Welcome to AGNULA, "A GNU/Linux Audio" software distribution. On this disc you will discover a wide variety of sound and music applications, all running under the GNU/Linux operating system and all for free. Free software in the context of the AGNULA distribution takes its meaning from the definitions put forth by the Free Software Foundation. To qualify as truly free the software must ensure the following liberties to its users and developers :
The AGNULA distribution is designed to give musicians an entire Linux system optimized for sound and music production. AGNULA is based on these premises :
THE GNU/LINUX AUDIO SYSTEM
Almost all Linux distributions include an audio system, normally comprised of the lowest-level sound support (kernel modules and drivers), a middle tier of necessary ancillary software (mixer, format converter, file players, etc.), and the highest level of the applications software. AGNULA adheres to this basic division of system levels, but at each level we find a high degree of customization and optimization.
Underneath It All
At the kernel level only the soundcore object is retained. AGNULA's audio driver system is the latest package from ALSA (the Advanced Linux Sound Architecture), a project designed to replace the ageing OSS/Free kernel sound driver modules. ALSA provides users with support for a modern sound system and provides developers with a modern audio applications programming interface (API). The project supports a wide variety of consumer-grade soundcards and audio chipsets, but it also includes support for some excellent professional and semi-pro audio interfaces. ISA, Plug-and-Play, PCI, USB, and serial port devices are all supported under ALSA. For developers the ALSA API has resulted in a high degree of interoperability between applications, giving the user the ability to freely connect ALSA-aware applications in creative and productive configurations.
AGNULA's Linux kernel has been optimized for low-latency. The patches that have been applied can dramatically reduce latency in multimedia systems to well within professionally acceptable ranges, demonstrating another powerful aspect of the GNU/Linux system. In addition to the low-latency patches we have applied the preemptive kernel patch to ensure low-latency over extended periods of time (e.g., more than 24 hours continuous performance). The realtime clock driver has been compiled into the kernel to provide high-accuracy timing for RTC-aware applications. Finally, kernel support for optimized hard-disk usage has been enabled and the hdparm utility is invoked during system start-up to ensure peak disk I/O.
The Middle Ground
AGNULA's middle tier software includes the various ALSA utilities (such as the alsamixer and aconnect programs) and the JACK audio connection kit, a low-latency sound server for a network of JACK-aware clients. We have included as many such clients as could be found, and we have encouraged all Linux audio developers to provide JACK support in future versions of their software. AGNULA also includes support for the LADSPA plugins from Richard Furse's Computer Music Toolkit (CMT) and Steve Harris's collection. LADSPA is the Linux Audio Developers' Simple Plugin Architecture, an API that has engendered some excellent plugins that are available for use by any LADSPA-aware application.
The distribution strives to make the low- and middle-level software layers as transparent as possible to the new user. Utilities such as alsamixer or aconnect are always available from the master menu or the command line. We have also provided versions of those (and other) utilities with GUIs for users working in the X window system, such as the alsamixergui, ALSA MIDI Patch Bay, and QJackConnect software. Sox is another such piece of middle level utility software. SoX has been called "an audio Swiss Army knife" in recognition of its variety of uses. SoX is best known for its file format conversion utility, but it also provides a simple player and recorder along with a respectable selection of special effects such as reverb and chorus. AGNULA includes the standard-issue command-line version of Sox and a version with GUI for X.
At The Top
At last we arrive at the level of most interest to the normal user: applications ! GNU/Linux has long enjoyed a large number of useful audio and MIDI applications, and AGNULA has combed such listings as Freshmeat and the Linux Sound & Music Applications sites for the best of free audio software. So what will you actually find here ? Well, let's take a quick look at the kinds of software included with AGNULA :