How to use
- Add an audio file.
- Adjust FFT size, frequency scale (linear/log) and dB range.
- Hover (or use the arrow keys) to read time, frequency and level; export PNG images of the current view.
Worked example
A 1 kHz test tone shows a single bright horizontal line at 1,000 Hz on the spectrogram.
Supported formats and limits
| Input | MP3, WAV, M4A, Ogg, FLAC, WebM |
|---|---|
| Output | PNG (waveform), PNG (spectrogram) |
| Limits | About 23 minutes of 48 kHz stereo audio (46 minutes mono); decoded into memory. |
| Engine | Radix-2 FFT (Hann, Hamming, Blackman or rectangular window) in a Web Worker; canvas rendering |
Limitations
- Larger FFT sizes give finer frequency detail but blur fast changes in time.
Questions
Which FFT size should I use?
Larger sizes separate close frequencies more finely but blur fast changes in time; smaller sizes show timing better. A 1 kHz test tone appears as one bright line at 1,000 Hz at any size.
How do I read a value?
Move the crosshair over the spectrogram, or use the arrow keys, and the readout lists the time, frequency and level at that point.
Privacy
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