Re: [linux-audio-dev] midi events in jack callback (was: Reborn)

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Subject: Re: [linux-audio-dev] midi events in jack callback (was: Reborn)
From: Paul Davis (pbd_AT_op.net)
Date: Thu Aug 15 2002 - 22:17:48 EEST


>On Wed, 2002-08-14 at 15:06, Paul Davis wrote:
>> >On Wed, 2002-08-14 at 13:21, Paul Davis wrote:
>> >
>> >> a "pull" model ("hey client: do this much work right now").
>> >
>> >Should the "this much work" be constant? Ie, should I be dealing with
>> >midi events (of which there may or may not be some) inside or outside the
>> >process callback?
>>
>> the process() callback is the only place where you can discover "what
>> time it is". given that midi events will typically need this to be
>> useful, they will they need to be dispatched from within it, but they
>> may have timestamps in the future and thus get queued at some level
>> (your app, a user-space library, a device driver, etc.)
>
>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.

however, its worth noting that ardour's dormant "sequencer thread" is
designed around a similar idea, but not with this restriction.

--p


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