Subject: Re: [linux-audio-dev] extending LADSPA, it's not that easy ......
From: David Olofson (david_AT_gardena.net)
Date: Tue Nov 07 2000 - 04:26:44 EET
On Mon, 06 Nov 2000, Steve Harris wrote:
> On Mon, Nov 06, 2000 at 08:55:31AM -0500, Paul Barton-Davis wrote:
> > >Well, I have "simple" answers for all of those questions, and it's no
> > >big deal to implement it. However, if it's a part of the API all
> > >hosts and/or plugins *have* to deal with it one way or another, or
> > >we'll soon end up with lots of "classes" of LADSPA plugins, which
> > >won't run on host of all other classes, and/or won't work together
> > >with plugins of certain classes. Not very nice, especially not for
> > >the end-user.
> >
> > we already have this. LADSPA allows a plugin to not implement
> > run_adding(). some hosts may have good reasons to not run such
> > plugins. as far as i could tell, most plugins in the CMT set (thanks,
> > richard!) don't implement run_adding(). not nice.
>
> Why is this bad? My understanding of the LADSPA callbacks was that you
> were only intented to implement run_adding if you could do so with some
> performance gain over the host doing it. Is there a good reason to
> implement it anyway?
The problem is that the host needs the feature for performance, while
the plugin developers get to do the extra hacking...
And yes, there are quite a few cases where you can eliminate extra
copying/extra mixer plugins with this extension. However I don't think
the version *without* the standardized output gain control is very
useful in most of the cases I have in mind. (Channel -> bus/send
stages in mixing consoles, and voice outputs on synthesizers and
samplers, for example.)
//David
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