I'm not sure that is possible in Vegas with or without Boris's beat reactor,

This is the BCC spectrum, it's straight across the screen, it can be manipulated with colour, wave, ripple, transform etc.

I tried to create a simple circular version with the wave spectrum emitting outwards/inwards or both, like this -

but the only options I could think of to wrap the spectrum into a circle were the Sphere or Layer Dimension options (I think there's another I can't think of), I tried the little planet type effects, none were quite right

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There is another BCC+Audio Visualizer but this also only creates a circular pattern from the default straight, there's a few presets, they're also straight or circular based,

To create a heart like that I think it would need to follow a Path but as far as I know that isn't possible in Vegas, It would be good if Boris added 'Follow or align to Mocha Path in the BCC+Audio Visualizer fx so that custom shapes could be created.

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This the Boris vid that shows manipulated the spectrum using Beat rector in Particle array, I'd need to have another look but I don't think there's an option in there to change from the basic square / sphere / wave type options, here's some of the presets.

https://borisfx.com/videos/create-different-audio-visualizers-with-continuum-s-beat-reactor/

The presets above use a .BSP file, it gives you an option to Load your own but I don't know how to create .BSP files so I've never played with that, I think I did ask Boris once but it needed Adobe Illustrator, maybe it was Title Studio because I believe that also uses .BSP files..

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If there is another option to do this I would be interested...

How to do it in the shape of a heart?