mp4, m4a - MPEG 4 Audio file extension(확장자)

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What is the difference between M4A and MP4 files?

This is the most popular question we get and seems to cause the most confusion to people new to MPEG 4 Audio. The existance of 2 different file extensions that can be used to represent MPEG 4 Audio files is unfortunate. MP4 files may or may not contain MPEG 4 Audio. If you see a M4A file you always know that it contains only MPEG 4 Audio. MP4 can be used for MPEG 4 video files, combined video and audio files, or just plain MPEG 4 audio. Apple Computer started using and popularizing the M4A file extension to denote the file was an unprotected (non digital rights management) MPEG 4 Audio file. They did this because MP4 was too general (video, video/audio or audio) and might confuse some media players. Now MPEG 4 Audio has its own file extensions, M4A, to avoid any possible problems with being confused with video files. It is recommended that you use the .m4a file extension rather than .mp4 on your audio files. In fact, more and more programs are now encoding only using M4A.