Newsgroup: it.tlc.cellulari.motorola
Titolo: Creare suonerie polifoniche

Salve, posseggo una sterminata collezione di file midi,
posso creare dei file suonerie polifoniche in modo da poterle mandare sul
newsgroup o su un sito?
Grazie, Renzo.

Sarebbe bello sapere quali canali midi utilizzare, quali strumenti (ad
esempio la batteria la si assegna al canale 10?), quale lunghezza temporale
massima e quale dimensione file massima.

 wrote in message
news:DjAP9.60053$TC5.1...@twister1.libero.it...

Queste sono delle specifiche sul C330:
Ring Tone
The C330 product is fully MIDI 1.0 compliant, and therefore the device
supports any data
format described in The Complete MIDI 1.0 Detailed Specification.
Audio Formats
The C330 handset supports the following audio formats:
Scalable Polyphony MIDI (SP-MIDI) 1.0
iMelody
MIDI is the preferred audio format.
Audio Guidelines
The following are suggested guidelines to maximize sound quality while
reducing the overall file
size of a MIDI Ring Tone file for use with the C330 handset.
Tip 1: Use MIDI's running status feature
In the MIDI standard, a key-on or a key-off event will use at most three
bytes each. However,
when several key events occur on the same MIDI channel, the running status
feature can be
used. In principle, running status means that the first byte of, say, a
key-on event is omitted. In
addition, the key-on event having a velocity of zero is equivalent to the
key-off event. Thus,
combining running status with key-on events that have zero velocity reduces
the number of
bytes needed to encode all key events.
EXAMPLE:
Without using the running status, features, the sequence
91 2E 23 8E, 91 2B 50 8E, 81 2E 64 00, 81 2B 64 00
represents "Key 2E ON" Velocity 23 MIDI Ch 1", "Key 2B ON Velocity 50 MIDI
Ch 1", "Key 2E
OFF Velocity 64 MIDI Ch 1", "Key 2B OFF Velocity 64 MIDI Ch 1". Using the
running status
feature reduces the sequence to:
91 2E 23 8E, 2B 50 8E, 2E 00 00, 2B 00 00,
That is, the command byte is omitted and velocity zero is used for key off.
Tip 2: Use Standard MIDI File (SMF) type 1
The MIDI content can be stored in a Standard MIDI File (SMF) of type 0 or
type1. In a type 0
SMF, the file format uses one header chunk with one track chunk. In a type 1
SMF, the format
uses one header chunk with several track chunks. SMF type 2 should not be
used.
In general, it is more efficient to store the MIDI data as a type 1 file.
The increased efficiency is
achieved because each track contains only one MIDI channel and one
instrument (This is often
the case). The running status feature can be applied on each individual
track, thereby reducing
the track size. To further reduce the size of the file, use one track per
used MIDI channel. That
is, if a temple/conductor track exists, merge it with the first instrument
track. Remove all
unnecessary meta events such as the "track name" and "lyric" meta events.
To summarize, the following measures can be taken in order to reduce the
SMF:
1. Use SMF type 1 (Or verify that a type 1 file is smaller than a type 0
file and use the
smallest file).
2. Use running status.
3. One and only one instrument per track. Try not to change channels.
4. Do not change tempo in the middle of the music. That is, set the tempo
once.
5. Use beat, instead of SMPTE, to set the tempo.
6. Do not use Copyright Text Fields.
7. Limit the use of continuous controller information such as pitch-bend and
volume.
8. Turn off the options below:
? Sequence Number - MIDI sequence ids
? Text - embedded text for any optional fields
? Sequence / Track Name
? Instrument Name
? Lyric
? Marker - for synchronization purposes
? Cue Point
? Midi Channel Presix - associate channels with all events following
? Sequencer-Specific settings
Items one through three above optimize the encoding of the notes, while
items four to eight
optimize the overall melody. The above measures provide an SMF file that is
ready-made for
compression. However, prior to compression, the composer/content author can
add a few
values for key velocity, thereby increasing the redundancy of the file.
Tip 3: Consider the Frequency Response
While the handset's Wavetable Synthesizer is capable of producing all notes
called out by the
MIDI Specification, the 16-level polyphonic speaker limits its frequency
response. The speaker
cannot produce sounds above 4 kHz (approximately MIDI note C9) and rolls off
quickly below
800Hz (approximately MIDI Note G6). Therefore, the recommended note range
for a ring tone is
between G6 and C9, assuming that the lowest MIDI note is C0. Notes beneath
G6 can still be
produced at a lower amplitude level, however.
Ciao
--
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