Music Editor should contain following:
1) It should have design like in the pictures;
2) It should work fast. I think about Native code for music editing part;
3) User should have ability to change audio file and save it after this. User can change the part of the file! Not only full file!
4) App should work with formats: mp3, wav, m4a, aac, wma, flac;
5) User can change: equalizer, bass and echo settings of the file or the part of the file;
6) User should be able to press play button. And after this user can change equalizer, bass or echo and user should hear difference during playing mode!
7) User should have ability to save current settings. After this he can work with file or save the file;
8) User should have ability to name the file and put it anywhere he want in the smartphone;
9) User should see the percents when app process some work and when user can not do anything.