To diff common binary files in git using appropriate external converters such as unrtf, pandoc, docx2txt.pl, odt2txt, git-xlsx-textconv, git-xlsx-textconv.pl or pptx2md, add to ~/.config/git/config the lines
[diff]
[diff "pdf"]
binary = true
textconv = "f(){ if command -v pdftotext >/dev/null 2>&1; then pdftotext -layout -enc UTF-8 -nopgbrk -q \"$1\" -; else cat \"$1\"; fi; }; f"
# textconv = pdfinfo
cachetextconv = true