Subject: Re: [linux-audio-dev] Re: [l Re: Plug-in API progress?
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: la syys 25 1999 - 02:16:48 EDT
>> what about the following scenario:
>> sequencer1 continuously changes the cutoff frequency of a LP filter-plugin,
>> the GUI slider moves reflecting the changes.
>
>Ok. Sequencer 1 somehow (directly or indirectly) sends events to both the
>filter plug-in, and the GUI element (which is in fact a plug-in as well).
>
>> sequencer2 records the automation parameters.
>
>It could request to become another recipient of all events sent to the filter
>plug-in. That is, another port to recieve a pointer to the same event buffer.
>
>(Can you see the problem that's been on my mind for a while? What if seuencer2
>would request event buffer mirroring from multiple sources? Yep, either the
>engine gets to merge buffers - which is a lot more expensive than passing over
>a pointer - or sequencer2 has to use one extra event port for each port it
>wants to mirror. Not sure yet if this really matters, or if it would be less
>expensive to pay somewhere else to solve this...)
let me just mention another problem. this one is *not* solved in
quasimodo yet either ...
typically, parameter updates occur because of the GUI requesting
them. therefore, under most circumstances, the GUI does not want to be
notified of a parameter update event - it was the sender! however, if
the parameter update was caused by something else, the GUI *does* need
to be notified.
how to distinguish cheaply and easily between these two cases ?
in quasimodo, it happens when you are loading a preset, for
example. the GUI requests the preset, but it doesn't do the actual
processing (which may or may not be all in the same thread as the
GUI). first, we load the plugin(s), and then we set the parameters,
and then we then make the patches between them (i.e. run-time edit the
DSP programs for the plugins). when the parameters get set, the GUI
should reflect the new values. they don't. how to avoid a redundant
loop in the common case is not obvious to me right now.
--p
This archive was generated by hypermail 2b28 : pe maalis 10 2000 - 07:27:12 EST