Re: [linux-audio-dev] Musical language / OO design questions...

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Subject: Re: [linux-audio-dev] Musical language / OO design questions...
From: David Olofson (audiality_AT_swipnet.se)
Date: su tammi  23 2000 - 19:24:35 EST


On Mon, 24 Jan 2000, Paul Winkler wrote:
> OK, I think I see the problem. I was thinking that, for realtime
> interaction, once we reach the "at" time for an event, subsequent
> changes or additions to that event will not be heard, unless the
> same event is called again later.

One thing that is pretty annoying about some sequencers is just that
you can't edit (in any useful way) when playing back. Cakewalk, for
example, requires some 10ths of a second of *MIDI* buffering, or
it'll stop playback for the slightest CPU load. (That is, you can't
use audio w/o increasing the MIDI buffering...)

Anyway, what's *really* annoying with CW is just that it ignore edits
after the start time of an event has been passed. When tweaking
string harmonies with some notes that are several bars long, that
becomes quite frustrating. As it can't play notes that should be
playing, but whose start times are before where you are when you
press start, you simply have to rewind and wait for several seconds
to hear the full result.

> But what if I follow David Slomin's suggestion to my question about
> event scheduling? Where every possible way of changing the data in
> an event caused an instantaneous and correct update to the data
> being queued for output(). I wonder how hard that would be.

Not too hard in theory, but hacking it into something not planned
that way could end up as a speghetti nightmare I guess... Perhaps
having very similar APIs for the event database and the sequencer
engine could help? Or, going the OOP way, where events are objects
with methods used to gather data during playback; make sure the
datbase->sequencer interface is connected to the edit methods.

Ah, useless high level design theory... I should go have some
sleep...! :-) (And I haven't been following this discussion closely
enough.)

//David

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