ClockLoop is a very simple JACK application for playing back audio loops.
Available as a source tarball.
ALSA, JACK and libsndfile.
Untar, run make. If it doesn't build its because you one of the required packages is not installed or in a weird place, hack the Makefile to fix it.
su -c "make install" to install, there is no uninstall, but it just installs one binary (clockloop) so it should be easy enough to get rid of.
Example: clockloop loop*.wav
Once its running you will need to hook up its ALSA sequencer MIDI inputs to a source of MIDI data and its JACK outputs to something.
Note on or Program change MIDI messages cause the program to switch between loops, cross-fading over the period of one loop. When it starts it will be playing loop 0 (the first one on the command line).
This program was written by Steve Harris, who was in a need of a very lightweight JACK loop player in a hurry. He used it for a gig, playing back loops captured by TimeMachine, another app originally written for that gig.
Its called ClockLoop because it was originally supposed to emit MIDI clock events each time it went round the loop, but I couldn't figure out how to make that work before the gig, so I ended up pressing Start on a MIDI clock generator box in time with the loops. Low tech but works. The clock generator code is still in there, but commented out, if anyone who understands ALSA sequencer wants to get it working that would be fantastic.
If you wish to take this over as a project then feel free, but I need another open source project like I need a hole in the head. I'l fix any glaringly stupid bugs, but beyond that, you're on your own :-)