Spectrogram Viewer

Overview

A spectrogram shows time from left to right, frequency from bottom to top and loudness as brightness. It's the quickest way to see what a file really contains. This one uses a log frequency axis, so bass, voice and treble are all easy to read. Look for the shelf: lossy encoders cut everything above a set point, leaving a straight edge around 16 to 20 kHz. A 'lossless' file with that edge was made from an MP3.

Check if a FLAC is realSpot the encoder shelf that gives away a copy made from a lossy file.
Track down noiseHum, whine and hiss have clear shapes in a spectrogram that a waveform hides.
See what a filter didCompare before and after and watch the band disappear.

Set

Audio Tools 17

Neighbours

01 Audio Transcriber 02 Generate AI Music 03 Audio Converter 04 BPM Detector 05 DJ Booth 06 Extract Audio from Video

Specification

Command: audio.spectrogram
Set: Audio
Input: MIXED
Output: —
Max file: 1GB
Batch: single file

MPEG WAV FLAC MP4 OGG OPUS AAC WEBM

Runtime

Engine: ffmpeg-wasm 0.12
Threads: — workers
Isolated: —
WebGPU: —
Memory: —

Transport 0 B

Your file is opened, worked on and saved inside this tab. This tool has no upload step, so your file has nowhere else to go.

Keys

Search: ⌘K
Panels: ⌘1 · ⌘2
Full width: F
All keys: ⌘/

How it works

Drop a file

It's decoded on your device at 48 kHz, so the whole audible range stays visible.

Watch it build

Columns appear as they're computed, not all at once.

Read the top edge

A straight cut-off near 16–20 kHz is an encoder shelf, not music.

Frequently asked

How do I tell whether a file came from a lossy source?

Look at the top of the picture. Real recordings fade out gradually. A lossy encoder cuts off everything above a set frequency and leaves a hard, straight line, usually near 16 kHz for a 128 kbps MP3 and near 20 kHz for a high-bitrate one. A FLAC with that line was made from a lossy file.

Why a log frequency axis?

A linear axis gives half its height to 10–20 kHz, where music has almost nothing, and squeezes the notes you care about into the bottom eighth. On a log axis every octave gets the same space.

What does the window size change?

A larger FFT window shows frequency in more detail but time less precisely: good for pitch and tuning, worse for seeing exactly when a drum hits. A smaller one does the opposite. 2048 is the usual middle ground.

Is my audio uploaded?

No. The file is decoded and analyzed in your browser and stays on your computer.

Keys

Search: ⌘K
Panels: ⌘1 · ⌘2
Full width: F
All keys: ⌘/