Describe the various audio formats used in digital media
In This Chapter, you’ll learn on:
The basics of Digital Audio formats
Identifying of the Various file types such as MP3,
AIFF, WAV, AAC, WMA and etc
The characteristics and use of the various audio
Basics of digital audio formats
An audio file format is a file format for storing digital
audio data on a computer system. This data can be
stored uncompressed, or compressed to reduce the file
size. It can be a raw bitstream, but it is usually a
container format or an audio data format with defined
Hundreds of file formats exist for recording and playing
digital sound and music files and most of these file
formats are software dependant. While different
operating systems have different popular music file
formats, we will focus on those that are well-known and
widely supported file formats.
File Format and Codec
An audio file format and audio codec
(compressor/decompressor) are two very different things.
Audio codecs are the libraries that are executed in
multimedia players. The audio codec is actually a computer
program that compresses or decompresses digital audio data
according to the audio file format specifications.
Most of the publicly documented audio file formats can be
created with one of two or more encoders or codecs. For
example, the WAV audio file format is usually coded in the
OCM format, as are the popular Macintosh AIFF audio files.
Although most audio file formats support only one type of
audio data (created with an audio coder), a multimedia
container format (as Matroska MKV or AVI) may support
multiple types of audio and video data.
Using the right compression
There are different kinds of compression for different
jobs. There are audio codecs (like MP3) that allow
you to quickly download music via the Internet and
store lots of songs on your portable player.
Most audio digital formats allow you to select
different degrees of compression when you're
creating, or encoding, a file. For instance, MP3 files
can be encoded at different rates of compression
for varying file size and sound quality. File resolution
is measured in kilobytes per second (kbps) — that is,
how many thousands of bytes it takes to store one
second of music. This figure is known as the bitrate.
The higher the resolution, the more information from
the original source is retained. A 256kbps file, for
example, holds twice as much data as a 128kbps
file. Generally, the smaller the bitrate, the more a
file is compressed and the more it will be subject to
a loss of quality.
However, smaller files are easier to store and
quicker to download or transfer. When you're
downloading files or encoding your own, consider
how you'll be using them, and choose from your
compression options accordingly.
The above chart shows the relative file sizes of the same three-minute song
saved in different formats, starting with the original CD track on the left.
The following table lists the music file types that are
supported in Windows (Without installing any
Below are audio file formats and codecs that
QuickTime Player can playback in Mac OS. (Without
installing any additional software)