The Moving Picture Experts Group or MPEG-4 standard, is a fourth generation container format for compressed video, audio and text, such as might be required for subtitle streams. The official extension is .MP4, though it is impossible to know what kind of streams an MP4 file holds from the extension alone. For this reason several non-standard extensions are used to indicate content, a practice popularized by Apple®. The .M4A extension is used for files that contain audio only, for example. Since some software won’t recognize an MP4 file, people often convert M4A to WAV files, the most common uncompressed audio format.
BonkEnc© Audio Encoder by Robert Kausch is a very popular, free audio converter for Windows® and WINE. This little program packs a handful of encoders to get from nearly any audio format to another. Add the M4A file you would like to convert, then click Options, General Settings and choose your encoder. To go from M4A to WAV files, select the Wave Out Filter from the drop-down menu. Click OK, then click the Convert icon, or go to Encode, Start Encoding. In seconds the program will create a new WAV file from the M4A, automatically using id3 tags in the title.
For Macintosh® and PC users who already have iTunes® installed, this program will convert M4A to WAV files too. First add the M4A file to the iTunes® Library (e.g. drag and drop it on to the Library icon). Choose iTunes® from the top menu bar, Preferences, click the General button, then the Import Settings button. From the pop-up menu, change the importing format to WAV and click OK. Next highlight the song(s) you wish to convert from M4A to WAV files, right-click on the highlighted files for a popup menu, and choose Advanced, then Create WAV version.
Although iTunes® is also free, BonkEnc@copy; is a very small download and does the job beautifully. PC users who don’t already have iTunes® installed and don’t own personal Apple® electronics will do well to use BonkEnc@copy;. It can also perform many other audio conversions and is bound to come in handy.
It is worth noting again that MPEG-4 is a compressed format, while WAV is not. Simply put, WAV files are larger than their M4A counterparts, so the resulting files in going from M4A to WAV will be larger than the originals. WAV files can always be converted to MP3 files of course, which are highly compressed files that are of lesser quality than WAV’s, but handy for portable digital players with limited storage capacity. Most free audio converters have the ability to create MP3 files from WAV files, including BonkEnc©.