VPScheduler_motorway_edition

When you build a custom sampling chain in ComfyUI - the SamplerCustomAdvanced route - you're responsible for the noise schedule, and the stock VPScheduler is one of the classic ways to generate it. "VP" stands for variance-preserving: it's the original DDPM-style beta schedule that SD 1.5-era models and some video models were trained on. This _motorway_edition clone produces the same SIGMAS, but stores them in the agilly1989 Motorway dict by key instead of handing them down a wire.

Motorway primer: start with MotorwayStart, then each _motorway_edition node trades data wires for key strings, reading and writing a shared dict that flows down one MOTORWAY connection. These nodes are auto-generated clones of core ComfyUI nodes, so the schedule math is identical to stock VPScheduler.

What it does. It computes a set of noise levels (sigmas) for a given number of steps (default 20), using the VP beta schedule controlled by beta_d (default 19.9), beta_min (default 0.1), and eps_s (default 0.001). The output is a SIGMAS object that feeds into a sampler like KSamplerSelect-driven custom chains or straight into the sampler node in a custom-sampling graph. The defaults match the classic schedule; the extra parameters exist because the schedule is a curve and the curve is tunable, but for 99% of users the defaults are correct.

The inputs that matter. MOTORWAY is optional - a scheduler has no data inputs, so connect an existing Motorway to add to it or leave it unconnected to act as a start. steps is the one you'll touch most. OUTPUT_SIGMAS_key (default SIGMAS) is where the schedule is stored in the dict. Output: the MOTORWAY port only - the sigmas live in the dict, and your sampler pulls them by key.

Common issues. The big one is choosing the wrong schedule family: a VP schedule is a specific, model-era choice, and modern flow-matching models want a different schedule entirely. If your sampling looks wrong or trains of thought about "sampler doesn't match the model" start - that's a schedule mismatch, not this node's bug. The Motorway's key/case traps apply as always: exact-match keys, and 'MotorwayClass' object has no attribute 'hash_' means you asked for a key that was never stored. And the standing caveat: the pack's current main branch has the clone registration commented out in __init__.py, so a node missing from your menu usually means that version.

Install via ComfyUI Manager (search "ComfyUI_agilly1989_motorway") or clone into custom_nodes, restart, no models to download. Solo-dev beta pack - the Motorway is a tidy-up layer, and for a custom-sampling chain that already has five nodes in it, one more piece of state in the dict is a fair trade.