Hi, I'm Joren. Welcome to my website. I'm a researcher in the field of Music Informatics, Music Information Retrieval, and Computational Ethnomusicology. Here you can find a record of my research and other projects I have been working on. Learn more »


Joren Six
University Ghent, IPEM

~ Audio Fingerprinting - Opportunities for digital musicology

The 27th of November, 2014 a lecture on audio fingerprinting and its applications for digital musicology will be given at IPEM. The lecture introduces audio fingerprinting, explains an audio fingerprinting technique and then goes on to explain how such algorithm offers opportunities for large scale digital musicological applications. Here you can download the slides about audio fingerprinting and its opportunities for digital musicology.

With the explained audio fingerprinting technique a specific form of very reliable musical structure analysis can be done. Below, in the figure section, an example of repetitive structure in the song Ribs Out is shown. Another example is comparing edits or versions of songs. Below, also in the figure section, the radio edit of Daft Punk’s Get Lucky is compared with the original version. Audio synchronization using fingerprinting is another application that is actively used in the field of digital musicology to align audio with extracted features.

Since acoustic fingerprinting makes structure analysis very efficiently it can be applied on a large scale (20k songs). The figure below shows that identical repetition is something that has been used more and more since the mid 1970’s. The trend probably aligns with the amount of technical knowledge needed to ‘copy and paste’ a snippet of music.

How much identical repetition is used in music, over the years

Fig: How much identical repetition is used in music, over the years.

The Panako audio fingerprinting system was used to generate data for these case studies. The lecture and this post are partly inspired by a blog post by Paul Brossier.

  • Structure in Ribs Out

    Structure in Ribs Out

  • Spectral peak Acoustic fingerprinting system

    Spectral peak Acoustic fingerprinting system

  • How much identical repetition is used in a set of 20k songs.

    How much identical repetition is used in a set of 20k songs.

  • Radio edit vs. original of Daft Punk's Get Lucky

    Radio edit vs. original of Daft Punk's Get Lucky

~ ISMIR 2014 - Panako - A Scalable Acoustic Fingerprinting System Handling Time-Scale and Pitch Modification

Panako poster At ISMIR 2014 i will present a paper on a fingerprinting system. ISMIR is the annual conference of the International Society for Music Information Retrieval is the world’s leading interdisciplinary forum on accessing, analyzing, and organizing digital music of all sorts. This years instalment takes place in Taipei, Taiwan. My contribution is a paper titled Panako – A Scalable Acoustic Fingerprinting System Handling Time-Scale and Pitch Modification, it will be presented during a poster session the 27th of October.

This paper presents a scalable granular acoustic fingerprinting system. An acoustic fingerprinting system uses condensed representation of audio signals, acoustic fingerprints, to identify short audio fragments in large audio databases. A robust fingerprinting system generates similar fingerprints for perceptually similar audio signals. The system presented here is designed to handle time-scale and pitch modifications. The open source implementation of the system is called Panako and is evaluated on commodity hardware using a freely available reference database with fingerprints of over 30,000 songs. The results show that the system responds quickly and reliably on queries, while handling time-scale and pitch modifications of up to ten percent.

The system is also shown to handle GSM-compression, several audio effects and band-pass filtering. After a query, the system returns the start time in the reference audio and how much the query has been pitch-shifted or time-stretched with respect to the reference audio. The design of the system that offers this combination of features is the main contribution of this paper.

The system is available, together with documentation and information on how to reproduce the results from the ISMIR paper, on the Panako website. Also available for download is the Panako poster, Panako ISMIR paper and the Panako poster.

  • General fingerprinter

    General fingerprinter

  • Fingerprint and modifications

    Fingerprint and modifications

  • Results after pitch shifting

    Results after pitch shifting

  • Results after time scale modification

    Results after time scale modification

  • Results after time stretching

    Results after time stretching

~ TarsosDSP PureData or MAX MSP external

Pitch detection pure data patch It makes sense to connect TarsosDSP, a real-time audio processing library written in Java, with patcher environments such as Pure Data and Max/MSP. Both Pure Data and Max/MSP offer the capability to code object, or externals using Java. In Pure Data this is done using the pdj~ object, which should be compatible with the Max/MSP implementation. This post demonstrates a patch that connects an oscillator with a pitch tracking algorithm implemented in TarsosDSP.

To the left you can see the finished patch. When it is working an audio stream is generated using an oscillator. The frequency of the oscillator can be controlled. Subsequently the stream is send to the Java environment with the pdj bridge. The Java environment receives an array of floats, representing the audio. A pitch estimation algorithm tries to find the pitch of the audio represented by the buffer. The detected pitch is returned to the pd environment by means of outlet. In pd, the detected pitch is shown and used for auditory feedback.

PitchDetectionResult result = yin.getPitch(audioBuffer);
pitch = result.getPitch();
outlet(0, Atom.newAtom(pitch));

Please note that the pitch detection algorithm can handle any audio stream, not only pure sines. The example here demonstrates the most straightforward case. Using this method all algorithms implemented in TarsosDSP can be used in Pure Data. These range from onset detection to filtering, from audio effects to wavelet compression. For a list of features, please see the TarsosDSP github page. Here, the source for this patch implementing pitch tracking in pd can be downloaded.

~ TarsosDSP on Android - Audio Processing in Java on Android

Audio on AndroidThis post explains how to get TarsosDSP running on Android. TarsosDSP is a Java library for audio processing. Its aim is to provide an easy-to-use interface to practical music processing algorithms implemented, as simply as possible, in pure Java and without any other external dependencies.

Since version 2.0 there are no more references to javax.sound.* in the TarsosDSP core codebase. This makes it easy to run TarsosDSP on Android. Audio Input/Output operations that depend on either the JVM or Dalvik runtime have been abstracted and removed from the core. For each runtime target a Jar file is provided in the TarsosDSP release directory.

The source code for the audio I/O on the JVM and the audio I/O on Android can be found on GitHub. To get an audio processing algorithm working on Android the only thing that is needed is to place TarsosDSP-Android-2.0.jar in the lib directory of your project.

The following example connects an AudioDispatcher to the microphone of an Android device. Subsequently, a real-time pitch detection algorithm is added to the processing chain. The detected pitch in Hertz is printed on a TextView element, if no pitch is present in the incoming sound, -1 is printed. To test the application download and install the TarsosDSPAndroid.apk application on your Android device. The source code is available as well.

AudioDispatcher dispatcher = AudioDispatcherFactory.fromDefaultMicrophone(22050,1024,0);

PitchDetectionHandler pdh = new PitchDetectionHandler() {
        public void handlePitch(PitchDetectionResult result,AudioEvent e) {
                final float pitchInHz = result.getPitch();
                runOnUiThread(new Runnable() {
                    public void run() {
                        TextView text = (TextView) findViewById(R.id.textView1);
                        text.setText("" + pitchInHz);
AudioProcessor p = new PitchProcessor(PitchEstimationAlgorithm.FFT_YIN, 22050, 1024, pdh);
new Thread(dispatcher,"Audio Dispatcher").start();

Thanks to these changes, the fork of TarsosDSP kindly provided by GitHub user srubin, created for a programming assignment at UC Berkley, is not needed any more.

Have fun hacking audio on Android!

~ Haar Wavlet Transform in TarsosDSP

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 example is available at the TarsosDSP release directory, the code can be found on the TarsosDSP github page.

  • Haar Wavelet Audio Compression

    Haar Wavelet Audio Compression

~ TarsosDSP Spectral Peak extraction

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.

    Spectral peaks of a flute. The first 10 harmonic are detected up until the Nyquist frequency.

~ International School on Systematic Musicology and Sound and Music Computing (ISSSM) 2014, Genova

From 9 to 20 March 2014 I was a student at the International School on Systematic Musicology and Sound and Music Computing. The aim of the course was to:

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.
  • Rolf Bader, Sound – Perception – Performance

ISSSM 2014 logo

~ TarsosDSP Paper and Presentation at AES 53rd International conference on Semantic Audio

TarsosDSP will be presented at the AES 53rd International conference on Semantic Audio in London . During the conference both a presentation and demonstration of the paper TarsosDSP, a Real-Time Audio Processing Framework in Java, by Joren Six, Olmo Cornelis and Marc Leman, in Proceedings of the 53rd AES Conference (AES 53rd), 2014. From their website:

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

A BibTeX entry for the paper can be found below.

  author      = {Joren Six and Olmo Cornelis and Marc Leman},
  title       = {{TarsosDSP, a Real-Time Audio Processing Framework in Java}},
  booktitle   = {{Proceedings of the 53rd AES Conference (AES 53rd)}}, 
  year        =  2014
  • Pitch Shifting

    Pitch Shifting

  • Samping


  • Flanger


  • Constant-Q


  • AES53


~ Doctoral defense Olmo Cornelis - Exploring the Symbiosis of Western and non-Western Music

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

~ IPEM D-Jogger featured on RTBF

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.

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