[PD] BUG in Linux/ALSA midi connection handling?

Jörn Nettingsmeier nettings at stackingdwarves.net
Wed Jun 20 15:07:29 CEST 2012

hi *!

there's this very annoying problem of PD autoconnecting to all available 
midi ports when using ALSA midi on Linux. since it wisely decides to 
also connect to all internal midi thru ports, it immediately enters an 
infinite midi loop on startup as soon as there is any controller with 
feedback active.

but there is a deeper underlying problem apparently: for every midi 
message that gets sent out, the corresponding port is reconnected. i 
guess that's not very scalable. i found this out by watching the 
qjackctl logs - they spit out one reconnection line for every outgoing 
midi cc.

as suggested by claude heiland-allen in another thread (subject "pure 
data midi autoconnect"), i'm now invoking pd with "-alsamidi -mididev 
1,1", which prevents autoconnection.

***interestingly, it also prevents the constant re-connection to the 
alsa sequencer ports on every outgoing message.***

i think this might be a hint that something is wrong somewhere in the 
alsa sequencer glue in pd.



Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT


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