Web Multimedia and Interactivity - Web Development and Design Foundations with XHTML - page 425

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.
11.2 Multimedia File Types
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
extension .aif).
● .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
format.
● .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-
ing video.
● .avi (Microsoft Audio Video Interleaved File for Windows). This was the original
standard video format for PC platforms and is still widely used.