I wanted audio files with chapters for gapless playback on mobile. And also to embed a nice thumbnail into that long chapterized audio file. The typical audio formats support this, but it turned out no software could do it all.

• ffmpeg could do the concatenation into one file.
• It couldn't embed the chapters, which mkvtoolnix can do.
• It also couldn't embed the thumbnail, which mutagen can do.
• Finally, I found nothing that writes a chapter file based on the smaller concatenated files.

I found myself executing the same couple of terminal commands all the time and decided to make this script.

Usage: ./concatAudio inputDir outputDir

Default behavior

requires per desired output file one subfolder in input

each subfolder respectively needs to have only mp3, opus or aac audio

those can be in various recursive folders

the naming of those files and subfolders should reflect the desired order

Chapters

priority: retrieve chapters from cue file

fallback: concat files and build chapters from individual files

Thumbnail

priority: embed cover from image file(s) in input folder

fallback: extract from pdf documents instead

fallback: extract from audio files themselves

Dependencies

• ffmpeg
• mkvtoolnix
• pdftoppm
• imagemagick
• wc
• mutagen

Todo List

depend a lot less on temp files and do much more in RAM avoid temporary name files, and also the chapter- and thumbnail files

rewrite in different programming language and use standard time packages, especially for the chapter file conversion functions