Hi, I'm Joren. Welcome to my website. I'm a research software engineer in the field of Music Informatics and Digital Humanities. Here you can find a record of my research and projects I have been working on. Learn more »
The TarsosDSP Java library for audio processing now contains an implementation of the Haar Wavelet Transform. A discrete wavelet transform based on the Haar wavelet (depicted at the right). This reversible transform has some interesting properties and is practical in signal compression and for analyzing sudden transitions in a file. It can e.g. be used to detect edges in an image.
As an example use case of the Haar transform, a simple lossy audio compression algorithm is implemented in TarsosDSP. It compresses audio by dividing audio into bloks of 32 samples, transforming them using the Haar wavelet Transform and subsequently removing samples with the least difference between them. The last step is to reverse the transform and play the audio. The amount of compressed samples can be chosen between 0 (no compression) and 31 (no signal left). This crude lossy audio compression technique can save at least a tenth of samples without any noticeable effect. A way to store the audio and read it from disk is included as well.
The algorithm works in real time and an example application has been implemented which operates on an mp3 stream. To make this work immediately, the avconv tool needs to be on your system’s path. Also implemented is a bit depth compressor, which shows the effect of (extreme) bit depth compression.
The TarsosDSP Java library for audio processing now contains a module for spectral peak extraction. It calculates a short time Fourier transform and subsequently finds the frequency bins with most energy present using a median filter. The frequency estimation for each identified bin is significantly improved by taking phase information into account. A method described in “Sethares et al. 2009 – Spectral Tools for Dynamic Tonality and Audio Morphing”.
The noise floor, determined by the median filter, the spectral information itself and the estimated peak locations are returned for each FFT-frame. Below a visualization of a flute can be found. As expected, the peaks are harmonically spread over the complete spectrum up until the Nyquist frequency.
Spectral peaks of a flute. The first 10 harmonic are detected up until the Nyquist frequency.
Give students an intensive course in the most advanced and current topics in the research fields of systematic musicology and sound and music computing. Give students the opportunity to discuss their research proposals/project with an international staff of teachers representing a variety of expertise in different domains of systematic musicology and sound and music computing. Teach students the most recent knowledge and basic skills needed to start a PhD. Give students the opportunity to join the research communities on systematic musicology, on sound and music computing.
Next to the lectures, the informal meetings with the professors was very interesting. I got to add some things to my ‘to read’ list:
Rolf Bader, Calculation of Helmholtz frequency of a Renaissance vihuela string instrument with five tone hole
Schneider, A. & Frieler, K. (2009) Perception of harmonic and inharmonic sounds: Results from
ear models. In S. Ystad, R. Kronland-Martinet & K. Jensen (Eds.), Computer music modeling and retrieval. Genesis of meaning in sound and music (pp. 18–44). Berlin: Springer.
Semantic Audio is concerned with content-based management of digital audio recordings. The rapid evolution of digital audio technologies, e.g. audio data compression and streaming, the availability of large audio libraries online and offline, and recent developments in content-based audio retrieval have significantly changed the way digital audio is created, processed, and consumed. New audio content can be produced at lower cost, while also large audio archives at libraries or record labels are opening to the public. Thus the sheer amount of available audio data grows more and more each day. Semantic analysis of audio resulting in high-level metadata descriptors such as musical chords and tempo, or the identification of speakers facilitate content-based management of audio recordings. Aside from audio retrieval and recommendation technologies, the semantics of audio signals are also becoming increasingly important, for instance, in object-based audio coding, as well as intelligent audio editing, and processing. Recent product releases already demonstrate this to a great extent, however, more innovative functionalities relying on semantic audio analysis and management are imminent. These functionalities may utilise, for instance, (informed) audio source separation, speaker segmentation and identification, structural music segmentation, or social and Semantic Web technologies, including ontologies and linked open data.
This conference will give a broad overview of the state of the art and address many of the new scientific disciplines involved in this still-emerging field. Our purpose is to continue fostering this line of interdisciplinary research. This is reflected by the wide variety of invited speakers presenting at the conference.
The paper presents TarsosDSP, a framework for real-time audio analysis and processing. Most libraries and frameworks offer either audio analysis and feature extraction or audio synthesis and processing. TarsosDSP is one of a only a few frameworks that offers both analysis, processing and feature extraction in real-time, a unique feature in the Java ecosystem. The framework contains practical audio processing algorithms, it can be extended easily, and has no external dependencies. Each algorithm is implemented as simple as possible thanks to a straightforward processing pipeline. TarsosDSP’s features include a resampling algorithm, onset detectors, a number of pitch estimation algorithms, a time stretch algorithm, a pitch shifting algorithm, and an algorithm to calculate the Constant-Q. The framework also allows simple audio synthesis, some audio effects, and several filters. The Open Source framework is a valuable contribution to the MIR-Community and ideal fit for interactive MIR-applications on Android. The full paper can be downloaded TarsosDSP, a Real-Time Audio Processing Framework in Java
@inproceedings{six2014tarsosdsp,
author = {JorenSixandOlmoCornelisandMarcLeman},
title = {{TarsosDSP, a Real-TimeAudioProcessingFrameworkinJava}},
booktitle = {{Proceedings of the 53rd AESConference (AES53rd)}},
year = 2014
}
Woensdag 18 december 2013 organiseerde Olmo Cornelis een concert in het kader van zijn doctoraat. De dag erna volgde zijn verdediging. Nogmaals proficiat Olmo met het mooie eeh mbirapunt. Hieronder staat kort wat uitleg over het project en het concert.
In zijn onderzoeksproject ‘Exploring the symbiosis of Western and non-Western Music’ stelde Olmo Cornelis de beschrijving van Centraal-Afrikaanse muziek centraal. Deze werd verkend via computationele technieken die de klank als signaal
benaderden. De verkregen informatie zorgde voor beïnvloeding van het artistieke oeuvre waarin steeds een mengeling van impliciete en expliciete etnische invloeden spelen.
In het kader van de afronding van dit doctoraal onderzoek spelen het HERMESensemble, het Nadar Ensemble, Maja Jantar en Françoise Vanhecke op 18 december werk van Olmo Cornelis dat tijdens dit project geschreven werd. Het onderzoeksproject Exploring the symbiosis of Western and non-Western Music werd in 2008 geïnitieerd aan het Conservatorium / School of Arts van de HoGent en werd gefinancierd door het onderzoeksfonds Hogeschool Gent.
Beeld: Noel Cornelis, Reality of Possibilities, 2012
Yesterday, December 4th 2013, the RTBF was at IPEM to do a small feature on research currently going on at the institue. The RTBF is the public broadcasting organization of the French Community of Belgium, the southern, French-speaking part of Belgium. The clip shows the D-Jogger in action, with me using it. The fragment is available on the RTBF website and is embedded below.
The journal paper Evaluation and Recommendation of Pulse and Tempo Annotation in Ethnic Music – In Journal Of New Music Research by Cornelis, Six, Holzapfel and Leman was published in a special issue about Computational Ethnomusicology of the Journal of New Music Research on the 20th of august 2013. Below you can find the abstract for the article, and the full text author version of the article itself.
Abstract: Large digital archives of ethnic music require automatic tools to provide musical content descriptions. While various automatic approaches are available, they are to a wide extent developed for Western popular music. This paper aims to analyze how automated tempo estimation approaches perform in the context of Central-African music. To this end we collect human beat annotations for a set of musical fragments, and compare them with automatic beat tracking sequences. We first analyze the tempo estimations derived from annotations and beat tracking results. Then we examine an approach, based on mutual agreement between automatic and human annotations, to automate such analysis, which can serve to detect musical fragments with high tempo ambiguity.
@article{cornelis2013tempo_jnmr,
author = {OlmoCornelis, JorenSix, AndreHolzapfel, andMarcLeman},
title = {{EvaluationandRecommendation of Pulse ant TempoAnnotationinEthnicMusic}},
journal = {{Journal of NewMusicResearch}},
volume = {42},
number = {2},
pages = {131-149},
year = {2013},
doi = {10.1080/09298215.2013.812123}
}
The DSP library for Taros, aptly named TarsosDSP, now includes an implementation of a Constant-Q Transform (as of version 1.6). The Constant-Q transform does essentially the same thing as an FFT, but has the advantage that each octave has the same amount of bins. This makes the Constant-Q transform practical for applications processing music. If, for example, 12 bins per octave are chosen, these can correspond with the western musical scale.
Also included in the newest release (version 1.7) is a way to visualize the transform, or other musical features. The visualization implementation is done together with Thomas Stubbe.
The example application below shows the Constant-Q transform with an overlay of pitch estimations. The corresponding waveform is also shown.
The journal paper Tarsos, a Modular Platform for Precise Pitch Analysis of Western and Non-Western Music by Six, Cornelis, and Leman was published in a special issue about Computational Ethnomusicology of the Journal of New Music Research on the 20th of august 2013. Below you can find the abstract for the article, and pointers to audio examples, the Tarsos software, and the author version of the article itself.
Abstract: This paper presents Tarsos, a modular software platform used to extract and analyze pitch organization in music. With Tarsos pitch estimations are generated from an audio signal and those estimations are processed in order to form musicologically meaningful representations. Tarsos aims to offer a flexible system for pitch analysis through the combination of an interactive user interface, several pitch estimation algorithms, filtering options, immediate auditory feedback and data output modalities for every step. To study the most frequently used pitches, a fine-grained histogram that allows up to 1200 values per octave is constructed. This allows Tarsos to analyze deviations in Western music, or to analyze specific tone scales that differ from the 12 tone equal temperament, common in many non-Western musics. Tarsos has a graphical user interface or can be launched using an API – as a batch script. Therefore, it is fit for both the analysis of individual songs and the analysis of large music corpora. The interface allows several visual representations, and can indicate the scale of the piece under analysis. The extracted scale can be used immediately to tune a MIDI keyboard that can be played in the discovered scale. These features make Tarsos an interesting tool that can be used for musicological analysis, teaching and even artistic productions.
Ladrang Kandamanyura (slendro pathet manyura), is the name of the piece used in the article throughout section 2. The album on which the piece can be found is available at wergo. Below a thirty second fragment is embedded. You can also download the thirty second fragment to analyse it yourself.
Below the BibTex entry for the article is embedded.
In the extended abstract, also titled Computer Assisted Transcription of Ethnic Music, it is described how the Tarsos software program now has features aiding transcription. Tarsos is especially practical for ethnic music of which the tone scale is not known beforehand. The proceedings of FMA 2013 are available as well.
During the conference there also was an interesting panel on transcription. The following people participated: John Ashley Burgoyne, moderator (University of Amsterdam), Kofi Agawu (Princeton University), Dániel P. Biró (University of Victoria), Olmo Cornelis (University College Ghent, Belgium), Emilia Gómez (Universitat Pompeu Fabra, Barcelona), and Barbara Titus (Utrecht University). Some pictures can be found below.
The TarsosDSP Java library for audio processing now contains an implementation of the Haar Wavelet Transform. A discrete wavelet transform based on the Haar wavelet (depicted at the right). This reversible transform has some interesting properties and is practical in signal compression and for analyzing sudden transitions in a file. It can e.g. be used to detect edges in an image.
UGent
aes53_tarsos_dsp.pdf
The journal paper Evaluation and Recommendation of Pulse and Tempo Annotation in Ethnic Music – In Journal Of New Music Research by Cornelis, Six, Holzapfel and Leman was published in a special issue about Computational Ethnomusicology of 
The journal paper Tarsos, a Modular Platform for Precise Pitch Analysis of Western and Non-Western Music by Six, Cornelis, and Leman was published in a special issue about Computational Ethnomusicology of 
