White Paper K700
12 February 2004
sizes. A disadvantage is the lack of specific
sound control. MIDI is ideal for polyphonic ring-
tones.
•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 efficient com-
pression method, removing all irrelevant parts of
a sound signal that the human ear cannot per-
ceive. The result is, for example, CD digital
audio (CDDA) 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 different 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 sharing music over the Internet.
•WAV
Windows media audio video. A wave file is an
audio file format created by Microsoft, that has
become a standard PC audio file format for
everything from system and game sounds to
CD-quality audio. A wave file is identified by a
file name extension of WAV (.wav). Used prima-
rily 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, for
example.
In addition to the uncompressed raw audio
data, the wave file format stores information
about the file's number of tracks (mono or ste-
reo), sample rate, and bit depth.
Songs may be stored in the File manager. The
folder system enables the user to organize songs
into groups and create simple playlists of MP3
songs.
Songs may be collected in numerous ways,
including Internet download and file transfer from a
PC.
The media player is intelligently aware of other
applications in the phone:
• Playback is paused when a telephone call is
made or received.
• Playback is paused if the user starts another
application which requires the audio channels to
be dedicated to it.
• Playback of MP3 files continues if the user
switches to another application, providing
music whilst using other applications such as
the phonebook or calendar, or playing games.
Polyphonic ringtones
Background
The word “polyphony” means producing several
tones at the same time. Almost all music that we
listen to consists of polyphonic melodies.
Early Ericsson mobile phones supported a
proprietary non-polyphonic format called eMelody.
Due to the musical limitations of eMelody, and the
popularity of creating, sending and downloading
ring melodies, Ericsson and Sony Ericsson,
together with other manufacturers, created the
more advanced but non-polyphonic sound format –
iMelody.
The introduction of the MIDI format revolutionized
sound quality. MIDI files are small, and perfect for
mobile devices, which have limited storage
capacity.
MIDI is a specification for a communications
protocol principally used to control electronic
musical instruments. MIDI is today a well known
standard used by many musicians, composers and
arrangers.
A MIDI signal or file does not contain any music. It
contains binary data (information) of how a melody
is played and when this data reaches a synthesizer,
the synthesizer will translate the binary data to
music, when connected to an amplifier with
speakers so that the sound becomes audible.
Please visit www.midi.org for more information.
SP-MIDI
SP-MIDI stands for Scalable Polyphony MIDI. SP-
MIDI is based on the MIDI format and adapted for
mobile phones and other portable products. The
objective is to secure inter operability between
products with different sound capabilities.