4th International Linux Audio Conference
27-30 April 2006 @ ZKM Karlsruhe, Germany

The LAC2006 Conference Proceedings are available for download now (3 MB).

For the Internet Audience:
All time data is in UTC+2 = CEST (Central European Summer Time)

  Thursday 27 April 2006 - Lecture Hall
12:00 Fons Adriaensen
Acoustical Impulse Response Measurement with ALIKI

Slides Paper

The Impulse Response of an acoustical space can be used for emulation of that space using a convolution reverb, for room correction, or to obtain a number of measures representative of the room s acoustical qualities. Provided the user has access to the required transducers, an IR measurement can be performed using a standard PC equipped with a good quality audio interface. This paper introduces a Linux application designed for this task. The theoretical background of the method used is discussed, along with a short introduction to the estimated measures. A short presentation of the program's features is also included.

13:00 Lunch break
14:00 Arthur Clay, Thomas Frey and Jürg Gutknecht
Unbounded: Aos & The GoingPublik Software


GoingPublik is a work for distributed ensemble and wearable computers. The core idea behind the work is a strategy of mobility employing a wearable computer system running a software based electronic scoring system. The score allows for composed improvisation, which permits improvisational elements within a compositional structure. By electronically monitoring the performer s physical positions during performance using universal inputs such as geographical positions obtained via satellites and sensors using the earth s magnetic field, the score makes suggestions to various degrees and times. This paper shows how electronic scoring can be self-regulating and depicts how performers using it are able to interact with one another and to create a unique choreographic dispersion of sound in space.

15:00 Lee Revell
Realtime Audio vs. Linux 2.6

Slides Paper

From the beginning of its development kernel 2.6 promised latency as low as a patched 2.4 kernel. These claims proved to be premature when testing of the 2.6.7 kernel showed it was much worse than 2.4. I present here a review of the most significant latency problems discovered and solved by the kernel developers with the input of the Linux audio community between the beginning of this informal collaboration in July 2004 around kernel 2.6.7 through the most recent development release, 2.6.16-rc5. Most of these solutions went into the mainline kernel directly or via the -mm, voluntary-preempt, realtime-preempt, and -rt patch sets maintained by Ingo Molnar (Molnar, 2004) and many others.

16:00 Asbjørn Sæbø and Peter Svensson
A Low-Latency Full-Duplex Audio over IP Streamer

Slides Paper

LDAS (Low Delay Audio Streamer) is software for transmitting full duplex high-quality multi-channel audio with low end-to-end latency over IP networks. It has been designed and implemented as a tool for research into distributed multimedia interaction and quality of service in telecommunications. LDAS runs on Linux, using the ALSA sound drivers and li-braries. It uses UDP as its transport protocol. A ow control scheme is used to keep the sender and receiver synchronised and to deal with transmission errors. Tests have shown end-to-end latencies (from analog input to analog output) down to less than five milliseconds over a minimal network.

17:00 Marije Baalman
swonder3Dq: software for auralisation of 3D objects with Wave Field Synthesis

Slides Paper

swonder3Dq is a small software program to auralise three dimensional objects with Wave Field Synthe- sis. It presents a new approach to model the radia- tion characteristics of sounding objects.

  Friday 28 April 2006 - Lecture Hall
11:00 Yann Orlarey, Albert Gräf and Stefan Kersten
DSP Programming with Faust, Q and SuperCollider


Additional Material:
lac2006_albert_graef.tgz (11 MB)

Faust is a functional programming language for real-time signal processing and synthesis that targets high-performance signal processing applications and audio plugins. The paper gives a brief introduction to Faust and discusses its interfaces to Q, a general-purpose functional programming language, and SuperCollider, an object-oriented sound synthesis language and engine.

  Saturday 29 April 2006, Track I
11:00 Fons Adriaensen
Design of a Convolution Engine optimised for Reverb

Slides Paper

Real-time convolution has become a practical tool for general audio processing and music production. This is reflected by the availability to the Linux audio user of several high quality convolution engines. But none of these programs is really designed to be used easily as a reverberation processor. This paper introduces a Linux application using fast convolu-tion that was designed and optimised for this task. Some of the most relevant design and implementation issues are discussed.

12:00 Josh Green
Sampled Waveforms And Musical Instruments

Slides Paper

Sampled Waveforms And Musical Instruments (SWAMI)is a cross platform collection of applications and libraries for creating,editing, managing,and compressing digital audio based instruments and sounds.These instruments can be used to compose MIDI music compositions or for other applications such as games and custom instrument applications.Discussed topics will include:common instrument file formats,Swami application architecture,Python scripted instrument editing,CRAM instrument compression,PatchesDB a web based instrument database,and basic usage of Swami.
13:00 Lunch break
14:00 Frank Barknecht
128 Is Not Enough - Data Structures in Pure Data


A lesser known feature of Miller Puckette s popular audio and media development framework Pure Data is the possibility to create user defined graph-ical data structures. Although the data structures are included in Pd for several years, only recently a sigificant number of users discovered and used this feature. This paper will give an introduction to the possibilities of Pd s data structures for composers and musicians and present several example applications.

15:00 Eric Lyon
A Sample Accurate Triggering System for Pd and Max/MSP

Slides Paper

A system of externals for Pd and Max/MSP is described that uses click triggers for sample-accurate timing. These externals interoperate and can also be used to control existing Pd and Max/MSP externals that are not sample-accurate through conversion from clicks to bangs.

16:00 Victor Lazzarini
Scripting Csound 5

Presentation Material

This article introduces a scripting environment for Csound 5. It introduces the Csound 5 API and discusses it use in the development of a TclTk scripting interface, TclCsound. The three components of TclCsound are presented and discussed. A number of applications, from simple transport control of Csound to client-server networking are explained in some detail. The article concludes with a brief overview of some other Csound 5 language APIs, such as Java and Python.

17:00 Hartmut Noack
Linux and music out of the box

Slides Paper

The perception of Linux audio software amongst so-called "average musicians" with no "geek" background is not as positive as it could be. Many musicians still think that there is not enough usability and too little Linux software available to produce an album. This proposal introduces design studies for a user interface dedicated to a Linux Audio Workstation (LAW) that I intend to build based on standard PC hardware. The interface intends to integrate all the main virtues of Linux audio software in a logical and self explanatory way, without encumbering their flexibility, to provide the same level comfort and intuitive operation as offered by suites such as Steinberg's Cubase. There will be no install-CD to be downloaded, as offered by Distros like Demudi or Agnula, but only some useful scripts and LFS-style documentation to enable people to rebuild the box itself if they wish to do so.

  Saturday 29 April 2006, Track II
15:00 Daniel James and Free Ekanayaka
64 Studio - creative and native

Slides Paper

This paper describes the high integration of proprietary software for the creative desktop,and the effort involved in creating a free software alternative which will run natively on the latest 64 bit x86 hardware.It outlines the author's reasons for creating a 64 bit distribution based on Debian,the packages selected,the business model of the 64 Studio company and the challenges for future development.

  Sunday 30 April 2006 - Lecture Hall
12:00 Martin Rumori
footils. Using the foo Sound Synthesis System as an Audio Scripting Language


foo is a versatile non-realtime sound synthesis and composition system based on the Scheme programming language (Eckel and González-Arroyo, 1994; Rumori et al., 2004; Rumori, 2005). It is mainly used for sound synthesis and algorithmic composition in an interactive type-render-listen-loop (the musician s read eval print-loop) or in conjunction with an editor like the inferior mode of emacs. Unlike with other sound synthesis languages, foo programs are directly executable like a shell script by use of an interpreter directive. foo therefore allows for writing powerful sound processing utilities, so called footils.

13:00 Lunch break
14:00 Jürgen Reuter
Ontological Processing of Sound Resources

Slides Paper

Modern music production systems provide a plethora of sound resources, e.g. hundreds or thousands of sound patches on a synthesizer. The more the number of available sounds grows, the more difficult it becomes for the user to find the desired sound resource for a particular purpose, thus demanding for advanced retrieval techniques based on sound classification. This paper gives a short survey of existing approaches on classification and retrieval of sound resources, discusses them and presents an advanced approach based on ontological knowledge processing.

The programme is subject to change.