Articles Tagged 'Computational ethnomusicology'

~ International Symposium on Computational Ethnomusicological Archiving

This weekend the University Hamburg – Institute for Systematic Musicology and more specifically Christian D. Koehn organized the International Symposium on Computational Ethnomusicological Archiving. The symposium featured a broad selection of research topics (physical modelling of instruments, MIR research, 3D scanning techniques, technology for (re)spacialisation of music, library sciences) which all had a relation with archiving musics of the world:

How could existing digital technologies in the field of music information retrieval, artificial intelligence, and data networking be efficiently implemented with regard to digital music archives? How might current and future developments in these fields benefit researchers in ethnomusicology? How can analytical data about musical sound and descriptive data about musical culture be more comprehensively integrated?

I was able to attend the symposium and contributed with a talk titled Challenges and opportunities for computational analysis of wax cylinders and by chairing a panel discussion. The symposium was kindly sponsored by the VolkswagenStiftung. The talk had the following abstract:

In this presentation we describe our experience of working with computational analysis on digitized wax cylinder recordings. The audio quality of these recordings is limited which poses challenges for standard MIR tools. Unclear recording and playback speeds further hinder some types of audio analysis. Moreover, due to a lack of systematical meta-data notation it is often uncertain where a single recording originates or when exactly it was recorded. However, being the oldest available sound recordings, they are invaluable witnesses of various musical practices and they are opportunities to improve the understanding of these practices. Next to sketching these general concerns, we present results of the analysis of pitch content of 400 wax cylinder recordings from Indiana University (USA) and from the Royal Museum from Central Africa (Belgium). The scales of the 400 recordings are mapped and analyzed as a set. It is found that the fifth is almost always present and that scales with four and five pitch classes are organized similarly and differ from those with six and seven pitch classes, latter center around intervals of 170 cents, and former around 240 cents.


~ Computational Ethnomusicology: Methodologies for a New Field

Comp ethno workshop From 27 to 31 March 2017 I have attended a workshop on Computational Ethnomusicology: Methodologies for a New Field at the Lorentz Center in Leiden. The workshop format was aimed at creating time for interdisciplinary discussion.

It was attended by a mix of (Ethno)musicologists, archivists, computer scientists and people identifying themselves as more than one of these categories by varying degrees. This mix ensured a healthy discussion and talks by Frans Wiering, Willard McCarthy, Emilia Gomez, and may more provided ample source material to discuss. These discussions ranged from the abstracts around schemata down to concrete of software tools for archive management.

On a more personal side the workshop did provide useful insights to contextualize my research and help form ideas that can be condensed in my PhD dissertation.


~ Tarsos, a Modular Platform for Precise Pitch Analysis of Western and Non-Western Music - In Journal Of New Music Research

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.

To read the full text you can either download Tarsos, a Modular Platform for Precise Pitch Analysis of Western and Non-Western Music, Author version. Or obtain the published version of Tarsos, a Modular Platform for Precise Pitch Analysis of Western and Non-Western Music, published version

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.

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@article{six2013tarsos_jnmr,
  author = {Six, Joren and Cornelis, Olmo and Leman, Marc},
  title = {Tarsos, a Modular Platform for Precise Pitch Analysis 
            of Western and Non-Western Music},
  journal = {Journal of New Music Research},
  volume = {42},
  number = {2},
  pages = {113-129},
  year = {2013},
  doi = {10.1080/09298215.2013.797999},
 URL = {http://www.tandfonline.com/doi/abs/10.1080/09298215.2013.797999}
}

~ FMA 2013 - Computer Assisted Transcripton of Ethnic Music

At the third international workshop on Folk Music Analysis we presented a poster titled Computer Assisted Transcription of Ethnic Music]. The workshop took place in Amsterdam, Netherlands, June 6 and 7, 2013.

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.

Computer Assited Transcription of Ethnic Music poster

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.


~ Tarsos 1.0: Transcription Features

Today marks the reslease of Tarsos 1.0 . The new Tarsos release contains practical transcription features. As can be seen in the screenshot below, a time stretching feature makes it easy to loop a certain audio fragment while it is playing in a slow tempo. The next loop can be played with by pressing the n key, the one before by pressing b.

Since the pitch classes can be found in a song, and there is a feature that lets you play a MIDI keyboard in the tone scale of the song under analysis, transcription of ethnic music is made a lot easier.

The new release of Tarsos can be found in the Tarsos release repository. From now on, nightly releases are uploaded there automatically.


~ ISMIR 2012 - Highlights

Logo ISMIR 2012The 13th International Society for Music Information Retrieval Conference took place in Porto, Portugal, October 8th-12th, 2012. This text contains links to some papers, toolkits, software presented there which are interesting for my research. Basically it contains my personal highlights of the conference. The ISMIR 2012 is described as follows:

The annual Conference of the International Society for Music Information Retrieval (ISMIR) is the world’s leading research forum on processing, searching, organizing and accessing music-related data. The revolution in music distribution and storage brought about by digital technology has fueled tremendous research activities and interests in academia as well as in industry. The ISMIR Conference reflects this rapid development by providing a meeting place for the discussion of MIR-related research, developments, methods, tools and experimental results. Its main goal is to foster multidisciplinary exchange by bringing together researchers and developers, educators and librarians, as well as students and professional users.

Tutorials

I saw an interesting tutorial on Jazz music and a tutorial on source separation. After an introduction, which detailed the experimental basis of the system, a source separator was introduced. The REPET source separator is a relatively simple system that yields reasonable results to split accompaniment from foreground melody.

Posters & Talks

The approach and the dataset used in N-gram Based Statistical Makam Detection on Makam Music in Turkey Using Symbolic Data is very interesting. More than 800 pieces of makam music where transcribed manually and analysed. Details about the dataset are available in the following paper: A Turkish Makam Music Symbolic Database for Music Information Retrieval: SymbTr.

Assigning a Confidence Threshold on Automatic Beat Annotation in Large Datasets by Zapata et al. shows a very interesting way to do exactly what the title says. Descriptive titles are descriptive.

A very practical tool to do melody extraction was presented by Justin Salamon. He created a Vamp Plugin with the name Melodia. Unfortunately the plugin is currently only available for windows, but Linux and OS X versions are in the pipeline. More about the algorithm implemented and background information can be found in the paper Justin presented: Statistical Characterisation of Melodic Pitch Contours and its Application for Melody Extraction. Another Vamp Plugin for melody visualization was also presented: Pitch Content Visualization Tools for Music Performance Analysis.

The ongoing work by Ceril Bohak and Matija Marolt on segmentation of folk music could be very useful to apply on Afican musics. The paper is called Finding Repeating Stanzas in Folk Songs.


~ ICMC 2012 - Sound to Scale to Sound, a Setup for Microtonal Exploration and Composition

Logo Universiteit UtrechtAt this years ICMC Conference, ICMC 2012 we presented a paper describing a way to experiment with tone scales and how to use Tarsos as a compositional tool. What follows are some pointers to the presentation, paper and to other interesting talks that were presented there.

ICMC 2012 was organized in Ljubljana from the 9 to 14 septembre and had a very dense program of talks, posters, presentations, demos and concerts.

Since 1974 the International Computer Music Conference has been the major international forum for the presentation of the full range of outcomes from technical and musical research, both musical and theoretical, related to the use of computers in music. This annual conference regularly travels the globe, with recent conferences in the Americas, Europe and Asia. This year we welcome the conference to Slovenia for the first time.

Sound to Scale to Sound, a Setup for Microtonal Exploration and Composition

Our contribution to the conference was a paper titled Sound to Scale to Sound, a Setup for Microtonal Exploration and Composition.

If you want to cite our work, this BibTeX entry is included for your convenience:

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@inproceedings{cornelis2012sound_to_scale,
  author     = {Olmo Cornelis and Joren Six},
  title      = {{Sound to Scale to Sound, a Setup for Microtonal Exploration and Composition}},
  booktitle  = {{Proceedings of the 2012 International Computer Music Conference,
               (ICMC 2012)}},
  year       = {2012},
  publisher = {The International Computer Music Association}
}

Program highlights

What follows are a number of pointers to my personal program highlights.

Verena Thomas presented two very well polished software tools. One to detect patterns in scores, called motifviewer and a tool to search in score databases in a multi-modal way. The Probado tool does score-to-audio alignment and much more.

Gibber is an impressive live-coding environment with an easy syntax. Since it is all done with javascript you can start playing with it immediately. Overtone Another live-coding environment, presented at the conference by Sam Aaron, was equally impressive. It is programmed using the Closure language.

At ICMC there were a number of tools to assist in composition. One of those is The Bach Project, by Andrea Agostini. Togheter with CatART by Diemo Swartz it forms a very expressive platform to work with sound, which was demonstrated by Aaron Einbond and Christopher Trapani in their paper titled Precise Pitch Control In Real Time Corpus-Based Concatenative Synthesis. Diemo Swartz presented work on Audio Mosaicing, it can be seen as a follow-up to AuidioGuild by Ben Hackbarth.

I also got to know the work by Thomas Grill, on his website a nice piece of software can be found a Python implementation of the Non Stationary Gabor Transform. Another software system I got to know is the functional signal processing programming language FAUST

My personal highlights of the concert programme include the works by Johannes Kreidler, Aura Pon, Daniel Mayer, Alexander Schubert and the remarkable performance by Dexter Ford. The concept behind Soundlog by Johannes Kretz was also interesting.


~ Analytical Approaches To World Music - Microtonal Scale Exploration in Central Africa

At the 2012 AAWM conference we presented a way to explore tone scales in the music of Central Africa. Since the audience consisted of (ethno)musicologists, the main focus of the presentation was on the applicication part, the technical aspects were only briefly mentioned.

The extended abstract can be consulted: Towards the tangible: microtonal scale exploration in Central-African music

The conference program itself was very diverse and interesting.


~ Guest Lecture at MIT - Ethnic Music Analysis: Challenges & Opportunities - Tarsos as a Case Study

Thursday the 3th of May I gave a guest lecture titled ‘Ethnic Music Analysis: Challenges & Opportunities’ it featured Tarsos as a Case Study. The goal was to identify the difficulties when dealing with ethnic music and to show a possible approach, the approach implemented by Tarsos.

The invitation to give the guest lecture came from Michael Cuthbert who is one of the driving forces behind music21. The audience was a small group of double majors in both musicology and computer science: the ideal profile to gather useful feedback.


~ Tarsos at 'Study Day: Tuning and Temperament - Insitute of Musical Research, London'

Tarsos LogoThe 17th of Octobre 2011 Tarsos was presented at the Study Day: Tuning and Temperament which was held at the Institue of Music Research in Londen. The study day was organised by Dan Tidhar. A short description of the aim of the study day:

This is an interdisciplinary study day, bringing together musicologists, harpsichord specialists, and digital music specialists, with the aim of exploring the different angles these fields provide on the subject, and how these can be fruitfully interconnected.

We offer an optional introduction to temperament for non specialists, to equip all potential listeners with the basic concepts and terminology used throughout the day.


~ Tarsos presentation at 'ISMIR 2011'

Tarsos LogoOlmo Cornelis and myself just gave a presentation about Tarsos at the at the 12th International Society for Music Information Retrieval Conference which is held at Miami.

The live demo we gave went well and we got a lot of positive, interesting feedback. The presentation about Tarsos is available here.

It was the first time in the history of ISMIR that there was a session with oral presentations about Non-Western Music. We were pleased to be part of this.

The peer reviewed paper about our work: Tarsos – a Platform to Explore Pitch Scales in Non-Western and Western Music is available from the ISMIR website and embedded below:


~ Makam Recognition with the Tarsos API

This article describes how to do makam recognition with a script that uses the Tarsos API.

The task we want to do is to find the tone scales most similar to the one used in recorded music. To complete this task you need a small set of theoretical scales and a large set of music, each brought in one of the scales. To make it more concrete, an example of Turkish classical music is used.

In an article by Bozkurt pitch histograms are used for – amongst other tasks – makam recognition. A maqam defines rules for a composition or performance of classical Turkish music. It specifies melodic shapes and pitch intervals, the scale. The task is to identify which of nine makams is used in a specific song. A simplified, generalized implementation of this task is shown here. In our implementation there is no tonic detection step. Also here we use only theoretical descriptions of the tone scales as a template and do not construct a template using the audio itself, as is done by Bozkurt. Ioannidis Leonidas wrote an interesting master thesis about makam recognition. Since no knowledge of the music itself is used the approach is generally applicable.

The following is an implementation in Scala a general purpose programming language that is interoperable with Jave . The first step is to write the Scala header. This is just some boilerplate code to be able to run the script from the command line – it assumes a UNIX-like environment and tarsos.jar in the same directory:

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#!/bin/sh
exec scala  -cp tarsos.jar -savecompiled "$0" "$@"
!#
import be.hogent.tarsos.util._
//other import statements

The second step constructs the templates the capability of Tarsos to create
theoretical tone scale templates using Gaussian kernels is used, line 8. See the attached images for some examples.

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val makams = List(        "hicaz","huseyni","huzzam","kurdili_hicazar",
                                        "nihavend","rast","saba","segah","ussak")

var theoreticKDEs = Map[java.lang.String,KernelDensityEstimate]()
makams.foreach{ makam =>
  val scalaFile =  makam + ".scl"
  val scalaObject = new ScalaFile(scalaFile);
  val kde = HistogramFactory.createPichClassKDE(scalaObject,35)
  kde.normalize
  theoreticKDEs = theoreticKDEs + (makam -> kde)
}

The third and last step is matching. First a list of audio
files is created by recursively iterating a directory and matching each file to
a regular expression. Next, starting from line 4, each audio file is processed.
The internal implementation of the YIN pitch detection
algorithm is used on the audio file and a pitch class histogram is created
(line 6,7). On line 10 normalization of the histogram is done, to
make the correlation calculation meaningful. Line 11 until 15 compare the
created histogram from the audio file with the templates calculated beforehand.
The results are stored, ordered and eventually printed on line 19.

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val directory = "/home/joren/turkish_makams/"
val audio_pattern = ".*.(mp3|wav|ogg|flac)"
val audioFiles = FileUtils.glob(directory,audio_pattern,true).toList

audioFiles.foreach{ file =>
  val audioFile = new AudioFile(file)
  val detectorYin = PitchDetectionMode.TARSOS_YIN.getPitchDetector(audioFile)
  val annotations = detectorYin.executePitchDetection()
  val actualKDE = HistogramFactory.createPichClassKDE(annotations,15);
  actualKDE.normalize    
  var resultList = List[Tuple2[java.lang.String,Double]]()
  for ((name, theoreticKDE) <- theoreticKDEs){
      val shift = actualKDE.shiftForOptimalCorrelation(theoreticKDE)
      val currentCorrelation = actualKDE.correlation(theoreticKDE,shift)
      resultList =  (name -> currentCorrelation) :: resultList
  }
  //order by correlation
  resultList = resultList.sortBy{_._2}.reverse
  Console.println(file + " is brought in tone scale " + resultList(0)._1)
}

A complete version of this script can is available: Tone scale matching script Results of the script when ran on Bozkurt’s dataset can be seen in the attached spreadsheet (openoffice format or excel format).

  • Theoretical template

    Theoretical template

  • Other theoretical template

    Other theoretical template

  • Actual Hicaz song overlayed with a theoretical template

    Actual Hicaz song overlayed with a theoretical template


~ Tarsos at 'ISMIR 2011'

Tarsos LogoA paper about Tarsos was submitted for review at the 12th International Society for Music Information Retrieval Conference which will be held in Miami. The paper Tarsos – a Platform to Explore Pitch Scales in Non-Western and Western Music was reviewed and accepted, it will be published in this year’s proceedings of the ISMIR conference. It can be read below as well.

An oral presentation about Tarsos is going to take place Tuesday, the 25 of October during the afternoon, as can be seen on the ISMIR preliminary program schedule.

If you want to cite our work, please use the following data:

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@inproceedings{six2011tarsos,
  author     = {Joren Six and Olmo Cornelis},
  title      = {Tarsos - a Platform to Explore Pitch Scales 
                in Non-Western and Western Music},
  booktitle  = {Proceedings of the 12th International 
                Society for Music Information Retrieval Conference,
                ISMIR 2011},
  year       = {2011},
  publisher  = {International Society for Music Information Retrieval}
}


~ Latex export functions

Tarsos, a software package to analyse pitch organization in music, contains a new output modality. It is now possible to export a pitch class histogram and a pitch class interval matrix to latex from within Tarsos. This makes documenting tone scales more efficient.

An example for a pitch class histogram and pitch class interval matrix can be seen. Also available is the latex source code.

  • Latex export of a pitch class histo.

    Latex export of a pitch class histo.

  • Latex export of a pitch class interval matrix

    Latex export of a pitch class interval matrix


~ Resynthesis of Pitch Detection Annotations on a Flute Piece

Tarsos, a software package to analyse pitch organization in music, contains a new output modality. Now it is possible to export resynthesized pitch annotations, detected by a pitch detection algorithm and compare those with the original sound. This can be interesting to see which errors a pitch detection algorithm makes.

Below you can listen to an example of synthesized pitch detection results compared with the original flute piece. The file starts with only the original flute sound (on the right channel) and gradually changes so only the synthesized annotations (on the left channel) can be heard.

Resynthesis of Pitch Detection Annotations on a Flute Piece by Joren Six


~ Tarsos at 'IPEM Open House'

IPEM Logo The 25th of May 2011 Tarsos was present at the IPEM open house.

IPEM (Institute for Psychoacoustics and Electronic Music) is the research center of the Department of Musicology, which is part of the Department of Art, Music and Theater Studies of Ghent University. IPEM provides a scientific basis for the cultural and creative sector, especially for music and performance arts, and does pioneering research work on the relationship between music body movement and new technologies. The institute consists of an interdisciplinary team but also welcomes visiting researchers from all over the world. One of its aims is also to actively try and validate research results during public events and by means of user studies.

There are close relations between the Royal Conservatory Ghent, where we are located, and IPEM. There is more information about the IPEM open house available. Also available is the program of the IPEM open house 2011

Tarsos was presented using a poster, a flyer and a live demo. The poster about Tarsos and the flyer about Tarsos are both downloadable.


~ Tarsos at 'Lectures on Computational Ethnomusicology'

Tarsos Logo This monday the 28th of February Tarsos will be presented at “Lectures on Computational Ethnomusicology” which is held at Izmir, Turkey. The presentation of Tarsos is available here.

Next to the interesting programme it is a great opportunity to meet Baris Bozkurt who has been working on similar research but applied to Makam music.

On wednesday the second of March there is a small seminar at Electrical and Electronics Eng. Dept. of İzmir Yüksek Teknoloji Enstitüsü where Tarsos will be presented also.


~ ARIP: Artistic Research In Progress

Voor ARIP heb ik een artikel over Tarsos geschreven. Het motiveert kort de bestaansredenen van Tarsos – een applicatie om toonhoogtegebruik in muziek te analyseren – en het artikel geeft een overzicht van de werking van Tarsos aan de hand van een voorbeeld. Hieronder zijn multimediale aanvullingen te vinden bij het artikel.

Ladrang Kandamanyura (slendro pathet manyura), zo heet het muziekfragment dat gebruikt werd in het artikel als voorbeeld van een stuk muziek met een ongewone (voor onze westerse oren toch) toonladder. De CD waarop het stuk te vinden is, is bij wergo te verkrijgen. Een fragment van 30 seconden is hier te beluisteren:

Het fragment kan je ook downloaden om zelf te analyseren met Tarsos.

Ladrang Kandamanyura (slendro pathet manyura)
Courtesy of: WERGO/Schott Music & Media, Mainz, Germany, www.wergo.de and Museum Collection Berlin
Lestari – The Hood Collection, Early Field Recordings from Java (SM 1712 2)
Recorded in 1957 and 1958 in Java – First release

Tarsos Live

Het onderstaande videofragment geeft aan hoe Tarsos gebruikt kan worden om in real time stemmingen te meten. Geluid afkomstig van een microfoon wordt dan meteen geanalyseerd en onmiddellijke feedback toont een gespeeld of gezongen interval. Het maakt kwarttonen of andere (ongewone) intervallen visueel duidelijk. Tarsos kan zo gebruikt worden door zangers of strijkers die willen experimenteren met microtonaliteit. Ook kan het handig zijn voor etnomusicologisch veldwerk: bijvoorbeeld om kora (een Afrikaanse harp) toonladders te documenteren.

  • Spectrogram

    Spectrogram

  • Annotaties

    Annotaties

  • Ambitus

    Ambitus

  • Toonladder

    Toonladder


~ Tarsos Live - Real Time Tone Scale Analysis

Tarsos LogoA new version of Tarsos was uploaded today and it contains an exciting (at least my kind of exciting) new feature. It is capable of real-time pitch analysis and tone scale construction. A video should make its use clear:

The immediate feedback is practical for educational purposes: it makes rather vague things like quarter tones or (uncommon) pitch intervals in general quite tangible. It could be used by singers or string players to explore microtonality or to improve their technique. Another use case is ethnomusicologic field-work: if you would want to research Kora tuning (an African harp) Tarsos could be a practical tool for real-time analysis.

Thanks to Olmo Cornelis and Wannes Gonnissen for playing the thumb piano and Saz respectively.


~ Tarsos in het jaarboek Orpheus instituut

Naar jaarlijkse gewoonte wordt er in het Orpheus instituut de Dag van het Artistiek onderzoek georganiseerd. Hieronder volgt een tekstje over het onderzoeksproject rond Tarsos dat in het jaarboek komt. Het jaarboek is een boekje met daarin een overzicht van artistieke onderzoeksprojecten aan Vlaamse instituten. Het wordt gepubliceerd naar aanleiding van de eerder aangehaalde “Dag van het Artistiek Onderzoek”.

Tarsos LogoHet doel van dit onderzoeksproject is het ontwikkelen van een methode om een cultuuronafhankelijke kijk op muzikale parameters te verkrijgen. Meer concreet worden er technieken aangewend uit Music Information Retrieval om toonhoogte, tempo en timbre te bestuderen. Aanpassing van bestaande, meestal westers georiënteerde, MIR-methodes moet leiden tot een gestructureerde documentatie van verschillende klankkleuren, toonschalen, metrische verhoudingen en muzikale vormen. Die beschrijving kan dienen als inspiratie voor de ontwikkeling van een artistieke compsitionele taal of kan gebruikt worden als bronmateriaal voor wetenschappelijk onderzoek rond ethnische muziek. Bijvoorbeeld om (de eventuele

teloorgang van) de eigenheid van orale muziekculturen objectief aan te tonen.

datasetIn de eerste fase van het onderzoek ligt de focus van het onderzoek op één van de meer tastbare parameters: toonhoogte. In etnische muziek is het gebruik van toonhoogte vaak radicaal anders dan westerse muziek die meestal gebaseerd is op de onderverdeling van een octaaf in twaalf gelijke delen. Om toonladders uit
muziek te extraheren en weer te geven werd het software platform Tarsos ontwikkeld. Met Tarsos is het mogelijk om automatische toonladderanlyse uit te voeren op een grote dataset of om manueel een gedetailleerde analyse te verkrijgen van enkele muziekstukken. De cultuuronafhankelijke analysemethode waarvan Tarsos gebruik maakt kan even goed toegepast worden op Indonesische, Westerse of Afrikaanse muziek.

Onze bedoeling is om Tarsos te gebruiken om evoluties in toonladdergebruik te ontdekken in de enorme dataset van het Koninklijk Museum voor Midden-Afrika. Is toonladderdiversiteit in Afrika aan het wegkwijnen onder invloed van Westerse muziek? Zijn er specifieke kenmerken te vinden over eventueel ‘uitgestorven’ muziekculturen? Dit zijn vragen die kaderen in het overkoepelende onderzoeksproject van Olmo Cornelis en waar we met behulp van Tarsos een antwoord op proberen te vinden.

Later krijgen de twee overige muzikale parameters, tempo en timbre, een gelijkaardige behandeling. In de laatste fase van dit toch wel ambitieuze onderzoekproject wordt de relatie tussen de parameters onderzocht.


~ Digital Music Research Network Workshop - Queen Mary University London

Queen Mary University Logo

Monday the 20th and Tuesday the 21th of December I attended two workshops at The Queen Mary University of London: The Machine Listening Workshop and Digital Music Research Network One-day Workshop 2010

At the workshop I had an interesting meeting with Dan Tidhar. He researches harpsichord temperament estimation at QMUL. Together they created the Tempest web service where you can upload harpsichord audio and let the system guess the temperament. The process is described in the paper “High precision frequency estimation for harpsichord tuning classification”. Although Tarsos was not officially part of the programme I hijacked the poster sessions to show a live demo of Tarsos with Dan’s dataset.

Another interesting talk was about 2032, a tunable synthesizer with definable Harmonics. It elaborates on the ideas of Sethares about tone scales .


~ Tarsos Presented at the "Perspectives for Computational Musicology" Symposium

Tarsos Logo Yesterday Tarsos was publicly presented at the symposium Perspectives for Computational Musicology in Amsterdam. The first public presentation of Tarsos, excluding this website. The symposium was organized by the Meertens Institute on the occasion of Peter van Kranenburg’s PhD defense.

The presentation included a live demo of a daily build of Tarsos (a Friday evening build) which worked, surprisingly, without hiccups. The presentation was done by Olmo Cornelis. This was the small introduction:

Tarsos – a Platform for Pitch Analysis of Ethnic Music
Ethnic music is a vulnerable cultural heritage that has received only recently more attention within the Music Information Retrieval community. However, access to ethnic music remains problematic, as this music does not always correspond to the Western concepts of music and metadata that underlie the currently available content-based methods. During this lecture, we like to present our current research on pitch analysis of African music. TARSOS, a platform for analysis, will be presented as a powerful tool that can describe and compare scales with great detail.

To give Tarsos a try ou can start Tarsos using JAVA WebStart or download the executable Tarsos JAR-file. A JAVA 1.5 runtime is required.


~ Tarsos User Interface Prototype

Tarsos now has an easy to use drag and drop User Interface. It can be used to extract tone scale information from audio files.

Start tarsos using JAVA WebStart.

Drag and drop works for scala tone scale files and different kinds of audio files. Audiofiles are transcoded automagically using an embedded ffmpeg binary which is platform dependend. It works on linux and windows, on other platforms only WAV files are supported.

Some of the current features:

  • Scala file extraction from audio
  • Real time pitch tracking
  • Real time pitch class histogram visualization
  • Alignment of pitch intervals with histogram using mouse dragging
  • MIDI Tuning messages based on scala files.
  • Histogram smoothing functions
  • … a lot more is available under the hood.
  • Analysis

    Analysis

  • Browser

    Browser


~ Rendering MIDI Using Arbitrary Tone Scales

Tarsos can be used to render MIDI files to audio (WAV) files using arbitrary tone scales. This functionallity can be used to (automatically) verify tone scale extraction from audio files. Since I could not find a dataset with audio and corresponding tone scales creating one using MIDI seemed a good idea.

MIDI files can be found in spades, tone scales on the other hand are harder to find. Luckily there is one massive source, the Scala Tone Scale Archive: A large collection of over 3700 tone scales.

Using Scala tone scale files and a midi files a Tone Scale – Audio dataset can be generated. The quality of the audio depends on the (software) synthesizer and the SoundFont used. Tarsos currently uses the Gervill synthesizer. Gervill is a pure Java software synthesizer with support for 24bit SoundFonts and the MIDI tuning standard.

How To Render MIDI Using Arbitrary Tone Scales with Tarsos

A recent version of the JRE needs to be installed on your system if you want to use Tarsos. Tarsos itself can be downloaded in the form of the Tarsos JAR Package.

Currently Tarsos has a Command Line Interface. An example with the files you can find attached:

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java -jar tarsos.jar --midi BWV_1007.mid --scala 120.scl --out bach.wav

The result of this command should yield an audio file that sounds like the cello suites of bach in a nonsensical tone scale with steps of 120 cents. Executing tone scale extraction on the generated audo yields the expected result. In the pich class histogram every 120 cents a peak can be found.

To summarize: by rendering audio with MIDI and Scala tone scale files a dataset with tone scale – audio information can be generated and tone scale extraction algorithms can be tested on the fly.

This method also has some limitations. Because audio is rendered there is no (background) noise, no fluctuations in pitch and timbre,… all of which are present in recorded audio. So testing testing tone scale extraction algorithms on recorded audio remains advised.

  • 120 Cents difference

    120 Cents difference


~ Tone Scale Matching With Tarsos

Tarsos can be used to search for music that uses a certain tone scale or tone interval(s). Tone scales can be defined by a Scala tone scale file or an exemplifying audio file. This text explains how you can use Tarsos for this task.

Search Using Scala Tone Scale Files

Scala files are text files with information about a tone scale. It is used to share and exchange tone scales. The file format originates from the Scala program :

Scala is a powerful software tool for experimentation with musical tunings, such as just intonation scales, equal and historical temperaments, microtonal and macrotonal scales, and non-Western scales. It supports scale creation, editing, comparison, analysis, …

The Scala file format is popular because there is a library with more than 3000 tone scales available on the Scala website.

Tarsos also understands Scala files. It is able to create a pitch class histogram using a gaussian mixture model. A technique described in A. C. Gedik, B.Bozkurt, 2010, "Pitch Frequency Histogram Based Music Information Retrieval for Turkish Music ", Signal Processing, vol.10, pp.1049-1063. (doi:10.106/j.sigpro.2009.06.017).

An example should make things clear. Lets search for an interval of 300 cents or exactly three semitones. A scala file with this interval is easy to define:

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! example.scl
! An example of a tone interval of 300 cents
Tone interval of 300 cents
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!
900
1200.0

The next step is to create a histogram with an interval of 300 cents. In the block diagram this step is called “Peak histogram creation”. The Similarity calculation step expects a list of histograms to compare with the newly defined histogram. Feeding the similarity calculation with the western12ET tone scale and a pentatonic Indonesian Slendro tone scale shows that a 300 cents interval is used in the western tone scale but is not available in the Slendro tone scale.

This example only uses scala files, creating histograms is actually not needed: calculating intervals can be done using the scala file itself. This changes when audio files are compared with each other or with scala files.

Search Using Audio Files

When audio files are fed to the algorithm additional steps need to be taken.

  1. First of all pitch detection is executed on the audio file. Currently two pitch extractors are implemented in pure Java, it is also possible to use an external pitch extractor such as aubio
  2. Using pitch annotations a Pitch Histogram is created.
  3. Peak detection on the Pitch Histogram results in a number of peaks, these should represent the distinct pitch classes used in the musical piece.
  4. With the pitch classes a clean peak histogram is created during the Peak Histogram construction phase.
  5. Finally the Peak histogram is matched with other histograms.

The last two steps are the same for audio files or scala files.

Using real audio files can cause dirty histograms. Determining how many distinct pitch classes are used is no trivial task, even for an expert (human) listener. Tarsos should provide a semi-automatic way of peak extraction: a best guess by an algorithm that can easily be corrected by a user. For the moment Tarsos does not allow manual intervention.

Tarsos

To use tarsos you need a recent java runtime (1.6) and the following command line arguments:

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java -jar tarsos.jar rank --detector TARSOS_MPM 
--needle audio.wav --haystack scala.scl other_audio.wav other_scala_file.scl
  • Data flow audio

    Data flow audio

  • Data flow scala

    Data flow scala

  • 300 cents interval

    300 cents interval

  • 12ET and 300 cents

    12ET and 300 cents

  • Slendro and 300 cents

    Slendro and 300 cents

  • Realistic Tone scale

    Realistic Tone scale


~ Tarsos Spectrogram

Today I created a spectrogram application using Tarsos. The application listens to an audio input, computes an FFT and at the same time calculates pitch. The expected pitch is overlaid on the spectrogram. All this happens real-time and is implemented using JAVA.

spectrum with pitch information (red)

This is the most recent version of the spectrogram implementation in java.

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float pitch = Yin.processBuffer(buffer, (float) sampleRate);
fft.transform(buffer);
double maxAmplitude = 0;
for (int j = 0; j < buffer.length / 2; j++) {
        double amplitude = buffer[j] * buffer[j] + buffer[j + 
                buffer.length/2] * buffer[j+ buffer.length/2];
        amplitude = Math.pow(amplitude, 0.5);
        colorIndexes[j] = amplitude;
        maxAmplitude = Math.max(amplitude, maxAmplitude);
}

If you want to test it yourself download the spectrogram jar package and execute:

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java -jar spectrogram.jar

~ Tarsos on GitHub

The JAVA software program we are developing is called Tarsos and can now be found on GitHub. GitHub is a web-based hosting service for projects that use the Git version control system.

Currently Tarsos is a collection of Java classes to create, compare and process pitch-frequency data using histograms. In it’s current state it is not usable for end-users.

Credits

Tarsos is developed at University College Ghent, Faculty of Music and uses a number of open source libraries:

  • Gervill: a software sound synthesizer, supports the MIDI Tuning Standard. API.
  • Jave: a wrapper for ffmpeg.
  • Apache Commons Math: a library of lightweight, self-contained mathematics and statistics components API.
  • JASS: a unit generator based audio synthesis programming environment. API.
  • Java-getopt: a port of the GNU getopt family of functions. API.
  • Ptplot a 2D plotting library. API.

~ Dataset

The dataset we use is the sound archive of the department of Ethnomusicology of the Royal Museum for Central Africa at Tervuren, Belgium. The archive was digitized during the DEKKMMA project. More information about the dataset can be foun on the website of the DEKKMMA project:

The archive is a collection of sound recordings of traditional music from Central Africa, with a particular focus on Congo and Rwanda. The sound archive contains about 3,000 hours of music recordings, the oldest of which date from 1910: Edison cylinders recorded by Hutereau in the Uele-province in Congo.

The archive contains several sound carriers (Edison cylinders, Sonofil wire, magnetic tapes, audiocassettes, disks, CD’s …) with associated metadata (paper files) and contextual data (photographs, films, video’s, books, documents of all kind).

The collection was created during and after the colonial era of the Belgian Kingdom in Central Africa. The RMCA collection forms for an important part the musical memory of Central Africa and in terms of size, documentation and musical quality, it is – without any doubt – the world’s most important sound archive for this region.

Using the meta data we did a rough geocoding of each recording to create an interactive map of the dataset.

  • Dataset

    Dataset


~ Development and Application of MIR Techniques on Ethnic Music

About

The aim of this research project is to gain novel musicological insights into a large dataset of music from Central Africa. While practising ethnomusicological research on this dataset, we to develop and publish useful software and methodologies for the (ethno)musicological research community.

From November 2009 until November 2013 this research project was organised at the School of Arts, University College Ghent, under supervision by Olmo Cornelis. Later, from November 2013 onwards, the project turned into a 2 year doctoral research project hosted at IPEM, University Ghent under the supervision of Marc Leman.

Partners



Royal Museum For Central Africa University Ghent  Institute for Psychoacoustics and Electronic Music University College Ghent, Hogeschool Gent School of Arts, Ghent