The 2nd annual Linux audio software conference took place again at the wonderful ZKM (Zentrum fur Kunst und Medientechnology) in Karlsruhe, Germany, from April 29 through May 2. Last year's conference was successful enough to acquire greater sponsorship this year, with significant contribution from ZKM itself and SuSE. Community support was much expanded, with more than 30 presentations and workshops, four concerts, a dance and a final round-table discussion.

Given the necessary restrictions of publication, it is not possible to relate more than a superficial account of the conference, so I limit myself here to enumerating the topics and giving brief reports where applicable. If this conference suffered from any fault it had to be the sheer number of presentations. Due to the quantity of topics, it was necessary to schedule parallel presentations, so no one could attend every presentation. Of course, this was no real fault at all; if the organizers had not scheduled simultaneous presentations, the conference could have lasted for eight days instead of four. This might have been pleasing to the participants but it certainly would have exhausted even the formidable patience and resources of the conference hosts and organizers.

The quality and depth of the presentations naturally varied, and the overall tone of discourse was technical without being obscure. Presenters came from almost every European nation, and all presented in English with skills at least passable and more often quite good--better than many of my countrymen, in fact. At no time did I find myself straining to understand what was said, and I must thank all the topic presenters for their English-speaking efforts.

In addition to the officially scheduled presentations, many impromptu BOF (birds of a feather) sessions were announced. Some of those sessions were attended as heavily as the official topics, and I suspect we'll see some of them attain official status next year. Hardware manufacturers were represented by the makers of the Lionstracs Mediastation X76 and the Hartmann Neuron synthesizers. Other hardware manufacturers were present as attendees, so perhaps next year we'll see an expansion of hardware-focused presentations.

By the way, I must confess that I found it difficult to attend some presentations simply because I was meeting so many new friends and having so many interesting conversations. Often I looked at the clock only to find that I had missed a topic completely while engaged in an absorbing impromptu dialog, and I suspect I'm not the only person who had that problem.

My own pace of activity was defined by the circumstances of my arrival in Karlsruhe. The train from the Frankfurt airport rolled into the Karlsruhe station at 10:59 AM, my keynote address was scheduled to begin at 11:00 AM, so six minutes after arriving in Karlsruhe I was in a lecture hall at ZKM, ready to deliver the kickoff speech. From that time until Sunday evening, my life was a whirlwind of presentations, meetings, workshops and lengthy late-night conversations. Like last year, I averaged about five hours of sleep per night, yet I must admit that this pace was more exhilarating than exhausting.

My kickoff speech was followed by presentations by Jaroslav Kysela and Takashi Iwai. Both developers are core ALSA programmers, so their presentations naturally focused on the advances and future of the ALSA sound system. ALSA is now the default sound system for the Linux kernel. Jaroslav provided a brief overview of ALSA's history in the past year, while Takashi's presentation focused on user-level troubleshooting techniques, illustrating many great tools for newbies and those of us who are not-so-newbies.

Paul Davis is perhaps the most widely respected Linux audio developer, both for his outstanding contributions to the software base as the chief architect of the Ardour and JACK projects and for his generosity and civility towards his colleagues. His first presentation gave us a look at his recent libfst project, a system for seamlessly integrating VST/VSTi plugins into the Linux audio software universe. VST/VSTi plugins are fundamental to the Windows/Mac audio software worlds, and their incorporation into Linux is a win for everyone. Incidentally, Paul's project builds upon work begun by Kjetil Matheussen at Norway's NoTAM and expanded by Torben Hohn, author of the gAlan system.

Developer Bob Ham revealed plans for his Linux Audio Session Handler (LASH), a system for saving and restoring the states of and connections between any number of LASH-aware audio applications. LASH is a much-needed system. As Linux audio applications continue to subscribe to the JACK bus, a means for saving and restoring their states becomes most valuable. Restoring the connections for a few applications is not particularly burdensome, but as more applications are used the LASH system becomes a necessity. LASH is still in its infancy, and interested developers are urged to contact Bob Ham through the Linux Audio Developers mail list (see Resources).

Fernando Pablo Lopez-Lezcano is best known to the Linux audio software community as the developer and maintainer of the Planet CCRMA packages, a set of RPMs designed to make a simpler entry point for new users interested in learning about Linux audio software. However, Fernando is also a respected composer and teacher, and his topic presentation focused on his use of the Lisp programming language in the Common Music and Common Lisp Music music composition and synthesis environment. This presentation was successful enough to warrant a BOF workshop, a good indicator of interest in the subject and Fernando's abilities as an enthusiastic instructor.

Day 1's final presentation came from Thomas Grill. Thomas presented his flext system, which writers of external additions for the popular Max/MSP and Pd sound synthesis systems can use to write code-compatible versions of their extensions. Flext especially is valuable in light of the fact that Max/MSP is commercial while Pd is free software.

As the television commercials say, "But wait, that's not all!". Day 1 ended with the first of four scheduled concerts, presenting works by Michael Edwards, Ludger Brummer, Fernando Lopez-Lezcano and Orm Finnendahl. All the pieces were composed with the use of free software tools, and each piece had its singular attractions. The overall style could perhaps be summarized as "non-beat-oriented electroacoustic music", and while it may not be to everyone's liking I'm quite fond of such music and I greatly enjoyed this concert. I must add that all the conference concerts took place in ZKM's extraordinary Kubus, a marvelous hall designed for performance and recording.

The second day started with two presentations by Pd mavens Orm Finnendahl and Frank Barknecht. At the same time, Martin Rumori presented his work on the foo sound synthesis language. After lunch the presentations continued with topics from Ivica Bukvic (on his RTMix interactive multimedia performance software , Yann Orlarey (on the FAUST audio programming language), Han-wen Nienhuys (music notation with LilyPond), Matthias Nagorni (demonstrating his Alsa Modular Synthesizer) and Fons Adriaensen (showing off his AEOLUS pipe organ synthesizer). Other demonstrations and presentations included Orm Finnendahl's personal use of Linux as a composer's workstation, Marije Baalman's use of wave field synthesis as utilized in her installation at ZKM, Benno Sennoner's revelations regarding the LinuxSampler project and a report from Christian Muhlethaler and Alexander Schuppisser on designing client software for the SuperCollider3 synthesis environment.

While these presentations took place, many other conference participants were on-hand for a Linux installation fest. For users a little too anxious about installing Linux there were also live CDs available from SuSE, the AGNULA/Demudi project and the APODIO group. Installfests have become quite popular at many Linux conferences, providing an excellent opportunity to see how the job is done and to pose questions to some of the outstanding talents in Linux development. The live Linux CD also has become a popular way to introduce Linux to potential new users without touching the base hardware, that is, nothing is installed to the user's hard-disk. The Demudi and APODIO live discs provide a wonderful means of introducing the new world of Linux audio software and are likely to become a common path for many new converts to the Way of the Penguin.

Stephen Bernsee (aka Stephen Sprenger) and associates provided the final presentation on Day 2 with their demonstration of the Hartmann Neuron Synthesizer. The Neuron is a Linux-powered general-purpose synthesizer with a unique software engine, using a neural network to process and shape sounds based on the output from an audio analysis program. Analysis/resynthesis is itself an old and honorable method of creating sound with computers, but the Neuron is unique in its use of a neural network at the resynthesis stage. The sound of the synth is quite good, although it would have been nice to hear more from this interesting hardware.

I must add that the Lionstracs group set up their Mediastation X76 in a main hallway for all to hear and play. I loved this machine, it has great sound and is filled with more musical amenities than I can name here. Dominico Colturato and his team (which includes the irrepressible Benno Sennoner) have much to be proud of with the Mediastation, and I sincerely wish them great success in the hardware synth world.

Day 3 began with one of the most eagerly anticipated presentations. Paul Davis's Ardour is one of the major projects in the Linux audio software community, and attendance for his presentation clearly reflected its importance. Though plagued by crashes caused by an errant plugin, Paul's demonstration was enjoyable and illuminating. Ardour is definitely a deep application, and Paul's demonstrations always impress me. Invariably I leave his Ardour demos saying to myself, "I didn't know it could do that!", and I suspect many people left this demonstration thinking the same thing.

After Ardour what could be more fitting than a slam course in audio engineering? Steve Harris and Joern Nettingsmeier provided exactly such a course, a two-hour "Audio Engineering in a Nutshell" presentation that enhanced and extended Steve's presentation from last year's conference. Alas, I was unable to attend this presentation, opting instead for Stefan Kersten's informative status report on his work to provide a GUI for SuperCollider3 on Linux. The day continued with topic presentations from Victor Lazzarini (signal processing application development at the National University of Ireland), Francois Dechelle and Patrice Tisserand (audio networking at IRCAM), Julien Claassen (Linux audio without GUIs) and yet more from Fons Adriaensen on using JAAA tools for precise audio measurement.

Once again I was unable to attend most of those presentations due to scheduled meetings with other interest groups. I did take time to watch Steve Harris's excellent presentation of the JAMin mastering suite. Mastering audio is one of those mysterious blends of science, engineering and art, and Linux now can claim proudly an outstanding tool for this unique and necessary stage of the recording process. Steve's demonstration provided a quick overview of the mastering process and revealed much of the rationale behind JAMin's design.

Following a break for dinner and beer, it was music, music and more music. Concert #2 was really more of a concert/demonstration event, with developers Julien Claaasen, Matthias Nagorni, Fons Adriaensen and Thomas Grill showing off their wares. Concert #3 continued the musical trends of the first night's concert, with compositions from Ramon Gonzalez-Arroyo, Matthew Burtner, Torsten Anders, Ivica Ico Bukvic, Panayiotis Kokoras and ZKM's own Ludger Brammer.

For those participants whose musical desires remained unfulfilled by three concerts, Day 3 offered an electronica concert with music and performances from Malte Steiner, Frank Barknecht, Eugene Kim, the ap group, Krzysztof Gawlas, Greg Kellum and Diemo Schwarz. Finally, the evening ended with dance music from DJ Lego and a party with students and other local citizens mingling with the conference population. It was a great opportunity for drinking, dancing and random casual conversation, and I hope the organizers plan another such evening for next year's meeting.

Computer music stalwart Dave Topper kicked off the last day of the conference with an introduction to his Graphical Audio Interface Application, while at the same time Stephane Letz reported on his work at GRAME porting and integrating the JACK audio server to the Mac OS X. Dave Topper then was joined by Matthew Burtner for a discussion of their work on "recombinant spatialization for ecoacoustic immersive environments" (sic). Andrea Glorioso summarized and projected the work of the AGNULA project. After lunch, I presented my own topic focused on various aspects of writing and publishing documentation for Linux audio software, with emphasis on issues surrounding user-level documentation and an overview of doing business as a Linux journalist and documentation writer. Following my presentation, Ivica Ico Bukvic discussed his experiences with and recommendations for introducing Linux as a viable alternative in the academic music & sound worlds.

The final scheduled event was a round-table discussion of the future of Linux audio software. Panel members included Fernando Lopez-Lezcano, Paul Davis, Takashi Iwai, Abdrea Glorioso, Ivica Ico Bukvic and myself. This discussion was a rather loose and casual conversation that served the purpose of wrapping up this wonderful conference. Topics ranged from predictions for the future of Linux audio software to our personal plans upon arrival home (mine was to sleep for three days). At the end of the discussion, plans for next year's conference were announced along with the happy news that it again would be held at ZKM.

A long last hurrah was held over pizza and beer at an excellent local restaurant, and once more we parted ways in the wee hours of the night, this time scattering to the corners of the world. I think it's fair to say we all returned home with new resolve and inspiration, and I'm sure many great things will come as a direct result of LAC2004.

Check the show Web site for updates on the availability of archived audio files, photographs and other documentation regarding LAC2004. This material might not be on-line yet, so please keep checking. Perhaps someone could add a comment below when the material is available. I also would like to send very special praise and thanks to Joern Nettingsmeier for his work setting up and maintaining the live audio feed throughout the conference. The archived audio should be available soon, so you can listen to the entire conference (minus the music, alas) at your leisure.

Great thanks and appreciation go to Goetz Dipper, Frank Neumann, Matthias Nagorni, Ludger Brummer and all the administration and staff at ZKM for their technical assistance and personal attention to the many matters and arrangements surrounding a conference of this size and scope. Schedules were maintained smoothly, technical preparations were complete and ready for use and help was always available to anyone needing directions or any other further assistance. ZKM is a fabulous place, perfect for a Linux audio conference. If you didn't make it there this year you'll have another chance to see Karlsruhe, ZKM and the remarkable crew of Linux audio developers and users during LAC2005. I hope to see you there!