International audience

Computations in most music retrieval systems strongly depend on the size of data compared. We propose to enhance performances of a music retrieval system, namely a harmonic similarity evaluation method, by first indexing relevant parts of music pieces. The indexing algorithm represents each audio piece exclusively by its major repetition, using harmonic descriptions and string matching techniques. Evaluations are performed in the context of a state-of-the-art retrieval method, namely cover songs identification, and results highlight the success of our indexing system in keeping similar results while yielding a substantial gain in computation time.

Query-by-tapping systems are content-based music retrieval systems that allow users to tap or clap in a microphone the rhythmic pattern of the melody requested. In this paper, a new query-by-tapping system is described. This system is based on adaptations of alignment algorithms successfully applied for melodic similarity estimation. A similarity score is computed according to the cost of the elementary operations necessary to transform the query into the musical piece tested. A new method for extracting the rhythmic pattern from audio signals is also presented. This method is based on the analysis of the variations of the kurtosis computed from the audio samples. Experiments performed on the MIREX 2008 database show that the alignment technique proposed performs better than the participating algorithms. They also confirm the interest of the kurtosis-based analysis method in the case of noisy percussive queries.

Retrieval systems for polyphonic music rely on the automatic estimation of similarity between two musical pieces. In the case of symbolic music, existing systems either consider a monophonic reduction based on melody or propose algorithms with high complexity. In this paper, we propose a new approach. Musical pieces are represented as a sequence of chords which are estimated from groups of notes sounding at the same time. A root and a mode are associated to each chord. Local alignment is then applied for estimating a similarity score between these sequences. Experiments performed on MIDI files collected on the Internet show that the system proposed allows the retrieval of different versions of the same song.

Existing symbolic music comparison systems generally consider monophonic music or monophonic reduction of polyphonic music. Adaptation of alignment algorithms to music leads to accurate systems, but their extensions to polyphonic music raise new problems. Indeed, a chord may match several consecutive notes, or the difference between two similar motifs may be a few swapped notes. Moreover, the substitution scores between chords are difficult to set up. In this paper, we propose a general framework for polyphonic music using the substitution score scheme set for monophonic music, which allows new operations by extending the operations proposed by Mongeau and Sankoff [15]. From a practical point of view, the limitation of chord sizes and the number of notes that can be merged consecutively lead to a complexity that remains quadratic.