Is there a way to sum Audio inputs?

[artnik]

I am working on a proposal for a live installation piece and I am wondering if there is a way to sum audio inputs.

I'd like to have visualizations that react to real-time stereo microphone input. The goal is to have three primary visual elements, one to react to LEFT channel, one to react to RIGHT channel, and one to react to the stereo mix.

With pre-recorded music this would be trivial, but I can't find a way to do it with live stereo input.

I had thought it might be possible to do it ADD-ing two Audio to Image modules, but there's no inverse operation to turn Image to Audio to use as a source for a modifier stack.

I can always double up on transforms/effects by doubling the modules I suppose (one for each channel, effectively summing the output), but I'm hoping there's a way to keep the wiring simple.

Suggestions?

[Magic]

There isn't currently a way to sum the input channels. Depending on what behavior you are after, you could combine a Depth Test module with source modules (Polygons/Images/etc.) that are then Translated in the z-dimension by their volume. So whichever is louder would be in front and would obscure the other one.

Or, if that isn't sufficient, a hardware-based solution would be to use a cheap little mixer in between the mic and the computer.

[artnik]

Suspected as much. (Although it won't work for this project, that Z-sorting trick is neat ).

Thanks Eric!

[Terry Payman]

It's a use case for Sadler's request to allow globals to be used in the expression modifier (which I've often wished for myself).

Here one could make a global ("GlobalSum") that summed two others ("GlobalLeftInput" & ("GlobalRightInput"), which would enable Artnik's Left, Right & Sum elements to be identical except for their selection of Global. Easy to incorporate Freq Ranges into the features of the GlobalLeftInput & GlobalRightInput.

viewtopic.php?f=8&t=856&hilit=globals+i ... t=10#p3763

So, how about allowing one (or many) global parameters to be used in the expression modifier? I can't think of any use-cases myself right now but a power user...

That's an interesting idea. I might be able to get the Expression modifier to use global parameters as variable names. So you could do something like:
Expression: MyGlobal1*MyGlobal2

I can't think of any use-cases either, but it certainly seems like it would have potential.

[Sadler]

Two transforms in series would allow you to add two channels for rotation, position and scaling. Two AudioToImage modules can be blended together to combine channels.

[artnik]

Two transforms in series would allow you to add two channels for rotation, position and scaling. Two AudioToImage modules can be blended together to combine channels.

Hey Sadler, yup, I have looked into both of these. Ultimately, doubling up on modules is going to be the solution, but I was hoping it would just be simpler if there was some way to combine the inputs.

With the AudioToImage approach, the issue is that there's no way to do the inverse operation to create an input value to plug into a modifier stack AFAIK. AudioToImage creates great visual output, but not value output.

I like Terry's suggestion that Globals could be made transparent to the Expression modifier. That would be a killer feature.