AAX, Audible Enhanced Audiobook File (.aax)
The AAX Audio file format
AAX is a file format used by Audible to store audio books. It's the enhanced and improved form of the AA file format. AAX is a popular audio book file extension for more visual books like children's books since it supports the display of images. Images are automatically shown in the player alongside when the audio book plays.
Technical details of AAX files
AAX files can contain – next to the usual audio data, bookmark and chapter information – images and other features like links as well. This makes it a very popular extension primarily for children's books. AAX files support a bitrate from 32 to 128 kbit/s. The audio data is AAC encoded which provides a very high audio quality. AAX files are heavily protected and can only be played with a paid Audible.com account. Since the files almost always contain DRM protection, it is nearly impossible to play them on any other player than Apple iTunes, iPod or the Amazon Kindle 2.