Dan Barry

Clustering NMF basis functions using Shifted NMF for monaural sound source separation

Non-negative Matrix Factorization (NMF) has found use in single channel separation of audio signals, as it gives a parts-based decomposition of audio spectrograms where the parts typically correspond to individual notes or chords. However, a notable shortcoming of NMF is the need to cluster the basis functions to their sources after decomposition. Despite recent improvements in algorithms for clustering the basis functions to sources, much work still remains to further improve these algorithms. To this end we present a novel clustering algorithm which overcomes some of the limitations of previous clustering methods. This involves the use of Shifted Nonnegative Matrix Factorization (SNMF) as a means of clustering the frequency basis functions obtained from NMF. Results show that this gives improved clustering of pitched basis functions over previous methods.

Interacting with large music collections: Towards the use of environmental metadata

Large music collections afford the listener flexibility in the form of choice, which enables the listener to choose the appropriate piece of music to enhance or complement their listening scenario on-demand. However, bundled with such a large music collection is the demanding task of manually searching through each entry in the collection to find the appropriate song required by the listener. This paper highlights the need for contextual and environmental information, which ultimately defines the listenerpsilas listening scenario. Here, the preliminary results of an online music survey are analysed. These results indicate the possibility of how environmental features may be used as metadata to indicate the listenerpsilas mood. Therefore, environmental features, such as location, activity, temperature, lighting and weather have great potential as metadata and hence may be used to create a personalised automatic playlist generator for large music collections.

Enabling access to sound archives through integration, enrichment and retrieval

Many digital sound archives still suffer from tremendous problems concerning access. Materials are often in different formats, with related media in separate collections, and with non-standard, specialist, incomplete or even erroneous metadata. Thus, the end user is unable to discover the full value of the archived material. EASAIER addresses these issues with the development of an innovative remote access system which extends beyond standard content management and retrieval systems. The EASAIER system has been designed with sound archives, libraries, museums, broadcast archives, and music schools in mind. However, the tools may be used by anyone interested in accessing archived material; amateur or professional, regardless of the material involved. Furthermore, it enriches the access experience enabling the user to experiment with the materials in exciting new ways. The system features; enhanced cross media retrieval functionality, multi-media synchronisation, audio and video processing, analysis and visualisation tools, all combined within in a single user configurable interface.

A Real-Time Framework for Video Time and Pitch Scale Modification

A framework is presented which addresses the issues related to the real-time implementation of synchronized video and audio time-scale and pitch-scale modification algorithms. It allows for seamless real-time transition between continually varying, independent time-scale and pitch-scale parameters arising as a result of manual or automatic intervention. We illuminate the problems which arise in a real-time context as well as provide novel solutions to prevent artifacts, minimize latency, and improve synchronization. The time and pitch scaling approach is based on a modified phase vocoder with optional phase locking and an integrated transient detector which enables high-quality transient preservation in real-time. A novel method for audio/visual synchronization was implemented in order to ensure no perceptible latency between audio and video while real-time time scaling and pitch shifting is applied. Evaluation results are reported which demonstrate both high audio quality and minimal synchronization error.

Interactive Music Archive Access System

The goal of the Interactive Music Archive Access System (IMAAS) project was to develop an interactive music archive access system which was capable of allowing an end-user to easily extract rhythmic, melodic and harmonic musical metadata descriptors from audio, and allow the user to interact with the archive contents in a manner not typically allowed in archive access systems. To this end, the IMAAS system incorporates a range of real-time interaction tools which allow the user to modify the retrieved audio in a number of ways including the ability to isolate individual instruments in stereo mixes, pitch and time-scale modification, and beat-synchronous looping. This demo gives an overview of the capabilities of the IMAAS application.

The DiTME Project: interdisciplinary research in music technology

This paper profiles the emergence of a significant body of research in audio engineering within the Faculties of Engineering and Applied Arts at Dublin Institute of Technology. Over a period of five years the group has had significant success in completing a Strand 3 research project entitled Digital Tools for Music Education (DiTME), followed by successful follow-on projects funded through both the European Framework FP6 and Enterprise Ireland Commercialisation research schemes. The group has solved a number of challenging problems in the audio engineering field and has both published widely and patented a novel sound source separation invention.