An Entropy Based Method for Local Time-Adaptation of the Spectrogram

Marco Liuni (1) , Axel Röbel (1) , Romito Marco (2) , Xavier Rodet (1)

1 IRCAM - Institut de Recherche et Coordination Acoustique/Musique
2 Dipartimento di Matematica "Ulisse Dini"

We propose a method for automatic local time-adaptation of the spectrogram of audio signals: it is based on the decomposition of a signal within a Gabor multi-frame through the STFT operator. The sparsity of the analysis in every individual frame of the multi-frame is evaluated through the Rényi entropy measures: the best local resolution is determined minimizing the entropy values. The overall spectrogram of the signal we obtain thus provides local optimal resolution adaptively evolving over time. We give examples of the performance of our algorithm with an instrumental sound and a synthetic one, showing the improvement in spectrogram displaying obtained with an automatic adaptation of the resolution. The analysis operator is invertible, thus leading to a perfect reconstruction of the original signal through the analysis coefficients.

Mots clés: adaptive spectrogram; sound representation; sound analysis; sound synthesis; frame theory; Rényi entropy; sparsity measures; frame theory.

Domaines: Traitement du signal et de l'image [eess.SP]; Traitement du signal et de l'image [eess.SP]

Marco Liuni, Axel Röbel, Romito Marco, Xavier Rodet. An Entropy Based Method for Local Time-Adaptation of the Spectrogram. Ystad, S.; Aramaki, M.; Kronland-Martinet, R.; Jensen, K. Exploring Music Contents, Springer Verlag, pp.60-75, 2011, Lecture Notes in Computer Science, Vol. 6684. ⟨hal-00626821⟩