Convert an MP3 file into a MIDI file using an online conversion tool such as the Bear File Converter or a downloadable file conversion tool such as ConverterLite or IntelliScore Ensemble, as of 2015. Alternately, convert the file using audio editing software such as Audacity.
Programs such as ConverterLIte and IntelliScore allow you to change the type of a wide range of files. You need to download the software to your computer in order to complete the conversion. Each program also includes different special features to help improve the overall conversion process, such as ConverterLite's option to select multiple files to convert at the same time.
To convert an MP3 file into a MIDI file using Bear File Converter, click on the Upload & Convert button to select the file in question and upload it to the site. The size of the file must be less than 50 megabytes in order to convert successfully.
Audio editing and mixing tools such as Audacity contain features that enable you to export audio tracks into different file formats. To use this feature, open Audacity and import the desired MP3. Use the program's tools to edit or modify the file as necessary, then choose the Export command and select MIDI as the file type.