Audacity

Tool to edit audio. Can be used for steganography.

Installation

sudo apt install audacity

Substract two audio files (steganography)

• Open Audacity.
• Click File->Import->Audio and choose first audio file.
• Click File->Import->Audio and choose second audio file.
• Select the first file and click Effect->Invert. Invert flips the audio upside-down, reversing their polarity. The positive samples (above the horizontal zero line in the Audacity Waveform) are moved below the zero line (so becoming negative), and negative samples are made positive.
• Click File->Export->Export as WAV to obtain a wav file with the two files combined. This will substract the first file (that was inverted) from the second file.
• Open the new file with Audacity.
• Right-click on the file and select Spectogram.
• The flag is displayed.