KfSinusoidalGetFrequency

KfSinusoidalGetFrequency is a read-only utility, the kind of node you'd never search for but reach for when a workflow surprises you. You feed it a sinusoidal curve and it hands back a plain FLOAT: the curve's frequency, in cycles per time step (per frame, in animation terms). That's it. One input, one output, no settings to fiddle with.

The trick that makes it slightly non-obvious: it doesn't read a stored frequency. The keyframed library keeps wavelength as the canonical parameter, so this node computes frequency on the fly as 1 / wavelength. That means GetFrequency and its sibling KfSinusoidalGetWavelength are literally reciprocals of each other - feed the same curve to both and the outputs multiply to 1.

When you'd actually use it

• Inspect a curve you didn't build. Entangled Curves nodes and the Adjust nodes hand you sinusoidal curves without telling you their parameters. This node tells you.
• Wire a number into something. The FLOAT output plugs straight into any numeric input, a math node, or a text display - so you can label a plot, log a value, or drive another parameter from it.
• Round-trip a design decision. Build a wave by wavelength, read it back by frequency, and confirm the two are consistent before you stack more curve math on top.

Inputs and outputs

• curve - a SINUSOIDAL_CURVE, and it's forceInput, meaning you can't type a value; you must wire in a curve from a constructor or Adjust node. If you don't see a way to set it manually, that's intentional.
• FLOAT output - frequency in cycles per frame. With a default KfSinusoidalWithFrequency curve you'll get 0.0833… (that's 1/12).

Installing it

Same as the rest of the pack - pure Python, no models to download. ComfyUI Manager, search "ComfyUI-Keyframed", or:

cd ComfyUI/custom_nodes
git clone https://github.com/dmarx/ComfyUI-Keyframed

then restart. It lives under keyframed → sinusoidal.

One honest caveat: for a beginner this node is rarely the missing piece - it's a transparency tool for when you want to know what your curve actually is. When you do want that, it's invaluable. You'll likely grab it alongside the curve-drawing utilities, which turn the same curves into images you can actually look at.