Abekas A60 A64 Digital Disk Recorder Preliminary Interface Manual Aug87

7/23/2019 Abekas A60 A64 Digital Disk Recorder Preliminary Interface Manual Aug87

1/84

Video Systems Inc.

Carlton

ompany

digital disk recorder A60 64

A60 64

Preliminary

igital Video

nterface

Manual


2/84

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


3/84

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


4/84

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


5/84

12 I 3 J L } ) J L l . ( ) ~ ~ C l l ? l l l

78

l l l


6/84

A60/A64 Dig i t a l Video In te r face Manual

2

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



7/84

A60/A64

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


8/84

A60/A64 Dig i t a l

Video

In te r face Manual

4

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


9/84

A60/A64 Dig i t a l

Video

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


10/84

A60/A64 Digital

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


11/84

A60/A64 Digital

Video

Interface Manual

7

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


12/84

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


13/84

A60jA64 Dig i t a l Video In te r face Manual 9

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


14/84

A60/A64 Dig i t a l Video

In te r face Manual 10

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


15/84

A60/A64

Digi t a l Video In t e r face Manual

11

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


16/84

A60/A64 Digital Video Interface Manual

12

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


17/84

A60/A64 Digi t a l Video In t e r f a c e Manual 13

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


18/84

A60/A64 Dig i t a l Video In te r face Manual 14

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


19/84


15

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


20/84

A60/A64 Dig i t a l

Video In t e r f a c e

Manual

16

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


21/84

A60/A64 Dig i t a l Video In t e r f a c e Manual

17

2.

SCSI


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


22/84

A60/A64 Dig i t a l Video In te r face Manual 18

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


23/84

A60 A64

Digi ta l

Video

Interface Manual

19

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


24/84

A60/A64

Digi ta l Video In ter face

Manual

20

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


25/84

A60/A64

Digi ta l Video Interface Manual 21

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


26/84

A60/A64 Digital

Video

Interface Manual 22

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


27/84

A60/A64 Digi ta l Video In te r face Manual

23

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


28/84


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


29/84

A60/A64 Digi t a l Video In t e r f a c e Manual

25

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


30/84

A60/A64 Digital

Video In ter face

Manual 26

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


31/84

A60/A64 Digital

Video

Interface Manual

27

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


32/84

A60/A64 Dig i t a l

Video

In te r face

Manual

28

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


33/84

A60/A64 Digi t a l Video In t e r face Manual

29

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


34/84

A60/A64

Digital Video Interface

Manual

30

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


35/84

A60 A64 Digi ta l

Video

Interface

Manual

31

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


36/84

A60/A64

Dig i t a l

Video

In te r face Manual

32

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


37/84

A60/A64 Digi ta l

Video

Interface

Manual 33

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


38/84

A60/A64 Digital Video In terface Manual

4

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


39/84


40/84


41/84

A60/A64 D ig i t a l Video I n t e r f ace

Manual 37

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


42/84

A60 A64 Dig i t a l Video In te r face Manual

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


43/84

A60/A64 Digi ta l

Video

Interface Manual

39

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)


44/84

A60/A64 Digi ta l

Video

Interface Manual

40

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)


45/84

A60jA64

Digital

Video Interface Manual

41

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


46/84

A60/A64 Digi ta l Video Interface Manual

42

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

Abekas A60 A64 Digital Disk Recorder Preliminary Interface Manual Aug87

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Transcript of Abekas A60 A64 Digital Disk Recorder Preliminary Interface Manual Aug87