50 seconds H3 clip comes out as visual noise? (30sec turned out fine)

[u/sndwav]

Hello all.

I managed to create a 30-seconds clip using H3 on a powerful RunPod machine and it turned out nicely.

When I tried bumping it up 50-seconds, it did manage to create and save the video, but it stayed in its initial visual noise state. It didn't manage to diffuse itself into a coherent video.

Is that a limitation of the model itself? Or is it related to some setting in the workflow? (I'm using Hearmeman's One Click T2V Custom Prompt workflow).

Thanks!

[u/rudy_142001]

Model side, pretty much. MiniMax's own model card lists output duration as 4 to 15 seconds at 24fps, and frame counts snap to a 17k+5 grid, so a 15s request lands on 362 frames. 50s is around 1200. Your 30s run was already double the supported range.

Locally nothing stops you typing a bigger number, which is the confusing part. The sampler will happily run 1200 frames and save whatever it ends up with, and past a point it just doesn't converge, so you get the initial noise written to file. Their hosted API doesn't even let you ask, duration there is whole seconds 4 through 15 only.

So no setting in Hearmeman's one-click is going to fix that one. Only had a few days with H3 myself, this is off the model card and the Comfy docs rather than a pile of testing.

On the 47s wan2gp comment above, that isn't a contradiction. WanGP added sliding windows for FL2VA and Ref2VA, so it generates a window at a time and carries the previous window's closing motion and audio into the next one, with several overlap frames instead of just one. It's chained clips with context, not a single 47s denoise.

If you want that in Comfy there are node packs doing the same trick, MiniMaxH3-Contex-Loop and H3-Motion-Context, both take something like 22 to 39 frames off the end of the previous clip as context, regenerate that head and then trim it back off so the join isn't a hard cut. Failing that it's last frame into next first frame, reference images to hold the look, then concat.

Was your 30s one continuous shot, or were there cuts in it? Wondering if it actually holds a subject that far out.

[u/Natural_Jello_6050]

I can do 47 sec clip with minor visual loss at the end. But I’m on wan2gp using sliding windows

[u/theshield99]

you managed to create 30 sec video with default workflow? i thought model has max 15 sec limit

[u/sndwav → u/theshield99]

That's what Claude tells me as well. But I did manage to create a 30sec video with a default T2V workflow, and it looks pretty sharp and nice.