Hi, in past I write simple plugin for generating MP3 waveform like SoundCloud, PSD thumbs, Office (excel,word,powerpoint), TXT file, CSV etc..with transparent background.
https://uloz.to/xZGPzvxv/file-image-generator-rar
It works on Windows (MS Office), but also in Linux (LibreOffice)
I dont have time to rewrite (some filters is old and not well code). Take a look :)