Y. A
component
f rames tore
w i l l
s t o re two
bytes per p ixe l but when
the
da ta i s
conver ted form
d i g i t a l to analog t he f i r s t
t h r e e
byte s i e
t h e f i r s t
luminance and
both the co lo r d i f f e rence
samples a re
supposed
to
be
co inc iden t . The f i r s t p ixe l
o f
each
p a i r
has
samples fo r a l l t h ree components, the
second
has
only a
luminance
va lue .
Example
convers ion
program
An
example
convers ion program
fo r
RG
va lues
ranged between 0 and
255
to
A60jA64 4:2:2 component
video
i s
provided a t t h e end t h i s
program i s not optimized
i t - i s in tended to
show
t h e
ind iv idua l
s t eps
in t h e convers ion .
The example
a l so
con ta ins a
r a the r slow
example of a FIR f i l t e r
which again i s not
p a r t i c u l a r l y
e f f i c i en t
bu t
l im i t s t he
co lo r
d i f f e r en ce
s igna l s to
the spec i f i ed
bandwidths.
I f the
bandwidth
of the co lo r d i f f e rence components
i s not
l imi ted
when
viewing t h e t h e
composi te
s igna l
c ross -co lo r
and
dot -c rawl
e f f e c t s
may
be observed
on
sharp
luminance
o r
chrominance
t r ans i t i ons
because of over lap of the
luminance
and
chrominance
components
in
the frequency
domain
of the composi te s igna l .
Framestore
dimensions
The A60jA64 holds
a
frame as
two f i e lds
720
p ixe l s per
l i ne
by
243
l i ne s
fo r
525 l i n e systems
and
288
fo r
625. The SCSI p o r t only
permi ts
the f rames tore
to be
accessed a
f i e l d
a t a
t ime whereas
the
Etherne t t r a ns f e r s can be e i t he r f i e l d o r
f rame.
Component
dev ices such as the A60 and A64 do not s u f f e r from t h e
same
co lo r
f i e l d
sequence
problems
presen t
in
analog
videotape
edi t ing .
The cho ice o f
ed i t
po in t s with VTRs i s
inf luenced
by the
need to
match the co lo r
subcar r i e r
phase
and
t h i s
only
r epea t s
every four
f i e l ds
eight for PAL .
PRELIMINARY
Framestore dimensions
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Of
course t he re i s st ll a
spa t i a l d i f fe rence between
t he two
f i e l ds
and
al though
t he
Disk Recorders
conta in
an
In te rpola tor
t ha t i s capable
o f
genera t ing a f i e l d 1 from a f i e l d 2 t t he
ve r t i ca l reso lu t ion of t he image i s
reduced.
Example
Component Data
The fo l lowing l i s t i n g shows a
l i ne
of the 100 Color bars which
are
i n t e rna l l y
genera ted i n the A60/A64.
They
a re provided
as an
example
o f
A60/A64
component d i g i t a l
video
format and
s ince
these
are used
t o l i n e up
the
analog c i r c u i t r y in t he machine they
are
t he
bes t
reference to work from.
The
r epea t
counts
a re
in
decimal
but
t he p ixe l
va lues
a re in
hex.
Note t h a t t he re are
a t
l e a s t 8 p ixe l s o f
t r ans i t i on between
each
co lo r
80 10
80
10
80
46 80
B4
80
EB
80
EB
35 *
80
EB
80
EB
White)
80
EB 80
EB
75
EB 82
E4
32
D8 8D
D2
10
D2
92
D2
36
*
10
D2
92
D2
Yellow)
10
D2 92
D2
1F D2
85
C7
79
B3 37 A9
A6
A9
10 A9
36
*
A6
A9
10 A9
Cyan)
A6 A9
10
A9 9B
A9
12
A3
57 96
D 90
36
90
22
90
36
*
36 90
22
90
Green)
36
90
22 90
45 90
35
87
9E
73
A5
6A
CA
6A
DE 6A
36
* CA
6A
DE 6A
Magenta)
CA
6A
DE
6A
BF
6A
EO
64
7C
57
EA 51
5A
51
FO
51
36
* 5A
51
FO
51
Red)
5A
51
FO
51
69
51 E3
47
C3 33
95
28
FO
28 6E
28
36
*
FO
28
6E
28
Blue)
FO
28
6E 28
E5
28
70
22 A2
16
7B 10
80
10
80
10
36
*
80
10 80
10
Black)
80
10
80
46 80
B4 80
EB
80
EB 80
EB
35 *
80
EB 80
EB
White)
80
EB
80 EB
80
B4 80 46 80
10 80
10
Blanking
ve r t i ca l
blanking
PRELIMINARY
Blanking
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v e r t i c a l
blanking
t r a d i t i o n a l l y t akes up 19 5
l i ne s
o f each 525
l i n e f i e ld
and
fo r
625
however
the
A60
and
A64
f rames tore
conta ins
a l l
but
9.5 of
the video
l i ne s
of t he
f i e ld
t ha t
i s 506 l i ne s
per
frame in 525 systems and 606 in 625
Horizontal
Blanking
The 720 samples
per
l i n e
a re a l l ac t ive
but t he values
should
ramp
up
from
b lack a t the ends of t he l i ne .
Analog Blanking
The s pec i f i ca t i on for t he ac t ive
por t ion
of
a
composite analog
l i ne i s s l i g h t l y l e s s than
the
d i g i t a l s tandard for in s tance
d ig i t a l
ac t i ve
l i n e
i s 53 3 us long
when
you
t ake
720/13 5
however
the
analog
ac t i ve l i ne
in the
NSTC
spec i s 52 7 us and in
PAL i s
51 95 us . This might
cause
3 to 8
p i xe l s
to be cropped a t e i t h e r
end
o f
the l i ne i the video
i s
passed through an analog device
t ha t adds blanking such
as a VTR
the d ig i t a l
l i n e
i s
supposed to
be cen te red in r e l a t ion to t he
analog
l i ne .
Safe Areas
SMPTE s t andard recommends a
Graphics
sa fe
area
with a 5 border
a l l
round
and
a
T i t l e sa fe area with
a 10 border to
account
for
the overscanning
o f
domest ic rece ive rs .
1.4 In te rpo la t ion
The
A60
and
A64 output
hardware does conta in an i n t e r po l a to r to
al low
it to genera t e a second f i e ld
from
one
To
genera te an adjacent f i e ld it i nev i t ab ly r e s u l t s in
a
los s of
v e r t i c a l
r e s o l u t i on s ince the new
f i e ld i s
spa t i a l l y
o f f s e t from
the
old one and
the
A60/A64 in te rpo la tes
ve r t i c a l l y
to
avoid
an
apparent
p ic tu r e
s h i f t .
PRELIMINARY
In t e rpo l a t i on
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1.5 Fi l te r ing
The simplest
way
to l imi t the
bandwidth
of dig i t a l ly sampled data
i s to sh i f t the
data
through
a
FIR (Fini te Impulse
Response)
f i l t e r .
These
are
also ca l led t raversa l
or
non-recursive
f i l t e rs .
l -
-
. /
2.
-,
7
1-
'
- - -
leo
h
I)
hCz
h
N-lJ
h
N-I)
I
I
I
I
-
FIR Fi l te r Diagram
In t h i s diagram
X n)
represents the input sample z are sample
period
delays heN) are
the f i l t e r
coeff ic ients and yen)
i s
the
output value equal to a
the
sum
of
the product terms.
The FIR
f i l t e r I f
the f i l t e r has 5
taps the f i l te red
data
i s
not
avai lable unt i l two more pixel values have been sh i f ted
in to
the
f i l t e r .
The F i l t e r
reg is te rs
should be f i l l ed
with a known value
(such
as
black)
before
the data is shif ted through and in
a
s imilar
way
the
l a s t
two
pixels
wil l
have
to
be
flushed
out
a t
the
end.
Ideal ly the incoming data stream needs to be padded with
a
black
border
equal
to ha l f the width
(aperture)
of the f i l t e r
otherwise
the data
a t
the end
of
one l ine wil l be f i l t e red in to the s t a r t
of
PRELIMINARY
Fi l te r ing
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t he next .
Fi l t e r des ign books such as
the
one mentioned in
the
bib l iography
give formulae for genera t i ng
the
coe f f i c i en t s given t he
number o f
t aps and the s i ze of t he r equ i red
pass
band (normally expressed
as
a f r ac t i on
o f
t he sampling f requency) .
An
odd
number of t aps a re normally chosen to give a
f i l t e r e d
samples t ha t a re coincident with t he input
da ta .
In t h i s appl i ca t ion the
terms
e i t h e r s ide o f
the
cente r w i l l be a
mirror image.
The va lues o f t he t aps a re normal ized such t ha t
they
add up
to
one
so
t h a t
i
the
incoming
da ta
i s
f l a t
t he
same
value
wi l l
be
output .
These magic
numbers
a re produced by t he program
eqf i r
found
in
the
IEEE publ i ca t ion Programs for
Dig i t a l
Signal Process ing .
To
l i m i t 13.5 M z luminance samples to 5.75 M z
-0.05674
0.01883
1.07582
0.01883
-0.05674
To l i m i t 13.5 M z chrominance samples to
2.5
M z
(only
genera t e
a l t e rna te
samples) .
0.14963
0.22010 0.26054
0.22010
0.14963
1.6 Gamma Correct ion
The luminance s igna l i s
not l i nea r
a cathode
ray tube
does not
have
a l i n e a r r e la t ionsh ip between vol tage app l i ed
and l i g h t
output .
Rather
than add cor rec t ion
c i r cu i t ry
to a l l
domest ic
rece ive rs
the t r ansmi t t ed
video
s igna l
i s
pr e - d i s t o r t ed .
This
cor rec t ion
funct ion
approximates to
a
square roo t o f
t he i n t ens i ty
in the
range 0.0 to
1.0 in
f ac t
it
i s equivalen t t o r a i s i ng to
the
power
of 1 /2 .2
PRELIMINARY
Gamma Correct ion
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Take
t h e
example o f a white hor izon ta l
l i ne
two frame) l i ne s
in
he igh t
t he re
i s
one
l i n e
in
each
f i e ld .
I f
these
l i nes
are
s h i f t e d
up
by ha l f a l i n e
in
l i nea r
terms the upper
l i ne
would
remain
peak white and two
adjacent
l i ne s
in
t h e o th e r
f i e l d
have
50 luminance. This w i l l seem t o f l i c ke r because of t he non
l i n e a r
response o f
t h e
phosphor
and the cor rec t answer
i s
to
use
l i ne s o f
50 r a i s e d
to
t h e power 1 /2 .2 o r 73
luminance.
Gamma cor rec t ion
should
be appl ied to
the RGB
va lues before they
are conver ted to
Y I and
components.
1.7
I l l e g a l Colors
Any RGB
co lo r can be encoded in
YUV components bu t
not
every YUV
combinat ion i s
a va l id
RGB
co lo r fo r ins tance YUV co lo r s with
l a rge
chrominance components and
littl
o r no
luminance
are
ou ts ide
RGB
space. I f
YUV space
i s a r ec tang le
RGB space
can be
viewed as t he
lozenge
in
the e a r l i e r
diagram place w i th in t he
r ec tang le .
Normal
TV
p i c t u re s do not con ta in h igh ly sa tu ra ted
co lo r s Computer
rendered images disp layed d i rec t l y
on
a
RGB
monitor can
con ta in
any co lo r in the RGB space
broadcas t s tandards
however
have
a more l imi ted co lo r
range.
The range of NTSC and P L
coded co lo r s
i s a subse t
o f
those
ava i lab le in RGB
components
because o f
r e s t r i c t i o n s on t he modula t ion o f
the
composite
s igna l .
The sa fe s t
way to
determine
whether an RGB
co lo r
i s l ega l o r
not
i s
to ca lcu la te
i t s
luminance
and
sa tu ra t ion
and
to
check
it
aga ins t the
l im i t s
fo r
t he composite s igna l . The
sa t u ra t i o n
should
be
ca l cu l a t ed
using t he composite weight ing fac to rs which
are
d i f fe ren t from
the
ones in
t h e
matr ix ca lcu la t ions above.
These
equa t ions
are
given
so
t ha t
the co lo r s o f rendered ob jec t s
can
be chosen from the l ega l
co lo r
space.
PRELIMIN RY
I l l e g a l Colors
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The
PAL
matr ix
i s
Y
= 0.299
*
r +
0.587
* g
+
0.114
*
b ;
u
=
-0 .147
*
r -
0.289
*
g
+
0.437
*
b;
V
=
0.615
*
r -
0.515
*
g -
0.100
*
b ;
sa t u ra t i o n = j
u l
+
v l.
For RGB va lues
, in the range
0.0
to
1 .0
Maximum excurs ion (Y + sa tu ra t ion
must be l e s s than
1.334
Minimum excurs ion (Y -
sa tu ra t ion
must
be gre a t e r than
-0 .339
The
NTSC
matr ix
i s
Y
=
0.299
*
r +
0.587
* g +
0.114
*
b;
I
=
0.596
*
r -
0.274
*
g -
0.322
*
b i
Q
=
0.211
*
r -
0.523
*
g +
0.312
*
bi
s a tu r a t i on
=
JIL
Q
For RGB
va lues in
the range
0.0
to
1 .0
Maximum excurs ion (Y +
sa tu ra t ion must be l e s s than o r
equal
to
Minimum excurs ion
(Y - sa tu ra t ion
must
be gre a t e r than -0 .251
100 Color
Bars a re not considered
v a l i d for
t ransmiss ion in NTSC
sys tems,
t he co lo r space i s normal ly l imi ted
to
t he
75 luminance
(100
sa tu ra ted co lo r
ba rs
with
a 100 white t h i s keeps
the
s igna l
wi th in
the
l im i t s of 100 -16 IRE un i t s .
PRELIMINARY
I l l e g a l
Colors
1 .0
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1 8
Pixe l
Aspect
Rat io
The
fo l lowing
diagrams
show the
e f f e c t ive
p ixe l
aspec t
r a t i o
fo r
525 and 625 l i n e
sys tems.
The ca lcu la t ions
are based
on
the
unblanked
video a rea f i t t i n g the 4:3
sc reen aspec t
r a t i o
525 l i ne s
486
162 3)
PRELIMINARY
720 180
*4)
o
1 : 1.1111
625 l i ne s
576
192 3)
720 180
4)
o
1 : 0.9375
Pixe l Aspect Rat io
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2.
SCSI
Appl ica t ion Notes
In t roduc t ion
This
i s a genera l d i scuss ion
of the
c a pa b i l i t i e s
of the
SCSI
s tandard ,
in tended to in t roduce the terminology assoc ia ted with
it Not a l l
the f ea tu res
and
opt ions
mentioned he re a re supported
by the
A60
o r t h e
A64
SCSI
adapte r .
The
SCSI
s tandard
has
evolved from the Shugart
Assoc ia tes
SASI
in te r face .
It
uses an e igh t b i t p a r a l l e l da ta bus with opt ional
pa r i t y over which
da ta i s t r a n s fe r r e d
us ing REQ
ACK
and ATN
handshake
l i nes .
At
any
moment t h e
bus
i s in one o f t en phases
spec i f i ed
by
the
f ive s igna l s
BSY
SEL,
C/O,
I /O
and
MSG.
The usual sequence
o f
phases i s BUS-FREE SELECTION COMMAND
DATA-IN
(or OUT
STATUS BUS-FREE. The
most confus ing aspec t o f
the i n t e r f a c e
i s
t h e way
t ha t t r a ns f e r s
are con t ro l l ed
by
the
per iphera l dev ice ( r e fe r red
to as
t h e Target)
r a the r than by
t h e
hos t computer ( the In i t i a t o r ) . Afte r the In i t i a t o r has
success fu l ly se lec ted the t a rge t it
i s
t h e
t a rge t
t h a t determines
the
the informat ion phase by dr iv ing
the C/D
command/data) , I /O
( in /out ) ,
and MSG message)
l i nes .
Messages prov ide an
add i t iona l
(opt ional) l aye r of communication
in
t h e
s imple s t case the
t a rge t
only sends
a
command complete
message a t
the
end
of the
SCSI
t r a ns f e r .
More
complex
implementat ions
can
use
messages to
con t ro l f ea tu res
l i k e
disconnec t and synchronous
t r ans fe r .
The
a b i l i t y
to suppor t
messages i s
ind ica ted to the Targe t
by
the i n i t i a t o r
during
the
se lec t ion phase.
Since
the Targe t
i s
dr iv ing the REQ
l i ne
the only
way fo r the
i n i t i a t o r
break the t a rge t s
chosen sequence
i s to
a s s e r t
ATN
Attent ion)
in
response to REQ
r a the r
than
ACK.
This ac t i o n should
cause
the
t a r g e t
to change to MESSAGE OUT phase to a l low
t h e
i n i t i a t o r to communicate i t s new informat ion.
This s tandard encourages device independence by
having
a common
command
s e t
app l icab le
to
most
mass
s to rage
per iphera l s ,
from
streaming t ape dr ives to wri te -once read-mul t ip le
opt ica l
d i sks .
The
r e a d and
w r i t e commands i ssued to a
per iphera l on t h e
bus
dea l with l og i c a l
block numbers
r a the r than
cy l inder
and
head
numbers.
PRELIMINARY
SCSI
Appl ica t ion
Notes
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This
al lows fo r
a
new
genera t ion
o f i n t e l l i g e n t
per iphera l
c on t ro l l e r s
t h a t
are ab le
to
t ake ca re of de fec t
mapping,
l oca l
backup and even
perform l oca l da ta
searches .
The block s i z e
and
t he l im i t s o f t he media eg max
number o f
blocks) w i l l vary from
device to device so
the SCSI
s tandard
provides commands to al low
the
hos t computer to
a
obta in
t h i s
informat ion
from t h e
c on t ro l l e r .
SCSI
commands a re grouped according to
t h e
c l a s s
o f
dev ice some
commands such as
the
Test u n i t Ready and Request Sense
are
supported by most
devices . Commands such
as Read and Write have
d i f f e r e n t parameters depending
on the
c lass o f
th e
t a r g e t device.
The
r e a d
command to
a d i rec t
access device such
as a
d i s k has
parameters
fo r
s t a r t block and t r ans fe r l ength . The
read command
to
a
sequen t ia l access
device
such
as
a
Tape
dr ive
has
t h e
same
code but
only has t he
t r ans fe r l ength
parameter .
2.1
Dif fe ren t
l eve l s o f implementa t ion
In r e a l i t y
most SCSI
implementations are
not as
gene ra l i zed
as
the
s tandard might sugges t . Typica l ly
the
hos t
device dr ive rs w i l l
have to
be
customized s l i gh t l y
fo r
a par t i cu l a r
SCSI dev ice to
enable or d i sab le some of the opt iona l f ea tu res
o f
t he spec.
There
are o f ten dev ice
dependent
commands ( espec ia l ly the
format
command) which can vary
depending
on t h e
capab i l i t i e s
of the
device.
Although
the
SCSI
s tandard
provides
a
mechanism
fo r
determining the
l i m i t s
of
a
device and the block
s izes
supported
Host
computers
of ten
make
assumpt ions about the block s i z e .
SCSI ID s
The
SCSI
bus can address
up
to e igh t separa te SCSI dev ices
(cont ro l le rs)
each o f which i n tu rn
can
have e igh t
l og i c a l un i t s
connected to
them. There
i s
a proposed extens ion to
t h e
SCSI
s tandard
to permi t t he address ing o f 64
devices.
Before
a
command
to
a par t i cu l a r
u n i t can
be
i ssued
the
appropr ia te c on t ro l l e r
has
to be se lec ted . Once
communication
between hos t and c on t ro l l e r i s
es tab l i shed
the
SCSI
command
such
as
r e a d
or seek )
i s
passed
to the
t a rge t . Par t o f
the command
block spec i f ie s
t h e l og ica l
u n i t
number
on t h e
se lec ted
device i s
being
addressed .
PRELIMIN RY
SCSI ID
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Multiple In i t i a to rs
There can be more than one i n i t i a to r on the bus in
which
case an
i n i t i a l Arbi t ra t ion bus phase has to be completed before a
prospect ive i n i t i a to r
can gain
control
of the
bus.
I f two
devices
are both
contending for
control a t
the
same
t ime the
winner
wil l
be the
one with
the highest device
ID.
Disconnection
In
multiple in i t i a to r / t a rge t s i tuat ions it may be useful
for
the
ta rge t
to disconnect ie re l inquish
control of
the
bus
mid-way
through
a SCSI
t rans fe r in order to allow
another i n i t i a to r
or
ta rge t to t rans fe r
data
while
the
f i r s t
ta rge t
i s
performing
a
seek. Both devices have to support arb i t ra t ion and
messages.
Single In i t i a to r option
In th i s case
the i n i t i a to r
does
not have to place i t s own ID
on
the
bus
during select ion since there are no
other
In i t i a to rs there
i s no need for the
Target
to
know
it s ID.
SCSI Pointers
The
SCSI
standard
expects
the
i n i t i a to r
to
have
some
sor t
of
context pointer as well as a data t rans fe r pointer . I f the ta rge t
i ssues
a Save Pointers message the In i t i a to r i s expected
to save
i t s
current context
in some way
so
tha t it can re turn
to the
same
s ta te on
rece ip t of a
Restore Pointers message. The save
and
res tore pointers messages are normally used before and
a f te r
a
disconnection, they can
also
be used
to
re turn to a known
s ta te
in
the event of an error Cie res ta r t ing a t rans fe r a t the l a s t
posi t ion
the
pointers
were saved ra ther than
from the
beginning .
Linked
Commands
Linked
commands
enable
commands
to
be
grouped
together in to
one
SCSI t ransact ion ie
the host does
not have to
intervene between
the individual t ransfers) t h i s i s par t icu la r ly useful for the
search
command where
the
i n i t i a to r
can
request
the t a rget to
search for some par t icu la r data and
then
t rans fe r
the
block where
PRELIMIN RY
Linked Commands
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the data was found as two l inked
commands.
Linked
commands
can
also
be used
to
ensure
tha t
commands
using
re la t ive
addressing
do
not get separated.
Synchronous Transfers
Synchronous
t rans fe r can
be
used to
speed
up data
t rans fe r phases,
ins tead
of using the
r ig id
overlapping REQ ACK handshake the REQ
and
ACK l ines
are pulsed
without waiting for a response
from the
other end. The speed of the t rans fe r
can s t i l l
be l imited s ince a
REQ ACK
offse t
i s establ ished
which
means
the ta rge t wi l l stop
request ing i f
t
i s s t i l l waiting for the offse t l imi t of ACKs.
This
permits
a maximum
data
ra te
of 3.3MHz.
Synchronous mode i s enabled by
the
Target and In i t i a to r exchanging
Synchronous Data Transfer Request messages and
i f
necessary
enter ing
in to
negot ia t ion to
establ ish
a mutually acceptable
t rans fe r
period ie the data rate)
and
the REQ ACK
offse t .
2.2 Physical specif icat ions
In
i t s
simplest form the
SCSI bus
uses 50
way
f l a t
Ribbon
cable
with a l te rna te odd
numbered)
l ines grounded. All the
bus
signals
are act ive
low.
The
maximum
cable
length
i s
6
meters.
Drive
capabi l i ty
The bus dr ivers are
intended
to be open
collec tor
or t r i s t a t e
dr ivers capable
of sinking
48
rn such as 7438 or
AM29864 .
Termination
The daisy chained bus has to be terminated a t both ends
with
each
signal
being
pulled
up to +5v with 2200hm and pulled down to
V
with
330ohm.
PRELIMINARY
Termination
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i f ferent ia l drivers
using the di f ferent ia l
drivers option the cable
length can
be
extended to
25
meters using
25 way
twisted pa i r cable.
Termination
becomes
1000hm
between di f ferent ia l pairs
and 3300hms
from the
+
signal
to
ground and
330 between
the
-
signal and
+5V.
One
of the grounded pins
becomes
a
Diff sense signal to protect
against plugging single ended systems
in to
di f ferent ia l ones.
Remote
terminator power
up to 1.0
A
a t V for
powering
remote terminators can optional ly
be
supplied.
2.3
Bus
Signals
All Bus
s ignals are act ive low the RESET
and
BSY signals are OR-tied
signals t ha t can be driven by more than one device a t
a
time.
Reset
BSY
SEL
DB 0-7
DB
Pari ty
REQ
ACK
ATN
MSG
~
I/O
PRELIMINARY
Indicates
a
bus
rese t condit ion
Indicates
the bus i s in use
Indicates
Selection or Reselect ion
phase
Eight b i t data
bus
Data
Bus Pari ty
Request
for
data
t rans fe r
by
the
Target
Acknowledgement of data
t rans fe r
from In i t i a to r
Driven by
In i t i a to r
to
indicate
a t ten t ion condit ion
Indicates
message phase
Different ia tes between Control
and
Data phases
Indicates
the direct ion of data t rans fe r
Bus
s ignals
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2.4
Bus Phases
BSY SEL
C/D I/O
MSG
Bus
Free 1 1
1
Arbi t ra t ion
0 0
1
Selection
0 0
1 1
Reselect ion
0 0
0
1
message in
0
1
0 0
0
message out 0
1
0 0
command
0
1
0
1
data in
0
1
0
1
data out
0
1
1 1 1
s ta tus
0
1
0 0
2.5
Error
condit ions
The normal mechanism for the ta rge t
to
report an error to the host
i s for the t a rget
to return
Check
Condition
in the s ta tus phase.
The In i t i a to r i s expected to
respond
with
a
Request
Sense command
which
allows the
ta rge t
to
describe
the error
condit ion in
more
deta i l .
2.6 In ter fac ing to
the Abekas Disk Recorders
The SCSI in terface for A60 and A6 the has been configured to
allow t
to
be in terfaced to
Hosts
using
the
simplest
implementation of the SCSI protocol. For th i s
reason
t has a
defaul t block s ize of 512 bytes
which
the more
f lex ib le
hosts can
change using
the Mode
se lec t
command
The A60
and
A6
expect video data to be in
a
f ixed
format
so i t s
not possible to re l iab ly place any
volume
l abe ls or f i l e system
s t ructure on the
disk
to
foo l
an
operat ing
system in to mounting
the A60
or
A6
as
a
normal system
disk.
The A60/A64 ei ther has to be
accessed
through customized
device
drivers or
has
to
be
ins ta l led
as
a
raw device.
PRELIMINARY Interfacing to the
Abekas
Disk
Recorders
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2.7 Example SCSI Trans fe r
The fol lowing sec t ion i l l u s t r a t e s t he sequence of bus phases and
the informat ion
t r ans fe r red to and
from the hos t
SCSI
c on t ro l l e r
fo r a read
o f
a
s ing le log ica l block a t 1234H
Speci fy Dest ina t ion ID 7
Speci fy Timeout
Period
Arbi t ra t e fo r con t ro l o f
bus
Selec t
with
Attent ion
Message out
Phase
Send
Ident i fy
log ica l u n i t 0)
and enable d i sconnect [CO]
Command Phase
Specify Transfe r length bytes
Command block
[08]
[00]
[12]
[34]
[01]
[00]
Message
in
Phase
Not implemented
by
A60/A64)
Save
po in te rs message [02]
the t a rge t
wants to
seek)
Message in Phase
Disconnect
message [04]
Target d i sconnected
Rese lec t ion
Determine
Rese lec t ing device
ID 7
PRELIMINARY
Example
SCSI
Trans fe r
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Message in Phase
Rese lec t ing
LUN i den t i f i ed
[80]
Message in
Phase
Not implemented by A60/A64)
Restore po in te rs message
[03]
Data in Phase
Specify Transfer
Count
200H bytes
Transfe r
da ta
se t up DM fo r a 512 byte t r ans fe r )
Sta tus Phase
Sta tus OK [00]
Message in Phase
Command complete Message
[00]
Target
disconnected
24
PRELIMINARY
Example SCSI Transfer
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3. CCIR 601
Reference
The
CCIR
601
inputs
and outputs to t he A64 and A60 cons i s t of
the
fo l lowing
implementat ion:
Components a re re fe r red to
as Cb
and
Cr r a the r than
B-Y) R-Y)
o r
U
and
V
This
i s
to avoid confusion with
the
unweighted color
d i f fe rence s igna l s
B-Y)
and R-Y) and t he weighted analog)
di f fe rence s igna l s
U
and V.
Matrices
The
equat ions
for
obta in ing
Y Cb
and Cr
from
R,
G
and
B
a re
as
fol lows
.
.
Y
=
0.299
R
0.587
G
0.114
B
Cb
=
-0 .1686
R -
0.3311
G
0.4997
B
Cr
=
0.4998
R -
0.4185
G -
0.0813
B
4:2 :2 Sampling
The
sampl ing
r a t e
i s
13.5
M z
fo r the
luminance
and
6.5
M z
for
each
o f
the chrominance
components. The samples
a re
grouped in to
sequences of
four as fol lows
Cb Y
Cr
Y Cb Y
Cr
Y
The f i r s t
t h ree
samples o f each group a re co-s i t ed t he second
luminance
sample has no corresponding chrominance
informat ion.
PRELIMINARY
4:2:2
Sampling
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Data
The values
00
and
FF
are
reserved
for
synchronizing
the data
stream and should not occur in the body of the data.
Luminance information coded as an
unsigned
byte in the range
10 EB 16
235)
where
16 corresponds to black
and
235 to peak
white. Chrominance components are
signed
quant i t ies offse t by 80
128) giving a range
of
10
FO
+/-112) the
EBU specif icat ion is
unclear about the range for chrominance components, t claims
there should be
224
quantizat ion levels centered
on 128,
the
problem being you
can t center
an
even
range,
i t s ei ther got
to
be
224 samples -112
+111 or 225 samples
-112
+112) .
A
l ine
of
data
has
the
following
format
sync preamble
type
data 1440 bytes)
sync
FF 00 00
xx
xx xx xx
. . .
xx xx xx FF 00
00
The type bytes have
the
following values.
video Lines
s ta r t
End
Vert ica l
Blanking
Lines
s t a r t
End
f ie ld
f ie ld 2
80
C7
90
D
B
EC
B
F1
type
XX
There are
three
bi t s to indicate f i r s t f ie ld , s t a r t of f ie ld
blanking and the s t a r t of
horizontal
blanking, the
res t of the
byte i s coded to protect
the
information
in these three bi t s . The
protect ion code
allows single
b i t
er rors to
be
corrected and
also
detects
double
b i t errors .
PRELIMIN RY
Data
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Blanking
The dig i ta l
video
data covers the the ent i re picture area there
are
no ha lf l ines both f ie lds have the same
number
of l ines . The
525 l i ne system has 243 l ines
per
f ie ld and the 625 l ine system
288.
Lines in the
framestore
are
numbered
from 0
.
607 the
f i r s t
active
video
l ine
for
a
525
l ine
system
i s 18
corresponding
to
analog
l ine 20 in the second f ie ld and for a 625 l ine system
t
i s
framestore
l ine
32
corresponding to
analog l ine 23 in
the
f i r s t
f ie ld .
The leading and t r a i l ing edges of the video data should ramp
up
from
black but
the
t rans i t ions
in the
middle
of the
ha lf l ines
are
supposed
to
be generated by some analog component
fur ther
down the
chain and
are
not specif ied in
the
dig i t a l signal .
Additional Notes
A60 wil l
f ree
run i f
there
i s no
analog reference.
The A6
wil l
not.
The
dig i ta l
inputs are independent of the output there i s a
framestore in
the machines.
The dig i t a l
inputs
and
outputs
do
not generate
or
recognize
any
anc i l la ry
data.
The
act ive video data i s not
modified ins ide the
machine
data can
be wri t ten in
the
act ive video areas with any value apar t from 00
and
FF.
PRELIMINARY
Additional Notes
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4. A60/A64 SCSI Data
Format
This
sec t ion
descr ibes the da ta format o f
t he A60/A64
SCSI
por t ,
The video da ta stream i s a
s i m i l a r format to
t h a t emanating CCIR
601
d i g i t a l video p o r t s with the add i t ion o f
l i ne
numbers and the
omiss ion
o f blanking.
The
a c t i v e video da ta passed through t h e
SCSI
i n t e r f a c e on
t he
A60/A64 conforms to
t h e
s tandards
for
4:2:2
Dig i t a l Component
Video
r e f e r r e d
descr ibed in
t h e preceding
sec t ion
There are no
v e r t i c a l blanking
l i ne s passed
through
the SCSI por t ,
hor izon ta l blanking normally
264 bytes
o f black)
i s
omi t t ed ,
in
its place i s an
Abekas
format a nc i l l a ry da ta
s ec t i o n
8 byte s in
length)
which
con ta ins
t he
l i ne number
o f
t he
fol lowing video
da ta . This
gives
1456
bytes
o f
da ta per l i ne : 8 bytes o f l i n e
number, 4 bytes
o f sync,
1440
bytes
o f
video
and 4 bytes
o f sync.
The video
i s
passed through t he
SCSI
p o r t
a
f i e l d a t
a
t ime . The
l i n e numbers
assoc ia ted with each
l i ne
are
f rame l i ne numbers
numbered from so t h a t fo r
a
625
l i ne system
the f i r s t f i e l d
con ta ins a l l
t h e
even
numbered
l i ne s
and these
a re displayed
above
t h e
corresponding odd l i ne s i n
the
second f i e l d .
Be
warned
t h a t
525 l i ne
systems have
a
s t range
f i e l d
order , the
f i r s t f i e l d t r ansmi t ted
in
t h e
NTS
system i s
t h e
lower f i e l d
so
the
top
l i n e in a
frame
i s
ac tua l ly in f i e l d 2.
The sync
pa t t e rn
00 FF FF i s used to charac te r i ze a nc i l l a ry da ta
as
s t a t e d
in
the
CCIR s tandard
however the r e s t of the l i n e number
da ta does
not
conform to any ex i s t ing
s tandard .
a nc i l l a ry
type)
length)
l i ne
number
00 FF FF 64
80
10
XX
XX
The
10
b i t
f rames tore l i n e number i s
s p l i t
over two
bytes as
fol lows to
avoid
using
00
and
FF).
b i t
1 X X X X X
4321
1 X X X X X
98765
The
fo l lowing two l i ne s are
examples
of the appropr ia te coding
PRELIMINARY A60/A64 SCSI
Data
Format
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l i ne 0 f i e l d 1
00 FF FF 64 80 10 80 80 FF 00
00
80 [Cb
Y
Cr
Y
]
FF 00 00 90
l i ne
123
f i e l d
2
00 FF FF 64 80 10 AC 86 FF 00 00
C
[Cb Y Cr Y . ] FF 00 00 DA
Block s i zes
In
order to s impl i fy t he t ask o f t r ans f e r r i ng a f i e ld t he length
of a
f i e ld
i s
rounded
up to make t a
mul t ip le o f
most
of t he
popular b lock
s i zes .
For a
525
l i n e
system
a
f i e l d
i s 368640
bytes long
Ox5AOOO)
which
gives 720 blocks of 512 bytes or 45 blocks o f
8192
by tes . There
a re
252 l i ne s in a 525 l i ne f i e l d inc luding b lanking) , there
i s
one whole l i n e and a f r ac t ion a t
the
end of the
t r ans fe r .
In t he case of a 625 l i ne system a f i e l d i s 450560 by tes long
Ox6EOOO)
which
gives 880 blocks of
512
bytes o r 55 blocks o f
8192
bytes .
There a re 304 l i ne s
in
a 625 l i n e
f i e ld
inc luding
blanking
so
t he re a re f i ve
l i ne s
and
a f r ac t ion padding t he end
of
t he t r ans fe r .
The f r ac t i ona l
l i ne s
j u s t s top in
the
middle t he re
i s
no
need
for
a
te rminat ing sync.
Active Lines
In any
f i e ld
l i ne s a t t he s t a r t
are used
for v e r t i c a l sync and a
f u r t he r 9 a re
blanked fo r
525 l i ne s and 16
for 625,
to
a l low fo r
ve r t i c a l
r e t r ace l eav ing 243
ac t ive
l i ne s
in
a 525 l i n e
f i e ld
and
288
for 625
l i ne s .
525
625
syncs
10.5 8.5
blanked
9
16
ac t ive
243 288
t o t a l
262.5 312.5
The f rames tores in t he
A64 and A60 a re
PRELIMINARY
A60/A64
SCSI Data Format
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capable
of
s tor ing
both
the act ive and the blanked l ines .
In Broadcast videotape appl icat ions the blanked l ines often carry
Vert ica l In terval
Time Code VITC) so
there i s
a fac i l i ty
for one
or two
of
them
selected
on the miscellaneous menu) to be s tored
and replayed
from disk.
The SCSI port dumps a l l of the l ines in the framestore, tha t i s
252 per 525
l ine
f ie ld and 304 for 625
l ines . Applications
rendering f ie lds for
th i s
SCSI format should include the blanked
l ines a t the top
of
the picture they should be
black since
they
are
only
for padding,
none
of
these
l ines
gets recorded
unless
they are selected as VITC l ines .
PRELIMIN RY
A60/A64 SCSI Data Format
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5.
SCSI
Reference Manual
The
A64-
in terface
wil l use
messages
i f
t
i s selected with ATN
asserted. The
Command
Complete message
i s
always
se t a t
the end
of a t rans fe r .
I f enabled the following Messages
are
sent by the
A64
Interface .
Ident i fy
Disconnect
The
only message
out
(of the in i t ia tor ) supported
i s
Ident i fy .
Disconnection
i s
opt ional
and i s
enabled
by
the
i n i t i a to r
se t t ing
the appropriate b i t in the i n i t i a l Ident i fy message.
The Save
poin te rs
and Restore
pointers messages
are not
t ransmit ted
before /af ter
Disconnection/Reselection.
Disconnection ( i f
enabled)
wil l occur during any command t ha t
requires
a seek.
In the
case
of
framestore data
t ransfers the
A64
wil l disconnect between each f ie ld t ransferred.
The A60 and A64
In ter faces
support arb i t ra t ion . As a
Target
the
A60 and
A64
wil l
arb i t r a t e for
control
of the bus
when
reselect ing
the i n i t i a to r
a f te r
a disconnection. Arbi t ra t ion has not been
tes ted
with
more
than
two
devices
on
the
bus.
The A60 and A64
In ter faces
are not
capable
of servicing
overlapping
requests
from two in i t i a to rs .
Linked
commands are
not supported.
Incoming Data Bus Par i ty
i s
not
checked. Outgoing
Data Bus Par i ty
i s generated.
In the event of a SCSI t rans fe r
hanging the
SCSI in ter face
wil l
t imeout
a f te r
a
period of
2 seconds inac t iv i ty and
issue
a bus
rese t .
s ta tus returns
s t a tus OK
except
for the
following er rors which
generate a check condit ion.
PRELIMINARY
SCSI Reference
Manual
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I l l e g a l Length
t he
parameter
fo r
a
seek
o r
space
command
i s
not
a
f i e l d
boundary
t he
t ranspor t command
da ta
i s
l e s s than 4.
End o f Medium
I f
a
spec i f i ed block i s of f the end o f
th e
disk .
The
e r r o r
i s ind ica ted by
a
b i t in the da ta re tu rned in response
to
a
r e q u e s t
sense
command.
There i s a
swi tch
on t he
A64
In te r face to al low
t h e
SCSI bus
r e se t
s igna l to cause
a r e se t
o f the
A64
In te r face .
625
l i n e f i e l d
has 6EOOOH
bytes per
f i e l d 525 l i n e
has
DOOOH
Block s i z e s 100H 1000H 256 4096) Bytes per
Block,
t he de fau l t i s
512 use t he
Mode
S e lec t
and
Mode Sense
commands to change o r
ve r i fy
t h e
s ize .
Seeks
commands should
only be
i ssued
to
f i e l d
boundar ies .
The l a s t f i e l d
on
the
d i s k
i s not
access ib le from the
SCSI
por t .
For a
25 o r 30
second machine
a t t empts to
wri t e
p a s t 25 o r 30
seconds w i l l not be de tec ted by the i n t e r f a c e and the
r e s u l t s w i l l
be unpredic table .
For
t h e
A64
the
SCSI
Targe t
Address
i s
s e t
using
a
DIP
swi tch
on
the i n t e r f a c e card ,
on the
A60
the
DIP
swi tch
i s located
on the
Computer
Card,
each c on t ro l l e r on the
bus inc luding
the hos t has
to have a
unique number.
Remote
con t ro l
s ing le frame
record ing
4-5 frames a
second.
The
SCSI
In t e r f a c e i s capable o f
a maximum
asynchronous
t r ans fe r r a t e
o f 1.1 Mbyte / sec .
Synchronous t r a ns f e r s
a r e not
ye t
suppor ted.
PRELIMINARY
SCSI
Reference
Manual
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5.1 Logical blocks
The block s ize
can
vary from 256 bytes to
4096 bytes.
This
information
can
be
obtained using
the
SCSI Block Limits command.
The
defaul t block
s ize i s
512
bytes . The
block
s ize can
be
changed
using the
Mode
Select
command
and confirmed using the
Mode
Sense
command.
The only r es t r i c t ion on
the
block s ize
i s
t ha t t
must be
an even
factor
of
the f ie ld s ize .
Note
t ha t i f the
power
i s
cycled
on the
A6
In ter face or some
error
causes
the SCSI
in terface
to rese t ,
the
block
s ize wi l l
re turn to 512 bytes .
The block s ize used for the
A60/A64
Offline storage tape i s
6C10H.
Tapes
should be compatible between A64s
and
A60s.
The
A60/A64 SCSI in terface only
accepts data as f ie lds ,
a
frame of
video has to be t ransferred as
two
f ie lds .
Transfers
le ss than a
f ie ld
in length
are buffered
in
the
A60/A64
framestore
unt i l the l as t
block in
the f ie ld i s
wri t ten ,
a t which
point
the whole
f ie ld i s
flushed to
the disk.
For
a s ingle
block
t rans fe r
sequence
to
complete
correct ly t
must
s t a r t on f ie ld
boundary
eg
logical block
address MO blocks per
f ie ld - -
0 and
end with
a logica l block address MO
blocks per
f ie ld
- - block per
f ie ld
- 1, in
other
words
even
though t i s
possible
to
t rans fe r
units of
less than a
f ie ld
the SCSI in terface
wil l
not
accept t ransfers tha t a ren t grouped
as
f ie lds .
5.2
SCSI Commands
The
A60/A64
can be
t rea ted as e i ther a Sequent ial device
eg Tape)
or a Direct Access
device eg
Disk). Commands
are supplied t ha t
support
ei ther
model.
Since
there
i s
some
overlap
both
read
commands have
the same op code but dif fe ren t parameters) Direct
Access
commands should be addressed to Logical
uni t
zero and
Sequential access
commands
to Logical uni t one.
PRELIMINARY
SCSI Commands
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The only occasion
where
the Logical uni t f ie ld i s important i s for
the
Read and
write commands
which
have
dif fe ren t
formats
for
di rec t
and sequential
access.
For
sequential
access the SCSI Interface
requi res
t ha t the
user
issues
a
rewind
command
or
a direc t
access
seek command) before
performing
any sequential
act ions, th i s
i s
because the
SCSI
in terface has no way
of
determining
the
posi t ion
of the disk heads
t
has to remember what
has happened
since
t
l a s t
issued a
goto
command to
the
A60/A64.
Similar ly i f
the control
panel
i s used or i f
se r ia l
protocol
commands are issued some
form
of direc t access command must be
issued before a sequential read
or wri te wil l work
correct ly
The descript ion
for each command
shows the
s t ructure
of the
command and gives the sequence of bytes t ha t are expected -
information supplied by the i n i t i a to r i s shown
as xx
The command
descript ion also
shows
the
SCSI Bus
phases tha t can
be expected
and
whether or
not the ta rge t
wil l
disconnect during the course of
the
t rans fe r
PRELIMINARY
SCSI Commands
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Request Sense
This
command
should be
i ssued
by t h e
I n i t i a t o r in
t h e
even t t h a t
Check
Condi t ion
s t a t u s i s re tu rned
by the A60/A64.
Non ex tended sense da ta
format
i s not suppor ted so
t h e
a l l o c a t i o n
l eng th Command byte
3
should be 8 o r
g re a t e r .
The
da ta re tu rned i s a l l
zeroes excep t f o r t h e I n co r r ec t
Length
i nd ica to r or the End o f Medium b i t s are s e t depending on t he e r r o r
cond i t ion .
Command
7
6
5
4
3
2
1
0
0
[
Command
]
03
1 00
2 00
3
00
4
[
Alloca t ion
Length
] 08
5
00
Disconnect
No
Data
In
7 6
5 4
3
2 1 0
0
V L
[
Class
]
[
Code
]
70
1
00
2 EOM
ILl
XO
Error
Flags
3
00
4
00
5
00
6
00
7
00
S ta tu s
OK
PRELIMINARY
Request Sense
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Rezero un i t
Seek to Fie ld Zero
Command
7 6 5 4
o Command
1 [
LUN
]
2
3
4
5
Disconnect
Yes
s t a t u s
O
3 2
Time
to complete
Four f i e lds .
PRELIMINARY
o
I
]
01
00
00
00
00
00
38
Rezero
un i t
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Read
Direct)
Read
up
to 55
blocks
of data from the A60/A64. Must
be
Issued to
Logical uni t 0 i f the di rec t
access
format i s
to
be used.
1 7 1 6 1 5 1 4 1 3 I 2
111
0 I
o [- Command -] 08
1 [ LUN -] [ LB
Addr
MSB
]
XX
2 [
Logical Block
Addr
-] XX
3 [ Logical Block Addr LSB
]
XX
4 [
Transfer
length
-] XX
5 00
Disconnect
Yes
Data In
Length
Block
Size
bytes of composite
video
s ta tus OK
or Check
Condition
Time to complete For each f ie ld
read
the
A64
wil l disconnect for
four f ie lds
and then take a t
leas t
s ix
f ie lds to DM the data out
of
the
Store.
I f
s ingle block t ransfers
are
used
the A60/A64 will
disconnect before t ransfer r ing each block but only the f i r s t block
of
each f ie ld will disconnect for longer than a few mill iseconds.
PRELIMINARY
Read
Direct)
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wri te Direct)
Must
be Issued to
Logical uni t 0 i f the di rec t
access format
i s to
be
used.
Command
I
7
I
6
I
5
I
4
I
3
I
2
I
1
I
0
I
0
[
Command
]
O
1
[
LUN
]
[
LB Addr MSB
]
XX
2
[
Logical
Block Addr
]
XX
3
[ Logical Block Addr
LSB
]
XX
4
[
Transfer length
]
XX
5
00
Disconnect Yes
Data
Out
Length
block
s ize bytes of composite video
s ta tus OK or Check Condition
Time
to
complete For each
f ield
wri t ten the A60/A64 wil l
disconnect for
nine f ie lds and then take
a t l eas t
s ix f ie lds
to
DM the data in to the s tore
PRELIMIN RY
write
Direct)
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Seek
Causes
a
seek
to
the given Logical Block
address
Command
7 6 5 4 3
2
1 0
o [ Command ] OB
1
[ LUN ] [
LB
Addr
MSB ] XX
2
[ Logical
Block
Addr
] XX
3
[ Logical Block
Addr
LSB ] XX
4
00
5 00
Disconnect
Yes
s ta tus
OK or Check Condition
Time to
complete
Four f ie lds .
PRELIMIN RY
Seek
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Read Direct Extended)
The
Extended Read
command
allows
for
longer t rans fe rs and la rger
Logical Block addresses than the 6 byte command.
Command
I
7
I
6
I
5
I
4
I
3
I
2
I
1
0
I
0
[ Command
]
8
1
[
LUN
]
00
2