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List:       kde-multimedia
Subject:    Re: arts filters
From:       degs <degs () giantblob ! com>
Date:       2001-07-23 6:32:12
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Thanks,

degs
On Sunday 22 July 2001 21:36, Stefan Westerfeld wrote:
>    Hi!
>
> On Fri, Jul 20, 2001 at 02:39:56PM +0100, degs wrote:
> > I'm trying to write some plug-ins for aRts and I have a couple of quick
> > questions.
> >
> > The sort of things I had in mind to implement would be useful for
> > recording applications - e.g. EQ/filtering, compression (as in dynamic
> > range reduction, not data compression), distortion, modulation/delay
> > effects etc. I've done a bit of this sort of thing before in Windows and
> > I know a bit about DSP but I don't know much about aRts.
>
> Great - well, writing plugins for aRts is quite easy actually, have a look
> at very simple ones (such as kdelibs/arts/flow/synth_add_impl.cc). A brief
> step-by-step description is also in
> kdemultimedia/arts/modules/README.modules.
>
> > I realize arts includes some of this stuff already but it seems more
> > aimed at modular synthesis than the DAW sort of thing I'm thinking of.
> >
> > My questions are:
> > - Is the plug-in API stable enough yet to make this viable now or should
> > I wait?
>
> The API is stable, that is, every plugin you write that works with any
> official released version of KDE2 will continue working in all higher
> versions.
>
> There are two things to say, however:
>  * everything that is in kdemultimedia (such as the gui stuff) is still
>    subject to change - especially guis might be relevant for you
>
>    I don't intend to change major issues, however the details of how guis
>    work might still be changed
>
>  * I am currently planning a new multithreaded engine for evaluating the
>    modules (should be in KDE2.3), which will be able to do things like
> taking advantage of multiprocessor CPUs.
>
>    However, the engine will only add the capability to write modules in a
>    really hard realtime capable, and multiprocessor safe way. "Normal"
>    modules will continue working as ever, and enhancing existing modules
>    to the new capabilities of the engine should not be too hard.
>
> So in short: just start ;).
>
> > - what existing plug-in might be a good starting point as a template to
> > copy, i.e. is simple, up to date, uses the API correctly, and is a simple
> > filter, in that it takes a stereo stream of samples and produces a stereo
> > sample stream result.
>
> A simple example might be Arts::StereoVolumeControl (as implemented in
> kdelibs/arts/flow/stereovolumecontrol_impl.cc), or Arts::Synth_FREEVERB
> (kdemultimedia/arts/modules/synth_freeverb_impl.cc).
>
> However, I just noticed that the freeverb doesn't emit change
> notifications, but I think you can think that on your own. You can also see
> how the GUI layer works in freeverb.
>
>    Cu... Stefan
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