Common Audio Terms

Bit rate:

A measure of the quantity of audio and/or video data transferred from your device’s memory to its audio and or video decoder. Different devices support different ranges of bit rates. Some devices are able to convert unsupported bit rates to supported bit rates, a process called ‘transcoding’.


Measured in megabytes or gigabytes. As with any other computer storage measure, the larger the number the larger the amount of data the device will be able to hold. Common sizes range from 128 MB to 30 GB. A small device will be able to hold a few audio book or music titles, while a device with a higher capacity will be able to hold many more titles. Higher storage capacity usually means higher price as well.


Part of a computer program that converts a specific computer file into information that can be played by a computer or device as audio, video, or both. Windows Media Player has all the necessary decoders to play the Overdrive media files. Some portable devices come with decoders that do not support the bit rates in which Overdrive media files are encoded.


The portable video or audio player to which you will transfer files for listening or viewing.

Mini USB:

Type of USB connector present on many smaller portable audio devices. Used to connect the device to a computer so that audio files may be transferred to the device.


Popular compressed audio file that can be played on most portable devices. This file type does not support Digital Rights Management (DRM) and is not used by Overdrive media files.


A compatibility program created by Microsoft to ensure that a portable device will be able to play music and/or video files compatible with Windows Media Player, WMA, WMV and Microsoft DRM. Not all the devices labeled as PlaysForSure support Overdrive media files, since there might also be hardware or bit rate compatibility issues. Overdrive Audio is not certified by PlaysForSure.

Supported bit rate:

The bit rate or rates for which a device is able to do the decoding process. If your device does not support the bit rate with which Overdrive encodes the media files and it is not capable of transcoding, it will not be able to play the file.


A Process that some portable audio devices perform to convert audio files from an unsupported bit rate to a supported bit rate.

Universal Serial Bus (USB)

Designed to allow peripherals to be connected to a computer without the need for expansion cards, USB ports have become standard equipment in modern computers. Most portable audio devices are connected to a computer using USB. The two most common types of USB connections are standard and mini.

Unprotected WMA:

A type of audio file compressed using the Windows Media Audio (.wma) technology. Overdrive uses DRM protected WMA for its media files. Your device must be able to play protected WMA files in order to download Overdrive media files.

Windows Media Player:

Free software that is necessary to play Overdrive media files. Windows Media Player comes as a standard component with the Microsoft Windows operating system. Although there are versions of Windows Media Player for other operating systems, Overdrive media files can currently only be played on Windows and Pocket PC operating systems.

Windows Media Audio (.wma)

A format developed by Microsoft to distribute compressed audio over the Internet. This format is used by Overdrive media files because of its excellent audio quality, file size, and Digital Rights Management (DRM) capabilities. Your portable device must be able to play protected WMA files in order to download Overdrive audio books.

Windows Media Video (.wmv)

A format developed by Microsoft to distribute compressed video over the Internet. This format is used by Overdrive video files because of its quality, download sizes, and Digital Rights Management (DRM) capabilities. Your portable device must be able to play protected WMV files in order to download Overdrive videos.

Abridged Audiobook:

A professional abridger “edits” the work from the original text to encompass the essence of the story while maintaining characterizations, plot lines and style. Most abridgements are done with author approval. Just as many book-based movies do justice to the book while not including every single scene, so an abridgement strives for the same goal of staying true to the spirit and content of the book

Audio Original/Audio Only/Spoken Word:

Audiobook products derived from sources other than book content. These programs include dramatic readings, stand-up comedy, seminars, conversations, etc. that have no book counterpart.


This format has been the most popular for audiobooks for the past two decades. Easy to use and with a wide install base, this technology still represents a significant piece of the audiobook market. A single cassette can hold more than 100 minutes of programming.


The popularity of this format is steadily increasing. Most cars now come standard with these players and inexpensive adapters are available for cars without factory installed CD players. Red Book specifications indicate that a single disc can hold up to 74 minutes of digital audio material. This is why you will find in many cases the same program requires more CDs than cassettes. CDs can also be played on computers and CD/MP3 players.

CD ROM Disk or Mini-disk:

These are sometimes included in audiobook packages to carry video and text if necessary or desired as added value. Digital download/Audio Download–Audiobook content can be transmitted digitally in different compressions to compatible players or listened to directly from the computer.


An audiobook format for which an MP3 player is required, only some CD/DVD players can currently read this format. While this emerging technology still has a relatively small install base, MP3CDs can hold a large amount of audio material on a single CD.


Audiobooks can come in trays, slides, jewel cases, sleeves, wallets and spined plastique books. Most audiobooks are shrink-wrapped and some have a mylar-seal. Outside boxes can be many different sizes due to the number of units inside and package design.

Unabridged Audiobook:

The complete, unaltered work.