Re: [Denemo-devel] I got JackMidi output working

[Jeremiah Benham]

On Sat, 2009-02-14 at 14:03 +0200, alex stone wrote:
> 
> 
> On Sat, Feb 14, 2009 at 1:19 PM, Richard Shann
> <address@hidden> wrote:
>         On Sat, 2009-02-14 at 09:32 +0000, Richard Shann wrote:
>         > BTW I recall writing up a suggestion for how Denemo could
>         store a sort
>         > of MIDI-track parallel to the Denemo music data in a score,
>         so that
>         > playback would be just shovelling the data from that track
>         to the MIDI
>         > out. Did you implement this, or are you creating the MIDI
>         data from
>         > the
>         > Denemo data on the fly?
>         
>         I see that you have checked in the jackmidi code, and the
>         answer is
>         neither.  What we have is not live MIDI out yet, but MIDI out
>         via an
>         intermediate file using JACK as an alternative to an external
>         midi
>         player (playmidi, timidity or what have you).

This is correct. I don't think we are going to notice any performance
penalty for doing things this way. Exportmidi is very fast. We can
optimize later if need be.  


> I have a question.
> Currently, when we set an external midi app to playback, and when the
> playback stops, the app closes. This isn't too bad with either
> timidity, or qsynth, but it's presented a bit of a challenge with
> linuxsampler. 

Use aplaymidi instead. It will send the midi data to LS. Now you can do
it via jackmidi also. 

> (Trying to assign a constant template, when LS opens and closes is a
> problem i haven't found an answer to just yet)

Just keep LS open using aplaymidi to write midi to its port.

> So in going forward with a multiport jackmidi structure, is this
> likely to be the case?
> Because if Denemo opens and closes jack ports, according to playback,
> then it will need to have some facility to 'autoconnect' each port per
> staff correctly, each time.

Thats what LASH is for. I have include LASH support in the last push
also. 

I need help testing all of this though. This is all very new stuff. It
seems kind of flaky. I am not sure if that is my fault or not. qjackctl
does not launch a2jmidid on startup like it suggests that it would.
Sometimes everything appears to connect but I need to restart a2jmidid
to get any sound. This is a thorn in the process. I am not sure if I am
doing something wrong causing it. 

> The alternative would be to have jackmidi ports assigned to staves in
> a constant connected state, according to user staff preference. (User
> assigns staff to port, and it stays that way.)

Rosegarden does something like this. If the ports change I think that
may create an issue. 

Jeremiah
 
> I'm still finding my way around the New Denemo, so if i've missed a
> setting that maintains an external app in a constant active state,
> then all of the above is moot.
>  
> Alex.
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