Creating thumbnail for different media

doc_thumbnail.sh

#!/bin/sh

## Draft tool to create thumbnails from office documents, since unoconv wasn't working for me.

soffice_cmd="/Applications/LibreOffice.app/Contents/MacOS/soffice"

input_file="$1"
extension="${input_file##*.}"
noext_filepath="${input_file%.*}"
tmp_filepath="${TMPDIR}docthumb-$(date +%s)"
output_format=jpg
cd "${TMPDIR}"

cp "${input_file}" "${tmp_filepath}.${extension}"
"${soffice_cmd}" --headless --convert-to pdf "${tmp_filepath}.${extension}"
gs -dNOPAUSE -dBATCH -r400 -sDEVICE=png16m -dTextAlphaBits=4 -dGraphicsAlphaBits=4 -sOutputFile="${tmp_filepath}.png" -dLastPage=1 "${tmp_filepath}.pdf"
magick mogrify -format ${output_format} -write "${noext_filepath}_thumb.${output_format}" -path "${TMPDIR}" -thumbnail 512x512 "${tmp_filepath}.png"

rm "${tmp_filepath}.png"
rm "${tmp_filepath}.${extension}"
rm "${tmp_filepath}.pdf"
rm "${tmp_filepath}.${output_format}"

echo "thumbnail written to '${noext_filepath}_thumb.${output_format}'"

thumbnail_generation_notes.md

Creating thumbnail for different media

Everything here expects a Unix type environment, as found on Linux or macOS X.

By File Type

Video

Using FFMPEG:

ffmpeg -i input.mp4 -ss 00:00:01.000 -vframes 1 output.png

Image

Using Image Magick (more info):

mkdir thumbs
magick mogrify  -format gif -path thumbs -thumbnail 512x512 *.jpg

PDF

Using Ghostscript,

To JPG:

gs -dNOPAUSE -dBATCH -sDEVICE=jpeg -sOutputFile=output.jpg -dLastPage=1 "input.pdf"

To PNG:

gs -dNOPAUSE -dBATCH -sDEVICE=png16m -sOutputFile=output.png -dLastPage=1 "input.pdf"

Then scale with Image Magick, as described in the "image" section

PowerPoint, Word, Excel

Using unoconv and Libreoffice (more info), though ruan into a few issues:

unoconv --export Quality=100 filename.pptx filename.pdf 

Using Libreoffice, Ghostscript and Image Magick:

input_file=inputfile.pptx
noext_filepath="${input_file%.*}"
soffice --headless --convert-to pdf "${input_file}"
gs -dNOPAUSE -dBATCH -sDEVICE=png16m -sOutputFile="${noext_filepath}.png" -dLastPage=1 "${noext_filepath}.pdf"
magick mogrify -format jpg -write "${noext_filepath}_thumb.png" -thumbnail 512x512 "${noext_filepath}.png"

Notes:

• on macOS X using soffice as /Applications/LibreOffice.app/Contents/MacOS/soffice
• support for MS Office docs: pptx, docx, xlsx, per testing
• support for Apple Office docs, though with some limitations: key, numbers, pages
  • it was hit and miss, with many outputted PDFs being blank

Libraries for Languages

Nodejs

• filepreview
  • Source: https://github.com/mlowasp/filepreview