# What constraints does ComfyUI's Wan2.1 VACE guide state for frame count, batch size, resolution and run time when doing reference, control, inpaint or first/last-frame video?

- id: art_01M5NPXF51QJG43ZPXCCZG2T9D
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T06, T08, T11 · tags: none
- updated: 2026-10-24T01:03:01.787Z
- url: https://veyrul.com/articles/art_01M5NPXF51QJG43ZPXCCZG2T9D

Problem. Setting VACE nodes so first/last frames take effect and avoiding shape errors. Conditions. docs.comfy.org VACE page (undated; carries its own warning that it needs updating and defers to template notes); VACE-14B and 1.3B models, Apache-2.0 per the page. Method. One template drives all tasks by bypassing nodes: text-to-video, reference-image video, control-video (depth-preprocessed) plus reference, mask inpainting from a first frame and mask, outpainting, and first/last frame (keyframe) interpolation. Constraints: image width/height should be divisible by 16 (the page warns that nodes that read image size can error otherwise); in the first/last-frame workflow the video length must satisfy (length - 1) divisible by 4, and Batch_size = length - 2. Models: wan2.1_vace_14B_fp16.safetensors (about 32 GB) or the 1.3B fp16 (about 7 GB) into diffusion_models; the 14B supports 480p and 720p, the 1.3B only 480p. The page reports on a 4090: 720x1280 for 81 frames about 40 minutes, 640...

Problem. Setting VACE nodes so first/last frames take effect and avoiding shape errors. Conditions. docs.comfy.org VACE page (undated; carries its own warning that it needs updating and defers to template notes); VACE-14B and 1.3B models, Apache-2.0 per the page. Method. One template drives all tasks by bypassing nodes: text-to-video, reference-image video, control-video (depth-preprocessed) plus reference, mask inpainting from a first frame and mask, outpainting, and first/last frame (keyframe) interpolation. Constraints: image width/height should be divisible by 16 (the page warns that nodes that read image size can error otherwise); in the first/last-frame workflow the video length must satisfy (length - 1) divisible by 4, and Batch_size = length - 2. Models: wan2.1_vace_14B_fp16.safetensors (about 32 GB) or the 1.3B fp16 (about 7 GB) into diffusion_models; the 14B supports 480p and 720p, the 1.3B only 480p. The page reports on a 4090: 720x1280 for 81 frames about 40 minutes, 640x640 for 49 frames about 7 minutes (single-GPU anecdote, no n). Failure modes. Using arbitrary frame counts with first/last frames; resolution not multiple of 16; assuming the page is current for CausVid LoRA templates (it says it is not). Limitations. Docs-only; templates not run. The 4090 timings are the page's own and unreplicated. Version and date. Docs fetched 2026-10-23.

Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.

Limitations: Timing numbers are unreplicated single-GPU statements; template state may have changed since the page was written.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://docs.comfy.org/tutorials/video/wan/vace.md",
      "note": "First/last frame section; First/last frame section; Tip on timing"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Problem. Setting VACE nodes so first/last frames take effect and avoiding shape errors. Conditions. docs.comfy.org VACE page (undated; carries its own warning that it needs updating and defers to template notes); VACE-14B and 1.3B models, Apache-2.0 per the page. Method. One template drives all tasks by bypassing nodes: text-to-video, reference-image video, control-video (depth-preprocessed) plus reference, mask inpainting from a first frame and mask, outpainting, and first/last frame (keyframe) interpolation. Constraints: image width/height should be divisible by 16 (the page warns that nodes that read image size can error otherwise); in the first/last-frame workflow the video length must satisfy (length - 1) divisible by 4, and Batch_size = length - 2. Models: wan2.1_vace_14B_fp16.safetensors (about 32 GB) or the 1.3B fp16 (about 7 GB) into diffusion_models; the 14B supports 480p and 720p, the 1.3B only 480p. The page reports on a 4090: 720x1280 for 81 frames about 40 minutes, 640x640 for 49 frames about 7 minutes (single-GPU anecdote, no n). Failure modes. Using arbitrary frame counts with first/last frames; resolution not multiple of 16; assuming the page is current for CausVid LoRA templates (it says it is not). Limitations. Docs-only; templates not run. The 4090 timings are the page's own and unreplicated. Version and date. Docs fetched 2026-10-23. · locator: First/last frame section; First/last frame section; Tip on timing · source: https://docs.comfy.org/tutorials/video/wan/vace.md

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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