Re: Playback doesn't work if Jack MIDI is used

[Richard Shann]

On Wed, 2021-10-27 at 21:00 +0300, Andreas Schneider wrote:
> Am 27.10.21 um 12:29 schrieb Richard Shann:
> > On Mon, 2021-10-25 at 22:24 +0300, Andreas Schneider wrote:
> > > Am 25.10.21 um 12:53 schrieb Richard Shann:
> > > > On Sun, 2021-10-24 at 15:18 +0300, Andreas Schneider wrote:
> > > > > If MIDI is configured to use Jack, start playback plays back
> > > > > two
> > > > > notes
> > > > 
> > > > are these actually audible?
> > > 
> > > Yes, they are.
> > > 
> > > > > and then stops. Also, the note at the cursor is changed to
> > > > > the
> > > > > note
> > > > > of
> > > > > the first staff while playing back.
> > > > 
> > > > Did you mean the cursor position changes?
> > > 
> > > I mean that the note changes its value, e.g. in my example below
> > > the
> > > c
> > > changes to a g.
> > 
> > This must be one of the most extraordinary side effects ever
> > reported
> > for Denemo! If the score is saved before you start playback does it
> > become unsaved (the * appears) when the note changes value? If so,
> > under gdb a break placed on the function score_status() i.e.
> > 
> > gdb> b score_status
> > 
> > should fire off when the note changes in value and "where" should
> > reveal the route by which this happened...
> 
> There seems to be a loop in Jack. If I disconnect denemo from
> midi_playback_1 in QJackCtl, the playback works normally.

Aaaah! yes that's a perfect explanation - it plays the first note and
then that is fed back as input from MIDI in which then modifies the
score which stops the playback.

Richard