# Interlace frame numbers with file output node

I have a setup in the compositor that takes a piece of footage, does some operations, and outputs 3 difference files. Let's call them output A, B, and C. I have the file output node with added sockets to output each. What this gives me in the output folder is each output followed by the frame number. For example, frame 1 will give me A-0001.png, B-0001.png, C-0001.png.

What I would like is to alter the frame number appended to the output files so that instead I would have A-0001.png, B-0002.png, C-0003.png. Frame 2 would then give A-0004, B-0005, C-0006.

The end result would triple the number of frames of the animation and have them interlaced.

Is this possible with the file output node? Is it possible with a script?

• I think, the frame number will only be added if you don't specify the complete filename but omit the ending (the file suffix like .png). However, you might script a complete filename including your desired frame numbers via a driver function. You should be able to calculate your frame number via (bpy.context.scene.frame_current - 1) * 3 + output_offset (with output_offset being 1..3 for A..C. in your custom function. – Samoth May 2 '16 at 8:18
• The File Output node seems to add the frame# and format regardless. If I tell it the output is A.png, it'll give me A.png0001.png. – Ascalon May 2 '16 at 20:06
• I have the same issue :( Seems no way to stop blender appending the exact frame number to the filename. – hedgehog90 Apr 23 '19 at 12:12
• Setting render.use_file_extension=False removes the extension, but the frame number is still added. – Martin R. Aug 20 '19 at 23:08

I'm maybe wrong but it seems there is no way to avoid Blender (2.8) to remove the frame number and the extension of the filename with CompositorNodeOutputFile object, as I'm rendering by a python script I finally fixed it by renaming the files with os.rename combined with a regular expression just after render.