Motorola E398 series Podręcznik użytkownika - Strona 21
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Sound
Patch
Number
121
122
123
124
125
126
127
none
MIDI 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 Motorola E398 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 the first byte of 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 type 1. 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 (often the case). The running status feature can be applied on each individual
track, thereby reducing the track size. To reduce the size of the file even further, use one
Patch Names
Breath Noise
Seashore
Bird Tweet
Telephone Ring
Helicopter
Applause
Gunshot
Drums
Valid MIDI
Note Numbers
48-72
48-72
48-72
48-72
48-72
48-72
48-72
35-81
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