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Linux Audio Mini-Conference

Jan 12 2004, Adelaide, South Australia

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10:00 Mark Greenaway: Linux Audio demos

The state of the art has advanced a great deal in Linux audio over the past couple of years. A finished piece of music incorporating digital audio, wavetable and virtual analogue synthesis can be produced entirely using free software tools.

I'll be demonstrating a selection of these tools and also important technologies enabling them such as JACK, ALSA and realtime scheduling.

I'll be demonstrating the following applications and tools:

  • sweep - sample oriented audio editor that supports LADSPA plugins
  • audacity - noise removal
  • fluidsynth - wave table synthesis/sample playback
  • alsamodularsynth - virtual analogue modular synthesis
  • hydrogen - drum machine/sequencer
  • ardour - multitrack recording and editing software, resembling ProTools
  • Muse/Rosegarden - MIDI/audio sequencers
  • freqtweak - All purpose audio mutilation

Mark has been using Linux since 1994, but he's far too busy trying to learn to play guitar better to have written any programs worth releasing. He plays guitar in Thatch Noir and has a habit of joining bands that never go anywhere.

12:00 Peter Chubb: Typesetting music with Lilypond

Music typesetting is hard. There are many packages to try to typeset music, but to get really beautiful results (i.e., easy to read when it's plonked on a music stand in front of you in the poor light that most of the venues I go to think is adequate for musicians), you have to do a *lot* of tweaking (or spend a fortune).

The three problems in music typesetting are:

  1. Inputting the music. Midi is fine for many instrument players, but I don't have a MIDI voicebox. GUIs are good for adjusting music once it's entered, but I've found them tedious for entering a whole score. So you're down to a music description language as the best general case.
  2. Checking the result. That's relatively easy; most programs will generate MIDI and let you listen to the result.
  3. Generating beautiful, easy-to-read output. Although you can get something printable from almost all the music typesetting programs, the input generally requires lots of tweaking to get something beautiful.

Enter Lilypond. Lilypond is a music typesetting tool that takes a text input language, and generates LaTeX. Lilypond encodes within it standard formats that result in very good output for most ordinary cases --- just as LaTeX did for TeX. Its input language uses Guile as an extension, so is almost infinitely flexible. And the output *is* beautifully readable.

Of course, Lilypond does have some drawbacks. In the talk, I'll give a quick demo, and talk about the good things and the bad things in Lilypond.

Peter Chubb is a kernel hacker, working with the open-source Gelato project at UNSW.

14:00 Tim Opie: jMusic and audio synthesis

jMusic is a programming library written for musicians in the Java programming language. This project hopes to develop a library that is simple enough for newbie programmers but sophisticated enough to enable composers to accomplish real work, whatever form that may take. jMusic is designed to be used as a compositional medium, therefore it is primarily designed for musicians - not computer programmers. jMusic includes audio synthesis and DSP, as well as full MIDI control. jMusic is open-source(GPL), and runs on most computer platforms.

This presentation will introduce the audience to jMusic and the tools that are contained within. A more indepth look at the audio synthesis processing applications will then be given, including the audio tools I am currently working on. The presentation will be given from more of a compositional angle, which for a lot of computer programmers is probably a very different angle, but it is the philosophy behind the structure and a lot of the decision making for how things work in jMusic.

See also:

15:00 Erik de Castro Lopo: The PDAudio Project

The PDAudio project uses Familiar Linux running on a HP/Compaq iPAQ Personal Digital Assistant (PDA), and a purpose built I/O card to record high quality digital audio at up to 96kHz, 24 bit, stereo onto Compact Flash memory cards.

The project was initiated by Len Moskowitz in the US who brought together hardware designers in the UK, Jaroslav Kysela in the Czech Republic who wrote the ALSA driver for the hardware and the author based here in Australia who wrote the recording application.

The project is interesting for the following reasons:

  • The way the project came together and the fact that the code will be released under the GPL.
  • The target system consists of a Strong-ARM CPU and all development work was done by cross-compiling from an x86 Linux machine.
  • The application's GUI was built using the same GTK+ widget set that is used by so many other Linux apps.
  • An audio recorder like this has a soft-real-time requirements.
  • The use of a number of advanced programming features of the Unix API including fork, multi-threading, mprotect, mmap, sched_set_scheduler and others.
  • Many interesting problems and solution were found.

See also Len Moskowitz's web page for PDAudio

Erik is the author of libsndfile and Secret Rabbit Code. He will be at this miniconf "with bells on!". Erik presented a tutorial on Linux DSP development at LCA2002 in Brisbane.

16:00 Conrad Parker: Remix

Remix is a C library for audio sequencing and mixing. It allows hierarchical, recursive composition of samples, PCM synthesis modules and LADSPA effects. It can be used for offline processing or within interactive applications.

Conrad is the author of the sound editor Sweep. He presented a tutorial on using Sweep at LCA2003 in Perth.

16:30 André Pang: DJing Beyond the Turntable

Vinyl and turntables have been the traditional components of the DJ for several decades. Even though musical technology has advanced greatly in that time period--in particular with computers and digital audio systems offering sound and music manipulation possibilities far beyond that of turntable-based mixing setups--DJing software on computers still seeks to emulate the traditional turntable metaphor in their user interfaces. In this talk, we explore user interfaces and concepts which permit live DJing to be performed much more easily than using turntable-based metaphors. These different DJ interfaces enable a new range of music manipulation techniques, such as just-in-time, on-the-fly edits and remixes of songs which can be tailored to the DJ's audience. To show that our ideas are not just theoretical, we will show a demonstration of how DJing can be performed much more easily than via the traditional turntable metaphor, using an open-source prototype implementation of our ideas.

Originally inspired by the music from the demoscene, André placed second in the Assembly'97 multichannel music competition, has a degree in audio engineering, mixes DJ sets entirely on computer, and doesn't do anywhere near enough clubbing as he should.