[LAD] ALSA sequencer port type flags

[Pedro Lopez-Cabanillas]

Hi,

I've received a complaint about VMPK not seeing other application's MIDI ports 
in the internal connections dialog. Among others, it doesn't list  
LinuxSampler ports. This isn't usually a big problem, because it is still 
possible to make the subscription using a connection manager like aconnect or 
qjackctl.

Anyway, the problem is that VMPK (using RtMIDI functions) enumerates and 
filters the existing ALSA sequencer ports in the system having the port type 
flag SND_SEQ_PORT_TYPE_MIDI_GENERIC, that means "This port understands MIDI 
messages." according to the alsa library documentation:
http://www.alsa-project.org/alsa-doc/alsa-lib/group___seq_port.html#g43e52ce669add7af811a5c59abe25faa

This is the same policy used for instance by aplaymidi, from alsa-utils. If 
you execute "aplaymidi --list", it doesn't show linuxsampler either. 

Please: can you add SND_SEQ_PORT_TYPE_MIDI_GENERIC to the sequencer ports of 
your synths, if the ports understand MIDI messages and are supposed to be 
subscribed by players or other applications? 

In addition, there are other interesting flags defined in the ALSA library  
that could be applied also to LinuxSampler, for instance:  
SND_SEQ_PORT_TYPE_SYNTHESIZER.
http://www.alsa-project.org/alsa-doc/alsa-lib/group___seq_port.html#ge670627e559f1c7892aa30df8febf722

Regards,
Pedro