VACE First and Last Frame Workflow Cutting off last frames.

[genericgod]

Hello,
I am asking here, because I am not sure if this an issue with comfy or the workflow itself.
I was trying this wan vace flf2v workflow (Modified with gguf node by city96): https://github.com/Comfy-Org/workflow_templates/blob/main/templates/video_wan_vace_flf2v.json

Problem is this workflow somehow causes a discrepancy between input and output frame count.:

Frames are set with an Int node, which is also connected to the "length" widget on the WanVaceToVideo node. So it should also have the correct number of frames set. As you can see all frames and masks should be correct:

But the output is always missing a few frames, no matter what I set the length to. Any ideas what the problem could be or is it a bug?

Output:

vace_issue.mp4

[comfyui-wiki]

If you're using the template, remember to set the corresponding values for "Length" and "Batch size". Set Batch size = Length - 2
Have you tested using the default template without making any changes? This workflow will be enhanced once we have the math node in the Core node.

1.mp4

[genericgod]

Thanks for your answer!

Have you tried using a different length than 81/79 frames?
I am asking, because I loaded the default template and it works without any changes, but changing the length to anything other than exactly 81 causes the problem I described.

Here are some examples:
This was made using the 14B GGUF but the 1.3B fp16 has the same problem for me.

81/79 frames (works):

81_frames.mp4

72/70 frames (doesn't work):

72_frames.mp4

82/80 frames (doesn't work):

82_frames.mp4

I don't know what could cause this. The workflow seems like it should work, but I'm no expert.
Maybe my comfy installation is somehow faulty?

[comfyui-wiki]

The step size for the length of WanVaceToVideo should be set to 4. It must be configured in a way that when 1 is subtracted from it, the resulting value is divisible by 4.

try:
85/83
73/71

I think I should update the template and add a note about it. I believe that this kind of issue can be resolved once the math nodes are included in the core nodes.

[genericgod]

Yes that was the problem! Thank you!

I saw in the documentation "step size 4" but I assumed it should be divisible by 4 without the +1. Now it works like this.