MPEG-2 AAC (Advanced
is the latest MPEG standard.
on perceptual audio coding. It is the consequent extension of existing
standards towards optimum coding efficiency. AAC is not compatible
with MPEG Audio Layers-1,2,3 . Due to that reason, AAC was
called NBC (non backwards compatible).
There is one method of compression in the new MPEG standard that is
backwards compatible, is the MPEG-2 BC the problem of this is that
very, very similar than the MP3.
AAC ? Is it really better
than MP3 ?
MPEG-2 Advanced Audio Coding (AAC),
AAC is more efficient than MP3 (MPEG-1 Layer 3) and is the state of the
actual state of the art in audio coding.
It is able to
include up to 48 audio channels, 15 low frequency
channels, 15 embedded data streams and has
capability. It also offers a better compression ratio than
means that compared to Layer 3, you get the same quality at 70% of the
bitrate. MPEG formal listening tests have demonstrate it is able
better audioquality at 96 kb/s than layer-3 (MP3) at 128 kb/s.
art in audio compression technology.
There are three AAC profiles
The Main profile
includes all tools available and delivers the best audio quality of the
three profiles. The LC (low complexity) profile comes along with a limited
Temporal Noise Shaping tool and without prediction. This reduces audio
quality for some special audio signals but saves a lot of computational
power in both encoding and especially decoding. The SSR profile (Scaleable
Sampling Rate) is a low complexity profile with a different filterbank
and a special gain control tool.
You need a Any Pentium PC 90MHz or above to decode
MPEG-2 AAC in realtime.
MPEG-2 AAC is the Data Compression for
the 21st Century.
An aac decoder and an aac encoder for
win32, based on the ISO
source code are avaible, but sound quality is not yet optimized:
for AAC (Aacenc v0.2)
Scaleable Sampling Rate(SSR)