Download Constraint-Based Spatialization This paper describes an application of constraint programming to interfaces for audio mixing. MidiSpace is an interface representing each sound source of a musical piece as a graphical icon, as well as an object corresponding to the listener in a window. MidiSpace is coupled to a spatialization system so that moving graphical objects modifies the audio mixing of the musical piece according to the respective position of the sound sources to the avatar. We further introduce a constraint-based mechanism which allows to maintain consistency in the overall mixing. Constraints represent properties of related sound sources, which should always remain true, and may be stated by the user through the interface. When an object is moved, a constraint solver uses the constraints to propagate changes. We describe the library of currently designed constraints, and propose an extension of the system to handle reproduction systems with multiple loudspeakers.
Download On the use of zero-crossing rate for an apllication of classification of percussive sounds We address the issue of automatically extracting rhythm descriptors from audio signals, to be eventually used in content-based musical applications such as in the context of MPEG7. Our aim is to approach the comprehension of auditory scenes in raw polyphonic audio signals without preliminary source separation. As a first step towards the automatic extraction of rhythmic structures out of signals taken from the popular music repertoire, we propose an approach for automatically extracting time indexes of occurrences of different percussive timbres in an audio signal. Within this framework, we found that a particular issue lies in the classification of percussive sounds. In this paper, we report on the method currently used to deal with this problem.