There are several layers to music/sound software starting nearest the hardware: #The sound system (jack, oss, alsa, arts) #The midi software synth (qsynth/fluidsynth, timidity) #The music editor & sequencer (rosegarden4, MusE) #Audio editor for editing wav files (Audacity, rezound)
For a quick HOWTO on all this see http://www.salisburys.net/linuxlog.html
The jack system is designed for professional work. It doesnt work well on a low power system (say less than 1GHz). You can to run with jack in realtime mode which needs a special flag in the kernel (realtime capabilities). libjackasyn provides the jacklaunch wrapper to start oss apps and send their output to jack (BUT: jacklaunch audacity segfaults). It works on top of alsa.
alsa works fine but cant share the sound device with other programs (actually it can with some tweaking: see http://alsa.opensrc.org/AlsaSharing ).
arts is the KDE sound server. It allows the sharing of the sound device, be it oss or alsa. There is a program artsdsp which will allow you to run most oss programs under arts - just say artsdsp <program> (unfortunately this doesnt work with timidity)
Basically it seems that for serious sequencing you need the capabilities of jack but for everything else (playing midi, editing wavs you can get away with arts).
Timidity is a MIDI player which is a breeze to install (remember to install the timidity-patches too), sounds gorgeous and allows easy alteration of pitch and tempo. Other effect are available from the command line. To use timidity as the midi out for rosegarden start it with the -iA flag. use -Os for alsa.
qsynth (a very pretty front end for fluidsynth) gives you access to sound fonts and some effects. You can use arsdsp qsynth to run qsynth within KDEs arts sound system. Set the audio out to oss but leave the midi out as alsa_seq. If youve got a good sound font qsynth seems the best solution, if not: stick with timidity.
A MIDI sequencer/composer package. Handles MIDI input and output. Rosegarden is good but without jack it cant play audio files, only midi. For midi only with score printing etc etc its great. For mixing audio samples with midi youd need to get jack working and rosegarden allows you to link to an external editor for editing sound files (Id use Audacity).
Having used MusE I prefer it to rosegarden but its a bit crashy at the moment (feb.04). You dont seem to get the interference in the sound from jack (perhaps because the interface is less flashy) and it has a set of built in soft synth interfaces which is a bit simpler than running up qsynth separately. It doesnt do notation.
Brahms appears to offer both MIDI and notation editing/printing but works through arts and I couldnt get it to use a decent set of midi voices.
Audio (wave) editors
Audacity is the best bet for most simple operations and is very pretty. It has no jack support but it does offer multitrack capability. The current time cursor doesnt work properly, probably because of the cacheing sound server.
rezound: jack support, pretty but no toolbar or right click menus, no multitrack
ardour: jack only, excellent multitrack recorder/editor
sweep: no jack output, no multitrack
glame: jack support, too lean for me
ecasound: no longer developed
Probably the best quality CD audio extraction tool around. A command-line tool to reads tracks from audio CDs as .wav files.
Encoding .wav files to OggVorbis files.