Spek is an acoustic spectrum analyser written in C and C++. It uses FFmpeg libraries for audio decoding and wxWidgets for the GUI.

• Supports all popular lossy and lossless audio file formats thanks to the FFmpeg libraries.
• Ultra-fast signal processing, uses multiple threads to further speed up the analysis.
• Shows the codec name and the audio signal parameters.
• Allows to save the spectrogram as an image file.
• Drag-and-drop support; associates with common audio file formats.
• Auto-fitting time, frequency and spectral density rulers.
• Adjustable spectral density range.
• Translated into 19 languages.