MiniMax H3 Sigma Shift (Ray)

MiniMax H3 Sigma Shift (Ray) is the raylight version of ComfyUI's MiniMaxH3SigmaShift node, and it exists for a very specific reason: MiniMax's H3 video model samples its video and audio streams on different schedules, and if you don't shift them separately, one of the two comes out wrong.

MiniMax H3 is the open-weights video model that generates synchronized video and audio - it's one of the few locally-runnable models that does both in a single pass. The catch is that its two modalities aren't tuned the same way. The video stream wants a higher sigma shift so its steps land where the motion and composition get established; the audio stream wants a much lower one, because sound doesn't need (or tolerate) the same early-noise treatment. Get the video shift too low and clips look stiff; leave the audio shift at the video value and the audio comes out mushy or weirdly over-processed.

That's why this node has exactly two inputs:

• shift_video - default 12.0. The sigma shift applied to the video path. MiniMax's reference value, and it's high on purpose.
• shift_audio - default 3.0. The sigma shift for the audio path. Notice the gulf - that gap is the node. If your H3 output has great video but bad audio (or vice versa), this pair is where you look.

Mechanically it's a thin wrapper: the code imports ComfyUI's own MiniMaxH3SigmaShift implementation and applies it inside the Ray workers, so the shift is set on the distributed model rather than just the host. ray_actors in, ray_actors out, chain it to your Ray sampler.

Two things to know

• It needs a recent ComfyUI. The node refuses to run if comfy_extras.nodes_minimax_h3 isn't available - it raises an error telling you to update ComfyUI. If you hit that, it's not a raylight bug, it's an upstream version check.
• This is the raylight-specific replacement for the stock node. If a MiniMax H3 workflow you downloaded expects MiniMaxH3SigmaShift and you're running distributed, swap in this node so the shift is honored by every worker instead of only the main process.

Install is the pack's standard route (ComfyUI Manager → "raylight", or clone + pip install -r requirements.txt), no model downloads. If you're not running MiniMax H3, this node is meaningless to you - it's that targeted. If you are, the defaults are right and the only real knob to touch is shift_audio when the audio side of a generation misbehaves.