The Analysis & Resynthesis Sound Spectrograph For Mac

The Analysis & Resynthesis Sound Spectrograph (formerly known as the Analysis & Reconstruction Sound Engine), or ARSS, is a program that analyses a sound file into a spectrogram and is able to synthesise this spectrogram, or any other user-created image, back into a sound.

The ARSS consists in two main parts, a spectrograph with a base-2 logarithmic frequency scale, and a spectrogram synthesiser.

Unlike most spectrographs which are based on STFTs (which perform the analysis by cutting the signal into small time slices to analyse these slices in the frequency domain), the ARSS is based on a filter bank followed by envelope detection, which means that the signal is cut into small frequency-domain slices, and then analysed in the time domain, in a manner quite similar to how analog spectrographs do.

The spectrogram synthesiser is based on modulation using horizontal lines of the image as envelopes. Each horizontal line is upsampled to the sampling rate of the desired final signal's sampling rate, and is then modulated with, depending on the synthesis mode chosen by the user, sines matching to the central frequency each horizontal line represent