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Pyzedv1.9.0

Spectrum analyzer

Six spectrum analyzers dancing to the same song: bars, blocks, line, filled, mirror and radial

class Visualizer(pz.App):
    def subscriptions(self):
        return [pz.frames(lambda dt: None)]   # redraw every frame


    def view(self):
        return ui.audio.Spectrum(magnitudes=engine.spectrum(512), variant="blocks", colors="fl")

From FFT bins to bands

Section titled “From FFT bins to bands”

magnitudes are decibels (−120 to 0), one per frequency bin — exactly what node.spectrum() and engine.spectrum() return. The analyzer groups them into bands bands spaced logarithmically (each band a little wider than the one before), the way the ear hears: an octave takes the same width at 100 Hz as at 5 kHz. Each band shows its loudest bin.

spacing says how your bins are spaced:

  • "log" (the default): already log-spaced from 20 Hz to half the sample rate, like the engine’s spectrum. They are only regrouped into bands.
  • "linear": evenly spaced from 0 Hz, like the output of a plain FFT (numpy.fft.rfft). The analyzer works out which bins belong to each band from sample_rate.

min_db and max_db are the bottom and top of the display.

Motion

Section titled “Motion”

Bars jump up at once and fall at falloff decibels per second (0 makes them follow the input exactly), so the display looks smooth even when the input flickers. With peaks=True a small cap stays on top of each bar and drops more slowly. The speed is measured in real time, so it is the same at 30 or 144 frames per second.

Looks and colors

Section titled “Looks and colors”
variant Looks like
"bars" Solid bars.
"blocks" LED segments, like a hi-fi.
"line" A glowing line through the band tops.
"filled" The same line with the area below filled.
"mirror" Bars centered vertically, for a symmetric look.
"radial" Bars around a circle, like a music visualizer.

colors is a palette ("fl", "neon", "fire", "ice", "magma", "viridis"…) or a list of colors. color_by="level" paints each bar from quiet (bottom) to loud (top); color_by="frequency" gives each band its own color from bass to treble. labels=True marks 100 Hz, 1 kHz and 10 kHz.

Property Default What it does
magnitudes () dB per frequency bin.
width, height 360, 140 Size in pixels.
variant "bars" See the table above.
bands 48 Number of bands.
spacing "log" How magnitudes are spaced: "log" (the engine) or "linear" (a plain FFT).
min_db, max_db -90, 0 Range shown.
colors, color_by "fl", "level" Palette and what it follows.
falloff, peaks 48, True Fall speed (dB/s) and peak caps.
sample_rate 48000 For the labels and the band edges.
labels, gap, background False, 2, "#0f1012"