This is not a matter of simply converting the files. M4P is Apple’s proprietary file format, essentially AAC with DRM. So, your first step would have to be to crack the DRM, thus leaving you with a simple M4A (AAC) file.
But I guess doing so is illegal. So … don’t. And let this be a reminder to not support DRM by buying DRM-crippled music. If they don’t trust you, they don’t deserve your money.
