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Introduction.
What is MP3? What is WAV? What is AIFF? What is AAC?

We are all used to accessing content in various file formats. Audio/Music and Sound is no exception and is available in a number of varying formats.

This document has been written to help you understand the main differences of the various audio formats in common use today.

Audio formats vary from WAV, MP3, AIFF to CD-A. The main thing to remember is that the higher the quality of the file, the higher the file size. Some modern day file formats simply compress these high quality files into an acceptable file size for worldwide distribution.



What is CD-A?
CD-A (Compact Disc Audio) is the format to which domestic and commercial CD players adhere. When you create a music CD on a computer it is burnt in the CD-A format. All music purchased from a music store on CD is in the CD-A format.

This is the standard Audio CD format and is used by all manufacturers of hi-fi, CD, Discman etc. Almost all CD burning software supports this format enabling anyone with a modern computer to create Audio CD's.

By default Audio CD's can hold 74 minutes of audio regardless of sound quality. All music on an audio CD is created as CD quality 44.1KHz, 16-Bit, Stereo. File size of CD-A compares to that of other uncompressed formats such as WAV and AIFF.


What is MP3?
MP3 was developed as a way of compressing the file sizes of traditional audio formats (WAV/AIFF) for easier and faster Internet distribution. It is in effect full quality music compressed to be as small as possible.

MPEG-1 Audio Layer 3, digital audio compression format achieving smaller file sizes by eliminating sounds the human ear can't hear or doesn't easily pick up. MP3 Technology basically compresses audio by removing unnecessary parts of the file. It optimizes the file to make it smaller whilst retaining as much sonic quality as possible.

MP3 as a general rule is a tenth (1/10) the file size of CD Audio or highest quality WAV or AIFF. MP3 was developed to make the file size of music files smaller so that online users could download them quicker; this enabled a new form of music distribution on the Internet.

Note - MP3 is short for MPEG Audio Layer 3. MPEG refers to the Moving Pictures Experts Group, an organization that sets international standards for digital formats for audio and video. The file-shrinking technology itself was developed by the Fraunhofer Institute in Germany.

As a rule near CD quality MP3 requires approx 2 MB per minute file space (about 1/10th of uncompressed WAV or AIFF).


What is WAV?
WAV is the native audio format developed by Microsoft and IBM for the Windows computer system. It stands for Windows Audio Version (WAV). It is an uncompressed audio format. This means that it is much larger in file size than MP3 but can support the highest possible audio recording quality as well as lower quality settings.

Almost all audio files ending with .WAV can be played on PC platform software. WAV supports the highest possible audio standards and was made to enable music to be digitised for use in the digital domain (Computers).

WAV can support music from the highest quality 48K recording through to Internet live streaming at 11K (about the quality of a hand-held radio).

By default, WAV consumes around 10 MB of space per minute.
3 minutes of music = 30 MB file space (CD quality).


What is AIFF?
AIFF (Audio Integrated File Format) is the native audio file format developed by Apple for the Macintosh computer platform. It is an uncompressed audio format. This means that it is much larger in file size than MP3 but can support the highest possible audio recording quality as well as lower quality settings.

Many audio editors and software can handle both WAV and AIFF audio formats. This format was developed as a way of putting audio files into a digitised format for use on computers. The digitisation of sound into a computer based file format has completely revolutionised music production, recording, distribution, performance and consumption.

AIFF can support music from the highest quality 48K recording through to lower quality recordings.

By default, AIFF consumes around 10 MB of space per minute.
3 minutes of music = 30 MB file space (CD quality).


What is AAC?
AAC (Advanced Audio Coding) is the next generation of audio codec developed by Fraunhofer that seeks to preserve audio quality at lower bit-rates. It means that it can result in higher quality sound than MP3 whilst remaining the same file size. This is a fairly new format but it supported by many of the new music players and media players.


What is Apple Lossless Encoding?
Apple Lossless (also known as Apple Lossless Encoder, ALE, or Apple Lossless Audio Codec, ALAC) is an audio codec developed by Apple Computer for lossless encoding of digital music.

Apple Lossless data is stored within an MP4 container with the filename extension .m4a. It is not a variant of AAC, but a totally new codec. iPods with a dock connector and recent firmware can play Apple Lossless encoded files. It does not utilize any digital restrictions management scheme, but by the nature of the container, it is thought that DRM can be applied to ALAC much the same way it can with other files in QuickTime containers.

Apple claims that audio files compressed with its lossless codec will use up about half the storage space that the uncompressed data would require.

The Apple Lossless Encoder was introduced as a component of QuickTime 6.5.1 on April 28, 2004 and thus as a feature of iTunes 4.5. The codec is also used in the AirPort Express's AirTunes implementation.


What is 'Real Audio' (.RA)?
Real Networks developed the Real Audio file format as an audio format for streaming music across the Internet. Like MP3 it retains high audio quality whilst keeping file sizes as low as possible to maximise download speed for Internet users. It is frequently used for Internet Radio as well as auditioning music files and audio books. The end user must have the Real Audio player installed on their machine to stream the .ra audio. A plug-in is available for other media players so that you can play Real Audio files with them.

Although most people do not actually play music in the ra format it is one of the most commonly used formats for streaming music and movies live across the internet.


What is 'Windows Media Audio' (.WMA)?
WMA is a proprietary compressed audio file format used by Microsoft. It was initially a competitor to the MP3 format, but with the introduction of Apple's iTunes Music Store, it has positioned itself as a competitor to the advanced audio coding format used by Apple.

It is part of the Windows Media framework. An initial reason for the development of WMA might have been that MP3 technology is patented and has to be licensed from Thomson for inclusion in the Microsoft Windows operating system.

Files in this format can be played using Windows Media Player, Winamp and many other alternative media players. The FFmpeg project have reverse-engineered and reimplemented the WMA format to allow its use on POSIX compliant operating systems such as Linux.


What about file purchased from Beatsuite.com?
Although we sell a range of products we aim to provide you with the highest possible audio quality.

Our Royalty Free Music Tracks are purchased as broadcast quality MP3 files. Some of our Flash Music Loops and Flash Sounds are sold as high quality WAV files. This is to make them simpler to use with whichever software your industry uses.

Audio formats can easily be converted into different file types. We recommend using Apple's iTunes. It can convert audio from CD-A, WAV, MP3, AAC and into CD-A, WAV, MP3 and AAC.

The various settings within Audio formats and what they mean

Sample Rate
Sample rate is the number of times per second that the music waveforms are captured digitally. The higher the sample rate, the higher the quality and the larger the file size. Be sure to choose a sample rate that is no higher than the rate used to originally store the music, or you'll waste space.
BR
Examples: Audio CD - 44.1 kHz,BRInternet Radio typically - 11 kHz


Sample Bit Size
The sample size is the number of bits used to store each sample taken as the music is encoded. The higher the sample bit size, the better the quality and the larger the file size.
Examples: 16-Bit / 8-Bit


Channels
Mono files are about half the size of stereo files. Mono is appropriate if you don't have stereo speakers or if your audio files are monaural. If you'll be listening to your song files using headphones or your stereo system, choose Stereo or Auto. Auto converts tracks that are already monaural into mono files, and stereo files into stereo files. Using music online such as on a website it may be fine to use the Mono setting, however, if you plan to use music where it will be amplified by a sound system or large screen TV/Projector then you would want the highest possible quality - Stereo.

Most modern day audio/video encoders and players support both Mono and Stereo formats.


Stereo Bit Rate
The higher the mono or stereo kilobits per second (kbps), the higher the audio quality and the larger the file size. The most common bit rates for stereo AAC/MP3 files is 128 kbps. Lower bit rates are more appropriate for sound files containing voice recordings (as opposed to music).


Converting Audio into different format
There are a host of audio programs and media players/encoders on the market for both the MAC and PC user. The most important fact when using one of these programs is to find one that you are comfortable with and therefore confident in its results.

We strongly recommend Apple's iTunes for converting MP3/WAV or AIFF audio files. It is easy to use; it's a fantastic MP3, CD-burning, music store and MP3 library program. It also has superb audio file conversion options. To download it
http://www.apple.com/itunes/download



Bibliography.
Apple Itunes help pages (offline)
http://en.wikipedia.org/wiki/Main_Page
www.MP3cdburner.ne


Help and support
http://www.apple.com/support/itunes


For more information please contact us
Written by Steve Bainbridge
The Beat Suite