HR Endless Sampler: open-source ComfyUI node renders any-length H3 videos on 16GB VRAM

rhradec · reddit · 2026-08-30

Developer hradec released ComfyUI-HR-Endless-Sampler (alpha), removing Minimax H3's duration and VRAM limits: any-length video at any resolution on just 16GB of VRAM — the author rendered a full 600-frame 1080p video. It's open source with a template workflow.

How it works: the sampler node splits a long video into chunks, automatically attaching the last frames of the previous chunk as continuation. It also uses Gemma 3 12B QAT as a "chunk director", splitting the overall prompt into per-chunk prompts, watching previous chunks for continuity, and verifying each chunk matches the intended time-slice of the overall action.

Companion nodes: a live preview (built on KJNodes with TAEH3 tiny VAE, frame-by-frame walking, hover shows each chunk's Gemma prompt and render time), plus save/load nodes that persist per-chunk prompts, timeline and timings. The save node, from the author's VFX background, decodes latents internally and exports unclamped floating-point EXR.

The author notes low-VRAM users benefit most, but high-VRAM users can also break H3's 15-second barrier and even render 4K or 8K.

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