I've been using Mp3tag for a long time now - years, in fact. I've never actually not been able to achieve something using it before.
I've recently started getting into audiobooks. I generally use the .m4b file format for this as it supports chapters fine and an audiobook from Audible can be lossless decoded into this format.
However, I often come across audiobooks in .mp3 format. Converting to .m4b for chapter support is possible but involves transcoding the audio and makes for a noticeable loss in audio quality (I assume this is because I'm transcoding from 64 kbps mp3s which are already compressed considerably).
I have noticed that mp3 chapters are becoming more prominent in the podcasting world. There are a few applications that cane help with this and strangely all seem to be for macOS only:
Podcast Chapters (Google this term to find it)
There is a command line Python tool (thus multi-platform) tool called
mp3chaps. I can't include a link to this as the max number of links a new user can include but Googling "mp3chaps github" will return the correct result.
I have been told by one of the developers of BookPlayer that even if an mp3 has the array of chapters metadata set, there's a ID3 tag (CTOC or tableOfContents) that is needed for Apple's API to properly parse the array. This tag only represents the IDs of the chapters in the proper order, but it's needed. Forecast has been verified to add this CTOC tag.
My feature request is as follows: is there anyway Mp3tag could become capable of creating and editing chapters in mp3 files for both podcast and audiobook use? There is no good solution for Windows at the moment and being able to use Mp3tag for this would be great.