<s>
Apple	B-Algorithm
Video	I-Algorithm
is	O
a	O
lossy	B-Algorithm
video	O
compression	O
and	O
decompression	O
algorithm	O
(	O
codec	B-General_Concept
)	O
developed	O
by	O
Apple	O
Inc	O
.	O
and	O
first	O
released	O
as	O
part	O
of	O
QuickTime	O
1.0	O
in	O
1991	O
.	O
</s>
<s>
The	O
codec	B-General_Concept
is	O
also	O
known	O
as	O
QuickTime	B-Algorithm
Video	I-Algorithm
,	O
by	O
its	O
FourCC	B-Application
RPZA	B-Algorithm
and	O
the	O
name	O
Road	O
Pizza	O
.	O
</s>
<s>
When	O
used	O
in	O
the	O
AVI	O
container	O
,	O
the	O
FourCC	B-Application
AZPR	O
is	O
also	O
used	O
.	O
</s>
<s>
The	O
bit-stream	O
format	O
of	O
Apple	B-Algorithm
Video	I-Algorithm
has	O
been	O
reverse-engineered	O
and	O
a	O
decoder	O
has	O
been	O
implemented	O
in	O
the	O
projects	O
XAnim	O
and	O
libavcodec	B-Language
.	O
</s>
<s>
The	O
codec	B-General_Concept
operates	O
on	O
4×4	O
blocks	O
of	O
pixels	O
in	O
the	O
RGB	O
colorspace	O
.	O
</s>
<s>
Because	O
Apple	B-Algorithm
Video	I-Algorithm
operates	O
in	O
the	O
image	O
domain	O
without	O
motion	O
compensation	O
,	O
decoding	O
is	O
much	O
faster	O
than	O
MPEG-style	O
codecs	B-General_Concept
which	O
use	O
motion	O
compensation	O
and	O
perform	O
coding	O
in	O
a	O
transform	O
domain	O
.	O
</s>
<s>
As	O
a	O
tradeoff	O
,	O
the	O
compression	O
performance	O
of	O
Apple	B-Algorithm
Video	I-Algorithm
is	O
lower	O
.	O
</s>
<s>
Runs	O
of	O
skip	O
blocks	O
are	O
coded	O
in	O
a	O
run-length	B-Algorithm
encoding	I-Algorithm
scheme	O
,	O
enabling	O
a	O
high	O
compression	O
ratio	O
in	O
static	O
areas	O
of	O
the	O
picture	O
.	O
</s>
<s>
This	O
can	O
be	O
interpreted	O
as	O
a	O
palette	B-Data_Structure
with	O
a	O
single	O
color	O
.	O
</s>
<s>
In	O
four	O
color	O
mode	O
,	O
each	O
pixel	O
in	O
a	O
block	O
is	O
decoded	O
as	O
one	O
of	O
four	O
colors	O
which	O
are	O
specified	O
in	O
a	O
palette	B-Data_Structure
.	O
</s>
<s>
The	O
same	O
palette	B-Data_Structure
is	O
used	O
for	O
a	O
run	O
of	O
length	O
between	O
one	O
and	O
32	O
blocks	O
.	O
</s>
<s>
Interpreted	O
as	O
vector	B-Algorithm
quantization	I-Algorithm
,	O
a	O
three-dimensional	O
vector	O
with	O
the	O
components	O
red	O
,	O
green	O
,	O
and	O
blue	O
is	O
quantized	B-Algorithm
using	O
a	O
codebook	O
with	O
four	O
entries	O
.	O
</s>
<s>
This	O
mode	O
is	O
lossless	O
and	O
equivalent	O
to	O
raw	O
PCM	B-Algorithm
without	O
any	O
compression	O
.	O
</s>
