Re: [linux-audio-dev] LADSPA run() blocksize

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Subject: Re: [linux-audio-dev] LADSPA run() blocksize
From: David Olofson (david_AT_gardena.net)
Date: Fri Nov 17 2000 - 11:58:47 EET


On Thu, 16 Nov 2000, Andrew Clausen wrote:
> Paul Barton-Davis wrote:
> >
> > does anyone have a solution as to how a LADSPA plugin can avoid
> > allocating any internal buffers in run(), when it needs to know the
> > maximum value of the argument to run() and/or run_adding() ?
> >
> > VST has "setBlockSize()", which the host calls to set an upper limit
> > on the number of samples that a plugin will be called with.
>
> /me is completely out of depth...
>
> I assume that allocating buffers is bad, because it might mean
> a call to brk(2) ?

Yep.

> Well, run_adding() isn't real-time (synchronous), right?

Why wouldn't it be? "_adding" just means that it adds to the output
buffers, rather than overwriting them.

Besides, the problem is the same for run() - some plugins need
to allocate internal buffers of the maximum buffer size, so they need
to know that size before they're in the RT threah, or they may get a
very unpleasant surprize in some run() or run_adding() call...

//David

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