[LAD] MIDI Running Status and ALSA, was: [LAU] Launchpad S and Linux

[Fons Adriaensen]

On Mon, Sep 30, 2013 at 07:32:36PM +0100, Kaspar Bumke wrote:
> On 28 September 2013 22:01, Fons Adriaensen <fons at linuxaudio.org> wrote:
> 
> > If the problem is the same as with the original LP, then
> > the ALSA driver can't do anything about it, unless it would
> > contain LP-specific code.
> >
> 
> But isn't the problem a general running-status problem if multiple programs
> are receiving from the same device? Is it a problem with the way the ALSA
> sequencer works (this seems to ring a bell somehow) as you said in the
> older thread that using Jack-MIDI would solve it?

ALSA will not look at the data sent by the LP or any other MIDI 
device unless that device is opened by some client. This *could*
be different - which would mean that ALSA would be monitoring all
devices all the time, even if nobody is interested - probably a
waste of CPU time. 

Jack-MIDI would solve it because the device would remain open
even while no app is using it (the client is Jack, not any app),
and running status would be preserved. 

The real source of the problem here is the LP firmware. Even if
you accept that using running status make sense (it doesn't in 
this case), it should at least send a status byte after a reset.

Ciao,

-- 
FA

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