Spek

Spek is free and open-source software available for GNU/Linux, BSD, Windows and macOS. It supports popular lossy and lossless audio file formats, uses multiple threads for faster analysis and ultra-fast signal processing, and lets you adjust the DFT window size and function for the best spectrogram quality; spectrograms can be saved as images, and files can be opened with drag and drop.

Spek is a lightweight application whose purpose is to help you build the spectrogram for an audio file in order to analyze the frequencies comprised in a sound. The layout is intuitive enough to be used without having to consult a help manual or watch online tutorials. Current versions of the program are written in C++ and use the FFmpeg libraries for audio decoding and wxWidgets for the interface.

Spek was designed with overall simplicity in mind, so it doesn't comprise many configuration settings; you can load audio files into the working environment using the built-in browse function or drag and drop operations. The spectrogram shows time on the horizontal axis and frequency on the vertical axis, with a color scale in dB; keyboard shortcuts switch the palette, the audio channel and stream, and the limits of the dynamic range.

To sum things up, Spek offers a simple yet efficient software solution when it comes to helping you generate spectrograms; it can be easily installed and used by all types of users regardless of their experience level. It is handy for checking whether a lossless file was actually converted from a lossy source, which shows up as a sharp cut-off of the high frequencies.

Spek offers ultra-fast, multi-threaded analysis for high-quality spectrograms of audio files across various formats.

Features:

• 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 saving the spectrogram as an image file
• Drag and drop support, associated with common audio file formats
• Translated into many interface languages