State of the Art: Linux Audio 2008, Part II

Many projects in this domain have strong development tracks. Bill Schottstaedt's great Snd continues to grow nicely, with many enhancements and fixes from its wide community of users and developers. Younger projects, such as Audacity (Figure 3), mhWaveEdit and Sweep, show current development, but unfortunately, the much-anticipated update for ReZound has yet to materialize, and we still await better JACK integration with Audacity and Sweep.

Figure 3. Audacity Soundfile Editor

LADSPA, the Linux Audio Developer's Simple Plugin API, is an excellent resource for audio plugin developers, and users now can enjoy many fine plugins created with the LADSPA API. Standout sets include Tim Goetze's CAPS suite, Steve Harris' indispensable SWH package and Tom Szilagyi's TAPS collection, but many other LADSPA gems are available. The overall collection continues to expand, albeit slowly.

The intentional simplicity of the LADSPA API necessarily restricted plugin designs primarily to effects and dynamics processing. The emerging LV2 specification takes LADSPA to the next level, particularly with regard to instrument plugins. LV2 competes with the DSSI (Disposable SoftSynth Interface), but the developers of both projects are working toward the common goal of providing Linux with something like the famous VST/VSTi plugin architecture for Windows.

Direct support for VST/VSTi plugins currently exists in two forms. Bridges, such as FST (FreeVST) and the dssi-vst utility, can run some native Windows VST/VSTi plugins directly under Linux, while Lucio Asnaghi's JOST Project works at porting open-source VST plugins to native Linux versions. Applications with support for VST/VSTi plugins (Windows or native Linux) include Ardour, Rosegarden, LMMS and QTractor. However, Ardour's support requires a special build procedure, and the resulting binary may not be redistributed.

The terms of the Steinberg API forbid the free redistribution of the VST SDK, so a mature LV2 is likely to be an attractive alternative for plugin developers. Time will tell, and although the specification is already a worthy contender, users need plugins. A few projects already address that need (see the list at lv2plug.in), but more would be better.

The developers of LMMS have resolved the issue in another way by coding a drop-in replacement for the needed VST SDK, making it possible to provide direct VST support without the Steinberg code. This development is recent, and it remains to be seen whether Linux audio developers will incorporate that solution into their own programs.

This domain can be divided between programs that function primarily as a composer's workspace and programs that function as music typesetting software. The magnificent LilyPond Project dominates the music typesetting category, and NtEd and Canorus are the best currently maintained notation-based composition interfaces. However, Werner Schweer's MuseScore rapidly is evolving into a superb WYSIWYG graphic interface for music composition, but it requires a cutting-edge installation of Qt and its other dependencies.

The Linux digital DJ can choose between two professional-grade mixers, UltraMixer and Mixxx, both of which are beyond their 1.0 releases and continue to display strong development tracks. Alexander Koenig's great “virtual scratcher” terminatorX has not been developed since 2004, but at version 3.82, it's safe to refer to it as mature.

The digital video jockey (VJ) is well served by the current crop of video mixers for Linux. Outstanding packages include FLxER, FreeJ, Gephex and Veejay, all of which work with video files and streams in ways analogous to the actions of audio disc jockeys. Video input can be scratched, stuttered, processed with special effects, and mixed with other video (and other media). Common laptops now are powerful enough to handle the audio and video resource demands of this evolving art form, especially if they're running Linux.

The Rivendell Project rules this domain. Rivendell (Figure 4) provides a complete solution for radio broadcasters (air-wave or network-based) who want to automate all or any part of their operations. The suite is an impressive achievement, with a fully professional set of features “...for the acquisition, management, scheduling and playout of audio content”, according to its Web site. The latest public release is version 1.0, and the project development status is current and ongoing.

Figure 4. Rivendell's Air Play/Main Log Panel