CLI · Audio Analysis

Spectro

A CLI tool that visualizes what's in your audio and tells you if it's been squashed by a codec. Shows compression artifacts, frequency loss, and can compare two files to see exactly where they differ.

Year 2025

Language Python

GitHub

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See Sound

A spectrogram shows what's really in your audio. The waveform just can't tell you that.

20kHz 10kHz 5kHz 1kHz 100Hz 20Hz

0:00 0:30 1:00 1:30 2:00

Lossy cutoff detected at 16kHz

default

Fast Mode

Quick and dirty. 1024-point FFT, 150 DPI, spits out a PDF. Good enough for when you just need a fast preview.

1024pt FFT

150DPI

PDFoutput

--quality

Quality Mode

The thorough version. 2048-point FFT, 300 DPI, outputs PNG. Way more detail if you're doing serious analysis or archival work.

2048pt FFT

300DPI

PNGoutput

--detect

Detect Mode

Detects frequency cutoffs, artifacts, and SBR flags. Tells you which codec messed with the file, so you don't have to stare at the spectrogram for an hour.

Closest profileMP3_128

Cutoff frequency16000 Hz

SBR detectedno

--compare

Compare Mode

Throws two files side by side and shows you exactly where they differ. Handy if you're trying to see what got lost in conversion.

2×inputs

diffspectrogram

sideby side

01 / 04

"
A frequency cutoff is a pretty good sign of lossy compression, but it's not absolute proof. And no cutoff doesn't mean it's lossless either. Spectro shows you what's there. You draw your own conclusions.
"

Design Philosophy

Built With

NumPy

SciPy

matplotlib

soundfile

FFmpeg

Python 3.9+