Composite image sequence only using one image in the sequence

Question

I am only getting a single frame of an image sequence used in my Compositor output frames.

I am trying to create a series of images from a single background (static) and an animation (png) sequence. If I use the sequence of "anim 0884.png":

through "anim 1274.png"

, a file open seems to indicate a sequence "anim ####.png", but only seems to find a single frame (Frames set to '1'), including if I click on the Match Movie Length in the Node Item properties.

If I keep this setting I only get "anim 0884.png" used in all frames of the output "composite 0884.jpg" through "composite 1274.jpg". :

If I set the image sequence Frames=387, I only get the last frame "anim 1274.png" used in all frames:

What am I overlooking? I need the composites to start at frame 884 because other animation occurs frames 1-883, that is rendered separately.

UPDATE: I finally found a combination that worked for but it is not at all intuitive, and ... it ONLY works if I run it from the command line (blender -b postRenderCompositing.blend -S Scene.compositing -s 884 -e 1050 -j 10 -a), not with ctrl-F12!

Here is a link to a zip containing the blend file and sample data: https://www.dropbox.com/s/rucw94302txj6ce/postRenderCompositing.zip?dl=0

Answer 1

EDIT: The settings in the Image Sequence node are a bit different then I epxlained before - my answer only worked because I tested it with an image sequence starting at frame #1 - while yours beings with #884. So here's how it all works together:

Your mistake is, you have set an Offset of 883 in the Image Sequence node and set your animation to render from frame 884 to 1271 (my month and year of birth :D ), while at the same time you have set Start Frame set to 1 in the Image Sequence node - but your animation starts at frame 884.

What the three values Frames, Start Frame and Offset do is the following:

1. Frames tells Blender how many images are in that sequence
2. Start Frame tells Blender on which frame the sequence should begin to run
3. Offset tells Blender what to add to 1, to get the image number on the specified Start Frame

So, in order to make this work you must either render the animation from frame 884 to 1271 and make Blender believe you have 1271 images starting at frame 1, set

Frames = 1271, Start Frame = 1, Offset = 0

in the Image Sequence node. This will render on each frame the image with the same number as the frame. So image#0001 on frame 1, image#0002 on frame 2 etc. Since your image sequence starts at #0884, the frames 1-883 will stay empty and the frames will start getting rendered at frame 884. If you would have set Frames to 388, then Blender will stay at image#0388 until the end of the animation which is not what you want (because there is no image#0388).

Or the better and more correct way would be, you render your animation from 884 to 1271 and set the following values in the Image Sequence node:

Frames = 388, Start Frame = 884, Offset = 883.

This way you can set the actual number of images your sequence has, and Start Frame tells Blender on which frame you want to render the first image of your sequence. Since the first image is usually #0001, you have to enter the Offset to tell Blender you don't want to begin with image #0001, but with 1+883 i.e. image#0884.

Whatever the range of your animation might be, let's say you want an animation starting at frame 1 and ending at frame 3000 - that's not really relevant for the Image Sequence node. You can render frames 1-3000, and if you want your image sequence to begin at frame 100, then set Start Frame = 100. Blender assumes you want image#0001 on frame 100, so you need the Offset = 883 to correct that.