Subject: Re: [linux-audio-dev] Audio distribution revisited
From: Benno Senoner (sbenno_AT_gardena.net)
Date: Thu Sep 14 2000 - 19:56:00 EEST
On Thu, 14 Sep 2000, you wrote:
> >
> > -- Much work needs to be done on making it easy to hook various apps
> > together. For instance there are a bunch of cool soft-synths out
> > there, but can you run two of them at once from a single MIDI
> > sequencer and record the result into a hard-disk recorder? >
>
> I've been wondering about this, too. It can be done so easily now in
> windows (VST instruments) that you start missing this feature in the linux
> environment. May be it's time to start thinking about a
> ladspa-instruments API.
yep this "ladspa-instrument"-like API is what we will need to integrate
audio sequencers with soft-synths.
But this model has to offer more features than VST does, since what I want
is that the EVO sampler can work as a plugin.
And as you probably know it is a multithreaded app (diskthread, audiothread,
midithread) which makes heavy use of lock-free data structures,
and a ladspa-instrument host has to take this into account, and must provide
a way to schedule disk , audio and midi requests in separate threads.
This will even allow to run several EVO's , other softsynths,
and audio/midi sequencers simultaneously perfectly syncronized.
For now if you want to throw in some food of thought , you are welcome.
But in the meantime I have to continue on the development of EVO to bring
it into an usable state so that we can see what the "ladspa-instrument" API
will be, based on a realworld API.
> In the mean time something like an audio loop back kernel
> module could help. Anybody aware of such a thing?
these loopbacks between apps are just temporary solutions,
(or for those who can live with delays)
since this model is not suitable to reliable 3msec latencies.
The ultimate audio/midi loopback solution will be a plugin scheduler
which runs all the modules within the same process , ensuring
perfect, sample accurate sync and <5msec latencies under high load.
tschüss,
Benno.
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