M4A is a filename extension for AAC container format and is developed by Apple Inc. M4A music is bought on the iTunes Store and does not come with DRM protection. In terms of quality, M4A is better than MP3 because it is lossless but still compressed. This means that it occupies less storage space and doesn’t lose quality over time.
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AA (Audible Audio) is an audio container format with a .aa filename extension and is used to store audiobooks. It can contain audiobook features such as spoken-word audio, bookmarks, chapter markers, and more. This format is supported by portable devices like Apple iPod, Amazon Kindle, ScanDisk Sansa, Creative Zen, and more.
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