42 research outputs found
Pitch-Informed Solo and Accompaniment Separation
ï»żDas Thema dieser Dissertation ist die Entwicklung eines Systems zur
Tonhöhen-informierten Quellentrennung von Musiksignalen in Soloinstrument
und Begleitung. Dieses ist geeignet, die dominanten Instrumente aus einem
MusikstĂŒck zu isolieren, unabhĂ€ngig von der Art des Instruments, der
Begleitung und Stilrichtung. Dabei werden nur einstimmige
Melodieinstrumente in Betracht gezogen. Die Musikaufnahmen liegen monaural
vor, es kann also keine zusÀtzliche Information aus der Verteilung der
Instrumente im Stereo-Panorama gewonnen werden.
Die entwickelte Methode nutzt Tonhöhen-Information als Basis fĂŒr eine
sinusoidale Modellierung der spektralen Eigenschaften des Soloinstruments
aus dem Musikmischsignal. Anstatt die spektralen Informationen pro Frame zu
bestimmen, werden in der vorgeschlagenen Methode Tonobjekte fĂŒr die
Separation genutzt. Tonobjekt-basierte Verarbeitung ermöglicht es,
zusÀtzlich die NotenanfÀnge zu verfeinern, transiente Artefakte zu
reduzieren, gemeinsame Amplitudenmodulation (Common Amplitude Modulation
CAM) einzubeziehen und besser nichtharmonische Elemente der Töne
abzuschÀtzen. Der vorgestellte Algorithmus zur Quellentrennung von
Soloinstrument und Begleitung ermöglicht eine Echtzeitverarbeitung und ist
somit relevant fĂŒr den praktischen Einsatz.
Ein Experiment zur besseren Modellierung der ZusammenhÀnge zwischen
Magnitude, Phase und Feinfrequenz von isolierten Instrumententönen wurde
durchgefĂŒhrt. Als Ergebnis konnte die KontinuitĂ€t der zeitlichen
EinhĂŒllenden, die InharmonizitĂ€t bestimmter Musikinstrumente und die
Auswertung des Phasenfortschritts fĂŒr die vorgestellte Methode ausgenutzt
werden. ZusĂ€tzlich wurde ein Algorithmus fĂŒr die Quellentrennung in
perkussive und harmonische Signalanteile auf Basis des Phasenfortschritts
entwickelt. Dieser erreicht ein verbesserte perzeptuelle QualitÀt der
harmonischen und perkussiven Signale gegenĂŒber vergleichbaren Methoden nach
dem Stand der Technik.
Die vorgestellte Methode zur Klangquellentrennung in Soloinstrument und
Begleitung wurde zu den Evaluationskampagnen SiSEC 2011 und SiSEC 2013
eingereicht. Dort konnten vergleichbare Ergebnisse im Hinblick auf
perzeptuelle BewertungsmaĂe erzielt werden. Die QualitĂ€t eines
Referenzalgorithmus im Hinblick auf den in dieser Dissertation
beschriebenen Instrumentaldatensatz ĂŒbertroffen werden.
Als ein Anwendungsszenario fĂŒr die Klangquellentrennung in Solo und
Begleitung wurde ein Hörtest durchgefĂŒhrt, der die QualitĂ€tsanforderungen
an Quellentrennung im Kontext von Musiklernsoftware bewerten sollte. Die
Ergebnisse dieses Hörtests zeigen, dass die Solo- und Begleitspur gemĂ€Ă
unterschiedlicher QualitÀtskriterien getrennt werden sollten. Die
Musiklernsoftware Songs2See integriert die vorgestellte
Klangquellentrennung bereits in einer kommerziell erhÀltlichen Anwendung.This thesis addresses the development of a system for pitch-informed solo
and accompaniment separation capable of separating main instruments from
music accompaniment regardless of the musical genre of the track, or type
of music accompaniment. For the solo instrument, only pitched monophonic
instruments were considered in a single-channel scenario where no panning
or spatial location information is available.
In the proposed method, pitch information is used as an initial stage of a
sinusoidal modeling approach that attempts to estimate the spectral
information of the solo instrument from a given audio mixture. Instead of
estimating the solo instrument on a frame by frame basis, the proposed
method gathers information of tone objects to perform separation.
Tone-based processing allowed the inclusion of novel processing stages for
attack refinement, transient interference reduction, common amplitude
modulation (CAM) of tone objects, and for better estimation of non-harmonic
elements that can occur in musical instrument tones. The proposed solo and
accompaniment algorithm is an efficient method suitable for real-world
applications.
A study was conducted to better model magnitude, frequency, and phase of
isolated musical instrument tones. As a result of this study, temporal
envelope smoothness, inharmonicty of musical instruments, and phase
expectation were exploited in the proposed separation method. Additionally,
an algorithm for harmonic/percussive separation based on phase expectation
was proposed. The algorithm shows improved perceptual quality with respect
to state-of-the-art methods for harmonic/percussive separation.
The proposed solo and accompaniment method obtained perceptual quality
scores comparable to other state-of-the-art algorithms under the SiSEC 2011
and SiSEC 2013 campaigns, and outperformed the comparison algorithm on the
instrumental dataset described in this thesis.As a use-case of solo and
accompaniment separation, a listening test procedure was conducted to
assess separation quality requirements in the context of music education.
Results from the listening test showed that solo and accompaniment tracks
should be optimized differently to suit quality requirements of music
education. The Songs2See application was presented as commercial music
learning software which includes the proposed solo and accompaniment
separation method
Automatic transcription of polyphonic music exploiting temporal evolution
PhDAutomatic music transcription is the process of converting an audio recording
into a symbolic representation using musical notation. It has numerous applications
in music information retrieval, computational musicology, and the
creation of interactive systems. Even for expert musicians, transcribing polyphonic
pieces of music is not a trivial task, and while the problem of automatic
pitch estimation for monophonic signals is considered to be solved, the creation
of an automated system able to transcribe polyphonic music without setting
restrictions on the degree of polyphony and the instrument type still remains
open.
In this thesis, research on automatic transcription is performed by explicitly
incorporating information on the temporal evolution of sounds. First efforts address
the problem by focusing on signal processing techniques and by proposing
audio features utilising temporal characteristics. Techniques for note onset and
offset detection are also utilised for improving transcription performance. Subsequent
approaches propose transcription models based on shift-invariant probabilistic
latent component analysis (SI-PLCA), modeling the temporal evolution
of notes in a multiple-instrument case and supporting frequency modulations in
produced notes. Datasets and annotations for transcription research have also
been created during this work. Proposed systems have been privately as well as
publicly evaluated within the Music Information Retrieval Evaluation eXchange
(MIREX) framework. Proposed systems have been shown to outperform several
state-of-the-art transcription approaches.
Developed techniques have also been employed for other tasks related to music
technology, such as for key modulation detection, temperament estimation,
and automatic piano tutoring. Finally, proposed music transcription models
have also been utilized in a wider context, namely for modeling acoustic scenes
Exploiting Piano Acoustics in Automatic Transcription
This work was supported by a joint Queen Mary/China Scholarship Council Scholarship.This work was supported by a joint Queen Mary/China Scholarship Council Scholarship.This work was supported by a joint Queen Mary/China Scholarship Council Scholarship.This work was supported by a joint Queen Mary/China Scholarship Council Scholarship.In this thesis we exploit piano acoustics to automatically transcribe piano recordings into a symbolic representation: the pitch and timing of each detected note. To do so we use approaches based on non-negative matrix factorisation (NMF). To motivate the main contributions of this thesis, we provide two preparatory studies: a study of using a deterministic annealing EM algorithm in a matrix factorisation-based system, and a study of decay patterns of partials in real-word piano tones. Based on these studies, we propose two generative NMF-based models which explicitly model different piano acoustical features. The first is an attack/decay model, that takes into account the time-varying timbre and decaying energy of piano sounds. The system divides a piano note into percussive attack and harmonic decay stages, and separately models the two parts using two sets of templates and amplitude envelopes. The two parts are coupled by the note activations. We simplify the decay envelope by an exponentially decaying function. The proposed method improves the performance of supervised piano transcription. The second model aims at using the spectral width of partials as an independent indicator of the duration of piano notes. Each partial is represented by a Gaussian function, with the spectral width indicated by the standard deviation. The spectral width is large in the attack part, but gradually decreases to a stable value and remains constant in the decay part. The model provides a new aspect to understand the time-varying timbre of piano notes, but furtherinvestigation is needed to use it effectively to improve piano transcription. We demonstrate the utility of the proposed systems in piano music transcription and analysis. Results show that explicitly modelling piano acoustical features, especially temporal features, can improve the transcription performance.Queen Mary/China Scholarship Council Scholarship
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Bayesian methods in music modelling
This thesis presents several hierarchical generative Bayesian models of musical signals designed to improve the accuracy of existing multiple pitch detection systems and other musical signal processing applications whilst remaining feasible for real-time computation. At the lowest level the signal is modelled as a set of overlapping sinusoidal basis functions. The parameters of these basis functions are built into a prior framework based on principles known from musical theory and the physics of musical instruments. The model of a musical note optionally includes phenomena such as frequency and amplitude modulations, damping, volume, timbre and inharmonicity. The occurrence of note onsets in a performance of a piece of music is controlled by an underlying tempo process and the alignment of the timings to the underlying score of the music.
A variety of applications are presented for these models under differing inference constraints. Where full Bayesian inference is possible, reversible-jump Markov Chain Monte Carlo is employed to estimate the number of notes and partial frequency components in each frame of music. We also use approximate techniques such as model selection criteria and variational Bayes methods for inference in situations where computation time is limited or the amount of data to be processed is large. For the higher level score parameters, greedy search and conditional modes algorithms are found to be sufficiently accurate.
We emphasize the links between the models and inference algorithms developed in this thesis with that in existing and parallel work, and demonstrate the effects of making modifications to these models both theoretically and by means of experimental results
Extended Nonnegative Tensor Factorisation Models for Musical Sound Source Separation
Recently, shift-invariant tensor factorisation algorithms have been proposed for the purposes of sound source separation of
pitched musical instruments. However, in practice, existing algorithms require the use of log-frequency spectrograms to allow
shift invariance in frequency which causes problems when attempting to resynthesise the separated sources. Further, it is difficult
to impose harmonicity constraints on the recovered basis functions. This paper proposes a new additive synthesis-based
approach which allows the use of linear-frequency spectrograms as well as imposing strict harmonic constraints, resulting in
an improved model. Further, these additional constraints allow the addition of a source filter model to the factorisation framework,
and an extended model which is capable of separating mixtures of pitched and percussive instruments simultaneously
Optimal spectral transportation with application to music transcription
International audienceMany spectral unmixing methods rely on the non-negative decomposition of spectral data onto a dictionary of spectral templates. In particular, state-of-the-art music transcription systems decompose the spectrogram of the input signal onto a dictionary of representative note spectra. The typical measures of fit used to quantify the adequacy of the decomposition compare the data and template entries frequency-wise. As such, small displacements of energy from a frequency bin to another as well as variations of timbre can disproportionally harm the fit. We address these issues by means of optimal transportation and propose a new measure of fit that treats the frequency distributions of energy holistically as opposed to frequency-wise. Building on the harmonic nature of sound, the new measure is invariant to shifts of energy to harmonically-related frequencies, as well as to small and local displacements of energy. Equipped with this new measure of fit, the dictionary of note templates can be considerably simplified to a set of Dirac vectors located at the target fundamental frequencies (musical pitch values). This in turns gives ground to a very fast and simple decomposition algorithm that achieves state-of-the-art performance on real musical data. 1 Context Many of nowadays spectral unmixing techniques rely on non-negative matrix decompositions. This concerns for example hyperspectral remote sensing (with applications in Earth observation, astronomy, chemistry, etc.) or audio signal processing. The spectral sample v n (the spectrum of light observed at a given pixel n, or the audio spectrum in a given time frame n) is decomposed onto a dictionary W of elementary spectral templates, characteristic of pure materials or sound objects, such that v n â Wh n. The composition of sample n can be inferred from the non-negative expansion coefficients h n. This paradigm has led to state-of-the-art results for various tasks (recognition, classification, denoising, separation) in the aforementioned areas, and in particular in music transcription, the central application of this paper. In state-of-the-art music transcription systems, the spectrogram V (with columns v n) of a musical signal is decomposed onto a dictionary of pure notes (in so-called multi-pitch estimation) or chords. V typically consists of (power-)magnitude values of a regular short-time Fourier transform (Smaragdis and Brown, 2003). It may also consists of an audio-specific spectral transform such as the Mel-frequency transform, like in (Vincent et al., 2010), or the Q-constant based transform, like in (Oudre et al., 2011). The success of the transcription system depends of course on the adequacy of the time-frequency transform & the dictionary to represent the data V
Automatic musical instrument recognition for multimedia indexing
Trabalho apresentado no Ăąmbito do Mestrado em
Engenharia InformĂĄtica, como requisito parcial
para obtenção do grau de Mestre em Engenharia
InformĂĄticaThe subject of automatic indexing of multimedia has been a target of numerous discussion and study. This interest is due to the exponential growth of multimedia content and the subsequent need to create methods that automatically catalogue this data. To fulfil this idea, several projects and areas of study have emerged. The most relevant of these are the MPEG-7 standard, which defines a standardized system for the representation and automatic extraction of information present in the content, and Music
Information Retrieval (MIR), which gathers several paradigms and areas of study relating
to music.
The main approach to this indexing problem relies on analysing data to obtain and
identify descriptors that can help define what we intend to recognize (as, for instance,musical instruments, voice, facial expressions, and so on), this then provides us with information we can use to index the data.
This dissertation will focus on audio indexing in music, specifically regarding the
recognition of musical instruments from recorded musical notes. Moreover, the developed system and techniques will also be tested for the recognition of ambient sounds
(such as the sound of running water, cars driving by, and so on).
Our approach will use non-negative matrix factorization to extract features from
various types of sounds, these will then be used to train a classification algorithm that
will be then capable of identifying new sounds