Summary: The frame value in input image nodes when set to Sequence fail in all circumstances when frame counts do not start with 0001.

Assuming image-0000, image-0001, image-0002, image-0003, it appears that one frame will be dropped from the series when using the offset value. In the above example, image-0000 will _always_ be missed despite an offset of -1.

Some bad mojo appears at work in the frame counts / offset from what I can tell. It would likely go unnoticed unless one uses large frames of numerical values to help visualize the problem.

Reproduction: Load the following four frames into the compositor. Set Auto-Refresh and Cyclic to on. Set the input node to the following values and note the sequence that results.

The following series occurs:

FRAMES(4) OFFSET(0) : 2, 3, 4, 4, 2, 3, 4, 4, 2, 3, 4, 4, 2
FRAMES(4) OFFSET(-1): 2, 2, 3, 4, 4, 2, 3, 4, 4, 2, 3, 4, 4
FRAMES(3) OFFSET(0) : 2, 3, 4, 2, 3, 4, 2, 3, 4, 2, 3, 4, 2
FRAMES(0) OFFSET(0) : 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1

It appears that there is some poor math logic in the frames setting. When there is a single frame in the series, the frames count should be 1 as opposed to 0. The math issue is likely causing further grief when things get more complicated, thereby dropping the first frame.

The bug also applies to bad mojo in background images and other areas.

Version: SVN 31622