SpectraGlyph

SpectraGlyph

Hide your logo in sound. Reveal it in the spectrogram.

A Windows desktop app that paints images and text into the upper spectrum of an audio file — usually inaudible in speakers, but crystal-clear when someone opens a spectrogram in Audacity, Spek, or Sonic Visualiser.

Highlights

• Dual modes: Invisible (>15 kHz) for a light touch on the mix, or Full range for bolder visuals.
• Image or text: drop PNG/JPG/WebP or type in the app.
• Masking: alpha, auto background, white/black removal, chroma key (any color), luminance, invert.
• Live spectrogram with a draggable time × frequency region; preview updates as you edit.
• Play what you see (original or watermarked) before you share.
• Export WAV, FLAC, or MP3 (with a clear warning when lossy codecs may affect the watermark).
• Recent files, presets, and a view guide you can copy so viewers match your FFT settings.
• English & Swedish UI (View → Language).
• Check for updates against GitHub Releases (in the built app).
• Long audio: for large or long files, choose full load or a time range to work faster.

Requirements

Windows 64-bit (primary target).

SmartScreen

The downloadable .exe is built with open tooling and is not signed with a commercial certificate. Windows may show SmartScreen the first time you run it — use More info → Run anyway if you trust this project.

How viewers reveal the watermark

1. Open the exported file in Audacity (or similar).
2. Switch to spectrogram view.
3. Typical settings: FFT 4096, Hann window, about 80 dB dynamic range.
4. Use the in-app View guide for a copy-paste cheat sheet.