How to Split M4B File into Many Tracks on Linux

I do have an audiobook with m4b extension, and I wish to split it into many tracks so that it becomes more manageable on my mobile.

Through splitting m4a into multiple files with ffmpeg, I successfully splitted m4a files.

My working command is ffmpeg -i <filename> -map 0 -f segment -segment_time 1800 -reset_timestamps 1 -c copy "$output%03d.m4a" -c:a aac which splits into 0.5 hour chunks.

I wish to do the same with my m4b file. I tried to rename it from .m4a to .m4b, and even though the audio worked on my PC the conversion failed, Showing:

[ipod @ 0x555697bea640] Could not find tag for codec mjpeg in stream #1, codec not currently supported in container                                       
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument