Topic: VST plugins & mixing/mastering workflow in your DAWs

[Gutbucket]

A question for if_then_else and TheJez specifically because they are actually building some of these tools, but open to replies from all-

Any insight into how I might create or have made a VSTplugin (ideally) or some other software tool that does something I've not found implemented elsewhere?

What I am looking to create is a four channel input > four channel output "circular panning" control or more accurately a "4 channel circular balance control" routine that uses a constant-power panning law so that perceived level does not change as the angular position of the balance pot is moved around the circle. 

[Gutbucket]

[Edit- There may already be something that does this that I haven't come across.  I'll search ambisonic tools, and maybe ask on the sursound mailing list.]

More detail (too much?) -
The circular balance control should achieve the following (I'm using numbered inputs and lettered outputs here, both of which "wrap fully around the circle" from input ch-4 back to ch-1 and from output ch-D to A.

The following cardinal orientations correspond to "hard-panned" balance positions:

1) With a panpot orientation of 0 degrees the signals are routed directly from input to output:
ch-1 > A 
ch-2 > B   
ch-3 > C 
ch-4 > D 

2) With a panpot orientation of 90 degrees, the signals are routed directly to the next "adjacent" output clockwise around the circle. ch-4 "wraps back around" to ch-A:
ch-1 > B 
ch-2 > C 
ch-3 > D 
ch-4 > A   

1) With a panpot orientation of 180 degrees, the signals are routed directly to the output on the opposite side of the circle:
ch-1 > C
ch-2 > D
ch-3 > A
ch-4 > B

4) With a panpot orientation of 270 degrees, the signals are routed directly to the next "adjacent" output counter-clockwise around the circle. ch1 "wraps" to ch4:
ch-1 > D
ch-2 > A
ch-3 > B
ch-4 > C

For panpot orientations exactly halfway between the positions above, the two immediately adjacent inputs are summed with an equal reduction in gain to both as required to achieve a constant power output, like panning a mono signal to the center position halfway between left and right by using a constant-power pan law:

5) With a panpot orientation of 45 degrees, the signals are routed with the following sums and gains:
ch-1 (-XdB) + ch-2 (-XdB) > A
ch-2 (-XdB) + ch-3 (-XdB) > B
ch-3 (-XdB) + ch-4 (-XdB) > C
ch-4 (-XdB) + ch-1 (-XdB) > D
where X = the gain reduction needed for equal power output of the sum.

etc..

For panpot orientations somewhere between those above, all three immediately adjacent inputs get summed, with unequal reductions in gain to each as required to achieve a constant power output:

6) With a panpot orientation somewhere between 0 and 45 degrees, the signals are routed with the following sums and gains:
ch-1 (smallest reduction in level) + ch-2 (intermediate reduction in level) + ch-3 (greatest reduction in level) > A
ch-2 (smallest reduction in level) + ch-3 (intermediate reduction in level) + ch-4 (greatest reduction in level) > B
ch-3 (smallest reduction in level) + ch-4 (intermediate reduction in level) + ch-1 (greatest reduction in level) > C
ch-4 (smallest reduction in level) + ch-1 (intermediate reduction in level) + ch-2 (greatest reduction in level) > D
where the reduction in level produces an equal power output in the sum.

etc..

I need to brush up on pan/balance laws to determine the appropriate constant power function and what reduction in gain that applies to each of the summed inputs.  In other words, the value of X and the value of smallest, intermediate, and greatest in the descriptions above.  With that I could draw a graph of balance position and the corresponding gain values applied to or each channel, looking sort of like a set of overlapping sine curves.  Such a graph would better describe the operation visually.

[TheJez]

Hi Gutbucket,
Unfortunately I don't have any practical experience with VST development. When googlin' a bit I see many options, e,g, downloading a SDK (software development kit) that helps to create a VST plugin from the bottom up. Something that seems very appealing is https://juce.com/. Apparently it can create the 'framework' for your algorithm that you can then export to become a VST or other types of plugins or even stand-alone applications for Win/Mac/Linux/Android! There seems to be many examples, tutorials etc.. I guess the learning curve might be steep, as is for the many other options apparently around. I guess for most options some C++ knowledge would be required. This site https://enphnt.github.io/blog/vst-plugins-rust/ could also provide some guidance...

The first step seems to be to get the math that gives the output for each channel, depending on the position of the panpot (0..360) and the inputs. I must admit math isn't my biggest asset...

I am curious why you'd want something like this. I find it hard to imagine what your four inputs might be and what turning the panpot would do to it...

[if_then_else]

For a 4-channel circular panning system with constant power, there are a few existing VST solutions that come close to your requirements:

VST MultiPanner offers 3D panning capabilities with constant power law implementation, supporting multiple channel configurations including custom routing4.

Panstation 2 provides circular panning with phase relationship control between channels, though it's primarily designed for stereo operation5.

However, none of these exactly match your specific need for a dedicated 4-channel circular balance control. The closest professional solution would be the DirectivityShaper by IEM plugins, which allows for multi-channel constant power panning while maintaining consistent perceived loudness across all positions.

[Gutbucket]

Thanks to you both.  If_then- I'll check those out when I can.  Jez- yes I'd figure the math out first and graph the transfer function. 

My use for such a thing is potentially twofold.  I'm sitting on a lot of four-channel baffled L/R/C/B recordings that I've made over the years using microphones facing in all four directions.  I have a few different methods for mixing those down to L/R stereo that I really like, and alternately for playing them back over multichannel playback systems.

One application is as a potential stereo mixdown tool for some of them where the angular orientation of the recording array was not optimally aligned with the orientation of the stage, room, and audience.  For example, in some the Left mic channel faces the "perceptual center" rather than the Center mic channel.  Such a situation would be standing off to the left with the closest PA to my Left and the majority of the audience and room off to my Right.  Fixing that is easy by just reassigning the channel routing as follows: L to C; C to R; R to B; and B to L.  I don't need the circular panner to do that.  And I do have some effective mix methods for correcting the ones which are askew by less than a full 90 degrees, but I've always been curious about alternate, faster, and potentially better ways of doing so.  Having the four cardinal directed channels available provides a much larger degree of freedom in doing this in comparison to having just two L/R channels.  I realize that simple sum-based panning may not work as well as I'd like in doing this, but I'd still love to try it.  Would be great to just "turn the knob" to reorient the 4-directional recording as desired.  A set and forget type of static adjustment.

The other application is essentially a dynamic implementation of the same for a somewhat more esoteric end, in enabling active mix-down of those four channel recordings to headphones while providing a rudimentary form of head-tracking.  Turning the knob in synchronously with my head would "turn the virtual mic array" in the same direction.  The B channel already gets filtering applied to it to perceptually spatialize it so as to sounds more diffuse and "coming from all around behind". Turning the knob would dynamically assign what information gets routed where.  Similarly I can EQ the Left, Right, Center, and Back inputs and outputs differently before and after going through the circular balance control.  Before fixes the recording the same as I would in a typical stereo mix down. Afterward would affects a form of HTRF filtering to better emulate the actual directional perception of sound arrival from different directions to the head, and even more advanced filtering could be applied if needed.  If it works, the obvious next step would be tying the circular pan-knob to a physical head tracker device.  If would enable the ability to virtually turn my head in the recorded performance space and listen in any direction during playback. 

Been thinking about this since starting to make recordings in this way back in 2006 or so.  And especially so after demoting the Smyth Realizer that does this to a far, far more advanced degree via manipulation of binaural convolution, so astoundingly convincing that at first I thought the headphones were turned off and I was hearing the actual sound sources distributed around the room as I turned around to look at them.

[kuba e]

Gut, I think this can be done via script in a Reaper. I was doing simple things in Rea script couple years ago. I know that it is also possible to create own GUI in Rea script. For example, this page explains it very nicely - https://www.admiralbumblebee.com/music/2018/09/22/Reascript-Tutorial.html . Unfortunately, I am very busy now. I will have a lot of work at least a year and a half. I need longer free time in a row to study everything again and to script it. It's an interesting task. If something changes in the future and I have more free time, I write to you.

[Gutbucket]

Thanks and same here.  Was wondering if it might be configured within Reaper. I may shift from Samplitude to Reaper at some point, or at least learn my way around Reaper, but I don't really have the time to commit to doing that at present, and will need to get up to speed before diving that deep!  Now noted for future reference.

[kuba e]

I looked at it and it's not such a complicated task. I tried ChatGPT and it generates some basic scripts. It looks pretty good. If I have one or two free weekends, I can try it. Maybe ChatGPT could generate the whole script if we ask him correctly.