[ardour-users] bypass/activate plugins with automation?

David Slimp rock808 at gmail.com
Tue Feb 14 01:11:23 PST 2006


The main reason I did not want to have two tracks for this is because
I found THIS in the Ardour Manual:

"[playlists] are not equivalent to tracks, which require extra CPU
time and significant memory space"

I'd prefer to not have an extra track if it's going to consume more CPU and
memory... especially when there is only 15 seconds of audio that needs
the 2nd plug in ... out of a 6 minute song.

The track contains audio for a guitar... 5:45 requires one plug-in, the
last 15 seconds require another.  If I was doing this live, I would have'
2 stomp-boxes, and would turn the distortion off while turning the reverb on.
Certainly there's a way to handle this on the computer, in a similar way?

... especially if more tracks are going to consume more RAM as the docs say.


On 2/14/06, Sampo Savolainen <v2 at iki.fi> wrote:
> Quoting David Slimp <rock808 at gmail.com>:
> > Am I missing something?
> > I'm not seeing a way to bypass/activate the plugins with automation.
> >
> > at a certain time, I want to stop one plugin and start another on the
> > same track.
> In fact. You are missing something. :)
> This is not possible at the moment, and probably won't be. This is not
> really a limitation in ardour's code, but a fact of life in signal processing.
> Say you have a track where you use a compressor. You have loads of make up
> gain dialed in the compressor. When you activate the plugin mid-signal, the
> compressor's make up gain will make a non-linear jump in the signal:
> crackles, in the basic sense.
> A compressor is still a simple case, as they don't inherently cause latency
> to the signal. But let's say the plugin is a convolution reverb which uses
> FFT in it's processing, thus delaying the signal by the amount of frames
> used in the FFT window.
> What happens to the signal when you activate the plugin mid-stream? Does the
> plugin spew out a zero signal for the duration of the FFT window? What
> happens when you deactivate the plugin mid-stream? The stream would jump
> forwards FFT window size samples. In both cases we would be producing nasty
> non-linearities, and not what you would want it to happen.
> This probably can be circumvented by making hacks in the code like running
> the same stream through both without and with the plugin and crossfading
> them. But I don't feel A) the workload is justified or B) that the end
> result would even be what people want.
> There are much simpler ways of doing this: Use multiple tracks or automate a
> value which in effect turns on/off the plugin you would want to activate or
> deactivate.
> A track means a certain path of effects: if there is audio on a track where
> you want radically different effecting, why not make another track? It's not
> like you'd be "running out of tracks" in ardour.. :)
>   Sampo

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