The MPEG-4 standard is a container format for compressed audio, video and text files, given the extension MP4. Apple® Inc. has made use of non-standard extensions to indicate the content of an MP4 file, since the extension is non-specific. For example, an MP4 file with audio only is given the extension .M4A, while the ringtones used in the Apple® iPhone® are further designated as M4R files. Many people have digital music in MP3 form. You can convert an MP3 to M4R file to make custom ringtones for your phone.
First, a short clip of the song will need to be edited out and saved to serve as the ringtone. The length should be under 30 seconds. Next the saved file must be converted to the M4R format. There are a number of ways to do this.
For those who prefer free services, many websites will convert an MP3 to M4R file for you. Once such site, mp3-to-m4r.net, allows you to upload your MP3 file, edit it, then the website saves the file for you in the proper format. By clicking on a button, the ringtone is sent directly to your iPhone®. This service is free and does not require registration.
Apple® iTunes® can also be used to convert an MP3 to M4R but the process is a little involved and the directions might be slightly different depending on the version. In general, the imported MP3 must be first converted to the AAC format (which is essentially the same as M4P), then manually renamed from an MP4 to an M4R file.
To use iTunes® to convert an MP3 files to M4R, add the MP3 file to your iTunes® Library. Right-click on the file and choose Get Info. On the Options tab enter the beginning and ending points for the ringer. (Optionally you can edit the MP3 file in an external editor before adding it to the Library.) Click OK. Right-click on the file once more, and choose "Create ACC version" from the popup menu.
Now navigate to the folder where iTunes® has saved this file. Use the computer’s Search feature to find the file name, or look in the default Music folder, then inside the iTunes® folder. Scroll down until you find the saved file, which will be an M4A file. Drag the file to the Desktop (a copy will be generated), then go into iTunes® and delete the original file. The Desktop copy will remain.
Return to the Desktop and rename the ringtone file with an M4R extension. If you cannot see file extensions, go to Folder Options (via Control Panel) and under the View tab, uncheck "Hide extensions for known file types" and try again. Once the file has been successfully renamed, click on it and iTunes® will import it into the Ringtones folder. Synch your iPhone® to upload the ringer.
Another way to convert an MP3 to M4R file is to open the MP3 file in any sound editor and create the edited ringer file, saving or exporting it to the Desktop as an MP3 file. Open the file in BonkEnc©, a free audio file converter for PC users. Under Options, General Settings, choose the MP4/AAC encoder, then click the convert button. The ringer will be converted to an M4A file. Rename it to M4R, and click on it to import it into the iTunes® Ringtones folder for future syncs.