During playback, you may vary the number of oscillators, up to 50; the success of this, of course, depends on how fast your machine can resynthesize the sound--on the SGI Indy the sound starts to break up at about 35 oscillators (hence the default value of 25).
BUGS: At present the playback is pretty rough (lots of clicking),
due to a windowing problem; the freeze frame sounds
pretty good. Future plans include a 'synth & save' option to
produce cleaner sounds.
Playback in general is still unstable, so be prepared
for crashes . . .
FILTERING
A pass band filter allows for a variety of filtering options.
Set the *lower* boundary frequency and the pass band width to
operate the filter. The filter can be moved in real time during
playback by using the slider to vary the lower frequency value, and by
entering new pass band widths.
THE GRAPHIC DISPLAY
The display shows frequency (x-axis) and amplitude (y-axis)
for each frame of the analyzed sound. Varying the number of
oscillators will increase or decrease the number of frequencies
displayed in order of greatest to least amplitude (again, only up to
the number of oscillators specified at the time of the analysis).
If the filter is employed, the active frequencies are highlighted (in a lovely shade of green), while the inactive frequencies are still displayed.
BUGS: Yes. Often little bits of lines remain on screen,
especially when freezing and conintuing, or when
changing playback directions. Also, I'm not sure that the
drawing of the frame really keeps up with the playback.
Freezing seems to kill the filter highlighting, too.
FINE TUNING
While a soundfile is in the freeze mode, you can grab individual
oscillators using the mouse, and change their amplitude and frequency
values. Any changes you make to that frame are 'permanent' for that
resynthesis (that is, there's no 'reset' button, though you can always
reload and reanalyze the soundfile). This is lots of fun, but takes
some practice to grab those tiny lines (it's all in the wrist).
BUGS: The graphic display of these changes hasn't been
integrated very well with the filtering graphics, so often
the latter are nixed.
VARIABLE PLAYBACK SPEED (in development)
At the moment I'm working on varying the playback speed
by repeating or skipping frames during playback. (My primary interest
is in slowing down the sound, so I'm not worrying too much about the
odd effects of skipping frames of sound at higher playback speeds.)
The interface for this feature is still in development, so it's not
yet available.
CREDITS
The prototype for this application was created by Brad Garton
in the fall of 1996, and I very grateful for all the time and energy he
spent in showing me the ropes during this project. Thanks as well to
all the Columbia Computer Music Center folks; especially to R. Luke
Dubois, Doug Geers, Terry Pender, and Matthew Suttor.
Emily Snyder Laugesen September 1997