Spectrogram
Real-time scrolling time-frequency display with multiple analysis backends, GPU acceleration, and configurable color mapping
How It Works
The spectrogram displays a scrolling history of spectral data as a 2D heatmap. Each vertical column represents one moment in time, and each horizontal row represents a frequency. Color intensity maps to signal level in dB.
Circular buffer, scrolling display
20 Hz – 22 kHz
Purple (low) → Red (high), adjustable range
Filament renderer with CPU fallback
Hidden labels, hover-reveal controls
Analysis Backends
The spectrogram can use any of AudioMap's analysis engines. Each produces different time-frequency characteristics.
FFT
128 – 131,072Traditional STFT. Fixed resolution, uniform frequency bins. Good for general use.
MRA
Stage: 128 – 2,048Multi-Resolution Analysis. Fine LF resolution with fast HF response. Latency-compensated per display point.
CWT
Bins: 128 – 2,048Continuous Wavelet Transform. Smooth, artifact-free display. No octave boundary artifacts.
CQT
BPO: 12 – 48Constant-Q Transform. Natural log-frequency resolution. Configurable bins per octave.
Superlet
Order: 1 – 10Super-resolution transform. Highest simultaneous time-frequency detail. CPU intensive.
Reassignment
Threshold: -40 – -10 dBSTFT sharpening overlay. Available for FFT, MRA, CQT modes. Blend control 0–100%.
Display Configuration
Color Scale
Two-value slider adjusts the dB range mapped to color. Narrower range increases contrast for specific level regions.
HSV colormap: purple (minimum) through green and yellow to red (maximum)
Temporal Smoothing
Available for CWT, CQT, and Superlet modes. Reduces frame-to-frame noise in the spectrogram display.
FIFO or IIR modes with configurable depth
MRA Latency Compensation
When using MRA, per-display-point FIFO delay lines align lower octave stages with higher ones for a coherent display.
Automatic — no user configuration required