Digital Sound

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Audio File Formats

As with graphic/images files, different systems use different file formats for audio. Many of these have become de facto standards through their multi-platform use. The format can usually be identified through their file name extension.

Some of the more popular extensions are listed in the following table:

Common Digital Audio File Formats

Extension	Name	System
.au or .snd	audio/sound	Sun, Mac, NeXT, UNIX
.aiff	AIFF	Apple, SGI
.voc	vocal	Soundblaster
.wav	WAVE	Microsoft
.mp3	MPEG 1 layer 3	cross platform

 

MP3

The hottest music format du jour is MP3. The MPEG 1 layer 3 audio codec format achieves CD audio quality with very high compression rates, ( a 12:1 compression rate achieves high quality with little degradation). The compression is determined by the sampling bit rate. Normally MP3 files are recorded at 128 or 112 kbit/sec. to obtain near Cd quality. The MP3 format can easily be divided to aid in real-time streaming audio across the Net, (with appropriate conection speeds). MP3 requires substantial processor power and a 16-bit sound card. Hardware MP3 players/recorder are just now starting to appear. There are free software MP3 players and encoders for listening and recording.

Be aware that there are many illegal mp3 sites on the Web offering pirated copies of copyrighted music. MP3 is simply another digital audio file format, there is nothing illegal about it. An individual may make a MP3 encoded copy of a recording from a CD that they own as long as they do not give it away, sell it or loan it to others. It is considered a backup copy that they can only keep and use as long as they own the CD. (If you make copies of CDs, then sell or give the CDs away and keep the MP3 copies, you are in violation of copyright laws.) There are artists who have released MP3 recordings to the general public and also non-copyrighted recordings are available.