Full-recording spectrogram and numeric export
Analyze the complete recording and export a labelled PNG, full STFT amplitude matrix and explicit window/time/frequency settings.
- 1Add input
- 2Adjust settings
- 3Get your result
Tool input and files are processed in this browser without being uploaded.
Before you start
Select an actual source channel and compute the full periodic-Hann STFT. Download PNG with t[s],f[Hz] and dBFS colour scale, every little-endian float32 amplitude bin, actual window-centre times, peaks and settings. Display may max-pool within image budgets while covering every window; complete numeric data remains downloadable. No recording prefix is silently selected.
How to use this tool
- Choose local WAV/MP3.
- Set parameters and inspect actual results,statistics or frame mappings.
- Listen/inspect and download complete outputs.
Supported inputs and limits
One supported WAV/MP3 up to30 MiB and80 MiB actual decoded PCM;1–8 channels,8–192kHz; combined downloads100 MiB. WAV uses existing PCM8/16/24/32 and float32/64 support; MP3 must actually decode in the browser. No microphone, upload or remote audio fetch.
MP3 priming/gapless behavior varies by browser: the same checked MP3 produced2.000s in Chrome and2.040s in WebKit. All times/frames follow this browser’s actual decoded PCM; cross-browser sample/duration identity is not guaranteed. PCM16 output rounds decoded*32768 and clamps[-32768,32767] without normalization; float/24/32/MP3 original encoding bytes are not preserved.
FFT power-of-two256…4096,hop=FFT/4,no left padding and a zero-padded final window. One-sided amplitude=absFFT/HannSum, doubled except DC/Nyquist. Up to4,000,000 cells and100,000,000 FFT work units, checked before computation. PNG spans full input time, assigns columns by window centres with nearest-window fallback for empty columns, and covers0…Nyquist. Peak bins are amplitude maxima; exact ties choose the lowest bin and report count. This is not pitch or source certification.
Worked example
Example input
8kHz4s,440Hz followed by880Hz.
Example options
{"fftSize":2048,"channel":1,"floorDb":-80}Example output
Full60×1025 amplitude matrix with61,500 cells and PNG0–4s timeline, verified against independent FFT.
When something does not work
Correct parameters or export supported WAV,reduce decoded/work budgets and rerun. Retain the source to adjust thresholds,channels or filters.
Frequently asked questions
Does shrinking the image discard numeric data?
No. Only display is pooled. Complete float32 linear amplitudes remain in the binary download; JSON defines layout and actual times.
Documentation & further reading
Related tools
Audio to WAV
Convert supported MP3 or WAV audio to 16-bit PCM WAV, with optional rate and channel settings.
Trim audio
Select one part of a WAV or MP3 recording and download the excerpt as WAV.
Merge audio
Put recordings or sound clips in order and join them into one WAV file.
Adjust audio volume
Raise or lower the volume and save a new WAV file.