Split 4-slide pages into separate ones

slide4to1.sh

#!/usr/bin/bash

#
# 0 -1                     -348
# -->|
# ----------------------->|
#
#    +----------+         +----------+
#    |          |         |          |
#    | SLIDE #1 |         | SLIDE #2 |
#    |          |         |          |
#    +----------+         +----------+<----------
#                                   -45         0
#              -393
#               |<-------------------------------

#
#  0 | |               
#    | |               
#    v |               
# -1 - |  +----------+ 
#      |  |          | 
#      |  | SLIDE #1 | 
#      |  |          | 
#      |  +----------+       - -319
#      v                     ^
# -251 -  +----------+       |
#         |          |       |
#         | SLIDE #3 |       |
#         |          |       |
#         +----------+ -68 - |
#                          ^ |
#                          | | 0


SRCNAME=$1
OUTNAME=$2
TMPDIR=tmp
rm -rf $TMPDIR
mkdir $TMPDIR

pdfseparate $SRCNAME "$TMPDIR/$SRCNAME-%d.pdf"
ls $TMPDIR/$SRCNAME-*.pdf | while read line; do
    pdfcrop --margins '-1   -1   -393 -319' $line $line-1.pdf
    pdfcrop --margins '-348 -1   -45  -319' $line $line-2.pdf
    pdfcrop --margins '-1   -251 -393 -68'  $line $line-3.pdf
    pdfcrop --margins '-348 -251 -45  -68'  $line $line-4.pdf
done

pdfunite $TMPDIR/$SRCNAME-*.pdf-*.pdf $OUTNAME