Ardour A Versatile, Open Source Digital Audio Workstaion
What is Ardour? Recording Mixing Editing Mastering Live Audio Effects Supports Linux and OS X. ProTools Logic (Mac) Sonar Studio (PC) Nuendo Cubase LE Digital Performer (Mac) GarageBand
JACK A versatile audio routing subsystem. Allows you to route physical inputs to multiple programs simultaneously. Allows you to connect outputs and inputs of programs into each other. Low latency Ardour uses this for its backend interfacing. It does not directly interface with the hardware.
Plug-in Support Ardour primarily supports the LADSPA plug-in format. (Linux Audio Developers Simple Plugin API) LADSPA plug-ins are open source and there are a large number of them available. If Ardour is running on OS X, it also natively supports Apple's Audio Units (AU) plug-ins. Ardour can also be compiled with native VST support, but this is not distributed with any of the binaries. Any plug-ins not supported can likely be run in stand alone mode and routed into Ardour through JACK.