<s>
A	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
(	O
or	O
sometimes	O
video	B-Algorithm
compression	I-Algorithm
format	I-Algorithm
)	O
is	O
a	O
content	O
representation	O
format	O
for	O
storage	O
or	O
transmission	O
of	O
digital	B-General_Concept
video	O
content	O
(	O
such	O
as	O
in	O
a	O
data	O
file	O
or	O
bitstream	B-General_Concept
)	O
.	O
</s>
<s>
It	O
typically	O
uses	O
a	O
standardized	O
video	O
compression	B-General_Concept
algorithm	I-General_Concept
,	O
most	O
commonly	O
based	O
on	O
discrete	B-General_Concept
cosine	I-General_Concept
transform	I-General_Concept
(	O
DCT	B-General_Concept
)	O
coding	O
and	O
motion	B-Algorithm
compensation	I-Algorithm
.	O
</s>
<s>
A	O
specific	O
software	O
,	O
firmware	B-Application
,	O
or	O
hardware	O
implementation	O
capable	O
of	O
compression	O
or	O
decompression	O
to/from	O
a	O
specific	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
is	O
called	O
a	O
video	B-Application
codec	I-Application
.	O
</s>
<s>
Some	O
video	B-Algorithm
coding	I-Algorithm
formats	I-Algorithm
are	O
documented	O
by	O
a	O
detailed	O
technical	O
specification	O
document	O
known	O
as	O
a	O
video	B-Algorithm
coding	I-Algorithm
specification	I-Algorithm
.	O
</s>
<s>
Some	O
such	O
specifications	O
are	O
written	O
and	O
approved	O
by	O
standardization	O
organizations	O
as	O
technical	O
standards	O
,	O
and	O
are	O
thus	O
known	O
as	O
a	O
video	B-Algorithm
coding	I-Algorithm
standard	I-Algorithm
.	O
</s>
<s>
Video	O
content	O
encoded	O
using	O
a	O
particular	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
is	O
normally	O
bundled	O
with	O
an	O
audio	O
stream	O
(	O
encoded	O
using	O
an	O
audio	O
coding	O
format	O
)	O
inside	O
a	O
multimedia	O
container	O
format	O
such	O
as	O
AVI	O
,	O
MP4	O
,	O
FLV	B-Operating_System
,	O
RealMedia	O
,	O
or	O
Matroska	O
.	O
</s>
<s>
As	O
such	O
,	O
the	O
user	O
normally	O
does	O
n't	O
have	O
a	O
H.264	B-Application
file	O
,	O
but	O
instead	O
has	O
a	O
.mp4	O
video	B-General_Concept
file	I-General_Concept
,	O
which	O
is	O
an	O
MP4	O
container	O
containing	O
H.264-encoded	O
video	O
,	O
normally	O
alongside	O
AAC-encoded	O
audio	O
.	O
</s>
<s>
Multimedia	O
container	O
formats	O
can	O
contain	O
any	O
one	O
of	O
a	O
number	O
of	O
different	O
video	B-Algorithm
coding	I-Algorithm
formats	I-Algorithm
;	O
for	O
example	O
the	O
MP4	O
container	O
format	O
can	O
contain	O
video	O
in	O
either	O
the	O
MPEG-2	B-Algorithm
Part	I-Algorithm
2	I-Algorithm
or	O
the	O
H.264	B-Application
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
,	O
among	O
others	O
.	O
</s>
<s>
Another	O
example	O
is	O
the	O
initial	O
specification	O
for	O
the	O
file	O
type	O
WebM	B-Application
,	O
which	O
specified	O
the	O
container	O
format	O
(	O
Matroska	O
)	O
,	O
but	O
also	O
exactly	O
which	O
video	O
(	O
VP8	B-Algorithm
)	O
and	O
audio	O
(	O
Vorbis	B-Algorithm
)	O
compression	O
format	O
is	O
used	O
inside	O
the	O
Matroska	O
container	O
,	O
even	O
though	O
the	O
Matroska	O
container	O
format	O
itself	O
is	O
capable	O
of	O
containing	O
other	O
video	B-Algorithm
coding	I-Algorithm
formats	I-Algorithm
(	O
VP9	B-Algorithm
video	O
and	O
Opus	B-Algorithm
audio	O
support	O
was	O
later	O
added	O
to	O
the	O
WebM	B-Application
specification	O
)	O
.	O
</s>
<s>
A	O
format	O
is	O
the	O
layout	O
plan	O
for	O
data	O
produced	O
or	O
consumed	O
by	O
a	O
codec	B-General_Concept
.	O
</s>
<s>
Although	O
video	B-Algorithm
coding	I-Algorithm
formats	I-Algorithm
such	O
as	O
H.264	B-Application
are	O
sometimes	O
referred	O
to	O
as	O
codecs	B-General_Concept
,	O
there	O
is	O
a	O
clear	O
conceptual	O
difference	O
between	O
a	O
specification	O
and	O
its	O
implementations	O
.	O
</s>
<s>
Video	B-Algorithm
coding	I-Algorithm
formats	I-Algorithm
are	O
described	O
in	O
specifications	O
,	O
and	O
software	O
,	O
firmware	B-Application
,	O
or	O
hardware	O
to	O
encode/decode	O
data	O
in	O
a	O
given	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
from/to	O
uncompressed	B-Device
video	I-Device
are	O
implementations	O
of	O
those	O
specifications	O
.	O
</s>
<s>
As	O
an	O
analogy	O
,	O
the	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
H.264	B-Application
(	O
specification	O
)	O
is	O
to	O
the	O
codec	B-General_Concept
OpenH264	B-Language
(	O
specific	O
implementation	O
)	O
what	O
the	O
C	B-Language
Programming	I-Language
Language	I-Language
(	O
specification	O
)	O
is	O
to	O
the	O
compiler	O
GCC	B-Application
(	O
specific	O
implementation	O
)	O
.	O
</s>
<s>
H.264	B-Application
)	O
,	O
there	O
can	O
be	O
many	O
codecs	B-General_Concept
implementing	O
that	O
specification	O
(	O
e.g.	O
</s>
<s>
x264	B-Language
,	O
OpenH264	B-Language
,	O
H.264/MPEG	B-Algorithm
-4	I-Algorithm
AVC	I-Algorithm
products	I-Algorithm
and	I-Algorithm
implementations	I-Algorithm
)	O
.	O
</s>
<s>
The	O
H.264	B-Application
specification	O
calls	O
H.261	B-Algorithm
,	O
H.262	B-Algorithm
,	O
H.263	B-Algorithm
,	O
and	O
H.264	B-Application
video	B-Algorithm
coding	I-Algorithm
standards	I-Algorithm
and	O
does	O
not	O
contain	O
the	O
word	O
codec	B-General_Concept
.	O
</s>
<s>
The	O
Alliance	O
for	O
Open	O
Media	O
clearly	O
distinguishes	O
between	O
the	O
AV1	B-Application
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
and	O
the	O
accompanying	O
codec	B-General_Concept
they	O
are	O
developing	O
,	O
but	O
calls	O
the	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
itself	O
a	O
video	B-Algorithm
codec	I-Algorithm
specification	I-Algorithm
.	O
</s>
<s>
The	O
VP9	B-Algorithm
specification	O
calls	O
the	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
VP9	B-Algorithm
itself	O
a	O
codec	B-General_Concept
.	O
</s>
<s>
As	O
an	O
example	O
of	O
conflation	O
,	O
Chromium	O
's	O
and	O
Mozilla	O
's	O
pages	O
listing	O
their	O
video	O
format	O
support	O
both	O
call	O
video	B-Algorithm
coding	I-Algorithm
formats	I-Algorithm
such	O
as	O
H.264	B-Application
codecs	B-General_Concept
.	O
</s>
<s>
As	O
another	O
example	O
,	O
in	O
Cisco	O
's	O
announcement	O
of	O
a	O
free-as-in-beer	O
video	B-Application
codec	I-Application
,	O
the	O
press	O
release	O
refers	O
to	O
the	O
H.264	B-Application
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
as	O
a	O
codec	B-General_Concept
(	O
"	O
choice	O
of	O
a	O
common	O
video	B-Application
codec	I-Application
"	O
)	O
,	O
but	O
calls	O
Cisco	O
's	O
implementation	O
of	O
a	O
H.264	B-Application
encoder/decoder	B-General_Concept
a	O
codec	B-General_Concept
shortly	O
thereafter	O
(	O
"	O
open-source	B-License
our	O
H.264	B-Application
codec	B-General_Concept
"	O
)	O
.	O
</s>
<s>
A	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
does	O
not	O
dictate	O
all	O
algorithms	O
used	O
by	O
a	O
codec	B-General_Concept
implementing	O
the	O
format	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
large	O
part	O
of	O
how	O
video	O
compression	O
typically	O
works	O
is	O
by	O
finding	O
similarities	B-General_Concept
between	I-General_Concept
video	I-General_Concept
frames	I-General_Concept
(	O
block-matching	O
)	O
,	O
and	O
then	O
achieving	O
compression	O
by	O
copying	O
previously-coded	O
similar	O
subimages	O
(	O
e.g.	O
,	O
macroblocks	B-General_Concept
)	O
and	O
adding	O
small	O
differences	O
when	O
necessary	O
.	O
</s>
<s>
While	O
the	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
must	O
support	O
such	O
compression	O
across	O
frames	O
in	O
the	O
bitstream	B-General_Concept
format	I-General_Concept
,	O
by	O
not	O
needlessly	O
mandating	O
specific	O
algorithms	O
for	O
finding	O
such	O
block-matches	O
and	O
other	O
encoding	O
steps	O
,	O
the	O
codecs	B-General_Concept
implementing	O
the	O
video	B-Algorithm
coding	I-Algorithm
specification	I-Algorithm
have	O
some	O
freedom	O
to	O
optimize	O
and	O
innovate	O
in	O
their	O
choice	O
of	O
algorithms	O
.	O
</s>
<s>
For	O
example	O
,	O
section	O
0.5	O
of	O
the	O
H.264	B-Application
specification	O
says	O
that	O
encoding	O
algorithms	O
are	O
not	O
part	O
of	O
the	O
specification	O
.	O
</s>
<s>
Free	O
choice	O
of	O
algorithm	O
also	O
allows	O
different	O
space	B-General_Concept
–	I-General_Concept
time	I-General_Concept
complexity	I-General_Concept
trade-offs	O
for	O
the	O
same	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
,	O
so	O
a	O
live	O
feed	O
can	O
use	O
a	O
fast	O
but	O
space-inefficient	O
algorithm	O
,	O
while	O
a	O
one-time	O
DVD	O
encoding	O
for	O
later	O
mass	O
production	O
can	O
trade	O
long	O
encoding-time	O
for	O
space-efficient	O
encoding	O
.	O
</s>
<s>
The	O
concept	O
of	O
digital	B-General_Concept
video	O
compression	O
dates	O
back	O
to	O
1952	O
,	O
when	O
Bell	O
Labs	O
researchers	O
B.M.	O
</s>
<s>
Oliver	O
and	O
C.W.	O
</s>
<s>
Harrison	O
proposed	O
the	O
use	O
of	O
differential	B-General_Concept
pulse-code	I-General_Concept
modulation	I-General_Concept
(	O
DPCM	B-General_Concept
)	O
in	O
video	B-Algorithm
coding	I-Algorithm
.	O
</s>
<s>
In	O
1959	O
,	O
the	O
concept	O
of	O
inter-frame	B-Algorithm
motion	B-Algorithm
compensation	I-Algorithm
was	O
proposed	O
by	O
NHK	O
researchers	O
Y	O
.	O
Taki	O
,	O
M	O
.	O
Hatori	O
and	O
S	O
.	O
Tanaka	O
,	O
who	O
proposed	O
predictive	O
inter-frame	B-Algorithm
video	B-Algorithm
coding	I-Algorithm
in	O
the	O
temporal	O
dimension	O
.	O
</s>
<s>
In	O
1967	O
,	O
University	O
of	O
London	O
researchers	O
A.H.	O
Robinson	O
and	O
C	B-Language
.	O
Cherry	O
proposed	O
run-length	B-Algorithm
encoding	I-Algorithm
(	O
RLE	O
)	O
,	O
a	O
lossless	B-Algorithm
compression	I-Algorithm
scheme	O
,	O
to	O
reduce	O
the	O
transmission	O
bandwidth	O
of	O
analog	O
television	O
signals	O
.	O
</s>
<s>
The	O
earliest	O
digital	B-General_Concept
video	B-Algorithm
coding	I-Algorithm
algorithms	O
were	O
either	O
for	O
uncompressed	B-Device
video	I-Device
or	O
used	O
lossless	B-Algorithm
compression	I-Algorithm
,	O
both	O
methods	O
inefficient	O
and	O
impractical	O
for	O
digital	B-General_Concept
video	B-Algorithm
coding	I-Algorithm
.	O
</s>
<s>
Digital	B-General_Concept
video	O
was	O
introduced	O
in	O
the	O
1970s	O
,	O
initially	O
using	O
uncompressed	B-General_Concept
pulse-code	B-Algorithm
modulation	I-Algorithm
(	O
PCM	B-Algorithm
)	O
requiring	O
high	O
bitrates	O
around	O
45200	O
Mbit/s	O
for	O
standard-definition	B-Device
(	O
SD	O
)	O
video	O
,	O
which	O
was	O
up	O
to	O
2,000	O
times	O
greater	O
than	O
the	O
telecommunication	O
bandwidth	O
(	O
up	O
to	O
100kbit/s	O
)	O
available	O
until	O
the	O
1990s	O
.	O
</s>
<s>
Similarly	O
,	O
uncompressed	B-General_Concept
high-definition	O
(	O
HD	O
)	O
1080p	O
video	O
requires	O
bitrates	O
exceeding	O
1Gbit/s	O
,	O
significantly	O
greater	O
than	O
the	O
bandwidth	O
available	O
in	O
the	O
2000s	O
.	O
</s>
<s>
Practical	O
video	O
compression	O
emerged	O
with	O
the	O
development	O
of	O
motion-compensated	B-Algorithm
DCT	B-General_Concept
(	O
MC	O
DCT	B-General_Concept
)	O
coding	O
,	O
also	O
called	O
block	O
motion	B-Algorithm
compensation	I-Algorithm
(	O
BMC	O
)	O
or	O
DCT	B-General_Concept
motion	B-Algorithm
compensation	I-Algorithm
.	O
</s>
<s>
This	O
is	O
a	O
hybrid	O
coding	O
algorithm	O
,	O
which	O
combines	O
two	O
key	O
data	B-General_Concept
compression	I-General_Concept
techniques	O
:	O
discrete	B-General_Concept
cosine	I-General_Concept
transform	I-General_Concept
(	O
DCT	B-General_Concept
)	O
coding	O
in	O
the	O
spatial	O
dimension	O
,	O
and	O
predictive	O
motion	B-Algorithm
compensation	I-Algorithm
in	O
the	O
temporal	O
dimension	O
.	O
</s>
<s>
DCT	B-General_Concept
coding	O
is	O
a	O
lossy	B-Algorithm
block	B-General_Concept
compression	I-General_Concept
transform	B-Algorithm
coding	I-Algorithm
technique	O
that	O
was	O
first	O
proposed	O
by	O
Nasir	O
Ahmed	O
,	O
who	O
initially	O
intended	O
it	O
for	O
image	B-General_Concept
compression	I-General_Concept
,	O
while	O
he	O
was	O
working	O
at	O
Kansas	O
State	O
University	O
in	O
1972	O
.	O
</s>
<s>
It	O
was	O
then	O
developed	O
into	O
a	O
practical	O
image	B-General_Concept
compression	I-General_Concept
algorithm	O
by	O
Ahmed	O
with	O
T	O
.	O
Natarajan	O
and	O
K	O
.	O
R	O
.	O
Rao	O
at	O
the	O
University	O
of	O
Texas	O
in	O
1973	O
,	O
and	O
was	O
published	O
in	O
1974	O
.	O
</s>
<s>
The	O
other	O
key	O
development	O
was	O
motion-compensated	B-Algorithm
hybrid	O
coding	O
.	O
</s>
<s>
In	O
1974	O
,	O
Ali	O
Habibi	O
at	O
the	O
University	O
of	O
Southern	O
California	O
introduced	O
hybrid	O
coding	O
,	O
which	O
combines	O
predictive	O
coding	O
with	O
transform	B-Algorithm
coding	I-Algorithm
.	O
</s>
<s>
He	O
examined	O
several	O
transform	B-Algorithm
coding	I-Algorithm
techniques	O
,	O
including	O
the	O
DCT	B-General_Concept
,	O
Hadamard	B-Algorithm
transform	I-Algorithm
,	O
Fourier	B-Algorithm
transform	I-Algorithm
,	O
slant	O
transform	O
,	O
and	O
Karhunen-Loeve	O
transform	O
.	O
</s>
<s>
However	O
,	O
his	O
algorithm	O
was	O
initially	O
limited	O
to	O
intra-frame	B-General_Concept
coding	I-General_Concept
in	O
the	O
spatial	O
dimension	O
.	O
</s>
<s>
In	O
1975	O
,	O
John	O
A	O
.	O
Roese	O
and	O
Guner	O
S	O
.	O
Robinson	O
extended	O
Habibi	O
's	O
hybrid	O
coding	O
algorithm	O
to	O
the	O
temporal	O
dimension	O
,	O
using	O
transform	B-Algorithm
coding	I-Algorithm
in	O
the	O
spatial	O
dimension	O
and	O
predictive	O
coding	O
in	O
the	O
temporal	O
dimension	O
,	O
developing	O
inter-frame	B-Algorithm
motion-compensated	B-Algorithm
hybrid	O
coding	O
.	O
</s>
<s>
For	O
the	O
spatial	O
transform	B-Algorithm
coding	I-Algorithm
,	O
they	O
experimented	O
with	O
different	O
transforms	O
,	O
including	O
the	O
DCT	B-General_Concept
and	O
the	O
fast	O
Fourier	B-Algorithm
transform	I-Algorithm
(	O
FFT	O
)	O
,	O
developing	O
inter-frame	B-Algorithm
hybrid	O
coders	O
for	O
them	O
,	O
and	O
found	O
that	O
the	O
DCT	B-General_Concept
is	O
the	O
most	O
efficient	O
due	O
to	O
its	O
reduced	O
complexity	O
,	O
capable	O
of	O
compressing	O
image	O
data	O
down	O
to	O
0.25-bit	O
per	O
pixel	B-Algorithm
for	O
a	O
videotelephone	B-Application
scene	O
with	O
image	O
quality	O
comparable	O
to	O
a	O
typical	O
intra-frame	B-General_Concept
coder	O
requiring	O
2-bit	O
per	O
pixel	B-Algorithm
.	O
</s>
<s>
The	O
DCT	B-General_Concept
was	O
applied	O
to	O
video	O
encoding	O
by	O
Wen-Hsiung	O
Chen	O
,	O
who	O
developed	O
a	O
fast	O
DCT	B-General_Concept
algorithm	O
with	O
C.H.	O
</s>
<s>
Smith	O
and	O
S.C.	O
Fralick	O
in	O
1977	O
,	O
and	O
founded	O
Compression	O
Labs	O
to	O
commercialize	O
DCT	B-General_Concept
technology	O
.	O
</s>
<s>
In	O
1979	O
,	O
Anil	O
K	O
.	O
Jain	O
and	O
Jaswant	O
R	O
.	O
Jain	O
further	O
developed	O
motion-compensated	B-Algorithm
DCT	B-General_Concept
video	O
compression	O
.	O
</s>
<s>
This	O
led	O
to	O
Chen	O
developing	O
a	O
practical	O
video	O
compression	B-General_Concept
algorithm	I-General_Concept
,	O
called	O
motion-compensated	B-Algorithm
DCT	B-General_Concept
or	O
adaptive	O
scene	O
coding	O
,	O
in	O
1981	O
.	O
</s>
<s>
Motion-compensated	B-Algorithm
DCT	B-General_Concept
later	O
became	O
the	O
standard	O
coding	O
technique	O
for	O
video	O
compression	O
from	O
the	O
late	O
1980s	O
onwards	O
.	O
</s>
<s>
The	O
first	O
digital	B-General_Concept
video	B-Algorithm
coding	I-Algorithm
standard	I-Algorithm
was	O
H.120	B-Algorithm
,	O
developed	O
by	O
the	O
CCITT	O
(	O
now	O
ITU-T	O
)	O
in	O
1984	O
.	O
</s>
<s>
H.120	B-Algorithm
was	O
not	O
usable	O
in	O
practice	O
,	O
as	O
its	O
performance	O
was	O
too	O
poor	O
.	O
</s>
<s>
H.120	B-Algorithm
used	O
motion-compensated	B-Algorithm
DPCM	B-General_Concept
coding	O
,	O
a	O
lossless	B-Algorithm
compression	I-Algorithm
algorithm	O
that	O
was	O
inefficient	O
for	O
video	B-Algorithm
coding	I-Algorithm
.	O
</s>
<s>
During	O
the	O
late	O
1980s	O
,	O
a	O
number	O
of	O
companies	O
began	O
experimenting	O
with	O
discrete	B-General_Concept
cosine	I-General_Concept
transform	I-General_Concept
(	O
DCT	B-General_Concept
)	O
coding	O
,	O
a	O
much	O
more	O
efficient	O
form	O
of	O
compression	O
for	O
video	B-Algorithm
coding	I-Algorithm
.	O
</s>
<s>
The	O
CCITT	O
received	O
14	O
proposals	O
for	O
DCT-based	O
video	B-Algorithm
compression	I-Algorithm
formats	I-Algorithm
,	O
in	O
contrast	O
to	O
a	O
single	O
proposal	O
based	O
on	O
vector	B-Algorithm
quantization	I-Algorithm
(	O
VQ	O
)	O
compression	O
.	O
</s>
<s>
The	O
H.261	B-Algorithm
standard	I-Algorithm
was	O
developed	O
based	O
on	O
motion-compensated	B-Algorithm
DCT	B-General_Concept
compression	O
.	O
</s>
<s>
H.261	B-Algorithm
was	O
the	O
first	O
practical	O
video	B-Algorithm
coding	I-Algorithm
standard	I-Algorithm
,	O
and	O
uses	O
patents	O
licensed	O
from	O
a	O
number	O
of	O
companies	O
,	O
including	O
Hitachi	O
,	O
PictureTel	B-Application
,	O
NTT	O
,	O
BT	O
,	O
and	O
Toshiba	O
,	O
among	O
others	O
.	O
</s>
<s>
Since	O
H.261	B-Algorithm
,	O
motion-compensated	B-Algorithm
DCT	B-General_Concept
compression	O
has	O
been	O
adopted	O
by	O
all	O
the	O
major	O
video	B-Algorithm
coding	I-Algorithm
standards	I-Algorithm
(	O
including	O
the	O
H.26x	B-Application
and	O
MPEG	O
formats	O
)	O
that	O
followed	O
.	O
</s>
<s>
MPEG-1	B-Algorithm
,	O
developed	O
by	O
the	O
Motion	O
Picture	O
Experts	O
Group	O
(	O
MPEG	O
)	O
,	O
followed	O
in	O
1991	O
,	O
and	O
it	O
was	O
designed	O
to	O
compress	O
VHS-quality	O
video	O
.	O
</s>
<s>
It	O
was	O
succeeded	O
in	O
1994	O
by	O
MPEG-2/H.262	O
,	O
which	O
was	O
developed	O
with	O
patents	O
licensed	O
from	O
a	O
number	O
of	O
companies	O
,	O
primarily	O
Sony	O
,	O
Thomson	O
and	O
Mitsubishi	O
Electric	O
.	O
</s>
<s>
MPEG-2	B-Algorithm
became	O
the	O
standard	O
video	O
format	O
for	O
DVD	O
and	O
SD	B-Device
digital	I-Device
television	I-Device
.	O
</s>
<s>
Its	O
motion-compensated	B-Algorithm
DCT	B-General_Concept
algorithm	O
was	O
able	O
to	O
achieve	O
a	O
compression	O
ratio	O
of	O
up	O
to	O
100:1	O
,	O
enabling	O
the	O
development	O
of	O
digital	B-General_Concept
media	O
technologies	O
such	O
as	O
video-on-demand	B-Application
(	O
VOD	B-Application
)	O
and	O
high-definition	B-Device
television	I-Device
(	O
HDTV	B-Device
)	O
.	O
</s>
<s>
In	O
1999	O
,	O
it	O
was	O
followed	O
by	O
MPEG-4/H.263	O
,	O
which	O
was	O
a	O
major	O
leap	O
forward	O
for	O
video	O
compression	O
technology	O
.	O
</s>
<s>
The	O
most	O
widely	O
used	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
is	O
H.264/MPEG	B-Application
-4	I-Application
AVC	I-Application
.	O
</s>
<s>
In	O
contrast	O
to	O
the	O
standard	O
DCT	B-General_Concept
used	O
by	O
its	O
predecessors	O
,	O
AVC	O
uses	O
the	O
integer	B-General_Concept
DCT	I-General_Concept
.	O
</s>
<s>
H.264	B-Application
is	O
one	O
of	O
the	O
video	O
encoding	O
standards	O
for	O
Blu-ray	O
Discs	O
;	O
all	O
Blu-ray	O
Disc	O
players	O
must	O
be	O
able	O
to	O
decode	O
H.264	B-Application
.	O
</s>
<s>
It	O
is	O
also	O
widely	O
used	O
by	O
streaming	O
internet	O
sources	O
,	O
such	O
as	O
videos	O
from	O
YouTube	B-General_Concept
,	O
Netflix	O
,	O
Vimeo	O
,	O
and	O
the	O
iTunes	O
Store	O
,	O
web	O
software	O
such	O
as	O
the	O
Adobe	B-Operating_System
Flash	I-Operating_System
Player	I-Operating_System
and	O
Microsoft	B-Application
Silverlight	I-Application
,	O
and	O
also	O
various	O
HDTV	B-Device
broadcasts	O
over	O
terrestrial	O
(	O
Advanced	B-Device
Television	I-Device
Systems	I-Device
Committee	I-Device
standards	I-Device
,	O
ISDB-T	O
,	O
DVB-T	O
or	O
DVB-T2	B-Protocol
)	O
,	O
cable	O
(	O
DVB-C	B-Device
)	O
,	O
and	O
satellite	O
(	O
DVB-S2	O
)	O
.	O
</s>
<s>
A	O
main	O
problem	O
for	O
many	O
video	B-Algorithm
coding	I-Algorithm
formats	I-Algorithm
has	O
been	O
patents	O
,	O
making	O
it	O
expensive	O
to	O
use	O
or	O
potentially	O
risking	O
a	O
patent	O
lawsuit	O
due	O
to	O
submarine	O
patents	O
.	O
</s>
<s>
The	O
motivation	O
behind	O
many	O
recently	O
designed	O
video	B-Algorithm
coding	I-Algorithm
formats	I-Algorithm
such	O
as	O
Theora	B-Algorithm
,	O
VP8	B-Algorithm
and	O
VP9	B-Algorithm
have	O
been	O
to	O
create	O
a	O
(	O
libre	B-Application
)	O
video	B-Algorithm
coding	I-Algorithm
standard	I-Algorithm
covered	O
only	O
by	O
royalty-free	O
patents	O
.	O
</s>
<s>
Patent	O
status	O
has	O
also	O
been	O
a	O
major	O
point	O
of	O
contention	O
for	O
the	O
choice	O
of	O
which	O
video	O
formats	O
the	O
mainstream	O
web	B-Application
browsers	I-Application
will	O
support	O
inside	O
the	O
HTML5	O
video	O
tag	O
.	O
</s>
<s>
The	O
current-generation	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
is	O
HEVC	B-Algorithm
(	O
H.265	B-Algorithm
)	O
,	O
introduced	O
in	O
2013	O
.	O
</s>
<s>
While	O
AVC	O
uses	O
the	O
integer	B-General_Concept
DCT	I-General_Concept
with	O
4x4	O
and	O
8x8	O
block	O
sizes	O
,	O
HEVC	B-Algorithm
uses	O
integer	B-General_Concept
DCT	I-General_Concept
and	O
DST	O
transforms	O
with	O
varied	O
block	O
sizes	O
between	O
4x4	O
and	O
32x32	O
.	O
</s>
<s>
HEVC	B-Algorithm
is	O
heavily	O
patented	O
,	O
with	O
the	O
majority	O
of	O
patents	O
belonging	O
to	O
Samsung	O
Electronics	O
,	O
GE	O
,	O
NTT	O
and	O
JVC	O
Kenwood	O
.	O
</s>
<s>
It	O
is	O
currently	O
being	O
challenged	O
by	O
the	O
aiming-to-be-freely-licensed	O
AV1	B-Application
format	O
.	O
</s>
<s>
,	O
AVC	O
is	O
by	O
far	O
the	O
most	O
commonly	O
used	O
format	O
for	O
the	O
recording	O
,	O
compression	O
and	O
distribution	O
of	O
video	O
content	O
,	O
used	O
by	O
91%	O
of	O
video	O
developers	O
,	O
followed	O
by	O
HEVC	B-Algorithm
which	O
is	O
used	O
by	O
43%	O
of	O
developers	O
.	O
</s>
<s>
+Timeline	O
of	O
international	O
video	B-Algorithm
compression	I-Algorithm
standards	I-Algorithm
Basic	O
algorithm	O
Video	B-Algorithm
coding	I-Algorithm
standard	I-Algorithm
Year	O
Publisher(s )	O
Committee(s )	O
Licensor(s )	O
Market	O
presence	O
Popular	O
implementations	O
DPCM	B-General_Concept
H.120	B-Algorithm
1984	O
CCITT	O
VCEG	B-Application
DCT	B-General_Concept
H.261	B-Algorithm
1988	O
CCITT	O
VCEG	B-Application
Hitachi	O
,	O
PictureTel	B-Application
,	O
NTT	O
,	O
BT	O
,	O
Toshiba	O
,	O
etc	O
.	O
</s>
<s>
Videoconferencing	B-Application
,	O
videotelephony	B-Application
Motion	B-Application
JPEG	I-Application
(	O
MJPEG	B-Application
)	O
1992	O
JPEG	O
JPEG	O
ISO	B-General_Concept
/	O
Open	B-License
Source	I-License
does	I-License
NOT	I-License
mean	I-License
free	I-License
!	I-License
</s>
<s>
QuickTime	B-Application
MPEG-1	B-Algorithm
Part	O
2	O
1993ISO	O
,	O
IEC	O
MPEG	O
Fujitsu	O
,	O
IBM	O
,	O
Matsushita	O
,	O
etc	O
.	O
</s>
<s>
Video	O
CD	O
,	O
Internet	O
video	O
H.262	B-Algorithm
/	I-Algorithm
MPEG-2	I-Algorithm
Part	I-Algorithm
2	I-Algorithm
(	O
MPEG-2	B-Algorithm
Video	I-Algorithm
)	O
1995	O
ISO	B-General_Concept
,	O
IEC	O
,	O
ITU-T	O
MPEG	O
,	O
VCEG	B-Application
Sony	O
,	O
Thomson	O
,	O
Mitsubishi	O
,	O
etc	O
.	O
</s>
<s>
29%	O
DVD	O
Video	O
,	O
Blu-ray	O
,	O
DVB	B-Application
,	O
ATSC	B-Device
,	O
SVCD	O
,	O
SDTV	B-Device
DV	O
1995	O
IEC	O
IEC	O
Sony	O
,	O
Panasonic	O
Camcorders	O
,	O
digital	B-General_Concept
cassettes	O
H.263	B-Algorithm
1996	O
ITU-T	O
VCEG	B-Application
Mitsubishi	O
,	O
Hitachi	O
,	O
Panasonic	O
,	O
etc	O
.	O
</s>
<s>
Videoconferencing	B-Application
,	O
videotelephony	B-Application
,	O
H.320	B-Application
,	O
Integrated	B-Protocol
Services	I-Protocol
Digital	I-Protocol
Network	I-Protocol
(	O
ISDN	B-Protocol
)	O
,	O
mobile	O
video	O
(	O
3GP	O
)	O
,	O
MPEG-4	B-Application
Visual	I-Application
MPEG-4	B-Application
Part	I-Application
2	I-Application
(	O
MPEG-4	B-Application
Visual	I-Application
)	O
1999	O
ISO	B-General_Concept
,	O
IEC	O
MPEG	O
Mitsubishi	O
,	O
Hitachi	O
,	O
Panasonic	O
,	O
etc	O
.	O
</s>
<s>
Internet	O
video	O
,	O
DivX	B-Application
,	O
Xvid	B-Algorithm
DWTMotion	O
JPEG	O
2000	O
(	O
MJ2	O
)	O
2001JPEG	O
JPEG	O
Digital	B-General_Concept
cinemaDCTAdvanced	O
Video	B-Algorithm
Coding	I-Algorithm
(	O
H.264	B-Application
/	O
MPEG-4	B-Application
AVC	I-Application
)	O
2003	O
ISO	B-General_Concept
,	O
IEC	O
,	O
ITU-T	O
MPEG	O
,	O
VCEG	B-Application
Panasonic	O
,	O
Godo	O
Kaisha	O
IP	O
Bridge	O
,	O
LG	O
,	O
etc	O
.	O
</s>
<s>
91%	O
Blu-ray	O
,	O
HD	B-Operating_System
DVD	I-Operating_System
,	O
HDTV	B-Device
(	O
DVB	B-Application
,	O
ATSC	B-Device
)	O
,	O
video	B-Application
streaming	I-Application
(	O
YouTube	B-General_Concept
,	O
Netflix	O
,	O
Vimeo	O
)	O
,	O
iTunes	O
Store	O
,	O
iPod	O
Video	O
,	O
Apple	B-Device
TV	I-Device
,	O
videoconferencing	B-Application
,	O
Flash	B-Operating_System
Player	I-Operating_System
,	O
Silverlight	B-Application
,	O
VOD	B-Application
Theora	B-Algorithm
2004	O
Xiph	B-Application
Xiph	B-Application
Internet	O
video	O
,	O
web	B-Application
browsers	I-Application
VC-1	B-Operating_System
2006	O
SMPTE	O
SMPTE	O
Microsoft	O
,	O
Panasonic	O
,	O
LG	O
,	O
Samsung	O
,	O
etc	O
.	O
</s>
<s>
Blu-ray	O
,	O
Internet	O
video	O
Apple	B-Algorithm
ProRes	I-Algorithm
2007	O
Apple	O
Apple	O
Apple	O
Video	O
production	O
,	O
post-productionHigh	O
Efficiency	O
Video	B-Algorithm
Coding	I-Algorithm
(	O
H.265	B-Algorithm
/	O
MPEG-H	O
HEVC	B-Algorithm
)	O
2013	O
ISO	B-General_Concept
,	O
IEC	O
,	O
ITU-T	O
MPEG	O
,	O
VCEG	B-Application
Samsung	O
,	O
GE	O
,	O
NTT	O
,	O
JVC	O
Kenwood	O
,	O
etc	O
.	O
</s>
<s>
Consumer	O
video	O
is	O
generally	O
compressed	O
using	O
lossy	B-Algorithm
video	B-Application
codecs	I-Application
,	O
since	O
that	O
results	O
in	O
significantly	O
smaller	O
files	O
than	O
lossless	B-Algorithm
compression	I-Algorithm
.	O
</s>
<s>
While	O
there	O
are	O
video	B-Algorithm
coding	I-Algorithm
formats	I-Algorithm
designed	O
explicitly	O
for	O
either	O
lossy	B-Algorithm
or	O
lossless	B-Algorithm
compression	I-Algorithm
,	O
some	O
video	B-Algorithm
coding	I-Algorithm
formats	I-Algorithm
such	O
as	O
Dirac	B-Application
and	O
H.264	B-Application
support	O
both	O
.	O
</s>
<s>
Uncompressed	B-Device
video	I-Device
formats	O
,	O
such	O
as	O
Clean	B-Device
HDMI	I-Device
,	O
is	O
a	O
form	O
of	O
lossless	B-Algorithm
video	O
used	O
in	O
some	O
circumstances	O
such	O
as	O
when	O
sending	O
video	O
to	O
a	O
display	O
over	O
a	O
HDMI	B-Protocol
connection	O
.	O
</s>
<s>
Interframe	B-Algorithm
compression	O
complicates	O
editing	O
of	O
an	O
encoded	O
video	O
sequence	O
.	O
</s>
<s>
One	O
subclass	O
of	O
relatively	O
simple	O
video	B-Algorithm
coding	I-Algorithm
formats	I-Algorithm
are	O
the	O
intra-frame	B-General_Concept
video	O
formats	O
,	O
such	O
as	O
DV	O
,	O
in	O
which	O
each	O
frame	O
of	O
the	O
video	B-Application
stream	I-Application
is	O
compressed	O
independently	O
without	O
referring	O
to	O
other	O
frames	O
in	O
the	O
stream	O
,	O
and	O
no	O
attempt	O
is	O
made	O
to	O
take	O
advantage	O
of	O
correlations	O
between	O
successive	O
pictures	O
over	O
time	O
for	O
better	O
compression	O
.	O
</s>
<s>
One	O
example	O
is	O
Motion	B-Application
JPEG	I-Application
,	O
which	O
is	O
simply	O
a	O
sequence	O
of	O
individually	O
JPEG-compressed	O
images	O
.	O
</s>
<s>
This	O
approach	O
is	O
quick	O
and	O
simple	O
,	O
at	O
the	O
expense	O
the	O
encoded	O
video	O
being	O
much	O
larger	O
than	O
a	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
supporting	O
Inter	B-Algorithm
frame	I-Algorithm
coding	O
.	O
</s>
<s>
Because	O
interframe	B-Algorithm
compression	O
copies	O
data	O
from	O
one	O
frame	O
to	O
another	O
,	O
if	O
the	O
original	O
frame	O
is	O
simply	O
cut	O
out	O
(	O
or	O
lost	O
in	O
transmission	O
)	O
,	O
the	O
following	O
frames	O
cannot	O
be	O
reconstructed	O
properly	O
.	O
</s>
<s>
Making	O
'	O
cuts	O
 '	O
in	O
intraframe-compressed	O
video	O
while	O
video	O
editing	O
is	O
almost	O
as	O
easy	O
as	O
editing	O
uncompressed	B-Device
video	I-Device
:	O
one	O
finds	O
the	O
beginning	O
and	O
ending	O
of	O
each	O
frame	O
,	O
and	O
simply	O
copies	O
bit-for-bit	O
each	O
frame	O
that	O
one	O
wants	O
to	O
keep	O
,	O
and	O
discards	O
the	O
frames	O
one	O
does	O
n't	O
want	O
.	O
</s>
<s>
Another	O
difference	O
between	O
intraframe	B-General_Concept
and	O
interframe	B-Algorithm
compression	O
is	O
that	O
,	O
with	O
intraframe	B-General_Concept
systems	O
,	O
each	O
frame	O
uses	O
a	O
similar	O
amount	O
of	O
data	O
.	O
</s>
<s>
In	O
most	O
interframe	B-Algorithm
systems	O
,	O
certain	O
frames	O
(	O
such	O
as	O
"	O
I	B-General_Concept
frames	I-General_Concept
"	O
in	O
MPEG-2	B-Algorithm
)	O
are	O
n't	O
allowed	O
to	O
copy	O
data	O
from	O
other	O
frames	O
,	O
so	O
they	O
require	O
much	O
more	O
data	O
than	O
other	O
frames	O
nearby	O
.	O
</s>
<s>
It	O
is	O
possible	O
to	O
build	O
a	O
computer-based	O
video	O
editor	O
that	O
spots	O
problems	O
caused	O
when	O
I	B-General_Concept
frames	I-General_Concept
are	O
edited	O
out	O
while	O
other	O
frames	O
need	O
them	O
.	O
</s>
<s>
However	O
,	O
this	O
process	O
demands	O
a	O
lot	O
more	O
computing	O
power	O
than	O
editing	O
intraframe	B-General_Concept
compressed	O
video	O
with	O
the	O
same	O
picture	O
quality	O
.	O
</s>
<s>
A	O
video	B-Algorithm
coding	I-Algorithm
format	I-Algorithm
can	O
define	O
optional	O
restrictions	O
to	O
encoded	O
video	O
,	O
called	O
profiles	O
and	O
levels	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
H.264	B-Application
format	O
includes	O
the	O
profiles	O
baseline	O
,	O
main	O
and	O
high	O
(	O
and	O
others	O
)	O
.	O
</s>
<s>
While	O
P-slices	B-General_Concept
(	O
which	O
can	O
be	O
predicted	O
based	O
on	O
preceding	O
slices	O
)	O
are	O
supported	O
in	O
all	O
profiles	O
,	O
B-slices	B-General_Concept
(	O
which	O
can	O
be	O
predicted	O
based	O
on	O
both	O
preceding	O
and	O
following	O
slices	O
)	O
are	O
supported	O
in	O
the	O
main	O
and	O
high	O
profiles	O
but	O
not	O
in	O
baseline	O
.	O
</s>
