This backend sends MIDI events to a group of user-chosen ALSA sequencer ports. The ALSA sequencer interface is very versatile, it can provide ports for audio cards hardware synthesizers (i.e. emu10k1) but also for software synths, external devices, etc.
This backend does not produce audio, MIDI events are handled directly from devices/programs behind the ALSA ports; in example, MIDI events sent to the hardware synth will be directly played.
Backend written by Giacomo Lozito.