Subject: Re: [linux-audio-dev] Ideas for AES/LAAGA/whatever (was Re: sound API libraries, servers, etc.)
From: Paul Davis (pbd_AT_Op.Net)
Date: Wed Apr 25 2001 - 15:07:09 EEST
>If you're designing a new plugin standard, can I throw a few ideas
>into the mix ? Here we go:
you need to understand the the plugin standard being discussed is
nothing like LADSPA (or VST). its not a way of connecting together DSP
units that do small well-defined jobs. its a way of gluing together
entire applications so that they can share devices and more
importantly their own data. the comparison in the win-macos world is
steinberg's ReWire, something entirely separate from VST.
as a result, the model of the audio interface presented by the plugin
API has to be as generic as possible, since the applications may want
to do very different things. The only limitations I want to see are:
* all processing is done channel by channel (there is no
concept of interleaved audio streams, for example)
* all audio samples are IEEE 32 bit floats.
* plugins will only ever be called upon to process 1-N frames at
a time, where N will be set by a call to their set_block_size()
callback.
there are no other semantics that i can think of.
>- Intelligent handling of silence. Many plugins can completely skip
> processing a frame if there is silence on their inputs - they just
> need an easy way to recognise that. In my plans the ->process call
> (or equivalent) passes to the plugin an array full of pointers to
> input/output buffers that the plugin should use. There is a
> standard 'all-zeros' buffer which is passed whenever there is no
> input or silence.
all true, but: (1) how does something decide that there is silence to
begin with and (2) this is too detailed to act as inter-application
glue IMHO.
>- Upgradable control inputs. Control inputs often have constant
these play no part in this kind of plugin system. Thats more like
LADSPA which is intended to support DSP plugins. This "standard" is
not - its just connecting applications that do audio stuff.
This archive was generated by hypermail 2b28 : Wed Apr 25 2001 - 15:45:35 EEST