It seems that mp3 to abc conversion is mostly related to a process of making musical notations (.abc) from some MP3 audio file. This should be possible with Harmony Assistant or any similar music notation tool that has this capability.
Convert Compressed audio and music file, mp3 songs or ringtones to Musical notation language file.
We have found one software suitable in our database for this conversion.
Multiplatform software - convert mp3 to abc on any platform
Harmony Assistant is a software for computer-assisted music composition and editing. Harmony Assistant comes with its own embedded software synthesizer (SoftSynth), which provides high quality output on basic sound cards, even without any external MIDI device, and includes hundreds of different instruments.
Convert from mp3 file
to abc file
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.