<s>
ANIM	B-Device
is	O
a	O
file	O
format	O
,	O
used	O
to	O
store	O
digital	O
movies	O
and	O
computer	O
generated	O
animations	O
(	O
hence	O
the	O
ANIM	B-Device
name	O
)	O
,	O
and	O
is	O
a	O
variation	O
of	O
the	O
ILBM	B-Operating_System
format	O
,	O
which	O
is	O
a	O
subformat	O
of	O
Interchange	B-Device
File	I-Device
Format	I-Device
.	O
</s>
<s>
Known	O
filetypes	O
for	O
Anim	B-Device
into	O
AmigaOS	B-Application
are	O
:	O
Anim1	O
,	O
Anim2	O
,	O
Anim3	O
,	O
Anim5	O
and	O
Anim7	O
.	O
</s>
<s>
Anim	B-Device
5	O
and	O
Anim7	O
should	O
be	O
able	O
to	O
contain	O
Audio	O
Data	O
,	O
being	O
a	O
complete	O
movie	O
animation	O
file	O
format	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
normal	O
ILBM	B-Operating_System
chunks	O
,	O
ANIM	B-Device
filetype	O
also	O
defines	O
:	O
</s>
<s>
The	O
ANIM	B-Device
IFF	O
format	O
was	O
developed	O
in	O
1988	O
at	O
Sparta	O
Inc.	O
,	O
a	O
firm	O
based	O
in	O
California	O
,	O
originally	O
for	O
the	O
production	O
of	O
animated	O
video	O
sequences	O
on	O
the	O
Amiga	B-Device
computer	I-Device
,	O
and	O
was	O
used	O
for	O
the	O
first	O
time	O
in	O
Aegis	O
Development	O
's	O
Videoscape	O
and	O
Video	O
Titler	O
programs	O
for	O
the	O
Amiga	B-Device
line	O
of	O
computers	O
.	O
</s>
<s>
Being	O
very	O
efficient	O
and	O
an	O
official	O
subset	O
of	O
existing	O
Amiga	B-Device
ILBM/IFF	O
standard	O
file	O
format	O
,	O
it	O
became	O
the	O
de	O
facto	O
standard	O
for	O
animation	O
files	O
on	O
the	O
Amiga	B-Device
.	O
</s>
<s>
Several	O
compression	O
schemes	O
have	O
been	O
introduced	O
in	O
the	O
ANIM	B-Device
format	O
.	O
</s>
<s>
Most	O
of	O
these	O
are	O
strictly	O
of	O
historical	O
interest	O
,	O
as	O
the	O
only	O
one	O
currently	O
used	O
is	O
the	O
vertical	O
run	B-Algorithm
length	I-Algorithm
encoded	I-Algorithm
byte	O
encoding	O
developed	O
by	O
Atari	O
software	O
programmer	O
Jim	O
Kent	O
.	O
</s>
<s>
Amiga	B-Device
Anim7	O
format	O
was	O
created	O
in	O
1992	O
by	O
programmer	O
Wolfgang	O
Hofer	O
.	O
</s>
<s>
A	O
video	O
file	O
format	O
originally	O
created	O
for	O
the	O
Commodore	B-Device
CDTV	I-Device
,	O
and	O
later	O
adapted	O
for	O
the	O
Amiga	B-Device
CD32	I-Device
,	O
was	O
called	O
CDXL	O
and	O
was	O
similar	O
to	O
the	O
ANIM	B-Device
file	O
format	O
.	O
</s>
<s>
A	O
minimum	O
Anim	B-Device
file	O
consists	O
of	O
three	O
ILBM	B-Operating_System
interleaved	B-Operating_System
bitmap	I-Operating_System
images	O
.	O
</s>
<s>
The	O
initial	O
frame	O
is	O
a	O
normal	O
run-length-encoded	O
,	O
IFF	O
picture	O
,	O
and	O
this	O
allows	O
a	O
preview	O
of	O
the	O
contents	O
of	O
the	O
file	O
.	O
</s>
<s>
The	O
Amiga	B-Device
switches	O
between	O
the	O
screens	O
almost	O
instantaneously	O
while	O
loading	O
further	O
frames	O
using	O
the	O
blitter	O
.	O
</s>
<s>
ANIM	B-Device
is	O
an	O
IFF	O
FORM	O
and	O
its	O
chunk	O
structure	O
is	O
as	O
follows	O
:	O
</s>
<s>
The	O
initial	O
FORM	O
ILBM	B-Operating_System
can	O
contain	O
all	O
the	O
normal	O
ILBM	B-Operating_System
chunks	O
,	O
such	O
as	O
CRNG	O
,	O
etc	O
.	O
</s>
<s>
The	O
BODY	O
will	O
normally	O
be	O
a	O
standard	O
run-length-encoded	O
data	O
chunk	O
(	O
but	O
also	O
any	O
other	O
legal	O
compression	O
mode	O
as	O
indicated	O
by	O
the	O
BMHD	O
)	O
.	O
</s>
<s>
The	O
subsequent	O
FORMs	O
ILBM	B-Operating_System
contain	O
an	O
ANHD	O
,	O
instead	O
of	O
a	O
BMHD	O
,	O
which	O
duplicates	O
some	O
of	O
BMHD	O
and	O
has	O
additional	O
parameters	O
pertaining	O
to	O
the	O
animation	O
frame	O
.	O
</s>
<s>
A	O
basic	O
assumption	O
in	O
ANIMs	B-Device
is	O
that	O
the	O
size	O
of	O
the	O
bitmap	O
,	O
and	O
the	O
display	O
mode	O
(	O
e.g.	O
</s>
<s>
The	O
DLTA	O
chunks	O
are	O
not	O
interleaved	B-Operating_System
bitmap	I-Operating_System
representations	O
,	O
thus	O
the	O
use	O
of	O
the	O
ILBM	B-Operating_System
form	O
is	O
inappropriate	O
for	O
these	O
frames	O
.	O
</s>
<s>
Anim	B-Device
format	O
allow	O
five	O
methods	O
of	O
compression	O
:	O
XOR	O
mode	O
,	O
Long	O
Delta	O
mode	O
,	O
Short	O
Delta	O
mode	O
,	O
General	O
Delta	O
mode	O
and	O
Byte	O
Vertical	O
Compression	O
.	O
</s>
<s>
Playback	O
of	O
ANIMs	B-Device
will	O
usually	O
require	O
two	O
buffers	O
,	O
as	O
mentioned	O
above	O
,	O
and	O
double-buffering	O
between	O
them	O
.	O
</s>
<s>
The	O
frame	O
data	O
from	O
the	O
ANIM	B-Device
file	O
is	O
used	O
to	O
modify	O
the	O
hidden	O
frame	O
to	O
the	O
next	O
frame	O
to	O
be	O
shown	O
.	O
</s>
<s>
When	O
using	O
the	O
XOR	O
mode	O
,	O
the	O
usual	O
run-length-decoding	O
routine	O
can	O
be	O
easily	O
modified	O
to	O
do	O
the	O
exclusive-or	O
operation	O
required	O
.	O
</s>
<s>
The	O
general	O
procedure	O
,	O
for	O
all	O
compression	O
techniques	O
,	O
is	O
to	O
first	O
decode	O
the	O
initial	O
ILBM	B-Operating_System
picture	O
into	O
the	O
hidden	O
buffer	O
and	O
double	O
buffer	O
it	O
into	O
view	O
.	O
</s>
<s>
The	O
Anim	B-Device
standard	O
of	O
Amiga	B-Device
influenced	O
the	O
development	O
of	O
Animated	O
GIF	O
format	O
.	O
</s>
