Automatically combine files to PDF based on the filename

Now that I've learned something new today from Thom Parker's post you can skip points 1 through 4 in my original post and simply replace them with an Action that only contains a save command.  This will convert all the .png files to PDFs.  Then proceed to step 5.    Searching "Action Wizard" on this site will get you started.  But like Try67 said, Acrobat might not be suited for such a high volume of files.  I suggest processing 100 files and timing it, then do the math to see how long it's going to take to process them all.  Then keep testing, while increasing the number of files by 100 until Acrobat invevitably crashes. This will give you an idea of how many files can be processed in a session.  I have had to do this for projects with thousands of files, but never anywhere close to millions.

For that quantity of files I would strongly recommend you use a stand-alone (preferably command-line) application, and not Acrobat. It's not suited for batch processing such a high volume of files.

Actually, this could easily be done with an Acrobat Action (batch process). Actions operate on all files in a folder. The action will automatically convert the png files to PDF, after which they can be saved and then a script can sort the file name, log it, and insert it into the appropiate combined PDF .

This will work, with a couple of caveats:

a)  The PDF pages will all be the same size, with the .png images scaled to fit on the page.

b)  You will have to break up this process, limiting the number of files process at one time, or Acrobat will crash.

1)  Create a blank PDF page with a button field that covers the entire page, and set the button and set the button layout to "Icon Only".

2) Create a .bat file that creates a text file list of all files in the folder (instructions in the link of the next point).

3)  Create your own "Action" (not the Action Wizard as it only operates on .pdf files). https://pdfautomationstation.substack.com/p/how-to-create-your-own-action-batch

4)  The script you write for this will import the .png file into the button field, flatten the pdf, save the pdf with same name as the .png file but with .pdf extension, close the file, reopen the template and repeat for the next file in the list.  You will end up with one PDF file for every png file.

5)  Create an Action (Action Wizard) that executes a JavaScript that:  Checks the file name of the PDF for the number of underscores.  If the file name contains more than one underscore, don't do anything.  If the file name name contains only one underscore, insert pages from the other files with anticipated file names.  You will have to run a loop of anticipated file names to the maximum possible number of pages and us a try/catch so errors will be ignored when file names of pages to insert are not present.