amesh(6D) amesh(6D)
amesh - audio spectrum analyzer
amesh
amesh computes an estimation of the spectrum of an audio input every
frame and displays a 3D graph of the last 25 frames in a window. The
frequencies range from 0 Hz on the left to half the input sampling rate
on the right.
The audio source should be selected using the audio control panel, and
the input gain should be adjusted to get a reasonable input level. amesh
does not copy the audio input to the output.
Holding down the middle mouse button acts as a track-ball interface to
change the viewing angle. Holding down the left mouse button and moving
the mouse zooms in and out on the graphics. The right mouse button pops
up a menu with the following items.
Draw Modes [Toc] [Back]
Each of three options on a sub-menu can independently toggled.
amesh will draw lines along the time axis, the frequency axis, the
amplitude axis, or any combination of the three. By default, lines
are drawn along the frequency axis.
Line Width [Toc] [Back]
This menu item varies the thickness of the line drawn. The default
is two pixel wide lines.
Color [Toc] [Back]
Toggles between monochrome and color displays. Color is the default.
Log Freq Scale [Toc] [Back]
Toggles between logarithmic and linear frequency scales. The default
is linear.
Tmesh [Toc] [Back]
Toggles between wire frame and shaded triangle mesh representations
of the power spectrum. The default is wire frame.
Wheel [Toc] [Back]
amesh can simulate a wheel rolling over a rough surface under the
influence of gravity. The frequency spectrum forms the rough
surface, which moves past the wheel. The wheel jumps off the
surface when it runs into a peak and then falls back due to gravity.
This menu option lets you turn the visibility of the wheel on or off
and lets you change your viewpoint to a "wheel's-eye" view or back
to normal.
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amesh(6D) amesh(6D)
FFT Size [Toc] [Back]
amesh estimates the power spectrum by performing a FFT on a fixed
number of consecutive samples from the input stream for each frame.
The number of samples is selected by the this menu item. The
default is 128 consecutive samples.
Quit Quits amesh.
The power spectrum is divided into 64 frequency bands evenly spaced
between 0 Hz and (Sampling Rate/2). If the input is sampled at 8Khz the
frequency bands go up to 4Khz. If the input sampling rate is 22Khz the
top frequency band is 11Khz etc. amesh estimates the power spectrum by
performing a FFT on the consecutive number of samples selected by the FFT
Size menu (default 128). Thus the main loop of amesh looks like:
while (TRUE) {
Read all available samples into the input buffer;
Perform FFT on the last 128 samples in the input buffer;
Compute power spectrum for 64 frequency bands
from the FFT output.
Plot the most recent 25 power spectra using GL.
}
/usr/demos/General_Demos/amesh/data wav sound files used by amesh
apanel(1)
PPPPaaaaggggeeee 2222 [ Back ]
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