<s>
MP3	B-Application
(	O
formally	O
MPEG-1	B-Application
Audio	I-Application
Layer	I-Application
III	I-Application
or	O
MPEG-2	B-Application
Audio	I-Application
Layer	I-Application
III	I-Application
)	O
is	O
a	O
coding	O
format	O
for	O
digital	O
audio	O
developed	O
largely	O
by	O
the	O
Fraunhofer	O
Society	O
in	O
Germany	O
under	O
the	O
lead	O
of	O
Karlheinz	O
Brandenburg	O
,	O
with	O
support	O
from	O
other	O
digital	O
scientists	O
in	O
the	O
United	O
States	O
and	O
elsewhere	O
.	O
</s>
<s>
Originally	O
defined	O
as	O
the	O
third	O
audio	O
format	O
of	O
the	O
MPEG-1	B-Algorithm
standard	O
,	O
it	O
was	O
retained	O
and	O
further	O
extended	O
—	O
defining	O
additional	O
bit-rates	O
and	O
support	O
for	O
more	O
audio	O
channels	O
—	O
as	O
the	O
third	O
audio	O
format	O
of	O
the	O
subsequent	O
MPEG-2	B-Algorithm
standard	O
.	O
</s>
<s>
MP3	B-Application
(	O
or	O
mp3	B-Application
)	O
as	O
a	O
file	O
format	O
commonly	O
designates	O
files	O
containing	O
an	O
elementary	O
stream	O
of	O
MPEG-1	B-Algorithm
Audio	O
or	O
MPEG-2	B-Algorithm
Audio	O
encoded	O
data	O
,	O
without	O
other	O
complexities	O
of	O
the	O
MP3	B-Application
standard	O
.	O
</s>
<s>
With	O
regard	O
to	O
audio	O
compression	O
(	O
the	O
aspect	O
of	O
the	O
standard	O
most	O
apparent	O
to	O
end-users	O
,	O
and	O
for	O
which	O
it	O
is	O
best	O
known	O
)	O
,	O
MP3	B-Application
uses	O
lossy	B-Algorithm
data-compression	I-Algorithm
to	O
encode	O
data	O
using	O
inexact	O
approximations	O
and	O
the	O
partial	O
discarding	O
of	O
data	O
.	O
</s>
<s>
This	O
allows	O
a	O
large	O
reduction	O
in	O
file	O
sizes	O
when	O
compared	O
to	O
uncompressed	B-General_Concept
audio	O
.	O
</s>
<s>
The	O
combination	O
of	O
small	O
size	O
and	O
acceptable	O
fidelity	O
led	O
to	O
a	O
boom	O
in	O
the	O
distribution	O
of	O
music	O
over	O
the	O
Internet	O
in	O
the	O
mid	O
-	O
to	O
late-1990s	O
,	O
with	O
MP3	B-Application
serving	O
as	O
an	O
enabling	O
technology	O
at	O
a	O
time	O
when	O
bandwidth	O
and	O
storage	O
were	O
still	O
at	O
a	O
premium	O
.	O
</s>
<s>
The	O
MP3	B-Application
format	O
soon	O
became	O
associated	O
with	O
controversies	O
surrounding	O
copyright	O
infringement	O
,	O
music	B-Application
piracy	I-Application
,	O
and	O
the	O
file	O
ripping/sharing	O
services	O
MP3.com	O
and	O
Napster	B-Application
,	O
among	O
others	O
.	O
</s>
<s>
With	O
the	O
advent	O
of	O
portable	O
media	O
players	O
,	O
a	O
product	O
category	O
also	O
including	O
smartphones	B-Application
,	O
MP3	B-Application
support	O
remains	O
near-universal	O
.	O
</s>
<s>
MP3	B-Application
compression	O
works	O
by	O
reducing	O
(	O
or	O
approximating	O
)	O
the	O
accuracy	O
of	O
certain	O
components	O
of	O
sound	O
that	O
are	O
considered	O
(	O
by	O
psychoacoustic	O
analysis	O
)	O
to	O
be	O
beyond	O
the	O
hearing	O
capabilities	O
of	O
most	O
humans	O
.	O
</s>
<s>
Compared	O
to	O
CD-quality	O
digital	O
audio	O
,	O
MP3	B-Application
compression	O
can	O
commonly	O
achieve	O
a	O
75	O
to	O
95%	O
reduction	O
in	O
size	O
.	O
</s>
<s>
For	O
example	O
,	O
an	O
MP3	B-Application
encoded	O
at	O
a	O
constant	B-General_Concept
bitrate	I-General_Concept
of	O
128kbit/s	O
would	O
result	O
in	O
a	O
file	O
approximately	O
9%	O
of	O
the	O
size	O
of	O
the	O
original	O
CD	O
audio	O
.	O
</s>
<s>
In	O
the	O
early	O
2000s	O
,	O
compact	O
disc	O
players	O
increasingly	O
adopted	O
support	O
for	O
playback	O
of	O
MP3	B-Application
files	I-Application
on	O
data	O
CDs	O
.	O
</s>
<s>
The	O
Moving	O
Picture	O
Experts	O
Group	O
(	O
MPEG	O
)	O
designed	O
MP3	B-Application
as	O
part	O
of	O
its	O
MPEG-1	B-Algorithm
,	O
and	O
later	O
MPEG-2	B-Algorithm
,	O
standards	O
.	O
</s>
<s>
MPEG-1	B-Algorithm
Audio	O
(	O
MPEG-1	B-Algorithm
Part	O
3	O
)	O
,	O
which	O
included	O
MPEG-1	B-Algorithm
Audio	O
Layer	O
I	O
,	O
II	O
and	O
III	O
,	O
was	O
approved	O
as	O
a	O
committee	O
draft	O
for	O
an	O
ISO/IEC	O
standard	O
in	O
1991	O
,	O
finalised	O
in	O
1992	O
,	O
and	O
published	O
in	O
1993	O
as	O
ISO/IEC	O
11172-3:1993	O
.	O
</s>
<s>
An	O
MPEG-2	B-Algorithm
Audio	O
(	O
MPEG-2	B-Algorithm
Part	O
3	O
)	O
extension	O
with	O
lower	O
sample	O
-	O
and	O
bit-rates	O
was	O
published	O
in	O
1995	O
as	O
ISO/IEC	O
13818-3:1995	O
.	O
</s>
<s>
It	O
requires	O
only	O
minimal	O
modifications	O
to	O
existing	O
MPEG-1	B-Algorithm
decoders	B-General_Concept
(	O
recognition	O
of	O
the	O
MPEG-2	B-Algorithm
bit	O
in	O
the	O
header	B-General_Concept
and	O
addition	O
of	O
the	O
new	O
lower	O
sample	O
and	O
bit	O
rates	O
)	O
.	O
</s>
<s>
The	O
MP3	B-Application
lossy	B-Algorithm
audio-data	O
compression	O
algorithm	O
takes	O
advantage	O
of	O
a	O
perceptual	O
limitation	O
of	O
human	O
hearing	O
called	O
auditory	O
masking	O
.	O
</s>
<s>
Perceptual	O
coding	O
was	O
first	O
used	O
for	O
speech	B-Application
coding	I-Application
compression	O
with	O
linear	B-Algorithm
predictive	I-Algorithm
coding	I-Algorithm
(	O
LPC	O
)	O
,	O
which	O
has	O
origins	O
in	O
the	O
work	O
of	O
Fumitada	O
Itakura	O
(	O
Nagoya	O
University	O
)	O
and	O
Shuzo	O
Saito	O
(	O
Nippon	O
Telegraph	O
and	O
Telephone	O
)	O
in	O
1966	O
.	O
</s>
<s>
In	O
1978	O
,	O
Bishnu	O
S	O
.	O
Atal	O
and	O
Manfred	O
R	O
.	O
Schroeder	O
at	O
Bell	O
Labs	O
proposed	O
an	O
LPC	O
speech	B-Application
codec	I-Application
,	O
called	O
adaptive	O
predictive	O
coding	O
,	O
that	O
used	O
a	O
psychoacoustic	O
coding-algorithm	O
exploiting	O
the	O
masking	O
properties	O
of	O
the	O
human	O
ear	O
.	O
</s>
<s>
That	O
same	O
year	O
,	O
a	O
psychoacoustic	O
masking	O
codec	B-General_Concept
was	O
also	O
proposed	O
by	O
M	O
.	O
A	O
.	O
Krasner	O
,	O
who	O
published	O
and	O
produced	O
hardware	O
for	O
speech	O
(	O
not	O
usable	O
as	O
music	O
bit-compression	O
)	O
,	O
but	O
the	O
publication	O
of	O
his	O
results	O
in	O
a	O
relatively	O
obscure	O
Lincoln	O
Laboratory	O
Technical	O
Report	O
did	O
not	O
immediately	O
influence	O
the	O
mainstream	O
of	O
psychoacoustic	O
codec-development	O
.	O
</s>
<s>
The	O
discrete	B-General_Concept
cosine	I-General_Concept
transform	I-General_Concept
(	O
DCT	B-General_Concept
)	O
,	O
a	O
type	O
of	O
transform	B-Algorithm
coding	I-Algorithm
for	O
lossy	B-Algorithm
compression	I-Algorithm
,	O
proposed	O
by	O
Nasir	O
Ahmed	O
in	O
1972	O
,	O
was	O
developed	O
by	O
Ahmed	O
with	O
T	O
.	O
Natarajan	O
and	O
K	O
.	O
R	O
.	O
Rao	O
in	O
1973	O
;	O
they	O
published	O
their	O
results	O
in	O
1974	O
.	O
</s>
<s>
This	O
led	O
to	O
the	O
development	O
of	O
the	O
modified	O
discrete	B-General_Concept
cosine	I-General_Concept
transform	I-General_Concept
(	O
MDCT	O
)	O
,	O
proposed	O
by	O
J	O
.	O
P	O
.	O
Princen	O
,	O
A	O
.	O
W	O
.	O
Johnson	O
and	O
A	O
.	O
</s>
<s>
The	O
MDCT	O
later	O
became	O
a	O
core	O
part	O
of	O
the	O
MP3	B-Application
algorithm	O
.	O
</s>
<s>
In	O
1985	O
,	O
Atal	O
and	O
Schroeder	O
presented	O
code-excited	B-Algorithm
linear	I-Algorithm
prediction	I-Algorithm
(	O
CELP	B-Algorithm
)	O
,	O
an	O
LPC-based	O
perceptual	O
speech-coding	O
algorithm	O
with	O
auditory	O
masking	O
that	O
achieved	O
a	O
significant	O
data	B-General_Concept
compression	I-General_Concept
ratio	I-General_Concept
for	O
its	O
time	O
.	O
</s>
<s>
IEEE	O
's	O
refereed	O
Journal	O
on	O
Selected	O
Areas	O
in	O
Communications	O
reported	O
on	O
a	O
wide	O
variety	O
of	O
(	O
mostly	O
perceptual	O
)	O
audio	O
compression	B-General_Concept
algorithms	I-General_Concept
in	O
1988	O
.	O
</s>
<s>
The	O
genesis	O
of	O
the	O
MP3	B-Application
technology	O
is	O
fully	O
described	O
in	O
a	O
paper	O
from	O
Professor	O
Hans	O
Musmann	O
,	O
who	O
chaired	O
the	O
ISO	O
MPEG	O
Audio	O
group	O
for	O
several	O
years	O
.	O
</s>
<s>
The	O
immediate	O
predecessors	O
of	O
MP3	B-Application
were	O
"	O
Optimum	O
Coding	O
in	O
the	O
Frequency	O
Domain	O
"	O
(	O
OCF	O
)	O
,	O
and	O
Perceptual	O
Transform	B-Algorithm
Coding	I-Algorithm
(	O
PXFM	B-Application
)	O
.	O
</s>
<s>
These	O
two	O
codecs	B-General_Concept
,	O
along	O
with	O
block-switching	O
contributions	O
from	O
Thomson-Brandt	O
,	O
were	O
merged	O
into	O
a	O
codec	B-General_Concept
called	O
ASPEC	O
,	O
which	O
was	O
submitted	O
to	O
MPEG	O
,	O
and	O
which	O
won	O
the	O
quality	O
competition	O
,	O
but	O
that	O
was	O
mistakenly	O
rejected	O
as	O
too	O
complex	O
to	O
implement	O
.	O
</s>
<s>
The	O
first	O
practical	O
implementation	O
of	O
an	O
audio	O
perceptual	O
coder	O
(	O
OCF	O
)	O
in	O
hardware	O
(	O
Krasner	O
's	O
hardware	O
was	O
too	O
cumbersome	O
and	O
slow	O
for	O
practical	O
use	O
)	O
,	O
was	O
an	O
implementation	O
of	O
a	O
psychoacoustic	O
transform	B-Algorithm
coder	I-Algorithm
based	O
on	O
Motorola	B-General_Concept
56000	I-General_Concept
DSP	B-Architecture
chips	I-Architecture
.	O
</s>
<s>
Another	O
predecessor	O
of	O
the	O
MP3	B-Application
format	O
and	O
technology	O
is	O
to	O
be	O
found	O
in	O
the	O
perceptual	O
codec	B-General_Concept
MUSICAM	O
based	O
on	O
an	O
integer	O
arithmetics	O
32	O
sub-bands	B-Algorithm
filterbank	O
,	O
driven	O
by	O
a	O
psychoacoustic	O
model	O
.	O
</s>
<s>
This	O
codec	B-General_Concept
incorporated	O
into	O
a	O
broadcasting	O
system	O
using	O
COFDM	O
modulation	O
was	O
demonstrated	O
on	O
air	O
and	O
in	O
the	O
field	O
with	O
Radio	O
Canada	O
and	O
CRC	O
Canada	O
during	O
the	O
NAB	O
show	O
(	O
Las	O
Vegas	O
)	O
in	O
1991	O
.	O
</s>
<s>
The	O
implementation	O
of	O
the	O
audio	O
part	O
of	O
this	O
broadcasting	O
system	O
was	O
based	O
on	O
a	O
two-chips	O
encoder	O
(	O
one	O
for	O
the	O
subband	B-Algorithm
transform	O
,	O
one	O
for	O
the	O
psychoacoustic	O
model	O
designed	O
by	O
the	O
team	O
of	O
G	O
.	O
Stoll	O
(	O
IRT	O
Germany	O
)	O
,	O
later	O
known	O
as	O
psychoacoustic	O
model	O
I	O
)	O
and	O
a	O
real	O
time	O
decoder	O
using	O
one	O
Motorola	B-General_Concept
56001	I-General_Concept
DSP	B-Architecture
chip	I-Architecture
running	O
an	O
integer	O
arithmetics	O
software	O
designed	O
by	O
Y.F.	O
</s>
<s>
The	O
simplicity	O
of	O
the	O
corresponding	O
decoder	O
together	O
with	O
the	O
high	O
audio	O
quality	O
of	O
this	O
codec	B-General_Concept
using	O
for	O
the	O
first	O
time	O
a	O
48kHz	O
sampling	B-Algorithm
frequency	I-Algorithm
,	O
a	O
20	O
bits/sample	O
input	O
format	O
(	O
the	O
highest	O
available	O
sampling	O
standard	O
in	O
1991	O
,	O
compatible	O
with	O
the	O
AES/EBU	O
professional	O
digital	O
input	O
studio	O
standard	O
)	O
were	O
the	O
main	O
reasons	O
to	O
later	O
adopt	O
the	O
characteristics	O
of	O
MUSICAM	O
as	O
the	O
basic	O
features	O
for	O
an	O
advanced	O
digital	O
music	O
compression	O
codec	B-General_Concept
.	O
</s>
<s>
During	O
the	O
development	O
of	O
the	O
MUSICAM	O
encoding	B-General_Concept
software	I-General_Concept
,	O
Stoll	O
and	O
Dehery	O
's	O
team	O
made	O
thorough	O
use	O
of	O
a	O
set	O
of	O
high-quality	O
audio	O
assessment	O
material	O
selected	O
by	O
a	O
group	O
of	O
audio	O
professionals	O
from	O
the	O
European	O
Broadcasting	O
Union	O
and	O
later	O
used	O
as	O
a	O
reference	O
for	O
the	O
assessment	O
of	O
music	O
compression	O
codecs	B-General_Concept
.	O
</s>
<s>
The	O
subband	B-Algorithm
coding	I-Algorithm
technique	O
was	O
found	O
to	O
be	O
efficient	O
,	O
not	O
only	O
for	O
the	O
perceptual	O
coding	O
of	O
the	O
high-quality	O
sound	O
materials	O
but	O
especially	O
for	O
the	O
encoding	O
of	O
critical	O
percussive	O
sound	O
materials	O
(	O
drums	O
,	O
triangle	O
,...	O
)	O
,	O
due	O
to	O
the	O
specific	O
temporal	O
masking	O
effect	O
of	O
the	O
MUSICAM	O
sub-band	B-Algorithm
filterbank	O
(	O
this	O
advantage	O
being	O
a	O
specific	O
feature	O
of	O
short	O
transform	B-Algorithm
coding	I-Algorithm
techniques	O
)	O
.	O
</s>
<s>
MP3	B-Application
is	O
directly	O
descended	O
from	O
OCF	O
and	O
PXFM	B-Application
,	O
representing	O
the	O
outcome	O
of	O
the	O
collaboration	O
of	O
Brandenburg	O
—	O
working	O
as	O
a	O
postdoctoral	O
researcher	O
at	O
AT&	O
T-Bell	O
Labs	O
with	O
James	O
D	O
.	O
Johnston	O
(	O
"	O
JJ	O
"	O
)	O
of	O
AT&	O
T-Bell	O
Labs	O
—	O
with	O
the	O
Fraunhofer	O
Institute	O
for	O
Integrated	O
Circuits	O
,	O
Erlangen	O
(	O
where	O
he	O
worked	O
with	O
Bernhard	O
Grill	O
and	O
four	O
other	O
researchers	O
–	O
"	O
The	O
Original	O
Six	O
"	O
)	O
,	O
with	O
relatively	O
minor	O
contributions	O
from	O
the	O
MP2	O
branch	O
of	O
psychoacoustic	O
sub-band	B-Algorithm
coders	I-Algorithm
.	O
</s>
<s>
The	O
song	O
"	O
Tom	O
's	O
Diner	O
"	O
by	O
Suzanne	O
Vega	O
was	O
the	O
first	O
song	O
used	O
by	O
Karlheinz	O
Brandenburg	O
to	O
develop	O
the	O
MP3	B-Application
format	O
.	O
</s>
<s>
Accordingly	O
,	O
he	O
dubbed	O
Vega	O
the	O
"	O
Mother	O
of	O
MP3	B-Application
"	O
.	O
</s>
<s>
In	O
1991	O
,	O
there	O
were	O
two	O
available	O
proposals	O
that	O
were	O
assessed	O
for	O
an	O
MPEG	O
audio	O
standard	O
:	O
MUSICAM	O
(	O
Masking	O
pattern	O
adapted	O
Universal	O
Subband	B-Algorithm
Integrated	O
Coding	O
And	O
Multiplexing	O
)	O
and	O
ASPEC	O
(	O
Adaptive	O
Spectral	O
Perceptual	O
Entropy	O
Coding	O
)	O
.	O
</s>
<s>
The	O
MUSICAM	O
format	O
,	O
based	O
on	O
sub-band	B-Algorithm
coding	I-Algorithm
,	O
became	O
the	O
basis	O
for	O
the	O
MPEG	O
Audio	O
compression	O
format	O
,	O
incorporating	O
,	O
for	O
example	O
,	O
its	O
frame	O
structure	O
,	O
header	B-General_Concept
format	O
,	O
sample	O
rates	O
,	O
etc	O
.	O
</s>
<s>
While	O
much	O
of	O
MUSICAM	O
technology	O
and	O
ideas	O
were	O
incorporated	O
into	O
the	O
definition	O
of	O
MPEG	O
Audio	O
Layer	O
I	O
and	O
Layer	O
II	O
,	O
the	O
filter	B-Application
bank	O
alone	O
and	O
the	O
data	O
structure	O
based	O
on	O
1152	O
samples	O
framing	O
(	O
file	O
format	O
and	O
byte	O
oriented	O
stream	O
)	O
of	O
MUSICAM	O
remained	O
in	O
the	O
Layer	O
III	O
(	O
MP3	B-Application
)	O
format	O
,	O
as	O
part	O
of	O
the	O
computationally	O
inefficient	O
hybrid	O
filter	B-Application
bank	O
.	O
</s>
<s>
A	O
working	O
group	O
consisting	O
of	O
van	O
de	O
Kerkhof	O
,	O
Stoll	O
,	O
Leonardo	O
Chiariglione	O
(	O
CSELT	O
VP	O
for	O
Media	O
)	O
,	O
Yves-François	O
Dehery	O
,	O
Karlheinz	O
Brandenburg	O
(	O
Germany	O
)	O
and	O
James	O
D	O
.	O
Johnston	O
(	O
United	O
States	O
)	O
took	O
ideas	O
from	O
ASPEC	O
,	O
integrated	O
the	O
filter	B-Application
bank	O
from	O
Layer	O
II	O
,	O
added	O
some	O
of	O
their	O
own	O
ideas	O
such	O
as	O
the	O
joint	O
stereo	O
coding	O
of	O
MUSICAM	O
and	O
created	O
the	O
MP3	B-Application
format	O
,	O
which	O
was	O
designed	O
to	O
achieve	O
the	O
same	O
quality	O
at	O
128kbit/s	O
as	O
MP2	O
at	O
192kbit/s	O
.	O
</s>
<s>
The	O
algorithms	O
for	O
MPEG-1	B-Algorithm
Audio	O
Layer	O
I	O
,	O
II	O
and	O
III	O
were	O
approved	O
in	O
1991	O
and	O
finalized	O
in	O
1992	O
as	O
part	O
of	O
MPEG-1	B-Algorithm
,	O
the	O
first	O
standard	O
suite	O
by	O
MPEG	O
,	O
which	O
resulted	O
in	O
the	O
international	O
standard	O
ISO/IEC	O
11172-3	O
(	O
a.k.a.	O
</s>
<s>
MPEG-1	B-Algorithm
Audio	O
or	O
MPEG-1	B-Algorithm
Part	O
3	O
)	O
,	O
published	O
in	O
1993	O
.	O
</s>
<s>
Files	O
or	O
data	O
streams	O
conforming	O
to	O
this	O
standard	O
must	O
handle	O
sample	O
rates	O
of	O
48k	O
,	O
44100	O
and	O
32k	O
and	O
continue	O
to	O
be	O
supported	O
by	O
current	O
MP3	B-Application
players	O
and	O
decoders	B-General_Concept
.	O
</s>
<s>
Thus	O
the	O
first	O
generation	O
of	O
MP3	B-Application
defined	O
interpretations	O
of	O
MP3	B-Application
frame	O
data	O
structures	O
and	O
size	O
layouts	O
.	O
</s>
<s>
Further	O
work	O
on	O
MPEG	O
audio	O
was	O
finalized	O
in	O
1994	O
as	O
part	O
of	O
the	O
second	O
suite	O
of	O
MPEG	O
standards	O
,	O
MPEG-2	B-Algorithm
,	O
more	O
formally	O
known	O
as	O
international	O
standard	O
ISO/IEC	B-Algorithm
13818-3	I-Algorithm
(	O
a.k.a.	O
</s>
<s>
MPEG-2	B-Algorithm
Part	O
3	O
or	O
backwards	O
compatible	O
MPEG-2	B-Algorithm
Audio	O
or	O
MPEG-2	B-Algorithm
Audio	O
BC	O
)	O
,	O
originally	O
published	O
in	O
1995	O
.	O
</s>
<s>
MPEG-2	B-Algorithm
Part	O
3	O
(	O
ISO/IEC	B-Algorithm
13818-3	I-Algorithm
)	O
defined	O
42	O
additional	O
bit	O
rates	O
and	O
sample	O
rates	O
for	O
MPEG-1	B-Algorithm
Audio	O
Layer	O
I	O
,	O
II	O
and	O
III	O
.	O
</s>
<s>
The	O
new	O
sampling	O
rates	O
are	O
exactly	O
half	O
that	O
of	O
those	O
originally	O
defined	O
in	O
MPEG-1	B-Algorithm
Audio	O
.	O
</s>
<s>
MPEG-2	B-Algorithm
Part	O
3	O
also	O
enhanced	O
MPEG-1	B-Algorithm
'	O
s	O
audio	O
by	O
allowing	O
the	O
coding	O
of	O
audio	O
programs	O
with	O
more	O
than	O
two	O
channels	O
,	O
up	O
to	O
5.1	O
multichannel	O
.	O
</s>
<s>
An	O
MP3	B-Application
coded	O
with	O
MPEG-2	B-Algorithm
results	O
in	O
half	O
of	O
the	O
bandwidth	O
reproduction	O
of	O
MPEG-1	B-Algorithm
appropriate	O
for	O
piano	O
and	O
singing	O
.	O
</s>
<s>
A	O
third	O
generation	O
of	O
"	O
MP3	B-Application
"	O
style	O
data	O
streams	O
(	O
files	O
)	O
extended	O
the	O
MPEG-2	B-Algorithm
ideas	O
and	O
implementation	O
,	O
but	O
was	O
named	O
MPEG-2.5	O
audio	O
,	O
since	O
MPEG-3	O
already	O
had	O
a	O
different	O
meaning	O
.	O
</s>
<s>
This	O
extension	O
was	O
developed	O
at	O
Fraunhofer	O
IIS	O
,	O
the	O
registered	O
patent	O
holders	O
of	O
MP3	B-Application
,	O
by	O
reducing	O
the	O
frame	O
sync	O
field	O
in	O
the	O
MP3	B-Application
header	B-General_Concept
from	O
12	O
to	O
11	O
bits	O
.	O
</s>
<s>
As	O
in	O
the	O
transition	O
from	O
MPEG-1	B-Algorithm
to	O
MPEG-2	B-Algorithm
,	O
MPEG-2.5	O
adds	O
additional	O
sampling	O
rates	O
exactly	O
half	O
of	O
those	O
available	O
using	O
MPEG-2	B-Algorithm
.	O
</s>
<s>
It	O
thus	O
widens	O
the	O
scope	O
of	O
MP3	B-Application
to	O
include	O
human	O
speech	O
and	O
other	O
applications	O
yet	O
requires	O
only	O
25%	O
of	O
the	O
bandwidth	O
(	O
frequency	O
reproduction	O
)	O
possible	O
using	O
MPEG-1	B-Algorithm
sampling	O
rates	O
.	O
</s>
<s>
While	O
not	O
an	O
ISO	O
recognized	O
standard	O
,	O
MPEG-2.5	O
is	O
widely	O
supported	O
by	O
both	O
inexpensive	O
Chinese	O
and	O
brand-name	O
digital	O
audio	O
players	O
as	O
well	O
as	O
computer	O
software	O
based	O
MP3	B-Application
encoders	I-Application
(	O
LAME	B-Algorithm
)	O
,	O
decoders	B-General_Concept
(	O
FFmpeg	O
)	O
and	O
players	O
(	O
MPC	B-Algorithm
)	O
adding	O
additional	O
MP3	B-Application
frame	O
types	O
.	O
</s>
<s>
Each	O
generation	O
of	O
MP3	B-Application
thus	O
supports	O
3	O
sampling	O
rates	O
exactly	O
half	O
that	O
of	O
the	O
previous	O
generation	O
for	O
a	O
total	O
of	O
9	O
varieties	O
of	O
MP3	B-Application
format	O
files	O
.	O
</s>
<s>
The	O
sample	O
rate	O
comparison	O
table	O
between	O
MPEG-1	B-Algorithm
,	O
2	O
and	O
2.5	O
is	O
given	O
later	O
in	O
the	O
article	O
.	O
</s>
<s>
MPEG-2.5	O
is	O
supported	O
by	O
LAME	B-Algorithm
(	O
since	O
2000	O
)	O
,	O
Media	O
Player	O
Classic	O
(	O
MPC	B-Algorithm
)	O
,	O
iTunes	O
,	O
and	O
FFmpeg	O
.	O
</s>
<s>
MPEG-2.5	O
was	O
not	O
developed	O
by	O
MPEG	O
(	O
see	O
above	O
)	O
and	O
was	O
never	O
approved	O
as	O
an	O
international	O
standard	O
.	O
</s>
<s>
MPEG-2.5	O
is	O
thus	O
an	O
unofficial	O
or	O
proprietary	O
extension	O
to	O
the	O
MP3	B-Application
format	O
.	O
</s>
<s>
MPEG-1	B-Algorithm
Audio	O
)	O
defined	O
three	O
formats	O
:	O
the	O
MPEG-1	B-Algorithm
Audio	O
Layer	O
I	O
,	O
Layer	O
II	O
and	O
Layer	O
III	O
.	O
</s>
<s>
The	O
ISO	O
standard	O
ISO/IEC	B-Algorithm
13818-3	I-Algorithm
(	O
a.k.a.	O
</s>
<s>
MPEG-2	B-Algorithm
Audio	O
)	O
defined	O
extended	O
version	O
of	O
the	O
MPEG-1	B-Algorithm
Audio	O
:	O
MPEG-2	B-Algorithm
Audio	O
Layer	O
I	O
,	O
Layer	O
II	O
and	O
Layer	O
III	O
.	O
</s>
<s>
MPEG-2	B-Algorithm
Audio	O
(	O
MPEG-2	B-Algorithm
Part	O
3	O
)	O
should	O
not	O
be	O
confused	O
with	O
MPEG-2	B-Application
AAC	I-Application
(	O
MPEG-2	B-Application
Part	I-Application
7	I-Application
–	O
ISO/IEC	B-Algorithm
13818-7	I-Algorithm
)	O
.	O
</s>
<s>
Nevertheless	O
,	O
compression	B-General_Concept
ratios	I-General_Concept
are	O
often	O
published	O
.	O
</s>
<s>
Compression	B-General_Concept
ratios	I-General_Concept
with	O
this	O
latter	O
reference	O
are	O
higher	O
,	O
which	O
demonstrates	O
the	O
problem	O
with	O
use	O
of	O
the	O
term	O
compression	O
ratio	O
for	O
lossy	B-Algorithm
encoders	O
.	O
</s>
<s>
Karlheinz	O
Brandenburg	O
used	O
a	O
CD	O
recording	O
of	O
Suzanne	O
Vega	O
's	O
song	O
"	O
Tom	O
's	O
Diner	O
"	O
to	O
assess	O
and	O
refine	O
the	O
MP3	B-Application
compression	B-General_Concept
algorithm	I-General_Concept
.	O
</s>
<s>
This	O
particular	O
track	O
has	O
an	O
interesting	O
property	O
in	O
that	O
the	O
two	O
channels	O
are	O
almost	O
,	O
but	O
not	O
completely	O
,	O
the	O
same	O
,	O
leading	O
to	O
a	O
case	O
where	O
Binaural	O
Masking	O
Level	O
Depression	O
causes	O
spatial	O
unmasking	O
of	O
noise	O
artifacts	B-Algorithm
unless	O
the	O
encoder	O
properly	O
recognizes	O
the	O
situation	O
and	O
applies	O
corrections	O
similar	O
to	O
those	O
detailed	O
in	O
the	O
MPEG-2	B-Application
AAC	I-Application
psychoacoustic	O
model	O
.	O
</s>
<s>
LAME	B-Algorithm
is	O
the	O
most	O
advanced	O
MP3	B-Application
encoder	I-Application
.	O
</s>
<s>
LAME	B-Algorithm
includes	O
a	O
VBR	O
variable	B-General_Concept
bit	I-General_Concept
rate	I-General_Concept
encoding	O
which	O
uses	O
a	O
quality	O
parameter	O
rather	O
than	O
a	O
bit	O
rate	O
goal	O
.	O
</s>
<s>
Later	O
versions	O
(	O
2008+	O
)	O
support	O
an	O
n.nnn	O
quality	O
goal	O
which	O
automatically	O
selects	O
MPEG-2	B-Algorithm
or	O
MPEG-2.5	O
sampling	O
rates	O
as	O
appropriate	O
for	O
human	O
speech	O
recordings	O
which	O
need	O
only	O
5512Hz	O
bandwidth	O
resolution	O
.	O
</s>
<s>
Working	O
in	O
non-real	O
time	O
on	O
a	O
number	O
of	O
operating	O
systems	O
,	O
it	O
was	O
able	O
to	O
demonstrate	O
the	O
first	O
real	O
time	O
hardware	O
decoding	O
(	O
DSP	B-Architecture
based	O
)	O
of	O
compressed	O
audio	O
.	O
</s>
<s>
Some	O
other	O
real	O
time	O
implementations	O
of	O
MPEG	O
Audio	O
encoders	O
and	O
decoders	B-General_Concept
were	O
available	O
for	O
the	O
purpose	O
of	O
digital	O
broadcasting	O
(	O
radio	O
DAB	O
,	O
television	O
DVB	B-Application
)	O
towards	O
consumer	O
receivers	O
and	O
set	O
top	O
boxes	O
.	O
</s>
<s>
On	O
7	O
July	O
1994	O
,	O
the	O
Fraunhofer	O
Society	O
released	O
the	O
first	O
software	O
MP3	B-Application
encoder	I-Application
,	O
called	O
l3enc	B-Application
.	O
</s>
<s>
The	O
filename	O
extension	O
.mp3	B-Application
was	O
chosen	O
by	O
the	O
Fraunhofer	O
team	O
on	O
14	O
July	O
1995	O
(	O
previously	O
,	O
the	O
files	O
had	O
been	O
named	O
.bit	O
)	O
.	O
</s>
<s>
With	O
the	O
first	O
real-time	O
software	O
MP3	B-Application
player	O
WinPlay3	B-Application
(	O
released	O
9	O
September	O
1995	O
)	O
many	O
people	O
were	O
able	O
to	O
encode	O
and	O
play	O
back	O
MP3	B-Application
files	I-Application
on	O
their	O
PCs	O
.	O
</s>
<s>
Because	O
of	O
the	O
relatively	O
small	O
hard	B-Device
drives	I-Device
of	O
the	O
era	O
( ≈500	O
–	O
1000	O
MB	O
)	O
lossy	B-Algorithm
compression	I-Algorithm
was	O
essential	O
to	O
store	O
multiple	O
albums	O
 '	O
worth	O
of	O
music	O
on	O
a	O
home	O
computer	O
as	O
full	O
recordings	O
(	O
as	O
opposed	O
to	O
MIDI	O
notation	O
,	O
or	O
tracker	B-Application
files	O
which	O
combined	O
notation	O
with	O
short	O
recordings	O
of	O
instruments	O
playing	O
single	O
notes	O
)	O
.	O
</s>
<s>
This	O
code	O
started	O
the	O
widespread	O
CD	O
ripping	O
and	O
digital	O
music	O
distribution	O
as	O
MP3	B-Application
over	O
the	O
internet	O
.	O
</s>
<s>
In	O
the	O
second	O
half	O
of	O
the	O
1990s	O
,	O
MP3	B-Application
files	I-Application
began	O
to	O
spread	O
on	O
the	O
Internet	O
,	O
often	O
via	O
underground	O
pirated	O
song	O
networks	O
.	O
</s>
<s>
After	O
some	O
experiments	O
using	O
uncompressed	B-General_Concept
audio	O
files	O
,	O
this	O
archive	O
started	O
to	O
deliver	O
on	O
the	O
native	O
worldwide	O
low-speed	O
Internet	O
some	O
compressed	O
MPEG	O
Audio	O
files	O
using	O
the	O
MP2	O
(	O
Layer	O
II	O
)	O
format	O
and	O
later	O
on	O
used	O
MP3	B-Application
files	I-Application
when	O
the	O
standard	O
was	O
fully	O
completed	O
.	O
</s>
<s>
The	O
popularity	O
of	O
MP3s	B-Application
began	O
to	O
rise	O
rapidly	O
with	O
the	O
advent	O
of	O
Nullsoft	O
's	O
audio	O
player	O
Winamp	B-Application
,	O
released	O
in	O
1997	O
.	O
</s>
<s>
In	O
November	O
1997	O
,	O
the	O
website	O
mp3.com	O
was	O
offering	O
thousands	O
of	O
MP3s	B-Application
created	O
by	O
independent	O
artists	O
for	O
free	O
.	O
</s>
<s>
The	O
small	O
size	O
of	O
MP3	B-Application
files	I-Application
enabled	O
widespread	O
peer-to-peer	O
file	O
sharing	O
of	O
music	O
ripped	O
from	O
CDs	O
,	O
which	O
would	O
have	O
previously	O
been	O
nearly	O
impossible	O
.	O
</s>
<s>
The	O
first	O
large	O
peer-to-peer	O
filesharing	O
network	O
,	O
Napster	B-Application
,	O
was	O
launched	O
in	O
1999	O
.	O
</s>
<s>
The	O
ease	O
of	O
creating	O
and	O
sharing	O
MP3s	B-Application
resulted	O
in	O
widespread	O
copyright	O
infringement	O
.	O
</s>
<s>
Major	O
record	O
companies	O
argued	O
that	O
this	O
free	O
sharing	O
of	O
music	O
reduced	O
sales	O
,	O
and	O
called	O
it	O
"	O
music	B-Application
piracy	I-Application
"	O
.	O
</s>
<s>
They	O
reacted	O
by	O
pursuing	O
lawsuits	O
against	O
Napster	B-Application
,	O
which	O
was	O
eventually	O
shut	O
down	O
and	O
later	O
sold	O
,	O
and	O
against	O
individual	O
users	O
who	O
engaged	O
in	O
file	O
sharing	O
.	O
</s>
<s>
Unauthorized	O
MP3	B-Application
file	I-Application
sharing	O
continues	O
on	O
next-generation	O
peer-to-peer	O
networks	O
.	O
</s>
<s>
Some	O
authorized	O
services	O
,	O
such	O
as	O
Beatport	O
,	O
Bleep	O
,	O
Juno	O
Records	O
,	O
eMusic	O
,	O
Zune	O
Marketplace	O
,	O
Walmart.com,	O
Rhapsody	O
,	O
the	O
recording	O
industry	O
approved	O
re-incarnation	O
of	O
Napster	B-Application
,	O
and	O
Amazon.com	B-Application
sell	O
unrestricted	O
music	O
in	O
the	O
MP3	B-Application
format	O
.	O
</s>
<s>
An	O
MP3	B-Application
file	I-Application
is	O
made	O
up	O
of	O
MP3	B-Application
frames	O
,	O
which	O
consist	O
of	O
a	O
header	B-General_Concept
and	O
a	O
data	O
block	O
.	O
</s>
<s>
The	O
MP3	B-Application
Data	O
blocks	O
contain	O
the	O
(	O
compressed	O
)	O
audio	O
information	O
in	O
terms	O
of	O
frequencies	O
and	O
amplitudes	O
.	O
</s>
<s>
The	O
diagram	O
shows	O
that	O
the	O
MP3	B-Application
Header	B-General_Concept
consists	O
of	O
a	O
sync	O
word	O
,	O
which	O
is	O
used	O
to	O
identify	O
the	O
beginning	O
of	O
a	O
valid	O
frame	O
.	O
</s>
<s>
This	O
is	O
followed	O
by	O
a	O
bit	O
indicating	O
that	O
this	O
is	O
the	O
MPEG	O
standard	O
and	O
two	O
bits	O
that	O
indicate	O
that	O
layer	O
3	O
is	O
used	O
;	O
hence	O
MPEG-1	B-Application
Audio	I-Application
Layer	I-Application
3	I-Application
or	O
MP3	B-Application
.	O
</s>
<s>
After	O
this	O
,	O
the	O
values	O
will	O
differ	O
,	O
depending	O
on	O
the	O
MP3	B-Application
file	I-Application
.	O
</s>
<s>
ISO/IEC	O
11172-3	O
defines	O
the	O
range	O
of	O
values	O
for	O
each	O
section	O
of	O
the	O
header	B-General_Concept
along	O
with	O
the	O
specification	O
of	O
the	O
header	B-General_Concept
.	O
</s>
<s>
Most	O
MP3	B-Application
files	I-Application
today	O
contain	O
ID3	O
metadata	O
,	O
which	O
precedes	O
or	O
follows	O
the	O
MP3	B-Application
frames	O
,	O
as	O
noted	O
in	O
the	O
diagram	O
.	O
</s>
<s>
The	O
MP3	B-Application
encoding	O
algorithm	O
is	O
generally	O
split	O
into	O
four	O
parts	O
.	O
</s>
<s>
Part	O
1	O
divides	O
the	O
audio	O
signal	O
into	O
smaller	O
pieces	O
,	O
called	O
frames	O
,	O
and	O
a	O
modified	O
discrete	B-General_Concept
cosine	I-General_Concept
transform	I-General_Concept
(	O
MDCT	O
)	O
filter	B-Application
is	O
then	O
performed	O
on	O
the	O
output	O
.	O
</s>
<s>
Part	O
2	O
passes	O
the	O
sample	O
into	O
a	O
1024-point	O
fast	O
Fourier	B-Algorithm
transform	I-Algorithm
(	O
FFT	O
)	O
,	O
then	O
the	O
psychoacoustic	O
model	O
is	O
applied	O
and	O
another	O
MDCT	O
filter	B-Application
is	O
performed	O
on	O
the	O
output	O
.	O
</s>
<s>
Part	O
4	O
formats	O
the	O
bitstream	O
,	O
called	O
an	O
audio	O
frame	O
,	O
which	O
is	O
made	O
up	O
of	O
4	O
parts	O
,	O
the	O
header	B-General_Concept
,	O
error	B-Error_Name
check	I-Error_Name
,	O
audio	O
data	O
,	O
and	O
ancillary	O
data	O
.	O
</s>
<s>
The	O
MPEG-1	B-Algorithm
standard	O
does	O
not	O
include	O
a	O
precise	O
specification	O
for	O
an	O
MP3	B-Application
encoder	I-Application
,	O
but	O
does	O
provide	O
example	O
psychoacoustic	O
models	O
,	O
rate	O
loop	O
,	O
and	O
the	O
like	O
in	O
the	O
non-normative	O
part	O
of	O
the	O
original	O
standard	O
.	O
</s>
<s>
MPEG-2	B-Algorithm
doubles	O
the	O
number	O
of	O
sampling	O
rates	O
which	O
are	O
supported	O
and	O
MPEG-2.5	O
adds	O
3	O
more	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
many	O
different	O
MP3	B-Application
encoders	I-Application
became	O
available	O
,	O
each	O
producing	O
files	O
of	O
differing	O
quality	O
.	O
</s>
<s>
Some	O
encoders	O
that	O
were	O
proficient	O
at	O
encoding	O
at	O
higher	O
bit	O
rates	O
(	O
such	O
as	O
LAME	B-Algorithm
)	O
were	O
not	O
necessarily	O
as	O
good	O
at	O
lower	O
bit	O
rates	O
.	O
</s>
<s>
Over	O
time	O
,	O
LAME	B-Algorithm
evolved	O
on	O
the	O
SourceForge	O
website	O
until	O
it	O
became	O
the	O
de	O
facto	O
CBR	O
MP3	B-Application
encoder	I-Application
.	O
</s>
<s>
Work	O
progressed	O
on	O
true	O
variable	B-General_Concept
bit	I-General_Concept
rate	I-General_Concept
using	O
a	O
quality	O
goal	O
between	O
0	O
and	O
10	O
.	O
</s>
<s>
Eventually	O
numbers	O
(	O
such	O
as	O
-V	O
9.600	O
)	O
could	O
generate	O
excellent	O
quality	O
low	O
bit	O
rate	O
voice	B-Application
encoding	I-Application
at	O
only	O
41kbit/s	O
using	O
the	O
MPEG-2.5	O
extensions	O
.	O
</s>
<s>
During	O
encoding	O
,	O
576	O
time-domain	O
samples	O
are	O
taken	O
and	O
are	O
transformed	O
to	O
576	O
frequency-domain	B-Algorithm
samples	I-Algorithm
.	O
</s>
<s>
Due	O
to	O
the	O
tree	O
structure	O
of	O
the	O
filter	B-Application
bank	O
,	O
pre-echo	O
problems	O
are	O
made	O
worse	O
,	O
as	O
the	O
combined	O
impulse	O
response	O
of	O
the	O
two	O
filter	B-Application
banks	O
does	O
not	O
,	O
and	O
cannot	O
,	O
provide	O
an	O
optimum	O
solution	O
in	O
time/frequency	O
resolution	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
combining	O
of	O
the	O
two	O
filter	B-Application
banks	O
 '	O
outputs	O
creates	O
aliasing	O
problems	O
that	O
must	O
be	O
handled	O
partially	O
by	O
the	O
"	O
aliasing	O
compensation	O
"	O
stage	O
;	O
however	O
,	O
that	O
creates	O
excess	O
energy	O
to	O
be	O
coded	O
in	O
the	O
frequency	O
domain	O
,	O
thereby	O
decreasing	O
coding	O
efficiency	O
.	O
</s>
<s>
Most	O
decoders	B-General_Concept
are	O
"	O
bitstream	O
compliant	O
"	O
,	O
which	O
means	O
that	O
the	O
decompressed	O
output	O
that	O
they	O
produce	O
from	O
a	O
given	O
MP3	B-Application
file	I-Application
will	O
be	O
the	O
same	O
,	O
within	O
a	O
specified	O
degree	O
of	O
rounding	B-Algorithm
tolerance	O
,	O
as	O
the	O
output	O
specified	O
mathematically	O
in	O
the	O
ISO/IEC	O
high	O
standard	O
document	O
(	O
ISO/IEC	O
11172-3	O
)	O
.	O
</s>
<s>
Therefore	O
,	O
comparison	O
of	O
decoders	B-General_Concept
is	O
usually	O
based	O
on	O
how	O
computationally	O
efficient	O
they	O
are	O
(	O
i.e.	O
,	O
how	O
much	O
memory	B-General_Concept
or	O
CPU	B-Device
time	O
they	O
use	O
in	O
the	O
decoding	O
process	O
)	O
.	O
</s>
<s>
Over	O
time	O
this	O
concern	O
has	O
become	O
less	O
of	O
an	O
issue	O
as	O
CPU	B-Device
clock	O
rates	O
transitioned	O
from	O
MHz	O
to	O
GHz	O
.	O
</s>
<s>
Encoder/decoder	B-General_Concept
overall	O
delay	O
is	O
not	O
defined	O
,	O
which	O
means	O
there	O
is	O
no	O
official	O
provision	O
for	O
gapless	O
playback	O
.	O
</s>
<s>
However	O
,	O
some	O
encoders	O
such	O
as	O
LAME	B-Algorithm
can	O
attach	O
additional	O
metadata	O
that	O
will	O
allow	O
players	O
that	O
can	O
handle	O
it	O
to	O
deliver	O
seamless	O
playback	O
.	O
</s>
<s>
When	O
performing	O
lossy	B-Algorithm
audio	O
encoding	O
,	O
such	O
as	O
creating	O
an	O
MP3	B-Application
data	O
stream	O
,	O
there	O
is	O
a	O
trade-off	O
between	O
the	O
amount	O
of	O
data	O
generated	O
and	O
the	O
sound	O
quality	O
of	O
the	O
results	O
.	O
</s>
<s>
The	O
person	O
generating	O
an	O
MP3	B-Application
selects	O
a	O
bit	O
rate	O
,	O
which	O
specifies	O
how	O
many	O
kilobits	O
per	O
second	O
of	O
audio	O
is	O
desired	O
.	O
</s>
<s>
The	O
higher	O
the	O
bit	O
rate	O
,	O
the	O
larger	O
the	O
MP3	B-Application
data	O
stream	O
will	O
be	O
,	O
and	O
,	O
generally	O
,	O
the	O
closer	O
it	O
will	O
sound	O
to	O
the	O
original	O
recording	O
.	O
</s>
<s>
With	O
too	O
low	O
a	O
bit	O
rate	O
,	O
compression	B-Algorithm
artifacts	I-Algorithm
(	O
i.e.	O
,	O
sounds	O
that	O
were	O
not	O
present	O
in	O
the	O
original	O
recording	O
)	O
may	O
be	O
audible	O
in	O
the	O
reproduction	O
.	O
</s>
<s>
When	O
this	O
type	O
of	O
audio	O
is	O
compressed	O
,	O
artifacts	B-Algorithm
such	O
as	O
ringing	O
or	O
pre-echo	O
are	O
usually	O
heard	O
.	O
</s>
<s>
A	O
sample	O
of	O
applause	O
or	O
a	O
triangle	O
instrument	O
with	O
a	O
relatively	O
low	O
bit	O
rate	O
provide	O
good	O
examples	O
of	O
compression	B-Algorithm
artifacts	I-Algorithm
.	O
</s>
<s>
Most	O
subjective	O
testings	O
of	O
perceptual	O
codecs	B-General_Concept
tend	O
to	O
avoid	O
using	O
these	O
types	O
of	O
sound	O
materials	O
,	O
however	O
,	O
the	O
artifacts	B-Algorithm
generated	O
by	O
percussive	O
sounds	O
are	O
barely	O
perceptible	O
due	O
to	O
the	O
specific	O
temporal	O
masking	O
feature	O
of	O
the	O
32	O
sub-band	B-Algorithm
filterbank	O
of	O
Layer	O
II	O
on	O
which	O
the	O
format	O
is	O
based	O
.	O
</s>
<s>
Besides	O
the	O
bit	O
rate	O
of	O
an	O
encoded	O
piece	O
of	O
audio	O
,	O
the	O
quality	O
of	O
MP3	B-Application
encoded	O
sound	O
also	O
depends	O
on	O
the	O
quality	O
of	O
the	O
encoder	O
algorithm	O
as	O
well	O
as	O
the	O
complexity	O
of	O
the	O
signal	O
being	O
encoded	O
.	O
</s>
<s>
As	O
the	O
MP3	B-Application
standard	O
allows	O
quite	O
a	O
bit	O
of	O
freedom	O
with	O
encoding	O
algorithms	O
,	O
different	O
encoders	O
do	O
feature	O
quite	O
different	O
quality	O
,	O
even	O
with	O
identical	O
bit	O
rates	O
.	O
</s>
<s>
As	O
an	O
example	O
,	O
in	O
a	O
public	O
listening	O
test	O
featuring	O
two	O
early	O
MP3	B-Application
encoders	I-Application
set	O
at	O
about	O
128kbit/s	O
,	O
one	O
scored	O
3.66	O
on	O
a	O
1	O
–	O
5	O
scale	O
,	O
while	O
the	O
other	O
scored	O
only	O
2.22	O
.	O
</s>
<s>
At	O
the	O
time	O
MP3	B-Application
files	I-Application
were	O
of	O
the	O
very	O
simplest	O
type	O
:	O
they	O
used	O
the	O
same	O
bit	O
rate	O
for	O
the	O
entire	O
file	O
:	O
this	O
process	O
is	O
known	O
as	O
Constant	B-General_Concept
Bit	I-General_Concept
Rate	I-General_Concept
(	O
CBR	O
)	O
encoding	O
.	O
</s>
<s>
Using	O
a	O
constant	B-General_Concept
bit	I-General_Concept
rate	I-General_Concept
makes	O
encoding	O
simpler	O
and	O
less	O
CPU	B-Device
intensive	O
.	O
</s>
<s>
These	O
are	O
known	O
as	O
Variable	B-General_Concept
Bit	I-General_Concept
Rate	I-General_Concept
.	O
</s>
<s>
The	O
bit	O
reservoir	O
and	O
VBR	O
encoding	O
were	O
actually	O
part	O
of	O
the	O
original	O
MPEG-1	B-Algorithm
standard	O
.	O
</s>
<s>
With	O
some	O
advanced	O
MP3	B-Application
encoders	I-Application
,	O
it	O
is	O
possible	O
to	O
specify	O
a	O
given	O
quality	O
,	O
and	O
the	O
encoder	O
will	O
adjust	O
the	O
bit	O
rate	O
accordingly	O
.	O
</s>
<s>
Users	O
that	O
desire	O
a	O
particular	O
"	O
quality	O
setting	O
"	O
that	O
is	O
transparent	B-Algorithm
to	O
their	O
ears	O
can	O
use	O
this	O
value	O
when	O
encoding	O
all	O
of	O
their	O
music	O
,	O
and	O
generally	O
speaking	O
not	O
need	O
to	O
worry	O
about	O
performing	O
personal	O
listening	O
tests	O
on	O
each	O
piece	O
of	O
music	O
to	O
determine	O
the	O
correct	O
bit	O
rate	O
.	O
</s>
<s>
A	O
test	O
given	O
to	O
new	O
students	O
by	O
Stanford	O
University	O
Music	O
Professor	O
Jonathan	O
Berger	O
showed	O
that	O
student	O
preference	O
for	O
MP3-quality	O
music	O
has	O
risen	O
each	O
year	O
.	O
</s>
<s>
Berger	O
said	O
the	O
students	O
seem	O
to	O
prefer	O
the	O
'	O
sizzle	O
 '	O
sounds	O
that	O
MP3s	B-Application
bring	O
to	O
music	O
.	O
</s>
<s>
An	O
in-depth	O
study	O
of	O
MP3	B-Application
audio	I-Application
quality	O
,	O
sound	O
artist	O
and	O
composer	O
Ryan	O
Maguire	O
's	O
project	O
"	O
The	O
Ghost	O
in	O
the	O
MP3	B-Application
"	O
isolates	O
the	O
sounds	O
lost	O
during	O
MP3	B-Application
compression	O
.	O
</s>
<s>
In	O
2015	O
,	O
he	O
released	O
the	O
track	O
"	O
moDernisT	O
"	O
(	O
an	O
anagram	O
of	O
"	O
Tom	O
's	O
Diner	O
"	O
)	O
,	O
composed	O
exclusively	O
from	O
the	O
sounds	O
deleted	O
during	O
MP3	B-Application
compression	O
of	O
the	O
song	O
"	O
Tom	O
's	O
Diner	O
"	O
,	O
the	O
track	O
originally	O
used	O
in	O
the	O
formulation	O
of	O
the	O
MP3	B-Application
standard	O
.	O
</s>
<s>
A	O
detailed	O
account	O
of	O
the	O
techniques	O
used	O
to	O
isolate	O
the	O
sounds	O
deleted	O
during	O
MP3	B-Application
compression	O
,	O
along	O
with	O
the	O
conceptual	O
motivation	O
for	O
the	O
project	O
,	O
was	O
published	O
in	O
the	O
2014	O
Proceedings	O
of	O
the	O
International	O
Computer	O
Music	O
Conference	O
.	O
</s>
<s>
So	O
,	O
multiplying	O
44100	O
by	O
32	O
gives	O
1411200	O
—	O
the	O
bitrate	O
of	O
uncompressed	B-General_Concept
CD	O
digital	O
audio	O
.	O
</s>
<s>
MP3	B-Application
was	O
designed	O
to	O
encode	O
this	O
1411kbit/s	O
data	O
at	O
320kbit/s	O
or	O
less	O
.	O
</s>
<s>
As	O
less	O
complex	O
passages	O
are	O
detected	O
by	O
MP3	B-Application
algorithms	O
then	O
lower	O
bitrates	O
may	O
be	O
employed	O
.	O
</s>
<s>
When	O
using	O
MPEG-2	B-Algorithm
instead	O
of	O
MPEG-1	B-Algorithm
,	O
MP3	B-Application
supports	O
only	O
lower	O
sampling	O
rates	O
(	O
16000	O
,	O
22050	O
or	O
24000	O
samples	O
per	O
second	O
)	O
and	O
offers	O
choices	O
of	O
bitrate	O
as	O
low	O
as	O
8kbit/s	O
but	O
no	O
higher	O
than	O
160kbit/s	O
.	O
</s>
<s>
By	O
lowering	O
the	O
sampling	O
rate	O
,	O
MPEG-2	B-Application
layer	I-Application
III	I-Application
removes	O
all	O
frequencies	O
above	O
half	O
the	O
new	O
sampling	O
rate	O
that	O
may	O
have	O
been	O
present	O
in	O
the	O
source	O
audio	O
.	O
</s>
<s>
As	O
shown	O
in	O
these	O
two	O
tables	O
,	O
14	O
selected	O
bit	O
rates	O
are	O
allowed	O
in	O
MPEG-1	B-Application
Audio	I-Application
Layer	I-Application
III	I-Application
standard	O
:	O
32	O
,	O
40	O
,	O
48	O
,	O
56	O
,	O
64	O
,	O
80	O
,	O
96	O
,	O
112	O
,	O
128	O
,	O
160	O
,	O
192	O
,	O
224	O
,	O
256	O
and	O
320kbit/s	O
,	O
along	O
with	O
the	O
3	O
highest	O
available	O
sampling	B-Algorithm
frequencies	I-Algorithm
of	O
32	O
,	O
44.1	O
and	O
48kHz	O
.	O
</s>
<s>
MPEG-2	B-Application
Audio	I-Application
Layer	I-Application
III	I-Application
also	O
allows	O
14	O
somewhat	O
different	O
(	O
and	O
mostly	O
lower	O
)	O
bit	O
rates	O
of	O
8	O
,	O
16	O
,	O
24	O
,	O
32	O
,	O
40	O
,	O
48	O
,	O
56	O
,	O
64	O
,	O
80	O
,	O
96	O
,	O
112	O
,	O
128	O
,	O
144	O
,	O
160kbit/s	O
with	O
sampling	B-Algorithm
frequencies	I-Algorithm
of	O
16	O
,	O
22.05	O
and	O
24kHz	O
which	O
are	O
exactly	O
half	O
that	O
of	O
MPEG-1	B-Algorithm
.	O
</s>
<s>
MPEG-2.5	O
Audio	O
Layer	O
III	O
frames	O
are	O
limited	O
to	O
only	O
8	O
bit	O
rates	O
of	O
8	O
,	O
16	O
,	O
24	O
,	O
32	O
,	O
40	O
,	O
48	O
,	O
56	O
and	O
64kbit/s	O
with	O
3	O
even	O
lower	O
sampling	B-Algorithm
frequencies	I-Algorithm
of	O
8	O
,	O
11.025	O
,	O
and	O
12kHz	O
.	O
</s>
<s>
On	O
earlier	O
systems	O
that	O
only	O
support	O
the	O
MPEG-1	B-Application
Audio	I-Application
Layer	I-Application
III	I-Application
standard	O
,	O
MP3	B-Application
files	I-Application
with	O
a	O
bit	O
rate	O
below	O
32	O
kbit/s	O
might	O
be	O
played	O
back	O
sped-up	O
and	O
pitched-up	O
.	O
</s>
<s>
Earlier	O
systems	O
also	O
lack	O
fast	B-Application
forwarding	I-Application
and	O
rewinding	O
playback	O
controls	O
on	O
MP3	B-Application
.	O
</s>
<s>
MPEG-1	B-Algorithm
frames	O
contain	O
the	O
most	O
detail	O
in	O
320kbit/s	O
mode	O
,	O
the	O
highest	O
allowable	O
bit	O
rate	O
setting	O
,	O
with	O
silence	O
and	O
simple	O
tones	O
still	O
requiring	O
32kbit/s	O
.	O
</s>
<s>
MPEG-2	B-Algorithm
frames	O
can	O
capture	O
up	O
to	O
12kHz	O
sound	O
reproductions	O
needed	O
up	O
to	O
160kbit/s	O
.	O
</s>
<s>
MP3	B-Application
files	I-Application
made	O
with	O
MPEG-2	B-Algorithm
do	O
n't	O
have	O
20kHz	O
bandwidth	O
because	O
of	O
the	O
Nyquist	O
–	O
Shannon	O
sampling	O
theorem	O
.	O
</s>
<s>
Frequency	O
reproduction	O
is	O
always	O
strictly	O
less	O
than	O
half	O
of	O
the	O
sampling	B-Algorithm
frequency	I-Algorithm
,	O
and	O
imperfect	O
filters	O
require	O
a	O
larger	O
margin	O
for	O
error	O
(	O
noise	O
level	O
versus	O
sharpness	O
of	O
filter	B-Application
)	O
,	O
so	O
an	O
8kHz	O
sampling	O
rate	O
limits	O
the	O
maximum	O
frequency	O
to	O
4kHz	O
,	O
while	O
a	O
48kHz	O
sampling	O
rate	O
limits	O
an	O
MP3	B-Application
to	O
a	O
maximum	O
24kHz	O
sound	O
reproduction	O
.	O
</s>
<s>
MPEG-2	B-Algorithm
uses	O
half	O
and	O
MPEG-2.5	O
only	O
a	O
quarter	O
of	O
MPEG-1	B-Algorithm
sample	O
rates	O
.	O
</s>
<s>
Resampling	O
to	O
12000	O
(	O
6K	O
bandwidth	O
)	O
is	O
selected	O
by	O
the	O
LAME	B-Algorithm
parameter	O
-V	O
9.4	O
.	O
</s>
<s>
Older	O
versions	O
of	O
LAME	B-Algorithm
and	O
FFmpeg	O
only	O
support	O
integer	O
arguments	O
for	O
the	O
variable	B-General_Concept
bit	I-General_Concept
rate	I-General_Concept
quality	O
selection	O
parameter	O
.	O
</s>
<s>
The	O
n.nnn	O
quality	O
parameter	O
(	O
-V	O
)	O
is	O
documented	O
at	O
lame.sourceforge.net	O
but	O
is	O
only	O
supported	O
in	O
LAME	B-Algorithm
with	O
the	O
new	O
style	O
VBR	O
variable	B-General_Concept
bit	I-General_Concept
rate	I-General_Concept
quality	O
selector	O
—	O
not	O
average	B-General_Concept
bit	I-General_Concept
rate	I-General_Concept
(	O
ABR	O
)	O
.	O
</s>
<s>
A	O
sample	O
rate	O
of	O
44.1kHz	O
is	O
commonly	O
used	O
for	O
music	O
reproduction	O
,	O
because	O
this	O
is	O
also	O
used	O
for	O
CD	O
audio	O
,	O
the	O
main	O
source	O
used	O
for	O
creating	O
MP3	B-Application
files	I-Application
.	O
</s>
<s>
As	O
Internet	O
bandwidth	O
availability	O
and	O
hard	B-Device
drive	I-Device
sizes	O
have	O
increased	O
,	O
higher	O
bit	O
rates	O
up	O
to	O
320kbit/s	O
are	O
widespread	O
.	O
</s>
<s>
Uncompressed	B-General_Concept
audio	O
as	O
stored	O
on	O
an	O
audio-CD	O
has	O
a	O
bit	O
rate	O
of	O
1,411	O
.2kbit/s	O
,	O
(	O
16	O
bit/sample	O
×	O
44100	O
samples/second	O
×	O
2	O
channels	O
/	O
1000	O
bits/kilobit	O
)	O
,	O
so	O
the	O
bitrates	O
128	O
,	O
160	O
and	O
192kbit/s	O
represent	O
compression	B-General_Concept
ratios	I-General_Concept
of	O
approximately	O
11:1	O
,	O
9:1	O
and	O
7:1	O
respectively	O
.	O
</s>
<s>
Non-standard	O
bit	O
rates	O
up	O
to	O
640kbit/s	O
can	O
be	O
achieved	O
with	O
the	O
LAME	B-Algorithm
encoder	O
and	O
the	O
freeformat	O
option	O
,	O
although	O
few	O
MP3	B-Application
players	O
can	O
play	O
those	O
files	O
.	O
</s>
<s>
According	O
to	O
the	O
ISO	O
standard	O
,	O
decoders	B-General_Concept
are	O
only	O
required	O
to	O
be	O
able	O
to	O
decode	O
streams	O
up	O
to	O
320kbit/s	O
.	O
</s>
<s>
Early	O
MPEG	B-Application
Layer	I-Application
III	I-Application
encoders	O
used	O
what	O
is	O
now	O
called	O
Constant	B-General_Concept
Bit	I-General_Concept
Rate	I-General_Concept
(	O
CBR	O
)	O
.	O
</s>
<s>
The	O
software	O
was	O
only	O
able	O
to	O
use	O
a	O
uniform	O
bitrate	O
on	O
all	O
frames	O
in	O
an	O
MP3	B-Application
file	I-Application
.	O
</s>
<s>
Later	O
more	O
sophisticated	O
MP3	B-Application
encoders	I-Application
were	O
able	O
to	O
use	O
the	O
bit	O
reservoir	O
to	O
target	O
an	O
average	B-General_Concept
bit	I-General_Concept
rate	I-General_Concept
selecting	O
the	O
encoding	O
rate	O
for	O
each	O
frame	O
based	O
on	O
the	O
complexity	O
of	O
the	O
sound	O
in	O
that	O
portion	O
of	O
the	O
recording	O
.	O
</s>
<s>
A	O
more	O
sophisticated	O
MP3	B-Application
encoder	I-Application
can	O
produce	O
variable	B-General_Concept
bitrate	I-General_Concept
audio	O
.	O
</s>
<s>
MPEG	O
audio	O
may	O
use	O
bitrate	O
switching	O
on	O
a	O
per-frame	O
basis	O
,	O
but	O
only	O
layer	O
III	O
decoders	B-General_Concept
must	O
support	O
it	O
.	O
</s>
<s>
The	O
final	O
file	O
size	O
of	O
a	O
VBR	O
encoding	O
is	O
less	O
predictable	O
than	O
with	O
constant	B-General_Concept
bitrate	I-General_Concept
.	O
</s>
<s>
Average	B-General_Concept
bitrate	I-General_Concept
is	O
a	O
type	O
of	O
VBR	O
implemented	O
as	O
a	O
compromise	O
between	O
the	O
two	O
:	O
the	O
bitrate	O
is	O
allowed	O
to	O
vary	O
for	O
more	O
consistent	O
quality	O
,	O
but	O
is	O
controlled	O
to	O
remain	O
near	O
an	O
average	O
value	O
chosen	O
by	O
the	O
user	O
,	O
for	O
predictable	O
file	O
sizes	O
.	O
</s>
<s>
Although	O
an	O
MP3	B-Application
decoder	O
must	O
support	O
VBR	O
to	O
be	O
standards	O
compliant	O
,	O
historically	O
some	O
decoders	B-General_Concept
have	O
bugs	O
with	O
VBR	O
decoding	O
,	O
particularly	O
before	O
VBR	O
encoders	O
became	O
widespread	O
.	O
</s>
<s>
The	O
most	O
evolved	O
LAME	B-Algorithm
MP3	B-Application
encoder	I-Application
supports	O
the	O
generation	O
of	O
VBR	O
,	O
ABR	O
,	O
and	O
even	O
the	O
older	O
CBR	O
MP3	B-Application
formats	O
.	O
</s>
<s>
Layer	O
III	O
audio	O
can	O
also	O
use	O
a	O
"	O
bit	O
reservoir	O
"	O
,	O
a	O
partially	O
full	O
frame	O
's	O
ability	O
to	O
hold	O
part	O
of	O
the	O
next	O
frame	O
's	O
audio	O
data	O
,	O
allowing	O
temporary	O
changes	O
in	O
effective	O
bitrate	O
,	O
even	O
in	O
a	O
constant	B-General_Concept
bitrate	I-General_Concept
stream	O
.	O
</s>
<s>
Encoder	O
mp3PRO	B-Algorithm
used	O
ancillary	O
data	O
to	O
encode	O
extra	O
information	O
which	O
could	O
improve	O
audio	O
quality	O
when	O
decoded	O
with	O
its	O
own	O
algorithm	O
.	O
</s>
<s>
The	O
MP3	B-Application
standards	O
do	O
not	O
define	O
tag	O
formats	O
for	O
MP3	B-Application
files	I-Application
,	O
nor	O
is	O
there	O
a	O
standard	O
container	O
format	O
that	O
would	O
support	O
metadata	O
and	O
obviate	O
the	O
need	O
for	O
tags	O
.	O
</s>
<s>
These	O
tags	O
are	O
normally	O
embedded	O
at	O
the	O
beginning	O
or	O
end	O
of	O
MP3	B-Application
files	I-Application
,	O
separate	O
from	O
the	O
actual	O
MP3	B-Application
frame	O
data	O
.	O
</s>
<s>
MP3	B-Application
decoders	B-General_Concept
either	O
extract	O
information	O
from	O
the	O
tags	O
,	O
or	O
just	O
treat	O
them	O
as	O
ignorable	O
,	O
non-MP3	O
junk	O
data	O
.	O
</s>
<s>
Playing	O
and	O
editing	O
software	O
often	O
contains	O
tag	O
editing	O
functionality	O
,	O
but	O
there	O
are	O
also	O
tag	B-Application
editor	I-Application
applications	O
dedicated	O
to	O
the	O
purpose	O
.	O
</s>
<s>
ReplayGain	O
is	O
a	O
standard	O
for	O
measuring	O
and	O
storing	O
the	O
loudness	O
of	O
an	O
MP3	B-Application
file	I-Application
(	O
audio	O
normalization	O
)	O
in	O
its	O
metadata	O
tag	O
,	O
enabling	O
a	O
ReplayGain-compliant	O
player	O
to	O
automatically	O
adjust	O
the	O
overall	O
playback	O
volume	O
for	O
each	O
file	O
.	O
</s>
<s>
MP3Gain	B-Language
may	O
be	O
used	O
to	O
reversibly	O
modify	O
files	O
based	O
on	O
ReplayGain	O
measurements	O
so	O
that	O
adjusted	O
playback	O
can	O
be	O
achieved	O
on	O
players	O
without	O
ReplayGain	O
capability	O
.	O
</s>
<s>
The	O
basic	O
MP3	B-Application
decoding	O
and	O
encoding	O
technology	O
is	O
patent-free	O
in	O
the	O
European	O
Union	O
,	O
all	O
patents	O
having	O
expired	O
there	O
by	O
2012	O
at	O
the	O
latest	O
.	O
</s>
<s>
MP3	B-Application
patents	O
expired	O
in	O
the	O
US	O
between	O
2007	O
and	O
2017	O
.	O
</s>
<s>
In	O
the	O
past	O
,	O
many	O
organizations	O
have	O
claimed	O
ownership	O
of	O
patents	O
related	O
to	O
MP3	B-Application
decoding	O
or	O
encoding	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
uncertainty	O
about	O
which	O
patents	O
must	O
have	O
been	O
licensed	O
in	O
order	O
to	O
create	O
MP3	B-Application
products	O
without	O
committing	O
patent	O
infringement	O
in	O
countries	O
that	O
allow	O
software	O
patents	O
was	O
a	O
common	O
feature	O
of	O
the	O
early	O
stages	O
of	O
adoption	O
of	O
the	O
technology	O
.	O
</s>
<s>
The	O
initial	O
near-complete	O
MPEG-1	B-Algorithm
standard	O
(	O
parts	O
1	O
,	O
2	O
and	O
3	O
)	O
was	O
publicly	O
available	O
on	O
6	O
December	O
1991	O
as	O
ISO	O
CD	O
11172	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
patents	O
required	O
to	O
implement	O
MP3	B-Application
expired	O
in	O
most	O
countries	O
by	O
December	O
2012	O
,	O
21	O
years	O
after	O
the	O
publication	O
of	O
ISO	O
CD	O
11172	O
.	O
</s>
<s>
The	O
various	O
MP3-related	O
patents	O
expired	O
on	O
dates	O
ranging	O
from	O
2007	O
to	O
2017	O
in	O
the	O
United	O
States	O
.	O
</s>
<s>
If	O
only	O
the	O
known	O
MP3	B-Application
patents	O
filed	O
by	O
December	O
1992	O
are	O
considered	O
,	O
then	O
MP3	B-Application
decoding	O
has	O
been	O
patent-free	O
in	O
the	O
US	O
since	O
22	O
September	O
2015	O
,	O
when	O
,	O
which	O
had	O
a	O
PCT	O
filing	O
in	O
October	O
1992	O
,	O
expired	O
.	O
</s>
<s>
If	O
the	O
longest-running	O
patent	O
mentioned	O
in	O
the	O
aforementioned	O
references	O
is	O
taken	O
as	O
a	O
measure	O
,	O
then	O
the	O
MP3	B-Application
technology	O
became	O
patent-free	O
in	O
the	O
United	O
States	O
on	O
16	O
April	O
2017	O
,	O
when	O
,	O
held	O
and	O
administered	O
by	O
Technicolor	O
,	O
expired	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
many	O
free	B-License
and	I-License
open-source	I-License
software	I-License
projects	O
,	O
such	O
as	O
the	O
Fedora	O
operating	O
system	O
,	O
have	O
decided	O
to	O
start	O
shipping	O
MP3	B-Application
support	O
by	O
default	O
,	O
and	O
users	O
will	O
no	O
longer	O
have	O
to	O
resort	O
to	O
installing	O
unofficial	O
packages	O
maintained	O
by	O
third	O
party	O
software	O
repositories	O
for	O
MP3	B-Application
playback	O
or	O
encoding	O
.	O
</s>
<s>
Technicolor	O
(	O
formerly	O
called	O
Thomson	O
Consumer	O
Electronics	O
)	O
claimed	O
to	O
control	O
MP3	B-Application
licensing	O
of	O
the	O
Layer	O
3	O
patents	O
in	O
many	O
countries	O
,	O
including	O
the	O
United	O
States	O
,	O
Japan	O
,	O
Canada	O
and	O
EU	O
countries	O
.	O
</s>
<s>
MP3	B-Application
license	O
revenues	O
from	O
Technicolor	O
's	O
administration	O
generated	O
about	O
€100	O
million	O
for	O
the	O
Fraunhofer	O
Society	O
in	O
2005	O
.	O
</s>
<s>
In	O
September	O
1998	O
,	O
the	O
Fraunhofer	O
Institute	O
sent	O
a	O
letter	O
to	O
several	O
developers	O
of	O
MP3	B-Application
software	O
stating	O
that	O
a	O
license	O
was	O
required	O
to	O
"	O
distribute	O
and/or	O
sell	O
decoders	B-General_Concept
and/or	O
encoders	O
"	O
.	O
</s>
<s>
This	O
led	O
to	O
the	O
situation	O
where	O
the	O
LAME	B-Algorithm
MP3	B-Application
encoder	I-Application
project	O
could	O
not	O
offer	O
its	O
users	O
official	O
binaries	O
that	O
could	O
run	O
on	O
their	O
computer	O
.	O
</s>
<s>
The	O
project	O
's	O
position	O
was	O
that	O
as	O
source	O
code	O
,	O
LAME	B-Algorithm
was	O
simply	O
a	O
description	O
of	O
how	O
an	O
MP3	B-Application
encoder	I-Application
could	O
be	O
implemented	O
.	O
</s>
<s>
They	O
,	O
along	O
with	O
its	O
United	O
States	O
subsidiary	O
Audio	O
MPEG	O
,	O
Inc	O
.	O
previously	O
sued	O
Thomson	O
for	O
patent	O
infringement	O
on	O
MP3	B-Application
technology	O
,	O
but	O
those	O
disputes	O
were	O
resolved	O
in	O
November	O
2005	O
with	O
Sisvel	O
granting	O
Thomson	O
a	O
license	O
to	O
their	O
patents	O
.	O
</s>
<s>
Motorola	O
followed	O
soon	O
after	O
,	O
and	O
signed	O
with	O
Sisvel	O
to	O
license	O
MP3-related	O
patents	O
in	O
December	O
2005	O
.	O
</s>
<s>
In	O
September	O
2006	O
,	O
German	O
officials	O
seized	O
MP3	B-Application
players	O
from	O
SanDisk	O
's	O
booth	O
at	O
the	O
IFA	O
show	O
in	O
Berlin	O
after	O
an	O
Italian	O
patents	O
firm	O
won	O
an	O
injunction	O
on	O
behalf	O
of	O
Sisvel	O
against	O
SanDisk	O
in	O
a	O
dispute	O
over	O
licensing	O
rights	O
.	O
</s>
<s>
In	O
February	O
2007	O
,	O
Texas	O
MP3	B-Application
Technologies	O
sued	O
Apple	O
,	O
Samsung	O
Electronics	O
and	O
Sandisk	O
in	O
eastern	O
Texas	O
federal	O
court	O
,	O
claiming	O
infringement	O
of	O
a	O
portable	O
MP3	B-Application
player	O
patent	O
that	O
Texas	O
MP3	B-Application
said	O
it	O
had	O
been	O
assigned	O
.	O
</s>
<s>
Alcatel-Lucent	O
has	O
asserted	O
several	O
MP3	B-Application
coding	O
and	O
compression	O
patents	O
,	O
allegedly	O
inherited	O
from	O
AT&	O
T-Bell	O
Labs	O
,	O
in	O
litigation	O
of	O
its	O
own	O
.	O
</s>
<s>
Other	O
lossy	B-Algorithm
formats	O
exist	O
.	O
</s>
<s>
Among	O
these	O
,	O
Advanced	B-Application
Audio	I-Application
Coding	I-Application
(	O
AAC	O
)	O
is	O
the	O
most	O
widely	O
used	O
,	O
and	O
was	O
designed	O
to	O
be	O
the	O
successor	O
to	O
MP3	B-Application
.	O
</s>
<s>
There	O
also	O
exist	O
other	O
lossy	B-Algorithm
formats	O
such	O
as	O
mp3PRO	B-Algorithm
and	O
MP2	O
.	O
</s>
<s>
They	O
are	O
members	O
of	O
the	O
same	O
technological	O
family	O
as	O
MP3	B-Application
and	O
depend	O
on	O
roughly	O
similar	O
psychoacoustic	O
models	O
and	O
MDCT	O
algorithms	O
.	O
</s>
<s>
Whereas	O
MP3	B-Application
uses	O
a	O
hybrid	O
coding	O
approach	O
that	O
is	O
part	O
MDCT	O
and	O
part	O
FFT	O
,	O
AAC	O
is	O
purely	O
MDCT	O
,	O
significantly	O
improving	O
compression	O
efficiency	O
.	O
</s>
<s>
When	O
the	O
digital	O
audio	O
player	O
market	O
was	O
taking	O
off	O
,	O
MP3	B-Application
was	O
widely	O
adopted	O
as	O
the	O
standard	O
hence	O
the	O
popular	O
name	O
"	O
MP3	B-Application
player	O
"	O
.	O
</s>
<s>
Sony	O
was	O
an	O
exception	O
and	O
used	O
their	O
own	O
ATRAC	O
codec	B-General_Concept
taken	O
from	O
their	O
MiniDisc	O
format	O
,	O
which	O
Sony	O
claimed	O
was	O
better	O
.	O
</s>
<s>
Following	O
criticism	O
and	O
lower	O
than	O
expected	O
Walkman	O
sales	O
,	O
in	O
2004	O
Sony	O
for	O
the	O
first	O
time	O
introduced	O
native	O
MP3	B-Application
support	O
to	O
its	O
Walkman	O
players	O
.	O
</s>
<s>
There	O
are	O
also	O
open	O
compression	O
formats	O
like	O
Opus	B-Algorithm
and	O
Vorbis	B-Algorithm
that	O
are	O
available	O
free	O
of	O
charge	O
and	O
without	O
any	O
known	O
patent	O
restrictions	O
.	O
</s>
<s>
Some	O
of	O
the	O
newer	O
audio	O
compression	O
formats	O
,	O
such	O
as	O
AAC	O
,	O
WMA	B-Application
Pro	O
and	O
Vorbis	B-Algorithm
,	O
are	O
free	O
of	O
some	O
limitations	O
inherent	O
to	O
the	O
MP3	B-Application
format	O
that	O
cannot	O
be	O
overcome	O
by	O
any	O
MP3	B-Application
encoder	I-Application
.	O
</s>
<s>
Besides	O
lossy	B-Algorithm
compression	I-Algorithm
methods	O
,	O
lossless	B-Algorithm
formats	I-Algorithm
are	O
a	O
significant	O
alternative	O
to	O
MP3	B-Application
because	O
they	O
provide	O
unaltered	O
audio	O
content	O
,	O
though	O
with	O
an	O
increased	O
file	O
size	O
compared	O
to	O
lossy	B-Algorithm
compression	I-Algorithm
.	O
</s>
<s>
Lossless	B-Algorithm
formats	I-Algorithm
include	O
FLAC	B-Application
(	O
Free	B-Application
Lossless	I-Application
Audio	I-Application
Codec	I-Application
)	O
,	O
Apple	B-Algorithm
Lossless	I-Algorithm
and	O
many	O
others	O
.	O
</s>
