Midi Audio Guidelines - Motorola W760R Media Manual

123 Bird Tweet
124 Telephone Ring
125 Helicopter
126 Applause
127 Gunshot
none Drums

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 W760r/VA76r handset.
Tip 1: Use MIDI's running status feature
In the MIDI standard, a key-on or a key-off event uses, 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 feature, the following 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, as is 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 track for each MIDI channel. That is, if a temple/conductor track
exists, merge it with the first instrument track and remove all unnecessary meta-events such as the "track
name" and "lyric" meta-events.
W760r/VA76r Media Guide
Sound
48-72
48-72
48-72
48-72
48-72
35-81
Page 31