Expression

Every animation tool has the same boring problem: you want a parameter to move - drift up, pulse, wobble, ease in - and hand-keyframing 120 frames of it is drudgery. Expression is the shortcut. You type a formula, and it hands you a set of keyframes. sin(t*2)*10 is the default and it's a genuinely good place to start: a gentle oscillation you can wire into almost anything.

ComfyTV is jtydhr88's canvas app that turns ComfyUI into a full media workbench - ~190 stages, each its own node. Expression is one of its "parameter infrastructure" pieces: instead of animating pixels, it generates a stream of numbers that drives another stage's parameter. It's the math version of what After Effects expressions do for a slider.

How it works

The node evaluates your expression over time, where t is time in seconds (or frames - that's what rate and fps are for). The result is written as keyframes at your chosen rate. Two useful details:

• Wire an optional video in and it reads duration and fps from the source, so your animation exactly covers the clip without you doing the arithmetic.
• There's a seed for deterministic pseudo-randomness, which matters more than you'd think - a seeded noise(t) expression gives you organic motion you can regenerate identically.

The output is keyframes (COMFYTV_TEXT), and that's the odd part if you're new here: this node's output isn't pixels or video, it's data to feed another stage's animated parameter.

The inputs that matter

• expression - your formula in t. Keep it simple and readable; this is the whole node.
• field - what the keyframes drive: v, scale, opacity, x, y, or rotation. Pick the parameter you're animating so the downstream stage knows what the numbers mean.
• rate (default 10) - keyframes per second. Higher = smoother, and costlier to the downstream stage.
• duration (default 5s) and fps (default 24) - overridden automatically if you wire in a video.
• seed - for deterministic randomness in the expression.

Every ComfyTV stage also carries hidden internal inputs (force_run_token, project_id, parent_output_id) populated by the frontend - that's the per-node Run plumbing. Leave them alone.

Installing it

ComfyTV installs as one pack - ComfyUI Manager, or:

cd ComfyUI/custom_nodes
git clone https://github.com/jtydhr88/ComfyTV

Full backend restart, then it's under ComfyTV → VideoFX. The one gotcha that bites people: on ComfyUI Desktop, macOS, or multiple installs, clone into the running instance by absolute path, confirm custom_nodes/ComfyTV/__init__.py (not a nested folder), and fully restart. The pack declares zero pip deps - mostly a frontend - though video stages lazily import PyAV, so pip install av if anything video-related errors.

Common issues

• Nothing animates - the keyframes went somewhere, but no downstream stage is consuming them. This node only produces data; you have to wire the keyframes output into a parameter that accepts it.
• Motion is way too fast or slow - that's rate versus the clip's fps. Wiring the video in fixes this automatically; otherwise match fps to your footage.
• Expression errors - formulas are evaluated as math over t; a syntax slip fails fast. Test incrementally - start with t, then add the wobble.