What is an AA file?
A file with an extension .aa is specified for storing digital audio data file format includes the file of the Audible AudioBook. These files are used to store spoken audio recordings of the Audible. The AA files are designed to store audiobooks too. These AA files are designed to store the word audio in spoken form and support bookmarks, chapter markers, etc. Data in these files include raw but stream in the format of audio coding. Along with encryption of digital rights management these files contain audio clips.
AA File Format
Amazon holds the audible and these files can be used on various devices. To use these files on Windows Media Player, conversion to a more efficient file format like MP3 is needed. AA file is a category of the audio file but there is a difference between a simple MP3 file and an audible file. These files can be protected through DRM so they cannot be converted into other audio formats even if they are widely used.
Brief History of AA File Format
The company Amazon launched its product known as Audible player in 1998. Audible is an American online service that provides the facility for audiobooks and podcasts. So these files with the .aa extension got their origin along with the launch of this service. In 2003 Audible made a deal to an agreement with Apple. It has the capability of being an exclusive provider for iTunes books. In 2008, Amazon claimed to buy Audible. In later years it got updated and modified according to modern needs and compatibility services. In 2020, it was last modified when Audible made some payment modifications.
AA File Format Specifications
These files can be compatible with various devices. Players for these files are available on Android and iOS devices. Some versions of these files are not compatible with Linux. Associated programs to these files are available online for Windows PC. For Mac OS Apple iTunes is the associated program for these files. These files also provide encapsulation of sound encoded in MP3. There have been following several qualities available from Audible but downloads are currently only available for “Format 4” and “Enhanced” formats.
| Format name | Bitrater | Sample rate | Bit depth | Channel | MBytes/hour | Container | Quality description |
|---|---|---|---|---|---|---|---|
| Audible Enhanced Audio (.aax) | 32 - 128 kbit/s | 22.050 - 44.10 kHz | Unknown | Mono or stereo | 28.8 | MPEG-4 Part 14 | AAC sound |
| Format 4 (.aa) | 32 kbit/s | 22.050 kHz | 16bit | Mono | 14.4 | MP3 | MP3 sound |
| Format 3 (.aa) | 16 kbit/s | 22.050 kHz | 16bit | Mono | 7.2 | Unknown | FM radio sound |
| Format 2 (.aa) | 8 kbit/s | 22.050 kHz | 16bit | Mono | 3.7 | Unknown | AM radio sound |
