If you want to play midi file on Linux, SuSE for example, you need the midi player. Amarok or some other players such as Banshee couldn’t play midi at all. I am not sure why, however, I found a command-line application called Timidity. It can be downloaded from http://download.opensuse.org/distribution/SL-10.1/inst-source/suse/i586/timidity-2.13.2-21.i586.rpm. Once installed, you can play it by issuing this command timidity file_name.midi.
Here is an example running timidity to play what4.midi:
kenno@localhost:~/> timidity what4.mid
Requested buffer size 32768, fragment size 8192
ALSA pcm ‘default’ set buffer size 32768, period size 8192 bytes
Playing what4.mid
MIDI file: what4.mid
Format: 1 Tracks: 5 Divisions: 480
Sequence:
Track name: Track 1
Track name: Guitar 2
Track name: Track 3
Track name: Percussion
Playing time: ~26 seconds
Notes cut: 0
Notes lost totally: 0
Enjoy the midi tune!