Subject: Re: [linux-audio-dev] LADSPA clarifications?
From: Conrad Parker (conrad_AT_vergenet.net)
Date: Mon Jul 15 2002 - 13:41:50 EEST
On Mon, Jul 15, 2002 at 12:00:37PM +0200, J?rgen Zimmermann wrote:
> Hello,
> I just joined the "linux-audio-dev" list a few days ago,
> and after some time studying the ladspa.h file, I have
> still some questions left:
>
> 1. Must the buffers assigned to audio input and audio output ports
> have the same length? Where is this stated???
> The sample implementations suggest so, though...
a) if you're an app (a ladspa host)
they must all be at least long enough to handle the SampleCount argument
you pass to the plugin's run() method.
noone will spank you if your buffers are too big, but your app might go
"kaboom" if you pass a longer SampleCount than what you've allocated.
you choose the SampleCount to run() for, and you choose the lengths of
the buffers ... in practice, if an app is coded to always call run with a
SampleCount of 256 (say), then there's not much point allocating either
input or output buffers any longer than that, which is why the code you've
looked at allocates buffers all of the same length.
b) if you're a plugin
well, the lengths of the buffers isn't up to you, but you should hope the
app author didn't screw up, and in your run() method you have to assume all
the input and output buffers are at least as long as the SampleCount the
app asked to run for.
>
> 2. Is there any range constraint applied to the audio content
> communicated by the audio input/audio output ports?
> VST e.g. does restrict the range from -1.0 to +1.0.
by convention, -1.0 to 1.0 (in most plugins and hosts)
K.
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