Insert a blank page between each existing page in a PDF document

Question

I've got a PDF and I want a fast way to insert a blank page every second page (except at the end). E.g. my PDF has the pages

1: A
2: B
3: C
4: D

it should look like:

1: A
2: empty
3: B
4: empty
5: C
6: empty
7: D

Is there any easy scripting way to do so? I thought of using pdftk but I don't know exactly if it's the easiest way to do... I'm running Windows 7.

Thanks so far!

Answer 1

Okay I did it myself using PHP and FPDI/FPDF:

<?php
error_reporting(E_ALL);
require_once('fpdi/fpdf.php');
require_once('fpdi/fpdi.php');

// Format für die einzelnen Folien:
$format = 'L';  // Entweder '' (horizontal) oder 'L' (Landscape!)

// Verzeichnis lesen
foreach(glob('infiles/*.pdf') as $file)
{
    $filename = basename($file);
    $fileout = 'outfiles/' . $filename;

    // Ausgabe-PDF
    $out = new FPDI();

    // Vorhandenes PDF einlesen
    $pagecount = $out->setSourceFile($file);

    // Alle Seiten nacheinander importieren
    for($i = 1; $i <= $pagecount; $i++)
    {
        // Importiere Seite
        $tpl = $out->importPage($i); // , '/MediaBox'

        // Vorhandene Seite
        $out->addPage($format);
        $out->useTemplate($tpl);

        if($i < $pagecount)
        {
            // Leere Seite anfügen (nur nicht am Ende)
            $out->addPage($format);
        }
    }

    $out->Output($fileout);
}

all files in the subdirectory 'infiles' will get blank Pages inserted and saved to 'outfiles' with the same filename!