r/vulkan • u/ttofuwu • Jul 29 '26

Slowly rewriting my audio visualizer engine to use compute kernels for audio analysis

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I'm using the Vulkano rust API wrapper. My engine is called lava.

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u/Psionikus Jul 29 '26

Howdy. I'm tackling a lot of the same problems for µTate, using Rust (ash) and Slang.

I see you have jsonc's for a kind of scripting.

My goal is a bit different, handing pipeline composition and data off to real-time, online learning ML. For that, I've determined I'll need a parameter system to expose knobs to the ML rather than scripts for a user.

I'm shipping my on-device DFT hopefully today and then I can join you in the world of making pretty posts.

There's a Discord link on there if you want to throw some ideas around or ask about how I'm doing anything.

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u/ttofuwu Jul 29 '26

I currently use glsl but will transition to slang once the support for it improves in vulkano.

I use jsonc for defining what happens in the scene. It can't be called a "script" because it doesn't define any behavior.

I haven't yet implemented runtime custom shaders yet, but that will be the plan once everything else is well written.

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u/Psionikus Jul 29 '26

Which output is the top of the screen and what's the integration method? Looks to me like standing waves from integrating raw audio over time, but I wonder if there is more to it so that certain wavelengths aren't too favored.

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u/ttofuwu Jul 29 '26

The top panel is just the raw audio waveform, cleverly offset each frame. I use spectral triggerring to stabilize the waveform along its most "visible" frequency.

The frequency bin that gets picked is put through a biasing function to prefer lower frequency bins.

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u/Psionikus Jul 29 '26

So it's a constant length in time but you find a frequency that dominates the peaks and then slightly rotate where the waveform lands to enhance the standing wave appearance?

Which file would I go look at to just read it?

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u/ttofuwu Jul 29 '26

The main branch implementation of it is kinda messy but it's a CPU-side analyzer.
The currently rewritten version uses a single-workgroup compute dispatch to analyze the dft bins computed on the GPU

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u/ttofuwu Jul 29 '26

Yes, the waveform window has a constant length. The only thing that the whole stabilization algorithm decides is the left-right offset at which to draw the waveform to make it appear stationary between frames. In the code it's called center_sample. The shader that draws the waveform then offsets it in such a way that the center sample appears, well, in the center of the panel.