git diff pptx

.gitattributes

*.pptx diff=pptx

.gitconfig

[diff "pptx"]
  textconv = unpptx

README.md

git diff pptx

1. Make sure you have iconv and perl in your PATH.
2. Put unpptx somewhere in your PATH and chmod +x unpptx.
3. Add the lines to your ~/.gitconfig.
4. Add the lines to your .gitattributes in your repo.

In addition to what Managing ZIP-based file formats in git by tante does, this setup adds line-breaks to huge xml chunks and ignores binaries for better diff result. So, binary changes do not appear in the diff result.

unpptx

#!/bin/sh
unzip -c -a $1 | iconv -f utf-8 -t utf-8 -c | perl -pe 's/></>\n</g' | perl -p -0777 -e 's/ extracting: .*( inflating: |\Z)/\1/s'