Subject: Re: [linux-audio-dev] do YOU support LASDPA? (was Re: Linux Audio plugin API's: where are we ?)
From: James McCartney (asynth_AT_io.com)
Date: Fri Apr 07 2000 - 17:40:45 EEST
Unfortunately LADSPA does not provide the services or performance guarantees
to be a SuperCollider unit generator plug in. I've listed previously some of
the shortcomings, and it is a lot more than just the real time
instantiation. At the risk of sounding like a broken record:
- Audio rate, control rate and scalars supported at all inputs.
- Sample accurate end time stamp calculation - if a plug in itself ends or
one of its input ends, it must calculate whether it has ended and at what
exact sample. If the output of a dynamically allocated event has ended, then
that event is deallocated and removed.
- Repatching while running. SC ugens recieve an InputsChanged() call so that
they may choose a new run function based on the rates of their inputs.
- More control over allocation - SC places the plug in into an SC virtual
machine object (i.e. the plug in does not allocate the space for itself) and
SC passes an allocator to the plug in for any further allocation.
- upon initialization a plug in must calculate its first output sample. This
allows downstream ugens to initialize themselves based on valid inputs and
allows a starting point for linear interpolation of control rate values over
audio buffers.
There are some other issues. Since SC supports multiple control rates and
patches can be built dynamically and then installed into the graph, a unit
generator's sample rate is not known until the activate call, not at the
time of instantiation.
LADSPA could be supported as some sort of static input/output stage
processing.
--- james mccartney james_AT_audiosynth.com <http://www.audiosynth.com>
SuperCollider - a real time synthesis programming language for the PowerMac.
<ftp://www.audiosynth.com/pub/updates/SC2.2.7.sea.hqx>
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