Traditional sound formats.
While streaming audio may be all the rage these days, there are various tried-and-true sound formats that you may want to use in some circumstances. These can effectively be used either as linked-files, or as embedded resources. Each of these methods has pros and cons which will be discussed later. The tricky thing about sound is that there are several common formats, none of which is truly cross-platform. Here is a very brief primer on the differences:

AIFF		Mac, Unix		variable sample rate		variable, but often large
AU		Cross			8 bit sound			yields small files
WAV		Windows			variable sample rate		about the same as AIFF
MOV		Cross			variable sample rate		also variable

The old-fashioned way.
If you don't want to assume that your users have the latest browsers or a hefty raft of plugins, you may want to use the tried and true method of linking to your audio files. To do this you will use the normal A HREF construction exactly as you would to link to another web page. The sound you link to must have the proper file name suffix. When the sound downloads completely, the user's browser or a helper application will play the sound.

You may want to provide links to the helper apps for your users if you want to be maximum helpful. It's sometimes a good idea to put sound files on your pages in more than one format to insure that anyone can listen to them.

Traditional sound formats.
Versions 3 and later of Navigator/Communicator and Explorer support embedded sounds. This method of using sound was pioneered by Microsoft with the BGSOUND tag. This tag looked something like this:

<bgsound src="sounds/riff.wav" loop="5"> Up until recently, this was the standard way to play a background sound with Explorer. Recently, however, Explorer made a move to support the EMBED tag, so BGSOUND is basically obselete at this point.

Both Navigator and Explorer can play sounds of the AU, AIFF, MIDI, and MOV formats. (Actually, I'm not 100% certain that Explorer supports all of those.) These sounds will be handled by the LiveAudio plugin in the case of Navigator. This plugin is bundled with Navigator, which gives it an advantage over some other audio methods requiring plugins. To get the sound to play you'll use code like this:

<embed src="sounds/noise.aiff" autoplay="true" loop="true"> Some references will recommend using both the BGSOUND and EMBED tags in the same page, but this is now obselete, and will result in Explorer trying to play the same sound twice. If you use the EMBED tag to include a QuickTime sound, you can give the user the normal QuickTime controller if you want to so that they can turn the sound off if they want to.

Converting sounds.
To convert sounds you can use SoundEdit, or SoundApp on the Mac. A nifty Mac Shareware program called SoundEffects can save sounds in AIFF format, and it's free. For Windows, a potentially nifty free program is CoolEdit.

New version of an old format - MP3
There is one non-streaming sound format which is getting a whole lot of play these days: MP3. This format is the latest iteration of the MPEG format (MPEG 1, version 3), an old-school way of efficiently compressing audio and video. This latest version of MPEG is so efficient that it brings audio down to 10% of it's original size without an appreciable sacrifice of quality. In practical terms, this means that a full CD-quality song can be compressed into about 3 MB, or about 1MB per minute. This format is currently all the rage amongst audio pirates everywhere, due to the fact that the format is high quality but does not support digital watermarking or encryption. Thus, college students and other unscrupulous people all over the world get into the habit of digitizing their favorite music, encoding it as MP3, and putting the files up on their web servers for their friends to enjoy. This practice is totally illegal, and is causing the music industry fits right now.

More commercial than MP3 - Liquid Audio
MP3 files are scary to record companies, and also to some artists. The reason is the fact that the quality is excellent, but copying the files is very easy and there is no copyright, licensing, or encryption technology built into the file format. Thus, unlicensed copies are indistinguishable from legitimate files put up on the Net with the knowledge of the copyright holder. Software authors in collaboration with the music industry are trying to develop and popularize new formats which will be easier to implement over the Internet while preserving the current money-making food chain. Liquid Audio is an example of this kind of format. Files are encoded in an encrypted format, which can only be played with the Liquid Audio software. This software provides security to the artist, and simultaneously reports rights information so that appropriate royalties can be paid to the copyright holder. Liquid Audio is probably the dominant commercial form of music distribution on the web right now.

Building Web Sites - ITP Winter 1999 - Mike Cosaboom, Instructor
mc39@acf2.nyu.edu