1TU München, Machine Intelligence & Signal Processing Group, MMK, Arcisstrasse 21, München 80333, Germany
2Université de Fribourg, Document Image and Voice Analysis, DIVA, Boulevard de Pérolles 90, Fribourg 1700, Switzerland
3Ecole Polytechnique Fédérale de Lausanne, Multimedia Signal Processing Group, Station 11, Lausanne 1015, Switzerland
4Ecole Polytechnique Fédérale de Lausanne, Signal Processing Laboratory (LTS5), Station 11, Lausanne 1015, Switzerland
5Imperial College London, Department of Computing, Machine Learning Group, 180 Queen’s Gate, London SW7 2AZ, UK
6University of Passau, Chair of Complex Systems Engineering, Innstrasse 33, Passau 94032, Germany