[linux-audio-dev] Re: Sidechains, was Re: [linux-audio-announce] [ANN] swh-plugins 0.3.4

[Mark Knecht]

On Sat, 2003-01-11 at 01:56, Steve Harris wrote:
> On Sat, Jan 11, 2003 at 02:10:44 +1100, Conrad Parker wrote:
> > (one bit LADSPA sidechain proposal below ;)
> > 
> > On Fri, Jan 10, 2003 at 09:21:38AM -0800, Mark Knecht wrote:
> > > 
> > >    I must admit publicly that within the Linux application environment that
> > > right now I'm pretty lost on how all these apps are using sidechain
> > > controls. Often when I admit I'm lost, one or two other lost souls come
> > > forward and suggest they are a bit lost also.
> > 
> > as there is no way in LADSPA to distinguish between the audio input
> > ports and the sidechains, there's no way for an app to create a
> > GUI interface that understands that difference.
> 
> Woah. Lets back up a bit. There is a lot of confustion about the word
> sidechain.
> 
> All it actually means is an input that is used as a replacement for the
> audio from the through path, that is used *for the purposes of control* it
> is not a control input.
> 
> What the original guy was talking about (I think) is ladspa plugins that
> could broadcast its input and other plugins that could receive it, using
> IPC (possible, but really, really ugly). It would not affect the hosts in
> any way.
> 
> His example was for when you have a compressor that needs to take a
> sidechain input, but your app doesn't allow routing between channels, eg.
> you need to map your drum output to the sidechain input, but sidechain L+R
> should be the bassline. You would put a broadcast module in the drum path,
> set it to transmit, and tell the compressor to receive its sidechain input.
> 
> What Conrad is talking about is distinguishing audio rate control inputs
> from control rate control inpputs, which is a valid concern, but unrelated
> to the original point.
> 
> - Steve

Steve,
   If the original point was from me, it was only asking how to sensibly
use a LADSPA plugin that the documentation says has sidechain inputs in
an app like Ardour. I think Paul answered that there was no sensible way
to use it today, which really answered my question.

   That said, I appreciate your clarification on the purpose of
sidechain inputs. I think I understood that, but a bit of additional
clarity never hurts.

Thanks,
Mark