Sony Ericsson P990i - Manual (Page 31)

White Paper P990i
31 January 2006
Preliminary version - P1F
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MP3 MP3 is the file extension for MPEG audio layer 3. Layer 3 is one of three coding schemes
(layer 1, layer 2 and layer 3) for the compression of audio signals. Layer 3 uses a very effi-
cient compression method, removing all irrelevant parts of a sound signal that the human
ear cannot perceive. The result is, CD digital audio (CDDA) is converted to MP3 with
almost untouched quality, compressed by a factor of around 12. The high compression of
audio in MP3 files makes them relatively small, though MP3 files can be created with dif-
ferent size and quality compromises. The small file size, together with the excellent
sound quality, are the main reasons for the MP3-format’s massive popularity when shar-
ing music over the Internet.
RMF
Rich Music Format
TM
. A file format developed by Beatnik combining the compact size of
MIDI files with the high quality of sampled sound.
WAV A wave file is identified by a file name extension of WAV (.wav). Used primarily in PCs, the
wave file format has been accepted as a viable interchange medium for other computer
platforms, such as Macintosh. This allows content developers to freely move audio files
between platforms for processing.
In addition to the uncompressed raw audio data, the wave file format stores information
about the file's number of tracks (mono or stereo), sample rate, and bit depth.
XMF Xtended Music Format
XMF is a technology for collecting other music and sound resources, such as Standard
MIDI Files, DLS instrument files, WAV or other digital audio files. XMF does not describe
musical notes, notation, instrument sounds or audio recordings. Instead, it allows con-
tent creators a method to collect all those elements and put them in a single file. In the
end, this means easier handling and more consistent predictable playback.
DLS The DLS file format is used to store both the digital sound data and articulation parame-
ters needed to create one or more 'instruments.' An instrument contains 'regions' which
point to WAVE 'files' (samples) also embedded in the DLS file. Each region specifies a
MIDI note and velocity range which will trigger the corresponding sound and also con-
tains articulation information such as envelopes and loop points. Articulation information
can be specified for each individual region or for the entire instrument.”
Real Audio 9 RealAudio is a proprietary encoding format from RealNetworks. It also supports reposi-
tioning during real-time playback.
eACC+
(EACC+, ACC+
V2) eACC+ is ACC+ with the addition of Parametric Stereo (PS). PS significantly increases
the codec efficiency a second time for low bit rate stereo signals.
ACC+
(HE ACC,
ACC+) ‘High-efficiency ACC’ is the offical MPEG name for the combination of ACC and Spectral
Band Replication (SBR). SBR is a bandwidth extension technique which enables audio
codecs to deliver the same quality at half the bit rate.