H3 support was written against ComfyUI's PR; it has since merged (57500fc5, shipped in
v0.30.0) and the weights are out. Everything the adapter assumed still holds — audio time
axis, 17k+5 grid, batch-1 forward, the imported optimized_attention symbol, every payload
key — so this is what the release itself changed, not a correction of the reading. LTX-2 /
LTXAV is untouched throughout: a project picks a family and both are first-class.
* i2v anchors now work on H3. LTX writes the image into the starting latent
(LTXVImgToVideoInplace); H3 has no such path — its anchor is a condition row packed
beside the text — so a scene's anchor image becomes a frame-0 keyframe pin instead, and
the LTX node is no longer run against an H3 latent. Studio hands the source image's
pixels to the sampler (it owns the CLIP, the sampler owns the VAE). Pins now MERGE, so
a first-frame anchor and a last-frame guide coexist: H3's own first-and-last mode.
* Frame geometry follows the model: frames per scene snap to the family's grid (LTX 8k+1,
H3 17k+5) in both frontends, in the graph builder, and in the sampler, and H3 renders at
its fixed 24 fps. Picking a family moves the project onto its geometry and says so.
* The two checkpoints are named. fl2va (anchors) and ref2va (references) load identically
and never reject each other's conditioning, so the run reports which mode it is in and
the setup panel spells out the split.
* Pipeline setup is no longer a placeholder: released, with the published filenames.
* Reference images can be encoded at the reference pipeline's 2048px short edge.
Fixes found on the way:
* A video reference lost its soundtrack between Studio and the sampler — Studio had
already announced it to the text encoder as <Audio 1>, so every later audio ordinal in
the prompt pointed one reference earlier than written.
* Easy Gen never knew it was on H3: its model config lives on the project, which the
shared capability check did not read, so every H3 warning silently reported LTX.
* An off-grid scene length failed with arithmetic instead of an explanation.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
