[re-]split opus files

[iconoclasthero]

One thing that I'd really like to do is add an option to allow the script to use the embedded chapter info from either the original m4b or an opus file. E.g., I have a big book that was originally two volumes and I need to break it back into those two volumes... But if I split it at the volumes with just ffmpeg -to / -ss, the index will be all fucked up... Based on what I looked at/remember of my code, the only way to do this is to use the split feature to break everything into pieces...but I'm fairly sure that I don't have anything as is that will split out opus so the code would need to either be separated into a separate opus tool or it would need to be refactored so that the part of m4b2opus that splits m4bs into m4as can also split opus into opus with the chapter names as part of the file names. It doesn't help that opustags doesn't do a great job with this.

Also, I'm vaguely considering starting to move this to python...which I don't want to do because I don't know python and don't want to learn it, but it might be worth using a real programming language rather than shell.

[iconoclasthero]

Also, support for chapter titles that are longer than 255 characters or whatever I'm allowed.

[iconoclasthero]

If this does get converted to python, it would make sense to use mutagen for the tag R/W as opposed to relying on external file operations with opustags.

[mrfragger]

Back when I used freac to make opus chaptered audiobooks it would name chapters based on metadata. So I would name the filenames and then add metadata to them. Now though with the script I use the metadata is added by ffmpeg when it concats them together into an audiobook.

For splitting you can see what I have in the script...I'll attach it. It can split into say 2m segments or whatever. Also can extract original chapter names and split on chapters. Although this takes about 20x longer..not sure why but it works.

SubStitcher 173KB

SubStitcherFeb242025.zip

I'm on a Mac so I should mention for Linux in substitcher.sh do a search and replace gsed/sed and gawk/awk
not sure for windows though if it'll work...no clue.

Mac do
brew install ffmpeg yt-dlp jq parallel imagemagick rename aha mkvtoolnix titlecase qpdf gnu-sed gawk

Linux
sudo apt install ffmpeg yt-dlp jq parallel imagemagick rename aha mkvtoolnix titlecase qpdf