iTunes will convert a CD/DVD to ACC; AIFF; Apple lossless; MP3 and WAV.
Choose iTunes > Preferences, click General, and click Import Settings.
In the Import Using pop-up menu, choose the format you want to convert songs to, and click OK to save the settings.
*Select one or more songs in your library and choose File > Create New Version > Create [format] Version.
MP4 isn't really a format, it's a container holding video and audio files. This would be more challenging as you would need to convert each of the files in the container. But if you only want the music files, iTunes will do it, for free.