Audio file formats are used to store digital audio. Audio files usually contain information about the included audio waveform's characteristics and how it is stored.

An audio file format usually specifies the sample rate, bit-depth, and type of compression used as well as other information that indicates how long the waveform is, how much data must be read per second of play-time, etc.

Most of an audio file's content is used to describe the individual audio samples that are played sequentially to reconstruct the waveform. The waveform data can be compressed in different ways to help reduce the inherently large size of a stream of audio samples. Every second of uncompressed CD quality (44.1 kHz, 16-bit, stereo) audio requires about 172 kilobytes.

Many audio file formats may also specify information about how the audio should be played as a musical instrument. This extra information starts to blur the line that seperates an audio file format from a patch file format and is usually included for use with software or hardware samplers.

Wave Files

Microsoft's Wave file format is the most commonly supported audio file format on the Windows platform. It is capable of storing waveform data in many different formats and an array of compression types. The most common type of wave file contains uncompressed (raw PCM) waveform data because it is the most widely supported among audio applications due the simplicity of decoding uncompressed data. Even though compressed audio continues to become more popular because of limited storage space and slow network speeds, Wave files still tend to contain uncompressed waveform data while other file formats (such as MP3) are used for compressed data.

See the Wave File Format guide for more information and an in-depth techinal specification.

Books: A Programmer's Guide To Sound