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| <h1>Do not drink the latents</h1> |
| <p class="sub">Evidence sheets for a MiniMax H3 packing question: when a keyframe |
| guide and a Ref2VA reference are used on the same conditioning, where does the |
| guide actually land? Two sheets, twenty cells at one seed: four ComfyUI builds |
| by five reference configurations, sixteen of which render and four of which |
| raise. Kept here rather than on the front page because it is a note for |
| one upstream discussion, not part of the Motion Lab.</p> |
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| <h2>The setup</h2> |
| <p>Guide rows are positioned from the text span, while reference blocks are |
| packed afterwards and advance the cursor the target video sits on. So every |
| reference slides the guide earlier relative to the clip it is meant to anchor. |
| The size of the slide is the reference's own cursor advance:</p> |
| <table> |
| <tr><th>reference</th><th>guide lands at</th><th>visible?</th></tr> |
| <tr><td>none</td><td>+0.0 units</td><td>on target frame 0</td></tr> |
| <tr><td>one image</td><td>−1.0 unit (−0.6 frames)</td><td>sub-frame, no</td></tr> |
| <tr><td>107-frame video plate</td><td>−150 units (−90 frames)</td><td>outside a 73-frame clip</td></tr> |
| </table> |
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| <h2>Does the guide land?</h2> |
| <img src="frame0.png" |
| alt="Grid of generated frame 0 across builds and reference configurations"> |
| <p class="cap">Row 1 is the input for each column. Below it, generated frame 0 |
| measured against the guide image (mean absolute error, 0–255). The image |
| reference columns hold the guide everywhere, because the slide is under one |
| frame. The video plate of the same scene is where it breaks: 33.91, and the |
| beaker in the guide is simply gone. Stock master has no row because it raises |
| <code>RuntimeError: shape mismatch</code> on all four reference configurations.</p> |
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| <h2>Does the reference do anything?</h2> |
| <img src="frame72.png" |
| alt="Grid of generated frame 72 across builds and reference configurations"> |
| <p class="cap">Frame 72 of 73. Swapping an image reference for a restyled |
| version of the same subject moves the output by about 12/255; swapping the |
| video plate moves it by about 51/255, and what transfers is framing, scale and |
| staging rather than identity. A single seed and a single subject, so read these |
| as a direction, not a law.</p> |
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| <h2>Reading the numbers</h2> |
| <p>Mean absolute error on 0–255 RGB, full frame. About 1.7 is seed-level |
| noise between two runs of the same configuration, about 5 is a cleanly anchored |
| frame, and a guide the model ignores lands near 70. The fix that produces the |
| clean rows is <a href="https://github.com/matlowai/ComfyUI/tree/fix/minimax-h3-keyframes-refs-compose">one |
| small branch</a>: derive the guide origin from the same reference advance the |
| target uses. It renders pixel-identical whether applied to master or on top of |
| the upstream PR.</p> |
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|
| <p style="margin-top:3em"><a href="../">back to the Motion Lab</a> |
| · <a href="https://github.com/matlowai/ComfyUI-MAINodes">repo</a> |
| · MIT</p> |
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