Making Music On The Commodore 128; The Envelope Statement - Commodore 128D User Manual

Making Music on the Commodore 128
The ENVELOPE The volume of a sound changes throughout the
Statement duration of the note, from when you first hear it
until it is no longer audible. These volume quali
ties are referred to as Attack, Decay, Sustain
and Release (ADSR). Attack is the rate at which
a musical note reaches its peak volume. Decay
is the rate at which a musical note decreases
from its peak volume to its midranged (sustain)
level. Sustain is the level at which a musical
note is played at its midranged volume. Release
is the rate at which a musical note decreases
from its sustain level to zero volume. The ENVE
LOPE generator controls the ADSR parameters
of sound. See Figure 7-4 for a graphical repre
sentation of ADSR. The Commodore 128 can
change each ADSR parameter to 16 different
rates. This gives you absolute flexibility over the
ENVELOPE generator and the resulting proper
ties of the volume when the sound is originated.
SUSTAIN LEVEL
Figure 7-4. ADSR Phases
One of the most powerful Commodore 128 I )
sound statements—the one that controls the
ADSR and waveform—is the ENVELOPE state- - -
ment. The ENVELOPE statement sets the differ- i^j
ent controls in the synthesizer chip which
makes each sound unique. The ENVELOPE -
gives you the power to manipulate the SID syn- j i
thesizer. With ENVELOPE, you can select partic
ular ADSR settings and choose a waveform for ^ ~
your own music and sound effects. The format i )
for the ENVELOPE statement is as follows:
ENVELOPE e[,a[,d[,s[,r[,wf[,Pw]]]]]] [' ]
140 USING C128 MODE—Sound and Music in C128 Mode
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