Thesis
Title: An Explorative, Hierarchical User Interface to Structured Music Repositories
Short Version (10 Pages + References and Figures): PDF
Abstract: Due to efficient compression
algorithms like MP3, the number as well as the size of digital music repositories
have increased dramatically over the past few years. Hence, effective methods
for finding pieces of music in such repositories are becoming more and more
important. Unfortunately, when working with traditional user interfaces which
solely provide text-based search, the user already has to know certain textual
properties of the songs he/she is looking for (e.g. name of the artist or album).
In contrast, the user interface which has been developed for this thesis is
based on graphical visualizations of musical similarities between the pieces
contained in the repository. This enables the user to exploratively browse through
the collection, an approach which is especially useful for discovering formerly
unknown pieces of music.
In order to provide different views of the music collection, five algorithms
which process the audio signals to measure musical similarities were analyzed.
For this purpose, an evaluation using the results of a manual classification
perfomed by the author was conducted. This manual classification is based on
a test repository composed of more than 800 MP3-files. Eventually, one rhythm-based
and one timbre-based algorithm were selected.
The developed user interface ViSMuC (Visualization of Structured
Music Collections) implements a method called Aligned Self-Organizing Maps in
which high-dimensional data is represented by a 2-dimensional map. The pieces
of music are visualized according to an adjustable weighting of their rhythmic
and timbral properties. Forming clusters of similar pieces, the resulting groups
are colored with respect to the number of songs they represent. Different colormaps
are available for this purpose. Since illustrating all pieces of a medium or
large collection on a single map would yield a tremendously complex and thus
unusable visualization, the user interface contains two hierarchical components.
Firstly, for each region of the map that represents a large number of songs,
a new map is provided. Secondly, the directory structure of the repository usually
forms a user-defined hierarchy which is also taken into account. Another important
part of the user interface is the visualization of arbitrary meta-information,
which can be taken, for example, from ID3-attributes or external databases.
The used technique illustrates the distribution of the values assigned to the
meta-information attributes over the complete map. Together with visualizations
that are based on the features gained from the similarity measures and their
projection to the map, the images showing these distributions facilitate the
interpretation of the map.