Duration Pixaroma

What it is for

Video models do not think in seconds, they think in frames. Worse, most of them will not accept just any number of frames: they want it to land on a particular pattern. MiniMax H3 wants every 17th frame plus 5, so 124 frames is fine but 120 is not. Wan and Hunyuan want every 4th frame plus 1.

That normally means wiring up two nodes: one holding the number of seconds, and one doing maths on it. This node is both of them, and it shows you the answer before you run anything.

Using it

• Click a length on the node, or drag the slider, depending on how you set it up.
• The orange line underneath tells you what will be sent: 5 s -> 124 frames.
• Wire frames into the length or frame count input of your video node.
• Open the gear on the node to change anything.

Choosing which lengths are allowed

This is the part worth setting up once per workflow. Under How you pick, choose Buttons and type the lengths you want, such as 3, 5, 10, and the node gives you one button each. Choose Slider instead and set a smallest and largest length, and you can drag anywhere between them. Type it lets you enter any number inside the range.

Buttons suit a workflow where you always use the same two or three lengths. A slider suits one where you want to fine tune. Two Duration nodes on the same canvas can be set up completely differently.

Telling it about your model

Under Convert to frames, pick your model and the node fills in the numbers. Picking a model COPIES its settings onto this node, so changing it later never disturbs another workflow.

If your model is not listed, set the three numbers yourself. FPS is the frame rate. STEP is the multiple the frame count has to land on. PLUS is what gets added on top. Setting STEP to 1 turns rounding off completely, so you just get seconds times frame rate.

MiniMax H3

24 fps, every 17 frames plus 5

Wan 2.x

16 fps, every 4 frames plus 1

Hunyuan

24 fps, every 4 frames plus 1

LTX

24 fps, every 8 frames plus 1

Plain frames

no rounding at all

Your own formula

Pick Custom formula if none of that fits, and write the maths yourself. a is the length in seconds, and you can use fps too. It understands the same functions as ComfyUI's own Math Expression node, so you can paste one straight across.

Only one of these is ever active. Choosing a model switches the formula off, and choosing Custom formula switches the model off. If your formula has a mistake in it the node says so and falls back to the numbers, rather than failing the whole run.

Why the length changes slightly

Rounding to your model's pattern almost always moves the length a little. Ask for 5 seconds at 24 frames per second and you get 124 frames, which is really 5.17 seconds. The node shows you both so it is never a surprise.

That is also why there are two outputs. frames is what your video node needs. seconds is the true length, so anything that has to line up with the picture, like audio, stays in step instead of drifting.

What comes out

frames

A whole number, already adjusted to your model's pattern.

seconds

The real length of the video, which is frames divided by frame rate.