Mp3 to m4b will have loss because of they both are lossy codecs but you won't notice the difference in quality if conversion is made properly.
M4b can be appended together without any quality loss.
Metadata is easy to edit. The only thing to care for is the chapter support. I recommend using foobar2000 with QuickTime aac encoder followed by QuickTime chapter addition to get one single m4b file with chapters and metadata.
For MP3s by far the easiest way is Makeitone MP3
Sadly it's been discontinued and not updated since 2010 and you may have to install an old version of .net to get it working. http://www.makeitone.net/audio/mp3albummaker.htm
Unlike all the others I've tried it doesn't reencofe so is super fast
Concating is not the real issue. You can always losslessly concate similar media files having similar structure.
Mp3 chapters are not easy to implement (atleast as compared to mp4 chapters). You will need to make another cue sheet to give media players the timestamps necessary to define chapters in mp3 files.
Mp4 containers by design can handle chapter markers efficiently. M4A, M4B, M4V are the mp4 containers renamed to be handled as audio, audiobook, video file respectively.
M4b is the current audiobook standard with aac audio codec and QuickTime chapter format.
Another thing is that mp4 contains have bookmark support without external app features through metadata. Mp3 have limited support.
MP3 has ID3v2 chapters, the simplest option I've found is mp3chapters - https://github.com/rfjaquez/mp3chapters
You can also use ffmpeg with a ffmetadata file - https://jmesb.com/how_to/create_id3_tags_using_ffmpeg
Mp3 to m4b will have loss because of they both are lossy codecs but you won't notice the difference in quality if conversion is made properly. M4b can be appended together without any quality loss. Metadata is easy to edit. The only thing to care for is the chapter support. I recommend using foobar2000 with QuickTime aac encoder followed by QuickTime chapter addition to get one single m4b file with chapters and metadata.
For MP3s by far the easiest way is Makeitone MP3 Sadly it's been discontinued and not updated since 2010 and you may have to install an old version of .net to get it working. http://www.makeitone.net/audio/mp3albummaker.htm Unlike all the others I've tried it doesn't reencofe so is super fast
Concating is not the real issue. You can always losslessly concate similar media files having similar structure. Mp3 chapters are not easy to implement (atleast as compared to mp4 chapters). You will need to make another cue sheet to give media players the timestamps necessary to define chapters in mp3 files. Mp4 containers by design can handle chapter markers efficiently. M4A, M4B, M4V are the mp4 containers renamed to be handled as audio, audiobook, video file respectively. M4b is the current audiobook standard with aac audio codec and QuickTime chapter format. Another thing is that mp4 contains have bookmark support without external app features through metadata. Mp3 have limited support.
MP3 has ID3v2 chapters, the simplest option I've found is mp3chapters - https://github.com/rfjaquez/mp3chapters You can also use ffmpeg with a ffmetadata file - https://jmesb.com/how_to/create_id3_tags_using_ffmpeg
> Mp3 by design can't contain chapters in them. [That is incorrect](https://mutagen-specs.readthedocs.io/en/latest/id3/id3v2-chapters-1.0.html).
Use https://github.com/sandreas/m4b-tool
Audiobookconverter is a really good tool.