FFT Window Lab

Offline simulator for the ESP-beatsy FFT256 and FFT1024 analyzers. It embeds the library's original Q15 window tables and follows the analyzer's input and output scaling.

Analysis settings

The 256 analyzer averages 8 frames by default.
Used for frequency-axis and timing calculations.
Selects the exact Q15 coefficients embedded from data_windows.c.
Logarithmic display starts at the first non-zero bin.
Bin spacing
—
sample rate / FFT length
Frame duration
—
one N-sample frame
Analyzer span
—
—
Coherent gain
—
mean of window coefficients
ENBW
—
equivalent noise bandwidth
Peak frequency
—
—
Simulation, not a live microphone or hardware capture. The library uses Q15 window coefficients, a 50% frame overlap and these analyzer-specific defaults: FFT256 averages power over 8 frames; FFT1024 calculates one frame. Floating-point FFT math here models the algorithm, but does not reproduce target-specific backend rounding bit for bit.

Window coefficients

—

FFT magnitude spectrum

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Input samples and windowed samples

The time plot shows the first FFT frame. The actual FFT256 output shown above averages eight overlapping frames, as the library does by default.

Matching library setup

This snippet selects the matching built-in window table for the chosen analyzer size. It does not configure a sample rate; the analyzer uses the sample rate of the running audio graph.