[alsa-devel] Help requested: new HSS1394 MIDI back-end

Sean M. Pappalardo - D.J. Pegasus spappalardo at mixxx.org
Sat Jun 9 10:42:51 CEST 2012

Hello again.

I just modified Mixxx's SCS.1d script to work with your custom sysex 
messages and tested with your latest patch. The .1d doesn't actually 
work 100% with this since Mixxx never receives some of the standard MIDI 
messages amid all of the sysex ones, and it's much worse when the 
platter is spinning and sending the tons of messages it does. This could 
be due to PortMIDI's lack of a callback mechanism, forcing Mixxx to poll 
it every 1ms because it's much more difficult to reproduce the problem 
using amidi -d. (Of course, amidi isn't sending data to the controller 
at the same time like Mixxx does.)

That said, the scratching works better in Linux that it does on Windows 
via libhss1394! (Not really a surprise since Windows has issues anyway.)

I also see an F9 message slip through once in awhile according to amidi -d:

That's most likely to happen if the unit is sending alot of standard 
MIDI messages (such as when I quickly move a slider that sends a CC) 
since the device is always sending F9 messages as timestamps. More F9 
messages slip through when the platter is spinning because then they 
come more frequently.

Thank you again very much for your time and work!

Sean M. Pappalardo
"D.J. Pegasus"
Mixxx Developer - Controller Specialist

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