60 research outputs found
Detecting Episodes with Harmonic Sequences for Fugue Analysis
International audienceFugues alternate between instances of the subject and of other patterns, such as the counter-subject, and modulatory sections called episodes. The episodes play an important role in the overall design of a fugue: detecting them may help the analysis of the fugue, in complement to a subject and a counter-subject detection. We propose an algorithm to retrieve episodes in the fugues of the first book of Bach's Well-Tempered Clavier, starting from a symbolic score which is already track-separated. The algorithm does not use any information on subject or counter-subject occurrences, but tries to detect partial harmonic sequences, that is similar pitch contour in at least two voices. For this, it uses a substitution function considering "quantized partially overlapping intervals" [Lemström and Laine, 98] and a strict length matching for all notes, except for the first and the last one. On half of the tested fugues, the algorithm has correct or good results, enabling to sketch the design of the fugue
Rhythm extraction from polyphonic symbolic music
International audienceWe focus on the rhythmic component of symbolic music similarity, proposing several ways to extract a monophonic rhythmic signature from a symbolic poly- phonic score. To go beyond the simple extraction of all time intervals between onsets (noteson extraction), we select notes according to their length (short and long extractions) or their intensities (intensity+/â extractions). Once the rhythm is extracted, we use dynamic programming to compare several sequences. We report results of analysis on the size of rhythm patterns that are specific to a unique piece, as well as experiments on similarity queries (ragtime music and Bach chorale variations). These results show that long and intensity+ extractions are often good choices for rhythm extraction. Our conclusions are that, even from polyphonic symbolic music, rhythm alone can be enough to identify a piece or to perform pertinent music similarity queries, especially when using wise rhythm extractions
Efficient pattern matching in degenerate strings with the BurrowsâWheeler transform
International audienceA degenerate or indeterminate string on an alphabet ÎŁ is a sequence of non-empty subsets of ÎŁ. Given a degenerate string t of length n, we present a new method based on the Burrows--Wheeler transform for searching for a degenerate pattern of length m in t running in O(mn) time on a constant size alphabet ÎŁ. Furthermore, it is a hybrid pattern-matching technique that works on both regular and degenerate strings. A degenerate string is said to be conservative if its number of non-solid letters is upper-bounded by a fixed positive constant q; in this case we show that the search complexity time is O(qm2). Experimental results show that our method performs well in practice
As We Are Blind
Ćuvres et Recherches 2019:01« As We Are Blind » (2016) est une installation pour « piano mĂ©canique et aura » de VĂ©ronique BĂ©land. Au centre dâune piĂšce Ă la scĂ©nographie Ă©purĂ©e, un piano Ă queue joue la partition la plus intime : celle du spectateur. Conductance, tempĂ©rature de la peau, poids de la main, rythme cardiaque... Chaque participant pose la main sur un capteur, et « As We Are Blind » calcule et interprĂšte une production musicale et photographique unique, qui rĂ©vĂšle lâ« aura » colorĂ©e de chaque spectateur
Détection de répétitions en tandem avec évolution (application aux séquences biologiques)
Une rĂ©pĂ©tition en tandem avec Ă©volution consiste en une suite de copies plus ou moins contiguĂ«s oĂč chaque copie est fortement similaire Ă celle qui la prĂ©cĂšde et Ă celle qui lui succĂšde. Il n'existe pas de notion de modĂšle comme pour les rĂ©pĂ©titions en tandem "classiques" et la premiĂšre et la derniĂšre copie peuvent ĂȘtre complĂštement diffĂ©rentes. Ce "nouveau" type de rĂ©pĂ©tition a Ă©tĂ© mis en Ă©vidence durant l'assemblage du gĂ©nome humain. Dans ce manuscrit, je commence par dĂ©finir, de façon formelle, les rĂ©pĂ©titions en tandem avec Ă©volution Ă partir des observations effectuĂ©es dans les sĂ©quences biologiques. AprĂšs avoir effectuĂ© des tests sur des logiciels de recherche de rĂ©pĂ©titions, je conclus qu'il n'existe pas de logiciel capable de les dĂ©tecter efficacement. J'ai alors conçu des algorithmes capables de dĂ©tecter ce type de rĂ©pĂ©titions : un premier algorithme, quadratique en la longueur de la sĂ©quence, puis un algorithme linĂ©aire. Ces algorithmes ont Ă©tĂ© implantĂ©s afin de mettre Ă disposition des biologistes des outils qui dĂ©tectent efficacement ces rĂ©pĂ©titions dans de trĂšs grandes sĂ©quences gĂ©nomiques, telles les chromosomes humains. Plusieurs mĂ©thodes de parallĂ©lisation sont Ă©galement prĂ©sentĂ©es. Les rĂ©sultats des tests rĂ©alisĂ©s sur des chromosomes montrent la prĂ©sence de ces rĂ©pĂ©titions dans plusieurs gĂ©nomes.An evolutive tandem repeat consists in a series of almost contiguous copies, such that each copy is strongly similar to its predecessor and its successor.There is no model and the first and the last copy can be completely different. It differs from a classical'' tandem repeat that considers a model and a radius around this model. This new'' type of repeat has been pointed out during the assembly of the human genome. In this manuscript, I first define, in a formal way, the evolutive tandem repeats from observations achieved in biological sequences. After having carried out tests using well known existing softwares, I conclude that no one was able to detect it correctly and that they are not part of the sequences that have been submitted to databanks. I therefore designed algorithms that are able to locate this specific type of repeats: a first algorithm, quadratric in the length of the sequence, then a linear one. These algorithms have been implemented in order to provide biologists with tools that detect efficiently these repeats in real large sequences, such as human chromosomes. Several parallelisation methods are presented too. The results of the carried out tests on chromosomes show the existence of such repeats in genomes.ROUEN-BU Sciences Madrillet (765752101) / SudocROUEN-BU Sciences (764512102) / SudocSudocFranceF
Computational Analysis of Musical Form
International audienceCan a computer understand musical forms? Musical forms describe how a piece of music is structured. They explain how the sections work together through repetition, contrast, and variation: repetition brings unity, and variation brings interest. Learning how to hear, to analyse, to play, or even to write music in various forms is part of music education. In this chapter, we briefly review some theories of musical form, and discuss the challenges of computational analysis of musical form. We discuss two sets of problems, segmentation and form analysis. We present studies in music information retrieval (MIR) related to both problems. Thinking about codification and automatic analysis of musical forms will help the development of better MIR algorithms
Une application web interactive pour l'analyse musicale
International audienceLe patrimoine musical peut se valoriser et sâeÌtudier graÌce aÌ des outils numeÌriques, que ce soit aÌ destination des speÌcialistes (musicologie systeÌmatique ou algorithmique), mais aussi pour les apprenants et le grand public. L'analyse musicale, aujourd'hui pratique musicale autonome, a une longue histoire d'interaction avec la peÌdagogie, notamment en matieÌre de composition, et peut aujourd'hui se pratiquer dans une deÌmarche d'humaniteÌs numeÌriques.Nous preÌsentons une application web permettant d'annoter des partitions et de comparer des analyses. Fruit dâune collaboration entre informaticiens de lâeÌquipe Algomus (Lille, Amiens) et musicologues, lâapplication repreÌsente graphiquement des eÌleÌments entrant en jeu dans l'analyse de partitions tonales, tels que les motifs, la structure, les fonctions harmoniques et les cadences. Nous proposons en exemple des eÌleÌments d'analyse de fugues du premier livre du Clavier bien tempeÌreÌ de J.-S. Bach ainsi que de quelques quatuors aÌ cordes. L'application web est disponible en licence libre pour faciliter sa diffusion, sa reÌutilisation et sa reÌappropriation par dâautres, chercheurs, peÌdagogues, musiciens ou meÌlomanes. Nous espeÌrons quâelle facilitera une pratique deÌmocratiseÌe et collaborative de l'analyse musicale
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