Subject: Re: [linux-audio-dev] midi events in jack callback (was: Reborn)
From: Bob Ham (node_AT_users.sourceforge.net)
Date: Fri Aug 16 2002 - 01:19:48 EEST
On Thu, 2002-08-15 at 20:17, Paul Davis wrote:
> >I was actually thinking of ignoring time-stamps except within the code
> >that sequences events. If my jack clients are given a midi event (eg,
> >noteon,) they should deal with it immediately. Same goes for their
> >despatches. Is this not what I should be doing?
>
> if your assumption is that you never get an event with an intended
> delivery time of anything but "right now", then that sounds fine.
>
> this seems like quite a restricting assumption.
Well, what I have in mind is a superclass that passes the midi events
to, eg a softsynth, through a virtual method. It wouldn't be much
trouble to make the superclass's code pay attention to time-stamps and
only make calls on those that are stamped "now". Except that removes
the ability for the softsynth to accept events in the future, but I'm
not sure how useful that would be.
I envisioned a system where a sequencer object delivers midi events to
the softsynth. Ie, all the time-specific magic would be in the
sequencer object, rather than the synth/wave/whatever objects. Thinking
more about it, tho, I can see this being bad. Each object would have at
least two threads, and those with jack callbacks having another. Lots
of room for things going wrong, time wise. I wanted it so that an
object isn't necessarily a jack client. Perhaps I'll have to change
that. More thinking to do, I fear.
Bob
-- Bob Ham: bob_AT_ham.org http://pkl.net/~node/
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