New in version 1.3
- Prevent possible resource leaks by making sure requesters
are ended before closing a project window
Introduction
Harmonics is a simple sound synthesizer program. Waveforms
are created by adding sine waves of different frequencies and
amplitudes. You are limited to working with 12 different fre-
quencies: The base frequency (called the first harmonic), the
base frequency × 2 (the second harmonic), the base frequency
× 3 (the third harmonic), and so on, up to the base frequency
× 12 (the twelfth harmonic).
Full source code included.
How to use Harmonics
Harmonics are added to the waveform simply by adjusting the
twelve sliders that determine the amplitude of each harmonic.
Setting a slider to zero (far left) leaves that harmonic out
of the waveform altogether. The resulting waveform is scaled
to use the full amplitude range.
You can test the waveform by playing tones with the keyboard.
The top two rows will give about an octave and a half to play
with, and the next two rows will let you play the next deeper
octave plus a bit. There are five octaves in total, and you
can choose which octaves are available on the keyboard using
keys F1-F4. If you manage to get sounds "stuck" by doing
things like changing octave while playing tones, you can kill
all sound by hitting the space bar.
Harmonics projects contain simply the setting of the twelve
sliders and so are very small files. In order to use your
sounds in other programs, you must use the "Export IFF" faci-
lity of the program. This will save a 5-octave IFF 8SVX sound
file that most Amiga music software will be able to load.
As mentioned above, the program generates 5 octaves of wave-
form data. However, you should observe the following limita-
tions:
Harmonics 5-8 may be inaudible or distorted in the highest
octave, and harmonics 9-12 may be inaudible or distorted in
the two highest octaves. Harmonics 1-4 will sound fine in all
octaves.
Therefore, if you wish to make use of all 5 octaves, you may
want to limit yourself to harmonics 1-4, and likewise, if you
wish to use all but the highest octave, you may only want to
use harmonics 1-8. If you need only the lower 3 octaves, you
will have no problems with any of the harmonics.
About the code
Version 1.1 of this program is a complete rewrite. The design
goals remain the same, however. It was originally created as
the sort of software you would have wanted for your Amiga
500/2000, and I deliberately limited myself to features
available in Kickstart 1.2 as a design exercise. None of this
has changed with the new version.
One of the main goals of the rewrite was to have one and only
one event loop handling everything including requesters. This
was achieved using callbacks, which also facilitated separa-
tion of user interface and project logic. Modularizing the
code was another goal.
Although it is not actually utilized, the code has been de-
signed with a multi-project capability in mind, In order to
introduce multi-project handling, you would in principle only
need to make a few changes to the "tool" module, which han-
dles the project logic, although in practice you would want
to make some changes to the "ui" module as well to accomodate
this.
The "guitools" module contains routines that can lay out
menus to look just like Gadtools, as well as functions to
easily create and reuse a couple of different types of re-
questers.
This program allocates sound channels dynamically when they
are actually needed to play sounds. The audio device features
a way of letting multiple programs play sounds and music si-
multaneously by stealing channels from each other and freeing
them up as soon as possible, and this program demonstrates
that - you can start up multiple instances and play in all of
them at once. This is handled by the "audio" module, which is
an abstraction layer on top of the audio device.
There are more modules, e.g. the "piano" module that imple-
ments the polyphonic keyboard, the "waveform" module that
generates the 5 octaves of samples, and the "io" module which
handles saving and loading.
History
1.3 (Dec 14, 2018)
- Prevent possible resource leaks by making sure requesters
are ended before closing a project window
1.2 (Sep 6, 2018)
- Minor fixes and tweaks
1.1 (Aug 28, 2018)
- Polyphonic keyboard
- Completely rewritten
1.0 (Sep 6, 2004)
- Original release.
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