1. Download and launch iSkysoft iPhone Ringtone Maker. iSkysoft iPhone Ringtone maker is a simple but powerful AAC to M4R converter ,You can download this m4r converter form iSkysoft.com,mediasoftmac.com or apple.com. 2. Input AAC music file You can choose the AAC which you want to convert to m4r, and drag the AAC file to the software directly. You can also input AAC files in iTunes library from the left category. By this way you can convert the purchased AAC music from iTunes Store to m4r as your iphone ringtone for free. 3. Trim aac to m4r iPhone Ringtone Drag and drop the slide bar to appoint the start point and end point for the m4r iPhone ringtone length. Alternatively, you can type exact time value into time-setting box. You can choose to preview the whole YouTube audio or video or just the trimmed part. In this way, you can trim 30s of the aac to m4r iPhone ringtone. Tips: You can enlarge the waveform to make more specific trim. 4. Start to Convert aac Music to m4r iPhone Ringtone After trimming aac file, click Start button to convert aac to m4r file. The trimmed aac music would be converted into M4R ringtone and saved on ringtone category of your iTunes. Just a few seconds, the aac will be finished to convert to m4r! you can learn more from here... http://www.iskysoft.com/topic-ringtone/convert-aac-to-m4r-iphone-ringtone-on-mac.html#194