Subject: [linux-audio-dev] Fwd: Re: Sidechains, was Re: [linux-audio-announce] [ANN] swh-plugins 0.3.4
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Fri Jan 10 2003 - 11:28:45 EET
Sorry, replied direct to Robert, not list.
----- Forwarded message from Steve Harris <S.W.Harris_AT_ecs.soton.ac.uk-----
Date: Fri, 10 Jan 2003 09:25:32 +0000
From: Steve Harris <S.W.Harris_AT_ecs.soton.ac.uk>
Subject: Re: Sidechains, was Re: [linux-audio-announce] [ANN] swh-plugins 0.3.4
To: Robert Jonsson <robert.jonsson_AT_dataductus.se>
On Fri, Jan 10, 2003 at 09:47:26 +0100, Robert Jonsson wrote:
> >SC4 is more-or-less like SC3, but has no sidechain and a subtly different
> >algorithm. The sidechain was confusing hosts.
> >
>
> Yes, I was wondering how the 3<-->2 port sidechain compressor plugin
> would be handled in hosts...
The answer is 'badly'. ;)
> What if the sidechain was a separate ladspa plugin that in turn uses
> some ipc mechanism to communicate to the plugin being controlled?
> I have no idea what kind of ipc is best for this, named pipes seem easy
> but they are probably slow, yes?
Pipes are non-deterministic, so banned in LADSPA. The only one thats an
option is shared memory.
> By using one of the controls of the ladspa plugin to select which
> sidechain "channel" (e.g. 1-10) they should send and receive on (much
> like a comm-radio) you could have several different sidechains up and
> running simultaneously.
Its an interesting idea.
> This construction has a number of interesting side effects (pun not
> intended):
> * 1-n setups can be produced, one sidechain can control several effects.
> * Atleast with named pipes the control would be application agnostic.
> The sidechain would not need to be used in the same host as the effect
> plugin.
The same is true of SHM, but if the hosts are not running in sample sync
all hell will break loose.
> * I don't know if other types of plugins are applicable to this, but
> since the sidechain is a separate plugin you could make _any_ plugin
> sidechain aware. mmmm audio controlled room-size for reverbs...mmmm
> :-D.
Ahh, theres a misundersantding about what sidechains do here, they really
are just an audio stream.
> Any thoughts?
Neat idea. Kinda evil though. Very tempting...
> Top priority is a LADSPA stereo delay, I couldn't find one in Steves
> collection.
> But it would also be nice with:
> - stereo autopanner
> - auto sweeping filters.
> Apologies if these infact are available and it's just my poor eyesight.
What do you want from a stereo delay? There is an left-centre-right delay,
but thats actually a mono delay that takes stereo input and pans the
result. A stereo delay would be easy to implemnt, what controls do you
want?
There is an auto-phaser (sweeping allpass filter), but no auto wah
(sweeping bandpass), or auto panner, true. I tend to build things like
that out of SSM or pd. But there should be complete plugins.
- Steve
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