Was sending this to the list but the last three replies came back blank….

Here's the discussion (with myself) so far…

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To simplify a composite, (and keep my sanity), I am trying to define the frame sequence for a bunch of elements with one variable that runs sequentially for a while, cycles, goes back to being sequential, back to cycling, etc.

I'm feeding a variable (channel file) into the File COP's to control which frames are read from disk.

No matter what I do, I can't get the file COP's to read in frames beyond the frame number of the image files that actually exist on disk. I've tried over-riding the frame range in the file COP and even putting dummy files on disk to “extend” the frame range.

I know there are other ways of doing this… using a series of Switch and Sequence COPs for example… but using a single channel as a frame index would be much simpler and easier to maintain.

Any suggestions?

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Seem to have this working now…

Choose “Use Next Frame” in the “Missing Frames” selector of the File COP.

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Well… I spoke too soon.

I can get this to work when manually messing with the COPs in the composite network, but when I go to output using a composite ROP or from a shell it dies with an “Unable to find file” errors.

I've always felt the File COP is trying to be too smart for it's own good… this seems to be such a simple procedure… I must be missing something.

BTW… using 9.0.787 on linux

I've had a lot of weirdness when I tried to do this as well … I'm a little curious why it doesn't just work like the file SOP?

Anyone know how to make it work exactly like the file SOP?

File COPs don't like expressions involving $F very much. This is partly because it makes determining the frame range and image type very difficult, and partly because any sort of “Missing Frame” substitution becomes almost impossible when general expressions are introduced.

The COP you want is the Time Warp COP. It does exactly what you're describing, and unless you use a “Frame Round” of “Blend”, it's free (no image cooking is done on that node).

I don't see how the TimeWarp COP will work for what I'm doing… which should be something extremely simple. (Please let me know if I'm not understanding how you see it working).

I have something like this in the file COP…

file_name.`ch(“fram_indx”)`.pic

Where “fram_indx” is a channel of (integers) sequential numbers and cycling numbers that correspond to image files that already exist on disk.

For example, say I've rendered frames 1-60, 181-240, and 301-400.

My 400 frame channel file would look something like this…

1…60 1…60 1…60 181…240 211…240 211…240 301…400

I don't think the file COP should be giving me a hard time with this.

Not that this is going to help with the file cop expression Floyd, but I would likely use a file cop for each of the frame ranges you want and then use a Sequence cop to assemble them.

I see, yeah I was needing this to work also but I thought it would be simpler than this. Still not clear on why this functions any differently than the file SOP.

Here's a working COP setup using timewarp which seems to accomplish the task, using keyframes or expressions (press the mantra render button to generate images first)

It's working nicely now.

Thank you Andrew for the example hip file.

Thank you “twod” for the TimeWarp COP suggestion. Apologies for not initially understanding how it worked. ops: