Performance Following: Real-Time Prediction of Musical Sequences Without a Score

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Searching Page-Images of Early Music Scanned with OMR: A Scalable Solution Using Minimal Absent Words

We define three retrieval tasks requiring efficient search of the musical content of a collection of ~32k page images of 16th-century music to find: duplicates; pages with the same musical content; pages of related music. The images are subjected to Optical Music Recognition (OMR), introducing inevitable errors. We encode pages as strings of diatonic pitch intervals, ignoring rests, to reduce the effect of such errors. We extract indices comprising lists of two kinds of ‘word’. Approximate matching is done by counting the number of common words between a query page and those in the collection. The two word-types are (a) normal ngrams and (b) minimal absent words (MAWs). The latter have three important properties for our purpose: they can be built and searched in linear time, the number of MAWs generated tends to be smaller, and they preserve the structure and order of the text, obviating the need for expensive sorting operations. We show that retrieval performance of MAWs is comparable with ngrams, but with a marked speed improvement. We also show the effect of word length on retrieval. Our results suggest that an index of MAWs of mixed length provides a good method for these tasks which is scalable to larger collections

Musicians and Machines: Bridging the Semantic Gap In Live Performance

PhDThis thesis explores the automatic extraction of musical information from live performances – with the intention of using that information to create novel, responsive and adaptive performance tools for musicians. We focus specifically on two forms of musical analysis – harmonic analysis and beat tracking. We present two harmonic analysis algorithms – specifically we present a novel chroma vector analysis technique which we later use as the input for a chord recognition algorithm. We also present a real-time beat tracker, based upon an extension of state of the art non-causal models, that is computationally efficient and capable of strong performance compared to other models. Furthermore, through a modular study of several beat tracking algorithms we attempt to establish methods to improve beat tracking and apply these lessons to our model. Building upon this work, we show that these analyses can be combined to create a beat-synchronous musical representation, with harmonic information segmented at the level of the beat. We present a number of ways of calculating these representations and discuss their relative merits. We proceed by introducing a technique, which we call Performance Following, for recognising repeated patterns in live musical performances. Through examining the real-time beat-synchronous musical representation, this technique makes predictions of future harmonic content in musical performances with no prior knowledge in the form of a score. Finally, we present a number of potential applications for live performances that incorporate the real-time musical analysis techniques outlined previously. The applications presented include audio effects informed by beat tracking, a technique for synchronising video to a live performance, the use of harmonic information to control visual displays and an automatic accompaniment system based upon our performance following technique.EPSR

Analyse de structures répétitives dans les séquences musicales

Cette thèse rend compte de travaux portant sur l inférence de structures répétitives à partir du signal audio à l aide d algorithmes du texte. Son objectif principal est de proposer et d évaluer des algorithmes d inférence à partir d une étude formelle des notions de similarité et de répétition musicale.Nous présentons d abord une méthode permettant d obtenir une représentation séquentielle à partir du signal audio. Nous introduisons des outils d alignement permettant d estimer la similarité entre de telles séquences musicales, et évaluons l application de ces outils pour l identi cation automatique de reprises. Nous adaptons alors une technique d indexation de séquences biologiques permettant une estimation e cace de la similarité musicale au sein de bases de données conséquentes.Nous introduisons ensuite plusieurs répétitions musicales caractéristiques et employons les outils d alignement pour identi er ces répétitions. Une première structure, la répétition d un segment choisi, est analysée et évaluée dans le cadre dela reconstruction de données manquantes. Une deuxième structure, la répétition majeure, est dé nie, analysée et évaluée par rapport à un ensemble d annotations d experts, puis en tant qu alternative d indexation pour l identi cation de reprises.Nous présentons en n la problématique d inférence de structures répétitives telle qu elle est traitée dans la littérature, et proposons notre propre formalisation du problème. Nous exposons alors notre modélisation et proposons un algorithme permettant d identi er une hiérarchie de répétitions. Nous montrons la pertinence de notre méthode à travers plusieurs exemples et en l évaluant par rapport à l état de l art.The work presented in this thesis deals with repetitive structure inference from audio signal using string matching techniques. It aims at proposing and evaluating inference algorithms from a formal study of notions of similarity and repetition in music.We rst present a method for representing audio signals by symbolic strings. We introduce alignment tools enabling similarity estimation between such musical strings, and evaluate the application of these tools for automatic cover song identi cation. We further adapt a bioinformatics indexing technique to allow e cient assessments of music similarity in large-scale datasets. We then introduce several speci c repetitive structures and use alignment tools to analyse these repetitions. A rst structure, namely the repetition of a chosen segment, is retrieved and evaluated in the context of automatic assignment of missingaudio data. A second structure, namely the major repetition, is de ned, retrieved and evaluated regarding expert annotations, and as an alternative indexing method for cover song identi cation.We nally present the problem of repetitive structure inference as addressed in literature, and propose our own problem statement. We further describe our model and propose an algorithm enabling the identi cation of a hierarchical music structure. We emphasize the relevance of our method through several examples and by comparing it to the state of the art.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

MusicBLAST - Gapped Sequence Alignment for MIR

We propose an algorithm, MusicBLAST, for approximate pattern search/matching on symbolic musical data. MusicBLAST is based on the BLAST algorithm, one of the most commonly used algorithms for similarity search on biological sequence data [1, 2]. MusicBLAST can be used in combination with an arbitrary similarity measure (e.g., melodic, rhythmic or combined) and retrieves multiple occurrences of a given search pattern and its variations. Different from many other pattern matching techniques, it can find incomplete and imperfect occurrences of a given pattern, and produces a significance measure for the accuracy and quality of its results. Like BLAST --- and different from many musical pattern matching approaches --- MusicBLAST retrieves heuristically optimised bi-directional alignments searching iteratively in forward and backward direction by starting at a dedicated seed note position of a performance