|Why not MP3?|
MPEG Audio Layer III, or simply "MP3", is a storage method for audio data. The high rate of compression is reached by using a lossy format that allows an efficient reduction of data, which are of little significance for human perception. The original MP3 audio format is not able to store additional information such as metadata in an MP3 file.
Through the use of ID3 tags ("Identify an MP3") this shortcoming could be satisfactorily resolved for music, but some of the desirable audiobook properties cannot be implemented with ID3 and MP3 only. These include, for example, chapter and bookmark information, different imagings for different sections of a file, and the appropriate categorization as an audiobook.
|Advanced Audio Coding – AAC|
Apart from enabling the transmission of the actual user data (video, audio, images, text), the container format "MP4" allows the integration of metadata and the use of copy protection in a single file. For audiobooks particularly interesting is the "Advanced Audio Coding" method, developed by the MPEG working group of ISO, based on MPEG-2 audio compression method.
AAC files (*.m4a – 'a' = Audio) can be compiled to "real" audiobooks with the help of the AAC Audiobook Creator (*.m4b – 'b' = Audiobook). When using compatible players (such as Apple's iPod), this format allows the implementation of all additional, for audiobooks useful features as mentioned above, such as chapters, bookmarking, optional imaging and automatic categorization.
Last change: 09/18/2011