Request: A-B selector plugin

[jpcima]

Idea: plugins for selecting between a pair of stereo signals

If it should be a knob, then the value can permit to crossfade the pair of signals.
with value=0 being full A, value=1 being full B

• input selector (2x2-in, 1x2-out)
• output selector (1x2-in, 2x2-out)

[falkTX]

There is already an x42 plugin for this, no? I think either the stereo balance or DJ EQ one

But this is something that fits the OK series.
For this you meant to have 4 ins and 2 outs, correct?

[jpcima]

There is already an x42 plugin for this, no?

That doesn't seem like it. Unless I miss something.

This picture is one case of interest.
It's to have an intermediate client (here "jest"), that I make route its signal into either effect A or B, for comparison purposes.

(also, there often comes up the opposite case where to select among 2 inputs to go into 1 fx, which is why I mention 2 plugins)

[falkTX]

"Stereo DJ X-Fade" plugin does exactly this.

[falkTX]

URI is http://gareus.org/oss/lv2/xfade

[jpcima]

Well not really, compared to the picture above. It has 4-in 2-out, vs 2-out and 4-in.

[falkTX]

Ah I get it now! A/B for output, not for input.

[jpcima]

Here's the faust equivalent code

import("stdfaust.lib");

process(Al, Ar) =
  As*Al,
  As*Ar,
  Bs*Al,
  Bs*Ar
with {
  As = hslider("[1] A-B select", 0.0, 0.0, 1.0, 0.001);
  Bs = 1.0-As;
};

[falkTX]

can you post the generated c++?
or how does one convert that in CLI, maybe I can setup that in the repo.

the cross-fade mode that the x42 plugin has is very handy, would be nice as an option.

[jpcima]

I'd likely tweak it a bit at first.
The linear xfade is possibly not the best choice, and a little smoothing will be desired.
I'll have a look what x42 used.

[falkTX]

I can setup some stub for the xfade plugin.
Any suggestions for the full plugin name?

[jpcima]

Any suggestions for the full plugin name?

AB output selector?

Faust code and C++
ABselect.tar.gz

(note the "LGPL with exception" mention on the smoothing function, I can work around in case it's a problem)

[falkTX]

A-B or AB ?

Any license is fine, this project doesnt need to be restrictive on that.

[jpcima]

From a quick search, it seems as if it's most often written as A/B.

[falkTX]

ok, A/B it is.

btw, I think an input version like the xfade plugin would be great here. so we have a matching set.
is this easy to setup? can you do that?
thanks

[jpcima]

Done (I've given both a quick test)
ABselectInput.tar.gz

[falkTX]

thanks again. looking at the code I do not really like the generated output style...
so I will make it integrated into the plugin class in a better way, but can leave the original faust as a comment.

how should this be credited in the sources?
copyright goes to GRAME? to you?

I was thinking basically just credit in-source like this:

/* This DSP is based on the following faust code by Jean Pierre Cimalando
import("stdfaust.lib");

process(l, r) =
  As*l, As*r,
  Bs*l, Bs*r
with {
  sel = hslider("[1] A-B select", 0.5, 0.0, 1.0, 0.001) : si.smoo;
  As = sqrt(1.0-sel);
  Bs = sqrt(sel);
};
*/

would this be ok and enough?

[jpcima]

This creates a mixed-license source file, whose parts will be assigned to either me or GRAME.
I rewrite it in c++ if that makes things easier, no big deal.

[falkTX]

I added the skeleton/stub code at 0e9856e
How do you want to proceed?

[jpcima]

A C++ version, just written.
I'm moderately confident that it should work but not tried.
ABSelectInput.h.txt

[jpcima]

Update because of forgetting to set the T60's
ABSelectInput.h.txt

[falkTX]

Cool. I will add this in myself later today if you are lacking on time.
I have a few things that need a bit more priority.

btw, do line graphs make any sense for these? I was thinking 3 lines. one for each pair.

[jpcima]

I'm away a moment, but I can integrate this into your stub shortly, no problem.

[falkTX]

We can perhaps close this one.

Compared to x42's version, the extra mode option it has is regarding crossfade (overlapping vs non-overlapping)
There is an extra mode where -75% negative means 100% signal 1 + 25% signal 2.

Right now the version as you made only has non-overlapping mode.
Is this overlapping mode something you can add?

[jpcima]

Is this overlapping mode something you can add?

Most likely. I asked around and received another answer:

• a gain normalizing mode, which adjusts the pair of signals at equal level, which seems indeed useful for A to B comparisons

Other:

• can we label the input audio with actual A/B related names, instead of 1,2,3,4? (DPF can do this if I recall right)

[falkTX]

can we label the input audio with actual A/B related names, instead of 1,2,3,4? (DPF can do this if I recall right)

You can yes, there is an optional function to set details of audio ports.

[mxmilkiib]

How about having a graphics of a bee on the plugin skin?

[falkTX]

well, no