HTML and CSS Reference
http://addons.mozilla.org/en-US/firefox/browse/type:7. Most plug-ins are free and can
be easily downloaded and installed. As a Web developer, one of your goals should be
usability. Some visitors will simply leave your page if you require them to download
and install a new plug-in. Stick with audio and video files that use the most popular
plug-ins because your visitors probably already have them.
Sounds can be used to set a mood for a Web site. They can also be used to provide
additional information—an explanation of an image, a message from the company's
chief executive officer, the pronunciation of a word, and so on. The next section dis-
cusses types of audio files used on the Web.
The following file extensions are commonly used to designate audio files :
● .wav (Wave file). This format was originally created by Microsoft. It is a standard
on the PC platform but is also supported by the Mac platform.
● .aiff (Audio Interchange File Format). This is one of the most popular audio file
formats on the Mac platform. It is also supported on the PC platform (use the
● .mid (Musical Instrument Digital Interface—MIDI). These files contain instructions
to recreate a musical sound rather than a digital recording of the sound itself. The
advantage of this concise format is small file size, but the disadvantage is the lim-
ited number of types of sounds that can be reproduced.
● .au (Sun UNIX Sound File). This is an older type of sound file that generally has
poorer sound quality than the newer audio file formats. It only uses 8-bit samples
instead of the 16-bit samples used by some of the newer audio file types.
● .mp3 (MPEG-1 Audio Layer-3). This sound file uses an advanced compression algo-
rithm that results in the MP3 file being about one-twelfth the size of the original
audio file. As mentioned in Chapter 1, podcasts typically use the MP3 audio file
● .ogg (Ogg Vorbis). This sound file format uses a relatively new audio compression
format that is comparable to MP3. However, it is open source. This means it is
not patented and free to use. Visit http://www.vorbis.com for more information
about this technology.
● .m4a (MPEG 4 Audio). This audio-only MPEG-4 format is supported by Quicktime,
iTunes, and iPods.
The following file extensions are commonly used to designate video files :
● .mov (QuickTime). This format was originally created by Apple and used on
the Macintosh platform. The QuickTime for Windows plug-in supports this
file format on the Windows platform. Because it has universal support, this
format is widely used on the Web. While other video file formats must down-
load the entire video file before playback , QuickTime is smart enough to
begin to play before the entire file is downloaded, giving the effect of stream-
● .avi (Microsoft Audio Video Interleaved File for Windows). This was the original
standard video format for PC platforms and is still widely used.